Ceriatone Forum

Hi All,
Been a lurker here for a short while..this is my first post.

Starting my 1st build..an OTS.  Hoping you guys are willing to hold my hand and get me through so I don't have to bother Nik too much.  I've done a fair amount of research on building amps, but no doubt I'll have some pretty dumb questions!!! 

Its a challenge just to figure out where the bits and pieces go.  Not so much the caps & resistors, but the screws and bits of wire.  eg...what's the 5 inches of blue teflon wire for???? (Seems to be for the Mid control??)
One problem is the layout and pics don't match.  The way the 1st Volume contol is wired, for example, differs between the layout and pics, though the net effect on the circuit is the same.  Its confusing though...I imagine even for an experienced amp tech/builder.  But I digress...

My first step is to assemble all the parts so I know that I have them all, and where they go. I've put in front & back panel stuff, tube sockets, brass standoffs. So far, so good.  I'm ready to start soldering.

I figured I'd start by doing some of the front panel.  Its hard to get in there with the controls mounted in the chassis, so I figured I'd take the front panel off, mount the controls on it and make some of the connections to the buss bar, then put the controls back into the chassis and continue from there.  Any comments?
Thanks in advance...
Jon

Welcome aboard Jon

There is a really good video by Tony McKensie on the OTS HRM build which is relevant to all OTS builds or any amp build for that matter.

I just left pics of a 2550 build in the British section here . The steps are really the same. Start by mounting all hardware, tube sockets, jacks,etc.
Then just work from the outside in.
Either way things will get tight and difficult.But persist
Needlenose pliers with a 45 degree bend at teeth are priceless for this stuff!
I took all components and stick them with scotch tape to a large print layout ( go to kinkos if you dont have access to plotter )then mark the points you connect/solder as you go.
Always double check your connections before soldering.
I use Loctite blue on all screw/nut's
Hmmm
thats all I can think of for now but its my bed time

I built the OTS FM50 first and it is a difficult but very rewarding project so good luck
and keep us posted.

Todd

Thanks Todd,
I've done a fair bit of reading and seen Tony's video several times so I've already implemented all your suggestions.
What I'll need help with is various specifics.

I started wiring the back panel AC socket, fuse and then noticed its dressed a little different than the pics.
My version uses a shorter wire/path, but now I'm wondering if that's going to increase hum.
I understand the principals of keeping certain wires apart from eachother - but again, not sure of the specifics.
Will post pics a bit later.

I might make a documentary similar to Tony's, which I found immensely helpful, and I emailed telling him so.

It would have been hard to pick a more difficult "first" build. Dumble was/is a very esoteric individual. His amps morphed and varied a lot over the years.
2nd, 3rd and 4th generation layouts. Skyliner Preamp is a big deal for some guys. The list goes on and on. I have a few different schematics and layouts I could send you, but I am not sure if it would not just serve to confuse matters even more. If I were you, I would just build to Ceriatone's print, do the best/cleanest job you can, and get help from the guys on this forum that have made these (Ceriatone) amps their personal hobby.
Good Luck

Hello GuitarHack, welcom aboard,

I don't know if you have done this yet, but I downloaded all the photos from Ceriatone site and then had a laptop or computer screen nearby to follow the layout of the photos as close as possible and staying as close to the way things are routed as possible. Also had the printout of the layout on photo paper for durability. You're right, there are some differences between the photos and what was sent in the kit. Mainly I paid close attention on what wire I used for the higher voltage areas. I tried to follow colors closely, but I was able to not use as much wire as was sent of certain colors and kept using it until it was gone. I ended up with some extra wire for another project. I'm frugal that way. To a fault sometiemes. :-[

I used the solid core wire for some of the switch and contol areas and some of the preamp tube wiring. I realized afterward that what would've been nice was to understand the breakdown of the key sections of the design and use the same color per section. Partly this was due to lack of knowledge at the time and some assumptions that weren't exactly correct. But none of this will cause any problems.

One change I did was wire the heater wires which are the twisted wires going to the filaments of the tubes above the tubes instead of in the corner. This is not anything to get worried about if you already done them. And then when it does come to a question or problems a picture tells a 1000 words. Take the time to photograph and post here. You'll get help.

Everything the previous posters said is really good info too. Take your time and when you start to get cranky at 2:00 AM stop and take a break.  ;)

Oh, and try not to bend the leads too much. They can take some abuse but not much and can lead to problems down the road. In fact if you think you really boogered up something it's better to redo or replace the component.

Thanks Hand & SoundPerf,

Ya, I knew I'd be in for it building a OTS, but I can't resist that tone, especially at that price. And...not looking for sympathy here, but I had a heart attack a month ago which left me kinda depressed and I thought a challenge like this would snap me out of it.  And it has!  So I'm enjoying the process, but really looking forward to actually gigging with the amp.

My plan is, as you said Hand, to build to C's print, get it operational, burn it in, then perhaps make some mods to my particular taste. I got a big copy of the layout on the wall, and a couple of 11 x 17's to mark up.  Also some 8 x 10's of the pics for reference.  They're clearer than blowing up the pics on my computer screen.

I've made my first connections but realized afterwards I didn't follow the dress in the pics.  Maybe you guys can tell me if I already screwed up, or am I OK in this particular instance? (pic below)  BTW, I plan to do the heaters 'in the air' as D did, and as Nik apparently now does too.

Any comments on the idea of making a few buss bar connections outside the chassis, then mounting the assembly and wiring up the rest of the front panel?  It seems really awkward to make the first few buss bar connections with everything inside.

Also have a question about Star Grounding.  As I understand it, the concept is to have one and only one ground point.
There are several ground points here - the buss bar and several ground lugs.  Ultimately everything's grounded to the chassis, so I guess that constitutes the 'single ground point'.  But, I would have thought that the ground lugs and buss bar would all be connected together, but they would all be insulated from the chassis, except for one - which would make contact with the chassis and therefore constitute the single ground point.  After all, what other ground points would there be besides the chassis??  Can anybody clarify this for me?
thanks all...

As far as the mains wiring. IMO and I could be mistaked, but I believe most have chosen not to wire up the ground switch. Are you planning on using it as a ground lift?

Good job on the printed photos. Like I said, I'm frugal and didn't want to waste the ink.  :-[

Sounds like you have done a good bit of research already and have a grasp on some of the details that aren't always known by a new person. Which I pretty much am, except for the fact that I have succesfully built one amp. (HRM 50)

About grounding, my instinct based on my education would be more in line with your thinking. Which is, you run into grounding issues when there is a large difference in ground plane potential from one point to another. I think in this case the key "power supply" grounds are to one point. And the signal grounds are going to the chassis in a couple spots, but is not going to cause any issues. I would get some other ideas about this beside mine. I can tell you my amp is very quiet.

Doing the contol wiring on the outside is a good idea, actually a must as far as I'm concerned.

Keep up the good work.

Sorry, don't know how the quoting works.  This is the first forum I've ever joined and posted on.

DO NOT use the Ground Switch.
Do not use the layout on this forum. Grab the layout from The Ceriatone web-site. That ground switch is old, left-over technology. Keep in mind, HAD started out by moddding Fender Twins/Fender Amps and that was just part of the game back then. Do not wire the ground switch. AND.....a "Ground Lift" is NEVER the mains ground. It is signal ground lift between 2 daisy chained amps.
if you are "star grounding" you may want to consider TWO. One for the power supply/output, and one for the preamp.
Best

+1

Get rid of Ground switch

I did all my wiring inside chassis, alot of people choose to do it outside of chassis as well. Compared to a PCB kit there is adequate room between components, just try not to touch the other wires with iron and burn 'em ( I've done that a few times too many). There is a good vid on doing tone stack outside of chassis on the soundgarage files ( The guy who does the vid is pretty funny too )

As far as noise issues, I try to at all times maintain atleast 1/4'' separation between wiring. I learned this while being a Fire alarm technician, always have to keep the low voltage separate from the high votage. There are some places where this is not possible.
the most sensitive runs will be in coax anyways!

While you have the ground switch off is a good time to do the wiring for the bias test points in that little area ( 1 watt resistors, Bias pot, output tube wiring ). It gets pretty tight there.

Anyways other than getting rid of that death cap switch ( ground switch ) keep chuggin!

Keep the pics coming, they will be the best way for the experienced guys to help out!

Todd

Thanks guys. No worries - I'm not connecting the ground switch.  Its just there to fill the hole.

I think I did this right, but would like some confirmation, please.
My kit is the OverTone 50 Special

This concerns the wire marked 'T' that goes from MV pot to PowerAmp In jack.

- at the MV pot, the shield connects via the little piece of wire to the left lug which grounds it to the buss bar.
- at the PowerAmp In jack, the shield is unconnected and the conductor goes to the tip lug on the jack.

In general, all the shielded wire is done this way...shield grounded at the source end and no connection at destination end.
That right??
Thanks

Yes, you only ground one end of coax.

I didn't take it to a tech for the first power up. I bet the farm and all was well.  :o
There is a start up process you can do that will eliminate most possibilities of catastropic failure. A variac is the best method. Are you familiar with the light bulb wired in series to the mains?

Thanks Chris,
Yes, I read about the light bulb trick.
I don't know if I have as much guts as you, but power up is still a long way away.
I'm finding this very slow going. I'm probably lucky to average 1 solder joint per hour!!!
So far I've got the back panel about 65% done and just a few joints on the front panel to hold the buss bar in place.
I didn't want to do too much of the front panel outside 'cause the pots don't sit straight without the orientation holes
and I could see where it would get hard to put the assembly back into the chassis.
Waiting for an answer from Nik about the pedal jack/switches.  There's a OD switch connection shown in the layout (BK9) that's different in the pic.  What fun for a guy who doesn't know the diff between a diode and a triode!

Those square green thingy's on the pedal switches...are they caps?  Do they have a polarity? The layout says the values should be (looks like) 0.1 micro farads but on the unit it says 104K.  Why do the big caps have polarity, but the little ones don't?? At least there's no marks to indicate any. :-\
Did I mention what fun this is???  Oh well, I asked for it!!!
Thank the Lord for places like this and knowledgeable kind people who inhabit it!!!

Google EIA capacitor codes
Here is a good suggestion I learned from someone else and it really worked for me.

Print your layout on a poster size sheet, take your meter and meter every resistor one at a time and with scotch tape stick the appropriate components onto the layout until all parts on layout. Use the EIA coding system for your cap values.
After this is done you will not have to question whether you are using the correct component.

Also the tube amp book from Dave Hunter is very useful for some of the terminology.
And then Soundperf just dug this up.
http://ampgarage.com/forum/viewtopic.php?t=9023


Hope that helps.

Todd

Thanks Todd,
Good suggestion. I already have the poster size layout.

Hey Guys,
My OTS 50 is coming along.  I'd post pics, but having trouble getting them in focus.  Besides, my build doesn't look as good as the ones I've seen here!

I was wondering about the Dale resistors - what's the deal with those? I've never seen resistors like that before.
Thanks

Military spec resistors
Tripped me out too, I was looking for color codes and at first thought I was short parts!