2203 Treble Peaking Circuit

[johnnyeggz]

I got this 2203 ri in a trade deal, and someone’s been tinkering in there. Now I’ve heard of the 470k/470pf treble peaker from the Preamp Vol to Low input being replaced with a 68k resistor, although I don’t really know what that mod does, but this amp was modded with just a wire , no resistor or cap or anything.

They changed the .022 coupler to .0022, I’m guessing to pull out some bass. I’m also guessing they pulled the treble peaker entirely because after the .0022 swap, it was too bright?

Being I’m using a Hot Mod V2 evo , I’m gonna leave the .0022 in place, and do the 220k/.0047 fixed depth because it just makes sense to me to keep it bass lean “up front” and add it “round back”, but that plain wire where the treble peaker used to be is bugging me, something needs to be there, correct?

 

[syscokid]

This could be an interesting thread, and eagerly awaiting for some good info from those with good knowledge…

 

[mickeydg5]

Well it does not have to and it depends if you like it as is versus adding components.
The Volume/bright capacitor circuit does load the grid for V1b.

 

[Pete Farrington]

something needs to be there, correct?

If it sounds good then it’s good. It hasn’t destroyed anything yet, right?
But if in doubt, isn’t it the simplest thing to lift the wire and try it both ways?

 

[johnnyeggz]

Without a SD 1 out front, it’s gainy but also farty.

I’ve a 68k and 470k/470pf on order, so we’ll find out.

 

[dtier]

With the hot mod installed it's really a different animal that the stock circuit. It's up to your ears. There is nothing harmful about the bypass wire. I doubt you will notice the 68k there but will notice the 470k/470pf. You're affecting the ac load to the first stage and changing band pass filtering. All have some effect.

The fixed resonance circuit is great but not for everyone. I like it for tighter/modern gain sounds but not for classic stuff. You can make it switchable or variable if needed.

FWIW I have never tried any of the hotmods. Gonna have to try one or build the circuit to sample for myself.

 

[johnnyeggz]

With the hot mod installed it's really a different animal that the stock circuit. It's up to your ears. There is nothing harmful about the bypass wire. I doubt you will notice the 68k there but will notice the 470k/470pf. You're affecting the ac load to the first stage and changing band pass filtering. All have some effect.

The fixed resonance circuit is great but not for everyone. I like it for tighter/modern gain sounds but not for classic stuff. You can make it switchable or variable if needed.

FWIW I have never tried any of the hotmods. Gonna have to try one or build the circuit to sample for myself.

The Hot Mod is really a great product, simple, especially with a 5751 or 12at7 in the first position.

Once the parts come, I think I’ll go 470k/470pf first. I’ve always read that clipping it out was a bad idea.

 

[TheKman76]

I don't see a problem leaving it this way, but if you're going to swap the 22n back in I'd be inclined to go back to stock with with the peaker. Maybe you're already experiencing blocking distortion causing the 'farty' sound. Adding a 100k will have little effect on the tone and may resolve this.

Modelling shows the current mod adds 5dB of lower-mid (400-700 Hz), fattening up the sound a little.

 

[johnnyeggz]

I don't see a problem leaving it this way, but if you're going to swap the 22n back in I'd be inclined to go back to stock with with the peaker. Maybe you're already experiencing blocking distortion causing the 'farty' sound. Adding a 100k will have little effect on the tone and may resolve this.

Modelling shows the current mod adds 5dB of lower-mid (400-700 Hz), fattening up the sound a little.

I’m gonna leave the .0022 for now, and see how it sounds with the fixed depth.

I‘ll swap the wire for a 100k tomorrow morning, I probably have one laying around somewhere, the rest of the components deliver Friday.

I just noticed another mod I missed.
Theres a resistor shrink wrapped to the the 2nd preamp tube, it looks to be going in series to the boards 470k 470pf 470k mixer
What the hell can that be?

 

[shredless]

Are you talking R9 R10 and pin 7 of the second tube?

 

[johnnyeggz]

Are you talking R9 R10 and pin 7 of the second tube?

Yes

 

[shredless]

I dont know...lve been looking through mods trying to find that one.

 

[johnnyeggz]

I dont know...lve been looking through mods trying to find that one.

Its coming out tomorrow, I can’t think of any reason for it to be there.

 

[shredless]

Yeah l have no idea what that mod is...

Hey you got me thinking today so l pulled my res mod out to try the hot mod without it.

I had the 220k bypassed with 0047 going to the middle lug of the ohm selector. I ditched the res/cap and went back to 4 ohm tap.

Im really liking it. The amp is so easy to play now. It seemed stiff and fought back before. Now the bass switch on hotmod thickens it up but not overwhelming.

I have all stock peakers and treble cap, 4.7k instead of 10k on v1, .0022 coupler like yours and a 22uf over the 820 plate resistor. I swapped my zener clipper for a freidman sat mod. Im really diggin it, but lve said that before.

 

[johnnyeggz]

Yeah l have no idea what that mod is...

Hey you got me thinking today so l pulled my res mod out to try the hot mod without it.

I had the 220k bypassed with 0047 going to the middle lug of the ohm selector. I ditched the res/cap and went back to 4 ohm tap.

Im really liking it. The amp is so easy to play now. It seemed stiff and fought back before. Now the bass switch on hotmod thickens it up but not overwhelming.

I have all stock peakers and treble cap, 4.7k instead of 10k on v1, .0022 coupler like yours and a 22uf over the 820 plate resistor. I swapped my zener clipper for a freidman sat mod. Im really diggin it, but lve said that before.

I’m still finding it a bit lean in the bass even with the deep switch engaged, but that 22uf you got on the 820 might be helping with that.

 

[shredless]

Yep l think so

 

[shredless]

I’m gonna leave the .0022 for now, and see how it sounds with the fixed depth.

I‘ll swap the wire for a 100k tomorrow morning, I probably have one laying around somewhere, the rest of the components deliver Friday.

I just noticed another mod I missed.
Theres a resistor shrink wrapped to the the 2nd preamp tube, it looks to be going in series to the boards 470k 470pf 470k mixer
What the hell can that be?

Hey l may have an answer for you...my thread on squealing... Pete said a generic fix is to add a grid stopper to the input of v2 and or v3...l bet thats what you have going on. You may get a squeal or worse if you pull it out. Its prolly just a small value to reduce the level hitting that tube enough to cut out oscillation.

I didnt realize how much an oscillation can affect an amp...sometimes they squeal, other times you cant hear them and they cut out sound all together or get super farty.

Im just now learning this while dealing with mine. Never had oscilating before.

Petes another good dude on here.

 

[johnnyeggz]

Hey l may have an answer for you...my thread on squealing... Pete said a generic fix is to add a grid stopper to the input of v2 and or v3...l bet thats what you have going on. You may get a squeal or worse if you pull it out. Its prolly just a small value to reduce the level hitting that tube enough to cut out oscillation.

I didnt realize how much an oscillation can affect an amp...sometimes they squeal, other times you cant hear them and they cut out sound all together or get super farty.

Im just now learning this while dealing with mine. Never had oscilating before.

Petes another good dude on here.

I found a few components in my very unorganized bag of tricks.

I don’t have a .0047 for the depth, but I do have an orange drop.0033, close enough to check it out.

I also have the stuff to add back the stock Treble Peaking, AND enough parts to do the JEL mod as well.

But I’m wondering if doing the JEL is kind of a waste of time being the Hot Mod kinda handles most of that stuff.

 

[shredless]

I think youre on the right track... It may be too much. Even the Hotmod dude...l think his name is Kevin??? said it may be too much when l bought mine. And now l agree.

I removed most of the JEL

But opinions vary and you wont know till you try...so sounds like your about to "tinker" with it

 

[dtier]

The JEL mod really heats up the existing stages, so 3 hotter stages vs 4 stages with Hotmod, or both which make get unstable without further adjustments. Are we having fun yet? The other question is do you need or want the original 2203 circuit. Euge Valvovirta has a lot of videos on the subject.