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| | |-+  Overtone Tweaking		 « previous next »
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Author Topic: Overtone Tweaking  (Read 26475 times)
BGSoul
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« on: February 06, 2008, 08:23:07 PM »
I assembled my Overtone kit recently. Great stuff. Everything was in the package ok. As a tip for you strat players this is what I did:
- Removed the 15pf cap on the master volume.
- Changed middle pot to 100k (add 180k cross the pot) and change middle cap 0.01u to 0.05u.
- Increase 270pf snubber caps on OD to 330pf.
- Remove 270pf/220k filter at the loop. This is bypassed with anything (or a patchcable) in the loop. But connected it really ruins the tone.

Now I have an awsome amp Grin Smooth dist and a great tone.
Good luck!
Håkan, sweden
« Last Edit: February 06, 2008, 08:32:47 PM by BGSoul » Logged
mcinku
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« Reply #1 on: February 06, 2008, 10:02:00 PM »
Thank you very much for these mods...
I prefer brighter sounding guitars (start, tele, even HB) and mods like these can be useful.

Can you elaborate a bit more what each mod actually does?
 Huh?
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ChrisL
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« Reply #2 on: February 07, 2008, 01:10:28 AM »
I'm on a similar track.

Master bright cap removed.
330pf snubbers on V2a and b.
120pf bright cap.
150 K pre OD resistor changed to 220k.
270pf/220K loop network removed.
Can't decide if I want to switch out the skyliner mid values or not.

I may try upping the OD plates to 180/220 and adjust the OD cathode bypass caps and resistors to typical values...seeing what the voltages are and adjusting the dropping string.

Also, I'm going to play with the presence cap value...maybe try a .47uf or something in between.

BGSoul...What is your opinion on adding a snubber between the PI plates on this amp?  There are a quite a few spots to smooth things out I 've just never tried it there.  Simple enough to try I guess.
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mcinku
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« Reply #3 on: February 07, 2008, 07:12:24 AM »
More options.... even better

Thanks guys
 Wink
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BGSoul
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« Reply #4 on: February 07, 2008, 12:04:21 PM »
Quote from: ChrisL on February 07, 2008, 01:10:28 AM
I'm on a similar track.

Master bright cap removed.
330pf snubbers on V2a and b.
120pf bright cap.
150 K pre OD resistor changed to 220k.
270pf/220K loop network removed.
Can't decide if I want to switch out the skyliner mid values or not.

I may try upping the OD plates to 180/220 and adjust the OD cathode bypass caps and resistors to typical values...seeing what the voltages are and adjusting the dropping string.

Also, I'm going to play with the presence cap value...maybe try a .47uf or something in between.

BGSoul...What is your opinion on adding a snubber between the PI plates on this amp?  There are a quite a few spots to smooth things out I 've just never tried it there.  Simple enough to try I guess.

I have to run som more tests on my amp. I'll try changing the bright cap, as it is now its unusable. But as my amp sounds now I'm rather satisfied (for a while I think Grin)
About snubbers on PI, I dont know - just to try!
As I us my other amp (CAA OD100) I always use it on the "gain channel" but lower my guitar vol to get a little crunchy sound for chords. When I try the same on the Overtones overdrive channel (not PAB engaged) the sound is to muddy Sad. And the clean channel is much too clean.... How do you use it - chords / solo?
« Last Edit: February 07, 2008, 12:21:26 PM by BGSoul » Logged
ChrisL
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« Reply #5 on: February 08, 2008, 12:37:39 AM »
Yes, a 270pf bright cap is a bit much but a 120pf or lower makes it more useable.  I think you have to tweak these amps for a 3/4 open guitar volume pot IF...lol... you are going to play any chords.  Otherwise you are right...it muddies up.  I don't think I've played a chord other than double stops in weeks. Grin

I've reserved myself to the thinking that while the cleans are stellar on this amp it is virtually impossible to switch between the OD and clean channel effectively with the shared tone stack.  For that reason I use the Overtone for OD and some other amp for cleans and an A/B box.  If I need a smaller rig I just use my modded Traynor YCV40wr which has great cleans and an equally nice OD channel with separate tone stacks.
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« Reply #6 on: March 05, 2008, 07:59:10 AM »
This is really going to show how little I know. I want to do some of the mods you are talking about but don't know where they all are. I figured out the bright cap and I think I understand where v2 a and b are but I don't know where the pre od resister is. How do I learn this stuff, I am already trying to learn so much now, my old man brain is on overload lol. I haven't got my amp yet, but I want smooth, no fizz dumble like tone and will do what ever it takes beside buying one unless I win the lottery then I will buy all of us one.

Why can't you build another tone stack?..dumb question?

By the way thanks for answering the questions I have already asked, I was home with a cold today and had way too much time on my hands.
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« Reply #7 on: March 05, 2008, 10:51:59 AM »
Quote from: wbfree on March 05, 2008, 07:59:10 AM
... but I don't know where the pre od resister is.

The resistor is North of OD 100K trimmer.

If you take a look at the OD tube V2 (layout) and go from pin 2 (grid), first you will find a 68K resistor, than 100K trimmer and than 150K ("pre OD resistor").
All those resistors/trimmer are known as a pre OD netwoork and Chris is talking about that 150K resistor.

Does that help?
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« Reply #8 on: March 05, 2008, 06:05:20 PM »
Quote from: mcinku on March 05, 2008, 10:51:59 AM
Quote from: wbfree on March 05, 2008, 07:59:10 AM
... but I don't know where the pre od resister is.

The resistor is North of OD 100K trimmer.

If you take a look at the OD tube V2 (layout) and go from pin 2 (grid), first you will find a 68K resistor, than 100K trimmer and than 150K ("pre OD resistor").
All those resistors/trimmer are known as a pre OD netwoork and Chris is talking about that 150K resistor.

Does that help?

Yes sir, thank you. When I get my amp I will want to know how to do some of this stuff, I am not a complete bozo, I just don't know what will do what and will need some input but until then I will be interested greatly in what you all do, many thanks mcinku Smiley
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« Reply #9 on: March 05, 2008, 09:10:59 PM »
When I get mine (within a day or two  Wink ), I'm sure not going to start messing with it right away. This is my first D style amp, so I have to learn how it responds to my playing and what it can do actually... and only then (maybe) I'll have a clue what I want to change... only then I'll start thinking about the tweaks.
...meaning, I'll give it a month and then we'll see

 Grin
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ChrisL
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« Reply #10 on: March 06, 2008, 12:30:09 AM »
wbfree,

Yes, there is a lot to wrap your head around with these circuits.  I'm lucky in that I was (am) a bit of an 18watt nut and I learned much from studying that circuit to death which is far more easy to understand. 

Since you have a cold (get well soon) and some time print out the great schematic that our brother forum member icracer has so graciously made available.  Compare and trace the schematic with Nik's layout so you get a feel for the circuit and the terminology.  Welcome to the madness.....bwaaaahhhaaha... If you really want to jump in the deep end spend some time over at the ampgarage in the Dumble discussions.  Those guys are all loony bin candidates...lol.
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« Reply #11 on: March 06, 2008, 12:56:30 AM »
Thanks Chris
I will study, I have a friend who is a tech but I can't afford to just send my amp out for every little thing, added to that is that I am a tweaker by nature, Look forward to having some fun.
Thx
Burnie
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« Reply #12 on: March 06, 2008, 03:59:15 AM »
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Re: 6v6's in the Overtone?
« Reply #1 on: February 11, 2008, 06:01:00 PM »    Reply with quote
No, I haven't tried them in this amp.  But, I did go back and forth between the original 6V6's and 6L6's in my Brownnote D'Lite.  In that case, I was going from a 6V6 optomized circuit to 6L6.

Just a heads-up (for everyone thinking of trying this) about swapping.  I haven't taken a close look at Nik's OT for the Overtone but I'm guessing it doesn't have dual Primaries....I'll check when I get home.  The pair of 6L6's want to see a primary impedance of around 5K and conversely a pair of 6V6's...8K.  Therefore, it isn't a simple case of re-bias and play.  You have an impedance mismatch BUT because there are 4,8, and 16 ohm secondary taps there is leeway to better approximate the correct primary impedance.

On the D'lite you have an 8K Pri OT  (6V6) that you want to "knock down" to 4 or 5K for 6L6's.  To do so just re-label the secondaries as 2, 4 and 8 ohms instead of 4,8, and 16.  I'm certainly no EE so correct me if my logic is wrong but 6L6 to 6V6 should be the opposite....8, 16, and 32 ohm instead of 4, 8, and 16.   All this being said, a 100% impedance mis-match can sound great and the OT should be able to handle it.

Discuss....


Chris I hijacked this from the 6V6 thread in the Overtone forum, Have you or anyone thought more about this. I am going to try it if it is possible. JJ 6v6's ccan handle plate voltages of 450 volts I am told, but I don't know squat about the rest of what you are talking about have you sussed any of this out.
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« Reply #13 on: March 16, 2008, 06:52:36 PM »
what wattage resistors are needed?
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erwin_ve
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« Reply #14 on: March 16, 2008, 07:00:06 PM »
Quote from: jake on March 16, 2008, 06:52:36 PM
what wattage resistors are needed?
You mean the pre-od trimmer resistor? 1/2 watt is fine.
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