Ultimate Chorus Mods

[cejay825]

(Preface: I use single coil Teles.)  Just thought I'd throw this out there for anybody who likes the Fender Ultra/Ultimate (non DSP) Chorus amps. I did this purely as an experiment but the results were phenomenal. Is it overboard...probably, just buy another amp...probably but if you have some time and willing to spend $50 on the amp, it really pays off. The biggest problem with these amps is the fact that they have cheap electrolytic and Tantalum caps in the signal path, with these removed it is an amazing transformation. Its a simple task but time consuming. All Tantalum caps that were changed were replaced with silver mica. The other polyester caps were merely upgraded. Attached schematic....Red circles indicate upgraded to mica or polyester caps, capacitance size is determining factor, all pico's are mica. BLUE circles indicate an electrolytic cap changed to non polar polyester cap. The yellow square (C6) was changed from 1000pf to 250pf, this one mod was a tremendous difference.

[gbono]

I missed something here. Tantalums? They would appear to be too expensive for a Fender amp of this vintage and design. Sure you don't mean ceramic?

[J M Fahey]

I had the same doubt here, tantalums are basically "special electrolytics" and used in large values, think 1uF or thereabouts; while silver mica are available in VERY SMALL values, measured in pF .

FWIW and to get an idea of the scale or units involved, 1 pF is 1000000 times smaller than 1uF , so I find it very unlikely that a "tantalum" can be replaced by a "silver mica".

By the way, I stated this and other doubts in another Forum where this exact same post appeared and met an angry response from the OP.

Oh well.

[Enzo]

Don't recall ever seeing tantalums in a fender.  I suppose it could happen.

Reducing the value of the brightness cap on that volume control should indeed reduce the brightness.

[cejay825]

.....By the way, I stated this and other doubts in another Forum where this exact same post appeared and met an angry response from the OP.

Oh well.

That wasn't anger.....you told me what I changed would make "no difference" and/or couldn't see how and as far as my ears could tell, it did.....but speaking of anger, just before that post I saw you lambaste a guy for wanting to repair/mod his 60's era amp, which there was a problem, that he did repair.

Anyway, getting back to amps.....yes both of you are correct, I stated the wrong type, they were the yellow axial ceramics not Tantalum.

Hey Enzo, any ideas on the chorus issue I posted in the other thread ? "Roland JC120 Too Bright"

[Enzo]

I drifted away from the Roland, if I recall it was aloud hum, then too bright, and now you mention chorus, so I have no idea where the thread went.  I'll try to reread it when I get a moment.

[mexicanyella]

Cejay, I don't intend the following to sound critical or like I'm doubting your ears...I am asking out of curiosity, and what I want to know applies to both this thread and the one about the JC120.

I'm curious about the point at which you decide to open the amp up and modify it, including what direction you want to modify it in. In your first post on this thread, you say that the main problem with these amps is the caps in them, which might mean more to someone with more electronics experience than me. But I'd like to know what you objected to that you couldn't address with different knob positions, or a pedal or two.

I do kind of like some of those non-DSP Fender SS combos (in particular, I like how they seem to stay pretty clean and bright, but be housed in kind of cheap-ass cabinetry, with speakers that seem to give it up early...so you can get a sort of amp-meltdown-chaos effect from them without using a lot of fizzy preamp gain. One of my favorite lap steel tones ever achieved came from a borrowed cranked Princeton Chorus, on a friend's recording). Anyway, in my case, I always felt able to tame overall brightness sufficiently by just adjusting the EQ differently than I would on my own amp. So I wonder what you experience upon plugging into the thing and deciding "I can't get it to do what I want without opening it up and replacing some __________________." Can't get rid of enough highs? Mid control not adjusting a center frequency you like? Something about the character of the hot channels dirt tone you thought you could improve on with circuit mods? That kind of thing is what I'd be interested to know, both here and in the JC thread.

Thanks

[cejay825]

Cejay, I don't intend the following to sound critical or like I'm doubting your ears...I am asking out of curiosity, and what I want to know applies to both this thread and the one about the JC120.

I'm curious about the point at which you decide to open the amp up and modify it, including what direction you want to modify it in. In your first post on this thread, you say that the main problem with these amps is the caps in them, which might mean more to someone with more electronics experience than me. But I'd like to know what you objected to that you couldn't address with different knob positions, or a pedal or two.

I do kind of like some of those non-DSP Fender SS combos (in particular, I like how they seem to stay pretty clean and bright, but be housed in kind of cheap-ass cabinetry, with speakers that seem to give it up early...so you can get a sort of amp-meltdown-chaos effect from them without using a lot of fizzy preamp gain. One of my favorite lap steel tones ever achieved came from a borrowed cranked Princeton Chorus, on a friend's recording). Anyway, in my case, I always felt able to tame overall brightness sufficiently by just adjusting the EQ differently than I would on my own amp. So I wonder what you experience upon plugging into the thing and deciding "I can't get it to do what I want without opening it up and replacing some __________________." Can't get rid of enough highs? Mid control not adjusting a center frequency you like? Something about the character of the hot channels dirt tone you thought you could improve on with circuit mods? That kind of thing is what I'd be interested to know, both here and in the JC thread.

Thanks

Wow, thats a deep question....I'll try to answer it but some of the content will be subjective.....which is one of my first answers. EVERYTHING tone wise is subjective, everyone is different, everyone has different tastes, everyone hears things differently.

I'm curious about the point at which you decide to open the amp up and modify it, including what direction you want to modify it in.

My guitar tastes are set in stone.....telecasters with vintage single coils....thats all I like, thats all I play. I use no pedals....guitar/cord/amp...with the exception of when I need overdrive, I use a Visual Sound Open Road (the only OD pedal I'll ever use). The buffer in this pedal is sheer magic, just having a Visual Sound pedal between the guitar and amp is an amazing difference. Once again, my ears, some people I've been around say they can definitely tell....others say "I think so". Thats a whole other thread though....no, I don't sell these pedals or have any affiliation. So, I don't adjust my guitar, I adjust my amp or amps.....is this crazy, yeah but its what I do. That being said, every amp offers something different (circuit wise).....when amps are made for mass marketing, manufactures try to find a happy medium for all styles of music and guitars. Some guitars will sound better with certain amps.....this is where the rise of boutique amps come in.......amps built for certain styles, sound and guitars.....but that is a whole other thread. Anyway getting back, i know the type of tone and reaction I want to hear and a few tweaks will usually get it done and sometimes not....I don't mind the time it takes to do this.

you say that the main problem with these amps is the caps in them

Here's a BIG subjective subject. The cap debate has been going on for years. There are two teams, 1. caps are caps 2. Different caps, different sound. It is "generally" agree upon though, that Polypropylene and Polyester have different sounds.....again thats a whole other thread. IMO electronics vary quite a bit over time.....in both their life cycle and manufacturing. Lets look at the amp in question, IMO in 25 years cap construction techniques, materials use and manufacturing processes have changed, not to mention cheap construction vs quality construction......does any of this matter ? I think so BUT there are others who will say no....its subjective and I don't wish to argue it...it doesn't end well. I will say though, I've changed caps in several audio devices and I can most times hear the difference....once again IMO.

But I'd like to know what you objected to that you couldn't address with different knob positions

I always felt able to tame overall brightness sufficiently by just adjusting the EQ differently

Can't get rid of enough highs? Mid control not adjusting a center frequency you like?

Tone Stacks are limited to how they are built.....changing the parameters of the components changes the reaction and frequency, greatly. I will never be able to tell you in words what I want to hear and whats in my head....lol maybe I've gone off the deep end....maybe I'm too picky.....people just hear things differently.

Something about the character of the hot channels dirt tone you thought you could improve on with circuit mods?

I only deal with the clean channels

Bottom line, I'm just sharing my experiences. Everything I've said here is purely my opinion. Here's something, there are amps that I liked as is and didn't feel the need to change, they are:

Holland Brentwood
Fender Cyber Twin
Vox AD100VT
Peavey Bandit 65
Traynor YCV40

Sorry for the long response....did I answer it?

[Enzo]

I have to say that Fender Princeton Chorus is one of my favorite solid state amps.

[mexicanyella]

Thanks for the detailed response. I think I can understand how someone would prefer a standard-config Tele straight into a particular-sounding clean amp, and I know I have encountered amps that sound good to me when other people play through them but that I can't adjust to a point that I like them for myself. I have never been able to enjoy playing through a Marshall amp, or any of several different varieties of Mesa products, even though I hear other people sound great through them.

FWIW, I used to be all about small tube amps, but have gradually evolved (devolved?) into using a hardtail single humbucker strat copy, a DOD bass compressor pedal and solid-state Peavey combos (a teal-stripe Peavey TKO 115 with a 15" Scorpion in it. Doesn't sound like a recipe for success, I know, but it really works well together to my ear. I had to adjust to thinking in graphic EQ terms for awhile before I figured out how to use it).

I recently traded a pedal for a Peavey Special 150 and I'm liking it but still adjusting to it, and so far its clean channel is pretty close to what I like but a little too clean, whereas the dirt channel is fun to play around on but more distorted than I really want, even at the bottom of the "Supersat" knob's range (never been a fan of channel-switching; I like to work the volume knob). If I don't grow to like either channel more for what it is with some more playing and tweaking, I may investigate ways to reduce the dirt channel's gain and see if can calm it down a bit.

I have recently spent a lot of time messing around with a borrowed Line 6 Pod 2.0 and ultimately decided it's not for me...but the one model in that thing that I really kind of liked was the "Jazz Clean" JC120 emulation. With the gain up around 60-70% , the lows cut and the highs and mids pushed a bit, it sounded pretty snappy and broke up a bit, and responded to playing/picking dynamics well. Made me want to try playing through a real JC120 sometime and seeing if I like that too. I suspect anything approaching the settings I had on a real JC120 would be up around 150 dB though.

Maybe more than you wanted to know. I kind of nerded out there...