Ceriatone Forum

Thanks to Gil Ayan and Scott Lerner!

http://www.sheetsofsound.net/images/OvertoneModded.pdf

Here's the BOM. Quantities are approximate. I suggest ordering a few extra of everything except the 350v electrolytic caps. These are the mouser catalog numbers.

(2) 140-XAL350V47-RC 350V 47uF 20%    
(2) 588-45F470E 5watts 470OHMS 1%    
(1) 72-RWM410-3K9-5 3.9k 3watts 5%
(3) 75-516D475M063-E3 4.7uF 63volts 20%
(3) 598-CD16FD331JO3F 330pF 500V +/-5%
(1) 598-CD15FD391JO3F 390pF 500V +/-5%
(1) 140-500S5-121K-RC 120pF 500V +/-10%
(2) 660-MF1/2LLT52R222J 2.2Kohms 5%    
(2) 71-RL20S-G-3.3K 1/2WATT 3.3KOHMS 2%    
(2) 660-CF1/2CT52R154J 150K ohm 5%    
(2) 71-CMF60150K00FHEK 1/2watt 150Kohms
(4) 71-RL20S-G-220K 1/2WATT 220KOHMS 2%
(2) 660-CF1/2C184J 1/2Watt 180Kohms 5%

Looks great Jaz...how do I reorient this thing or see the whole view? If I shrink it I still only get the area showing now. Operator error no doubt.

Yeah this will be fantastic - but I can only see a small section of the layout at the moment ???

Yes, just the power and PI section is visible.

Your tweek needs a tweek.

Jack, no joke, thanks for all the info you're passing on.

not sure what the problem is. I re-uploaded it and it seems to be ok now.

Yes it's fine now

Thanks

Great job Jack! Thanks.

Nice work!  ;D ;D ;D Just did the tweaks in a few minutes & although could only test at extremely low power- I can already hear the top end is much smoother & has lost that slightly abrasive edge - I suspect that is mainly the removal of the  high pass cap on the master vol?  I've left the other component legs connected so I could easily reconnect them should I want to reverse the mods - might be a useful tip guys?  Not sure what the resistor & the cap on the effex in/outs was doing anyway - anyone know?   ???

You sure you did them all? Not all of them were circled. It should take you 40-60 minutes to do them all.

Jack -

I'm re-posting a big thanks here. This is exactly what I and others here needed.

It seems to me that my concern for the caps holding any dangerous reserve current that could harm you is not warranted, that they seem to drain fairly quickly once the OTS shuts off. Has that been your observation or do you take other precautions when working inside your chassis?

I can't wait to get inside the chassis tomorrow!

Ken

I was nervous as hell the first time going in also.

Jack...again. Fantastic job on the tweaked layout!

Me too, I could only do a couple as some of the parts I orderd aren't right. I so happy the amp fired up that I'm not sure about the tweeks, I'd say I like them but I need some time to tell for sure.

I realise there's other component changes- I did the real easy one's first & checked the effect on my tone straight away- I can then easily reverse the mods should I not like them- I stopped because the simple mods did the trick as far as I'm concerned- I was already pretty happy with my stock OTS. I may delve further once I've had the chance to try at gig levels, as that's where it really counts!  Thanks again for the mod sheet! Great work!

What does snipping the cap on the master volume do for the tone?

I believe snipping the cap removes the 'treble bleed' function of the cap on the master volume- a common practice on valve/tube amps as it passes high frequencies through at lower volumes- rather like the 'loudness' control on a hi-fi.  I also own several old marshall amps- some of them sound good with it - some don't.  As soon as I removed one leg of the cap on my OTS I thought this removed the somewhat harsh overdrive tones at low volume- a very easy mod to do and a big bang for yer buck, going to try it at higher gig volume tomorrow to see the REAL difference ;D

keeps high treble frequencies from skipping the master volume. The idea of those types of bypass caps is to let the master volume effect frequencies below a certain point. The cap across them allows frequencies above a certain cutoff to jump through the cap, bypassing the master. In this case, the cap is so small, it's debatable whether it was doing much.

Mahalo(Thanks) Jack...great job!!!  You mentioned not all of the mods are highlighted?  Well...guess I have to find my reading glasses:-)

I don't think I said that. They are all in red. Not all of them are circled is what I meant.

Sorry my bad :-[  must be my not so good speed reading skills ;D

Here's a clip of mine with the mods.

Done with the changes for now. Big kudos to Gil Ayan and Scott Lerner for the circuit mods. They did the engineering, I did the soldering.

This clip features an Edwards '56 LP w/ P90s, clean, OD with Mid Boost and OD with PAB

http://www.sheetsofsound.net/demos/ceriatonemodded.mp3

http://www.sheetsofsound.net/demos/ceriatonemodded.wma

I updated the first post to include the mouser BOM for the tweaks. Can the moderator make this a sticky? How do I contact the moderator?

This is him...
http://ceriatoneforum.com/index.php?action=profile;u=1 (http://ceriatoneforum.com/index.php?action=profile;u=1)
 ;)

so, is Nik doing these mods?

what do you mean is nik doing these mods?

Here's another clip:

http://www.sheetsofsound.net/demos/ceriatonetweaked2.mp3

Hi Jake
Is Nik going to change the layout of the amp with these tweaks? I had the impression you made a remark about this in the TGP forum
you said "I believe Nik is now using a modified version of my (actually Ayan / Lerner) layout for his standard amp"

This weekend I did most of the mods, only the 270pF to 330pF snubber caps and the 2X 50uF voltage supply caps i didnt.

Clean has become world class. Overdrive needs a tweek, probably the snubbers will do the job. Let you know when done.
Excellent lay-out J. Zucker! Also thanks to Mondo, Ayan and Learner!

Good work jzucker on the layout.

One question. What about the 10k trimmer for the PI. #124 and the original Overtone had 5k. Should this be in RED also? And the 100k Level pot (from 250k)?

Yes, I'll have to double check mine. I guess it depends on which version you have. Mine already had the 100k level so I didn't see a change. Mine still has a 10k trimmer. I don't know about that one. I'll ask ayan.

Ok, so it looks like those were changes to the Overtone Niki already put into production. Maybe those could be annotated on the layout for those with the original, older versions that want to upgrade.

Not to complicate things, but it looks like Niki may have given you a layout file that did not incorporate his update to the way the switches in the back were wired. #124 used slide switches, but the Overtone uses toggles, and the pins on the toggle are "opposite" the throw of the lever.

mmmmm, thats why my footswitch only works when toggles are set to manual!. I thought I had just wired it wrong!!

By the way.. any tips on getting the same components from Jzucker´s BOM inside the EU? ;)

I'm still trying to find a good source here in the UK but it seems you can't get the same makes, and I don't know which are good and which aren't. You can get Spragues here http://www.hotroxuk.com/store/erol.html (http://www.hotroxuk.com/store/erol.html)

But his supply of resistors is very limited.

Maybe
www.conrad.com

hope this helps

I'm planning on doing my mod on my OT in a couple of days.  Just waiting on the parts to arrive.  I have been going through the list that Jack posted and comparing it to the tweaked layout.  I see only 1-150k resistor highlighted in red on the layout....the list calls for 2-metal film and 2-carbon film 150k resistors.  Which one do I use?  (Metal or carbon) Are the overage parts spares?  Sorry...noobie :-[ just wanting to be sure it's done right  ;D
Mahalo (Thanks)!!! ;D

Maybe check out

http://www.banzaieffects.com/

René

hey poipounder57

Yes, there are some parts in Jack's list that aren't needed. I believe the 150K resistor is one of those, perhaps the only one as I recall.  Where I could, I just replaced like with like. It's nothing to be too concerned over. If we get to the point where we start trying to hear the difference between a metal film resistor and a carbon based one, we're over the top IMHO.  :o That's when this guy starts heading for the door!


Ken

I'm in the same canoe - not much experience and trying to match up parts with the schematic. I created a spreadsheet comparing the BOM and schematic and sent it to Jack for comment. Hopefully he'll have the time to look it over and post a reply.

Mods finally done on mine. Massive improvement in the clean setting.  Blackface Fenderish.  Overdrive is also improved, but I'm getting much better sound from a bridge single coil than a variety of humbuckers.  My Seth Lover PAF doesn't sound very good at all.  It's in a Gibson scale length neck.  Suggestions?

Thanks again kenster!!!  I just rec'd my stuff from Mouser...hope to do the mods tomorrow. 

I had similar issues with a set of SD antiquity's in my Les Paul- they sounded a bit too 'dark'?  I solved this by replacing with humbucker sized P90's (single coils) which I much prefer- now I'm getting that David Gilmour neck pup tones and much more bite from the bridge.  Speaker type will also play a huge part- I love the G12-65 for lead tones- but it lacks a little sparkle for clean- so I'm having a cab built combining a G12-65 & either a Vintage 30 or Alnico Gold inside.  Try a brighter speaker- you can always cut the treble for Strats!

I'm attaching a pdf file comparing the BOM list parts, Mouser inventory and Schematic parts in red text (to the best of my eyesight). Can anyone help a newbie out and explain the discrepancies in the lists? I highlighted in yellow those parts where the component value appears different from the schematic (e.g. 4.7uF 63 volts Caps on the BOM versus 4.7uF 25 volts Caps on the schematic), or where the quantities on the BOM differ from the schematic (e.g., BOM lists four 220K Ohms resistors versus two identified on the schematic).

chipdog -

In a nutshell, a cap/resistor with a higher voltage rating is actually good. In the case of a cap being .47uf vs. .50uf, well, that's pretty close and getting the exact values aren't always possible. When you take the tolerances into consideration, +/- 5% in most cases, it's essentially the same callout.

Note that tighter tolerances are often preferred but you often pay a price premium for it. In most cases a really high tolerance, such as +/- 1%, isn't req'd. There are a couple of instances where that tight a tolerance is called for and I would stick with those for where they have been indicated to be used on the layout.

Hope that helps a bit.
Ken

Thanks Ken, that helps a lot. Regarding the schematic list, do you think I caught all of the "red-letter" items that should be modded?

chipdog

Nicely laid out list. ;D It looks correct as far as I can tell. To be smart, I think it wise to order a few more (2-3 maybe?) of each of the parts, particularly the large 470 ohm 5 watt resistor. They fit into a tight spot on the base of the power tubes and I boogered one up trying to get the bends correct. Better to have a few left over than come up short and have to re-order and pay an extra shipping fee.

Besides, more mods may come up and you might have a leg up on them with a few extra parts around. You just never know!

Cheers -
Ken

Thanks Mitch. Jack's P90 clip sure sounded good, so I'll try them in my LP double cut as you suggest.  I've got the 12 65s and EVs.  The Humbuckers just seem to lack the definition and do sound a bit dark/muddy in comparison to the single coils. I have single coil EMGs in one guitar that really gets close to Larry Carltons tone.  I have to believe that something will make the Humbuckers work, just not sure what. Scott Lerner's sound great in his SLX amps.  I wonder if there's another mod needed?

The Overtone has an inherently 'middle-frequency' bias- using humbuckers (especially un-potted one's like the SL's) makes this mid frequency hump even more pronounced; I suggest experimenting with changing the deep/bright switch caps in the amp - not sure what values you'd need to brighten the response - any of the other guys here could chip in with advice on that? 
??? ??? ???
I forgot to say that I also installed treble bleed caps in my Les Paul too- so if you dial back on the volume you don't  darken your tone- easy to do and plenty of advice on the web about that mod.  Maybe the deal with the Seth Lover pup's is that they were designed to mimic exactly the tones of original PAF's in Les Paul's - which were intended to be Jazz guitars!  You might also try Eric Johnson signature humbuckers- which look like standard pups still with all the noise cancelling etc... but sound much  like single coils- apparently Eric Johnson had the same 'too-dark' problem with humbuckers - so we're in good company then!  ;D

Thanks again Mitch.  I was actually wondering about the EJ dimarzios.  I also thought about the treble bleed cap, but the SLs are sufficiently far away from the sound I'm looking for that I think surgery is needed.  I have some P90s in my junk bin so I'll try them first in my faded Gibson LP DC.  My main guitar is a  Hamer custom Artist and that has the SLs.  If the P90s work in the LP I might try Seymour's Humbucker sized P90s.  Any suggestions on amp changes very welcome.

What value caps did you use Mitch. I'm about to do the same on my Ibanez 335.

Cheers

Hywel Harris

I have a question regarding the 330 pF caps on V-2...are these caps directional?  Does it matter which way they go on?  Thanks in advance:-)

The Volume bleed caps I use in my Les Paul have a .0022 mfd capacitor in parallel with a 100k resistor.  These values are recommended by Seymour Duncan and they work really well in my Les Paul- hope this helps-
Cheers, Mitch.

I think not since the originals weren't


Doesn't the 100k resistor prevent you turning the volume all the way off? I've seen it mentioned that you only need the resistor if the cap is switcheable on a push/pull pot so that you don't get a 'pop' when you switch it out of circuit.

I've bought 0.001 uF to do my 335. I'll let you know how it works.

Scotto, if you want clarity in a humbucker you have to go for low output vintage PAF type spec. If you go for higher output you will lose treble and gain mid, and this is the same for single coils. I have Fralin Vintage Hot and Blues Special s/c's and Fralin PAF h/b's They are all good but I like the vintage hots best, lovely clarity. You will also find a big difference in quality of tone between machine wound and handwound pups. Fralin does a really nice Unbucker with low output but unbalanced coils that tap really well, if I could find a set cheap I'd have them aswell.

Thanks Hywelg.  I believe the Seth Lovers that I have are vintage spec. I'll try the treble bleed in that guitar and a P90 in the other one. I'm traveling now so it will wait till next week.  I'll post results when I'm done.

Doesn't the 100k resistor prevent you turning the volume all the way off? I've seen it mentioned that you only need the resistor if the cap is switcheable on a push/pull pot so that you don't get a 'pop' when you switch it out of circuit.

I've bought 0.001 uF to do my 335. I'll let you know how it works.

The resistor in parallel actually ensures the volume control behaves normally- otherwise treble frequencies may get too 'out of balance' at the bottom end of the pot travel- so the opposite is true I guess, but please experiment- sometimes that extra clarity & treble boost might be what's needed... ;D

Cheers! Mitch

Thanks Jack for sharing the layout!!!  I completed the modifications and I'm loving it!!! :chairdance: :chairdance: :chairdance:

Aloha 8)

What was the answer to your question above?

Newbie question to Jack:

Will your mod make a big difference if the OTS is used at low volumes ? I will be using the amp with a Sadowsky Semi-Hollow - both are yet to arrive - but just to be prepared....

And if this is an improvement, will Nik of Ceriatone possibly do the tweaks ?...the amp is due on delivery within 8 weeks from now - so there is some time left.

P.S.: Guess who made me order the OTS  ;)

Thanks for the demos on YouTube. I wish you a nice day from Switzerland.

Mike

It sounds great at all volume levels. I have no problem getting a gorgeous jazz or gorgeous robben tone even at very low volumes. I also use a sadowsky semi and it gets a gorgeous jazz tone. I have some clips of that combo up on youtube at  http://www.youtube.com/sheetsofsound.

I believe Nik's now using the updated tweaked layout as his standard.

Thanks for the infos and of course the mod. Nik can do it exept for the two 470 Ohm resistors since they would prevent using EL34s as an alternative he says. I do not hope that this flexibility would counteract the benefits of the mod too much and I am also not aware if this will be the standard for the OTS then - but I am already very curious how this will all sound in the end. Gorgeous I suppose - as you do on your YouTube demos which I view already for some time....Again many thanks to you and also Nik - the reference in customer support.

FYI, I emailed Jack with the following questions (did I say I was a newbie?). His answers follow. Thanks Jack!

Sorry Jack, one last email before I heat up my soldering iron. Do each of the red letter mods on the schematic replace an existing component? For example, do the 350 Volt 47uF Caps replace the 100uF 450V Caps? Are there any mods that do not replace existing parts? Finally, there are two components circled on the Power Amp in Pre-amp out mod - did you snip them both?

From Jack:

the drawing should be self explanatory. The two 47uf caps are in parallel with the existing 100uf caps. The circled sections I snipped the caps/resistors. Make sure on the effect loop that the jumper wire between the two jacks is not snipped. Everything else will be replacing the existing part.

Hey, I completed the mods on my OTS this weekend and it sounds amazing. All the goods everyone has talked about are there. Thanks to Jack for bringing these to our attention.

The easiest and most profound changes to the tone of the OTS can be made to the tone stack. For instance: change the 150k slope resistor to 100k and change the 0.002mf treble cap to 1000pf or 500pf. This well drastically change the treble/mid/bass balance and you might like it. There are virtually infinite combinations that can be made to the tone stack that will alter the tone much more than adding 25mf capacitance to the filter network or upping the value of the preamp cathode bipass caps. Also, many people have stated that they hate the FET preamp. With a little tweaking mine sounds great. Just get the input voltage right (increase it by increasing the resistance to ground) and it sounds great. And after trying it; I really don't like the 470k screen resistor swap. Each to his /her own...

I didn't try all your possibilties; making such big differences random around the amp is nice for testing purposes.
Making the amp balanced for both clean/drive and PAB(with same tonesettings) is a long and painstaking art. I' m really glad that the mods presented, were balanced. For single coils it needs a little tweak around. But the amp right now is gigworthy for me.
Doing such big value swaps makes me wanna buy/build a second amp just for testing.

I compared the April 1 layout with the Jack Zucker modifications and the new layout per May 26, 2008.

The new layout follows all proposals of the Jack Zucker modifications (JZ mod) exept for:

1. JZ mod proposal: 2 X additional 50uF 350V parallel to the 2 X 100uF 450V
    April 1 layout: no additional caps
    May 26 layout: no additional caps (no change to old layout)
    Reason for non-adoption: not known per today

2. JZ mod proposal: 2 X 470 Ohm 5W instead of 2 X 1 KOhm 5W
    April 1 Layout: 2 X 1 KOhm 5W
    May 26 layout: no change
    Reason for non-adoption: EL34 compatibility
    ....and it was stated before that this would not really benefit sweeter
    cleans either

3. JZ mod proposal: 4.7uF 25V instead of 1uF 25V
    April 1 layout: 1uF 25V
    May 26 layout: 5uF 25V
    Reason for non-adoption: near adoption but not known per today why
    not exactly

4. JZ mod proposal: 4.7uF 25V instead of 2.2uF 25V
    April 1 layout: 2.2uF 25V
    May 26 layout: 5uF 25V
    Reason for non-adoption: near adoption but not known per today why
    not exactly

5. JZ mod proposal: 2 X 330pF instead of 2 X 220pF
    April 1 layout: 2 X 220pF
    May 26 layout: 2 X 390pF
    Reason for non-adoption: not known per today

Maybe someone (for example ampkits  ;)) could shed a light on points 1. and 5 ?

I've gigged my amp with and without the mods listed. Mod 1, added filter caps will not be noticeable at lowish volume levels, but at gig levels, say master on 7, this mod tightens the low notes, makes them a little cleaner whereas they can be a little blurry and wooly without the mod. Recommended. Incidentally, its important to get the 350v or some other small version, room is tight to fit them. I had some 500v sprague caps, which are really too big to fit, I had to shoe-horn them by sitting them on the bottom of the PT - not great.
Re mod 5, it works in tandem with mods 3 and 4 at fattening the OD channel. Its very fiddly to fit the new caps, and I bottled it and fitted 100pf caps in parallel with the existing 270pf ones, giving me 370pf value. Sounds good though with the other mods done and suits me much better.
Re mod 2 - most of the vintage amp guys recommend changing Fenders from 470 ohms to 1K, so I'm not sure why there is a recommendation to change the other way. I cant see there being a noticeable sound difference and safety is increased at 1K, this is the only mod I havent done.
Al

Hey, Jzucker's mod to change the bright cap from 390p to 120p seem to have become state-of-art on this forum, but perhaps the "old" value of 390p would be better suited to humbuckers???

I wound up with the Dimarzio EJ pickup.  It's brighter and more focused than the Seth Lover.  My objective is a setup that will work with both single coil and humbucker guitars. My single coil sounds are so good, I preferr not to mess with the amp anymore.  The EJ works pretty well.  Not perfect, but I'm still tweeking settings.  I think it will be fine once I'm done tweeking.

I've put 47p (mesures 44p) on my mastervolume . It really opens up the amp and my clean slund is at an all time high. Try it !

Is this on basis of the May 26 layout ? and when you say "on the mastervolume" where exactly between which two points ? ..and for which guitar / pickup is this worth a try ? All the best from Switzerland, Mike

Hi guys. I have an Overtone from the first batch of the year. Which means I have to change the pot. I´ll do the other mods too.

I´ve ordered all the parts from Jerry´s BOM and have them already.

Now I´m only missing the 100k alpha pot..

can anyone tell me if this is the right one:

http://www.banzaieffects.com/Alpha-16mm-split-shaft-100k-log-pr-17269.html

Thanks ;)

If you want to make things a bit easier you can simply tack a 220K resistor to the outside tabs of the pot. That will also make it easier to switch back to hear the difference or simply change the range to a "virtual" 150K or 90K pot by using a different resistor in parallel.

I got my "tweek" parts in yesterday from Nik. I went with him to make sure I was getting the correct parts. $20.00 shipped.

I put them in last night and the amp fired up (whew  :P ). First impression, the clean channel is even better. The od is different, I don't know if I'd say it was better at this point. I think I might need to readjust the internal trimmer?

Hi Mike,

You solder the 47p to the input tap and center tap of the mastervolume...those are the two legs that are NOT connected to ground.

Bluefendermanblues,

Thanks for the tip.  I soldered test clips to my master volume pot and tried a bunch of different cap values that were suggested by Dogears on the Amp Garage forum and wound up selecting the 47pf just as you said.  It really opens up the tone and makes my humbuckers sound much better.  I also noticed that it seems to smooth the overdrive sound as well.  Not sure how that works, but it sounds smoother to me.  Clean channel it also more open sounding (a bit brighter with better definition).  I highly recommend this mod to all Overtone users.  As previously mentioned, just solder the cap across the 2 legs that aren't going to  ground.  Lower values will give less brightness.  Dialing in your own preferred sound in is easy if you do the test clip thing and try a range of values. I tried from 33pf to 47 pf as per S. Lerner's advice.  If you are less ambitious, just go with the 47 and see if that works for you.

I've found these last few posts especially helpful ,thanks guys.

I have been experiencing a lack of brightness right from the start and it was made worse by the JZ mods. Reading this made it clear that the MV cap had something to do with it so I went and got some caps (33,47 and 68pf).

Now I haven't got any croc clips so I tack soldered two wires to the MV contacts and ran these in to a chocolate block and then fixed each of the caps in turn after having run it with no cap. 33 made a big difference, 47 was better and I can understand why went with that scotto but I tried the 68pf aswell and with the Bright (on) Pres (10)and Treble (8)in their original positions it was too bright but dialing them back took the edge away so I fixed that in permanently.

Its a lot better now but still a little dull with humbuckers but I reckon I'm going to have to live with that since its not as simple as changing a setting when changing guitars, I have coil tapped my Fralin PAF's and use the tap switch quite a lot.

Thanks again chaps.

Yes I'm struggling with JZ mods as well. IMO my amp is not to bright, so doing those mods does not make any sense to me. I play clean ch and I use OD ch as a boost (slight OD sound). I actually like the bright boost I get when I engage the OD switch, what I'm missing is a little low end. So what I want is to keep the hi end and add the low end.
I'm still thinking what would be the best approach to achieve that. I'm not sure but I think changing cathode bypass caps would help.

Mods I did so far is OD level pot to 100kL, pre OD resistor to 220K and bright cap to 120pF. I think I'm going to try to change V2b baypass cap from 1uF to 4.7uF and see what happens.

Any other ideas?
 ???

mckincu, I'm happy with the brightness now with the 68pf across the MV, but I'd be interested in what you think of the change to the bypass cap on V2. I'm going to experiment with a 5751 in v2 to try and cut back on the gain a little on OD, maybe even an ecc81 or 82 ( I will have to go and read up on their relative gain factors, can't remember what they are).

I would like to tweak further to get more high mids to give a little more sparkle without the piercing highs but I wouldn't know where to start with achieving that.

What tubes are you using currently? For example Ei tube  will give you far more sparkle compared to TungSol or JJ.
If you want less gain 100KL on the OD level is the way to go, just in case you're still using 250KA.

BTW what is the value of your bright cap?

I don't have any EI tubes but I'll see if I can get a couple to try. I changed the Level pot when I did the JZ mods, and changed the bright cap back to 120pf. Might change that back up to 150-180 tho'.

Regarding the mid tone section I read on the TAG forum, that if you want more low mids for example, then adjusting the mid cap is the easiest way...smaller value gives more low mids.
If you want more high-mids then increasing the treble cap would be the way to go and if you want 'more of everything below the high-mids' then decreasing the slope resistor would help.
The slope resistor mod will increase the bass along with the mids/low mids where the Mid cap mod will tend to just focus on the low-mids.
Something like that...

or
You could also try to play with mid control network... currently you have 250K/.001 and you could go with 100k/.05 which would give you even more "mid range sound". You could of course try different caps like .047,.022 and by putting a resistor in parallel with a 250k pot, you can make the pot whatever value you feel like.
...but hey, I'm not an expert, I'm just a guy who read everything on Dumble amps I could find on the web.  ;D ;D

My man, try to download the tsc software from this link: http://www.duncanamps.com/tsc/download.html

Its a tone circuit simulator, which enables you to try different values in at Fender (dumble), Marshall, Vox etc tone circuit. Try it and you will get a different impression of the slope reistors impact on the circuit.

Looking forward to hearing your thoughts on this

That seems really useful, thanks. I'll have a play and see what will increase the high mids. I  also try to find the tone stack schematic for my 5w SE amp and see if I can replicate it cos I really like the high mids on that.

Edit..

Do you have a saved file that approximates to the OTS? Looking at the Dumble schematics I'm not sure I understand which the OTS is copied from and what the effect of a cap across the Bass pot will be. And how do you cope with the R5(load) resistor being connected differently?.

Still, very useful to be able to play around with the values and see what the effect is to the response curve.

Surprised anyone would think the mods are dark. I typically keep my presence and treble at 10 O'Clock. Plenty of room to brighten things up. The 47pf mod only works in conjunction with a tube dumbleator and 8' cables. The idea is that the parasitic capacitance introduced in the cables reduces the brash high freq content and then the 47pf is passing through frequencies, some of which have been removed by the effect loop cables. If you use no loop and no dumbleator you are not even close to the robben and carlton mods. Not to say that it won't sound good but just keep those parameters in mind when you are modding. Frankly, adding brightness at the MV side is the wrong way to go IMO since turning the master up negates the effect of the bright cap.

Hey Jzucker,

whick guitar are you using??

 and which speakers ??

Important to know when you are talking about a bright sounding amp , without mods.

I'm beginning to think there are different OTS amps out there!. Marins clips, especially the clean strat ones seem nice and chimey to me and I think he said he recorded at quite low volume levels. Without the MV cap I was having to run the presence at full and treble at 7-8 and still it lacked sparkle. It was better when cranked up, and I mean loud, MV 4 or above.  Frankly I would like to dispense with the mv cap and have the tone stack do the right thing but I really don't know enough to start meddling, and anyway why is mine so different? I know I built it myself, but there really isn't that much that I could have done incorrectly and I have treble checked the wiring and my amp tech did the same prior to power up.

Celestion 1265 which are dark, greenbacks which are a little brighter and Wizards which are brighter still.

Ok, but surely you're a strat player -

uh, no. I have a couple les pauls, a sadowsky semi, a 339 and yes, a strat.

Hi,

I'm wondering how far the actual layout is from the modded layout ?

I receive my overtone today and I want to tweak a little bit the Overdrive channel which is a bit aggressive to my ears and taste.

There a little "peak" in upper frequencies or something that I can't describe with word that make the OD sound a little too bright / aggressive.

Nobody  :-[ :-[ ?

Turn down the overdrive trim pot to around 09:00 o'clock - looking towards the powersupply from the input side. That'll do it

That don't change my problem, even after turn down the OD trim it's still too trebbly / agressive for my taste. (I'm using old 12-65 in an old marshall 4x12 cabinet, not a trebbly speaker !)

I think I need some "tweaks" but I don't know which ones ! I mainly play strats, and I want to get close to that sort of liquid / sweet tone that John Mayer can obtains but I'm pretty far away !

http://www.youtube.com/watch?v=KXZHhUDohH8

I know that a 1k$ amp can't do what does a 3k$ amp but I'm sure that with few tweaks I can get closer to that sound.

This is part of a post reply, regarding har to get a great Fenderlike clean sound and great dumblelike OD from the same knob/switch settings.......

I've experimented a lot with my Overtone to resolve this puzzle and have arrived at the following modifications to give me both good (sort of fender) clean sounds and at the same time nice rounded OD tones:

- a 47pf on the (input) volume
- change the bright cap to 47 pf
- a 39pf on the master volume
- increase the snubbers to 2 x 470pf (trims off OD harchness)
- add a 2nf+470k trimmer across the OD ratio (od master vol), which lets you reduce the OD treble (ditto)
- maybe add a 4,7M resistor and a 47nF capacitor to the input of the OD, just before the 220k (trims off a little bottom fuzziness)
And use the following settings with a strat or tele:
Volume 7, bright off, mid off, rock on, treble 5, mid 5, bass 5, gain level 7, ratio 5, master any, prec 6,

And the following with a Les Paul
Volume 4, bright on, mid off, rock on, treble 6, mid 5, bass 4, gain level 5, ratio 5, master any, prec 7,

As I've said, you'll get both excellent cleans and very nice OD
- off course you have to adjust some of the od treble off on the cap/trim mounting on OD ratio control
- If the bottom end of the sounds gets too fuzzy in OD mode, you might add the Gill Ayan mod to the OD channel, which is adding a 4,7M resistor and a 47nF capacitor to the input of the OD, just before the 220k.

I use either a single 1x12" Celestion 12G65 or a 2x12" Celestion both with oval hole in the back.

Just remember that John Mayer uses, Overdrive pedals as well as using a TwoRock;
- Boss Blues Drive
- Tube screamer
- etc.

Good luck

By the way, great clip with John Mayer

Sorry if it sounds funy but I can do this with $300 transistor amp!

http://www.youtube.com/v/oXy-Iv44Mvw&hl=en&fs=1

Sound is before everything in the fingers we all know that ;)

I like the blue reflections from the stage lightning on your guitar........... ;)
just kidding, you're a great articulate player 

Thanks my friend,
It was just ordinary pub gig ;)

Listening to that JM video that was posted, it reminded me a little of a clip from one of my amps:

http://soundclick.com/share?songid=6706810

This is a Fender converted over to a Dumble circuit, similar to the overtone. Differences that contribute to the tone are as follows:

100k plate on V1 with 1.5k on cathode
220k&150k and 3.3&2.2k on V2
V1 bypass caps are 500uf and 25uf (not a typo, five-hundred)
Big output transformer iron (six 6L6, 180w)
Real 'Deep' switch. (on recording I'm using Deep on the clean and OD& PAB for the drive. Amp also has a "MID BOOST" but I'm not using it on the recording)
270pf snubbers.
Except for the PI and output sections the rest of it would be similar to the "Tweaked Layout" values.

Anyway here is the schematic of the amp in my recording, in case you want to copy anything into your Overtone.


BTW this is NOT my amp from the "Special Overtone Project" thread. This amp I am discussing sounds better with a Strat than my other.

Very nice! Lovely tone and great playing.

Hi everybody! I'm new here and like to say hello and thanks so far for helping and posting so much mods.
Just got an Overtone and an 18W TMB from Nik.
 I did not come to the 18W yet  :-[.
The Overtone is ok, but as posted here, with my LP I have some aggressive highs and buzzing basses.
Can you please explain how to set this trimmer? The other mods ar clear and will be done right after this.
Thanks!

Schematic re-posted as a JPEG.

Hi Ic-racer

I like your song and sound
http://www.soundclick.com/player/single_player.cfm?songid=6664325&q=hi&newref=1

Did you do this with the amp as per super twin-dumble-mod-layout ? Any other effects ?  ???

Mike

I haven't posted much as my amp was being worked on, I thought it was broken but ended up being a bad tube in the power section. While it was there he said he could mod it a bit and I want to document those changes and put them up on the site to see what people have to say about them. I need a PDF of the layout as of say last February so I can edit it with the changes. Does anyone happen to have anything like that, or know where I can get one.  I am not so good with schematics or I would draw it out, so the layout is the only way I can do it.
Thanks to all, glad to be back
Burnie

Email Nik, explain what you want to do and I'm sure he'll let you have the source file dating from Feb, if you promise not to distribute it, only images exported from it.

I have the layout with J Zuckers mods in PDF file and that particular file lets me edit so I will use it. I am such a noob at this stuff it will take some time but I sure would like some feedback when I get it done. Thanks Hywelg.
Burnie

I was searching for some stuff on Pritchard amplifiers for a mate who is into SS amps, and I came across this.

Pritchards are a solid state amp that has had a good reputation over the years, though it hasn't really been able to overcome the general valve amp reputation.

One part of their site has post by people who have ditched their valve amps for solid state Pritchards,

Owner of a Jade Dagger 1-12TB
 Jack Zucker, retired:
 Carr Rambler
 Naylor Electroverb 38

What I want to know, is this the same Jack Zucker?

 :o ;D ;D ;D ;)

Yours Sincerely

Mark Abbott

Well this Jack Z. definitely owns a tube amp, so maybe he changed his mind or there is more than one Jake. Z.

 ???

 ;)

Yes, that's me. I did sell a couple amps when I got the pritchard and it was fantastic but had a lot of quirks and Eric Pritchard was a good guy but wasn't quite sure how to dial it in . I'm convinced that he could do it if he had more good players involved in the tweaking process.

So what were the quirks?

From my experience you can get good tone from a SS amp or even a good pedal for that matter, but for me, I think the touch sensitive thing just isn't there with SS amps.

It is a funny thing to describe. I should point out that I am not a die-hard valve guy and I do own a Guitarport as it is very convenient, but it doesn't sound like an amp no matter how loud I turn up the monitors,

I have found with a good valve amp, it sounds good at nearly any setting.

Anyway tell me more about the Pritchard amp?

How does the Overtone compare to it?

Yours Sincerely

Mark Abbott

That's a generalization like saying you can't get a pristine clean out of a tube amp. The peavey bandit and the pritchard are both extremely touch sensitive. More so than many modern tube amps.

The problem with the pritchard is that he didn't have the treble and presence frequencies dialed in properly. It's like getting the correct bypass caps and coupling caps in a tube amp but much harder (for me at least) to experiment with... He used a couple players' opinions for dialing it in and i'm not sure he was using the "right" people.

The overtone is a completely different type of amp. My pritchard compared very favorably with my Allen Old Flame with a better master volume. It had more of a fender vibe to it but there's no reason why it couldn't be crafted with a dumble tone in mind. It just wasn't and Pritchard didn't seem to be interested in pursuing anything other than what they already had.

Thanks for the reply Jack. In regards to the tone sensitive thing I am referring to distorted tones, I have found I always have had greater control over an amp with my guitars volume control with a valve amp than a transistor amp.

Fender transistor amps and a Sansamp come to mind here. Of course this is a generalisation and there are bound to be amps that break this generatisation, but this is what I have experienced.

I wish you hadn't mentioned the Peavey Bandit, I use to play with a guy who used a Peavey Bandit, I hated the sound he got out of that amp!

When I think of lush transistor amps I think of the Roland JC-120, though the distortion and reverb (from memory) left something to be desired.

That is a shame about Pritchard, if you are going to make a solid state Fender, well you are wasting your time, why not simply buy the valve Fender?
He really needs to go beyond what he has already done. I was very curious about his PRS amp, but.....

Yours Sincerely

Mark Abbott

HI Jack,
besides a Overtone Special I also have a ALLEN OLD FLAME from the first
made.
How to improve the Master Volume?
The sound is only full with the Master at 10;

What does the master volume circuit look like?

Yours Sincerely

Mark Abbott

Hi Mark,
it`s a Dual 1M pot between PI and the 1,5k grid resistors with 0,1uF caps in front and behind.

Dear Wolfgang

That should sound pretty good as you are also able to get PI distortion. The only down side of that style of master volume is, speaker dampening and presence control operation are effected.

The one meg master volume pots prior to PI effect clean tones and the bass rolls off on low master volume settings.

How are you finding it's operation?

Yours Sincerely

Mark Abbott

I recently bought an OTS and I've noticed that there's two piggy backed 40 microfarad caps at 500 volt close to the mains transformer is this okay??

Pictures?

Sounds like this is one of the first series that had the Jack Zucker mods applied to it.. Search this thread and you'll probably see some photos similar to yours.

Edit.... Been and had a look, no photos in this thread. Seen some somewhere, just can't remember where. Anyone?

The HRMs can be really bright in OD mode, making it very har to dial in a usefull tone.
If you dial the treble trimmer down, the tone it totally killed.

My solution is adding a treble bleeder after the HRM tone stack. Its really simple.
I have used a small circuit, consisting of a 1n capacitor in series with a 150k resistor, added trom the input of the OD master to ground. Easy to mount between pot and bus bar.

Wih the treble beleeder added, you can turn up the treble trimmer on the HRM and it will sound nice and full.
 
 
 
 

Hi Fenderman,

Not a good idea! This would reduce highs but also would mess up high mids.
Here is a better solution. Get 12 way rotary switch, solder capacitors on each filament starting from 100pf … 200pf …. Up till 1200pf and install it same way as a RC treble bleed. This will only affect high frequencies and you’ll be amazed how smooth the tone will become.
That’s why I prefer non HRMs with bluesmaster clean and normal skyliner OD with such great filter. Trust me nothing comes closer.
That’s my little tone secret for you.
Cheers

The suggested treble bleed mod, was been published on the ampgarage.com by forumites Ayan and Dogears (Scott Lerner). These guys know the ropes and I wouldn't publish this mod if it didn't work. I use it in my amp and it gives my amp great bloom on the notes.  8)

Sure they know the ropes! but they don't know about my mod ;D
which makes amp more bloomy and pronounced.
Hear the bloom here and it is not a feedback, recorded without speaker, streight to the PC

Neck pickup http://www.drika.biz/bloom.mp3

Bridge pickup http://www.drika.biz/bloom2.mp3

Hi Pickmaster,

Sounds great - what does your mod consist of? is it the one you've posted a your ago with increased snubber value(s)??

No, It is one of my little secrets which I kept to myself ;D.
But for nice people on this forum I’ll publish it soon, just going out for couple of days.
Best wishes

Oi Captain Oates, come back! ;D

Okay, did you return yet?  ;)
Would love to know more about your bloom secret, before I actually get started on the building!

Sh..t! you’ve just reminded it to me mate! Indeed I’m back. :)

So:
Get the oil of Afro-dytee lady, :-*
An' the dust of the Grand Wazoo  ::)
You might not believe this, little circuit, but it'll cure your harsh tone too! 8)

I hope circuit is self explanatory and easy.
(http://www.drika.biz/hicut.JPG)

But don’t forget – my amps are NON HRM !!! It will still work but do you need it when you already have HRM trimmers?
For more “bloom” try to replace your 150k slope resistor with 68k.
Good luck.  :P  ;D

Thats also what I need for the clean channel for my Stray Cat as well.
Thanks for the share Pickmaster :)

Hmmm, this seems to be a mod to the Non-HRM OTS... Would this work with the HRM version as well, or is it essentially not needed with that circuit?

No HRM has the internal OD tone stack so you shouldn't need it. There is a case for having those TMB controls on the outside but, just play your amp out of its case and tweak till you're happy then put it back.

Thanks a million Doc. New year project......

Nice one! A treble bleed with various caps to choose from. A bit like the Steel string singer has now on the od channel?

Thanks for posting, I really liked this idea, even for my new BM50, so it is now implemented.  I tend to switch guitars a lot, humbucks->strats->P90s.  I've found that this amp really changes depending on the guitar and mine are all over the map and dialing in nice settings on one guitar does not always translate well to another.  It is nice to have a switch that can quickly "dial down" the extra OD treble that I experience with my strat and some other single coils.  My little knob fit nicely in the spot next to the logo with plenty of room on the backside for the capfest.  I don't know if this was the ideal way to wire it, but it works like a charm.

Bryan

(http://www.suthard.com/ceriatone/highcut1.JPG)
(http://www.suthard.com/ceriatone/highcut2.JPG)

Wow, that looks fantastic!
Well done my man, I’m glad you like it.
Best wishes

I saved a link to this thread because I thought it was such a brilliant idea.  Well my FM50 ME is here, it's a great amp, is currently up and running on the bench, and I've tamed the bulk of the ice-pick highs via the RG-400 cables with the C-lator.  I'm currently running the amp through the speaker an old Crate amp as a test/break-in thing, but an EVM-12L is in the future.  That being said, the amp is not blooming that much yet. I have at least 40-50 hours on it so far, but that aspect of the amp hasn't come to life as of yet.

So I think the 12-way switch mod is going to get done. I'll replace the unused ground switch on the back with the rotary switch and make use of a dead spot on the back.  If "bloom" doesn't come alive with that, then Plan B is to modify the slope resistor.  That's where I'm a little undecided.  I would think that throwing another resistor on top of the stock 150K slope resistor would drop that resistance by an appropriate amount.  The best thing, you could temporarily clip on different resistors to dial in the right resistance (essentially, "voice" that aspect of the amp).  Once the "optimum" (I know, subjective) value is found, then solder it in parallel and go.... 

Well, these two ideas got me thinking a bit.  Would a little variation in the slope resistor (either up or down in resistance) be adviseable?  I know bloom isn't feedback per se, but most amps that I've played that had good bloom could also feedback a bit if the guitar was too close, amp was too loud, etc...  Might it be a good idea to put a trimmer or small toggle to give me some limited options?  If tweaking the amp to add bloom does make it somewhat more prone to feedback, then having the option to "switch" off the additional resistor would return it to stock and theoretically return it to a less feedback prone configuration.  Am I off track about this?

Thanks for any input... 

Let’s forget for a moment about RG-400 cable and C-lator. Let’s make amp sound great without the additional gizmos. Afterwards it will sound fantastic with them as well.
1. Change 100k slope resistor to 68k 2watt. – bit more lower mids, compression and touch sensitivity.
2. add second 250pf capacitor to B2 tube, do not remove B1 250pf !!!
3. Put 3 way switch on master volume with OFF, 33, and 64pf caps.
4. Change RATIO’s (X) feeding 150k resistor to 10k and following 0,005mf cap to 0,01. You will thank me later.
5. Change MID-BOOST’s 390pf cap to 470, sweeter tone.
6. 12 way rotary is a very useful addition.

Good luck

Would these mods be us full with my OTS 50?
Also I was wondering if it would be possible to convert my 50 watt to a 100 watt.
I have the extra tube slots, I'm guessing a transformer swap would be the next step.

Yes, it will work for the OTS 50.
You have to definitely change an output transformer for a bigger one. I would change a power transformer as well, To much work though. :(

guys, can someone try to describe to me what these mods do for the clean channel?

Yes that's an interesting question!

I'll paypal anyone who can get me a soundclip of a strat on the clean channel of a regular ots with the jzucker mods TEN DOLLARS!!!  Seriously,  I know thats not a lot but I would really like to get some sonic feedback before diving into this.