Whiskey, you might be interested in the numerous mods for the C30 over at www.blueguitar.org, and our friend tubeswell has done many of them to his C30.
Education is what you're left with after you have forgotten what you have learned.
If you are looking at the Blue Guitar mods, the tonestack mod (including Boost Switch mod) is definitely worthwhile. It improves the voicing of the EQ section. I upped the plate resistor on V3A to 120k after doing that mod tho.
Its the OD channel mods I'm out to get now. I've tried and untried and re-tried these several times - I reckon I'm just about there. Difficult thing is to get the right amount of mids and highs and bass when the crucnch is engaged. There are alot of parts to play around with and a dang frustrating PCB setup to contend with everytime. (One time I took it apart and put it back together 6 times on a Saturday and then again seven times the following day, just to figure out which jumper lead(s) I'd broken.)
Building a better world (one tube amp at a time)
"I have never had to invoke a formula to fight oscillation in a guitar amp."- Enzo
If you are looking at the Blue Guitar mods, the tonestack mod (including Boost Switch mod) is definitely worthwhile. It improves the voicing of the EQ section. I upped the plate resistor on V3A to 120k after doing that mod tho.
Its the OD channel mods I'm out to get now. I've tried and untried and re-tried these several times - I reckon I'm just about there. Difficult thing is to get the right amount of mids and highs and bass when the crucnch is engaged. There are alot of parts to play around with and a dang frustrating PCB setup to contend with everytime. (One time I took it apart and put it back together 6 times on a Saturday and then again seven times the following day, just to figure out which jumper lead(s) I'd broken.)
Sounds like deja vu all over again!
The architecture of the OD channel is really tricky- too much bass and it just craps out (I won't even do it the honor of calling it "farting" ) And I think stock it is too fizzy.
If you can get a sound you like by adjusting the tone stack- only those settings aren't right for the Clean channel- then you might want to look at that resistor and capacitor hanging off the post gain control (R13 - 10k and C16 - .015uF) which I always figured was like a treble cut tone control on a guitar. For awhile I had replaced R13 with a 10k variable resistor, but I usually set to a total of ~8.1K so I ended up putting in a fixed resistor of that value. I thought doing that balanced out the two channels so that they could co-exist with the same tone stack.
Another component to look at is C2 - the .001uF coupling cap coming from V2A. Replacing that with a .01uF will thicken the OD channel a bit. Or split the difference and put in a .005uF.
One problem with fine-tuning the OD channel is that it is SO dependent on other factors- the guitar and pickups used, the tube complement and the speaker, not to mention the style of music you are playing and the relative volume.
One thing to remember- God will not condemn you to eternal damnation if you use a stomp box with your Classic 30. Sure it looks cool to be plugged in direct- just you and your guitar and your amp- but face it: unless you are going to cough up big bucks for a boutique amp (or whatever) a little bit of help from an FX pedal can go a long ways towards getting you the sound that you want.
A mod that never occurred to me involved the 2M2 local feedback resistor R21 from the plate to the grid of V1B. Many people have been clipping this out which will make the amp a little less "spongy" (Dumble used a 22M to 44M local feedback resistor on the second stage of his ODS for many years, although one early schematic showed a 2M2 resistor. I have a theory that the engineers at Peavey had looked at that particular schematic.... James Brown, are you reading this? )
Steve Ahola
P.S. I must be going crazy because I just bought a brand new Delta Blues 115 this morning, and thought that it sounded great right out of the box! The 15 inch speaker seems to cancel out a lot of the problems with the stock Classic 30. They added a tube guard and I suspect that they have revised the circuit a little bit (you can turn the OD channel Pre gain knob down low and the tone doesn't turn to mud).
Yes I still haven't dived back into this one yet (everytime I think, shall I do it now?, I then think, "Not quite sure if I'd have enough time right now" ) FWIW after a suggestion from Ampkat last year (or was it the year before?), I put Soldano SLO values right through the v1 and v2 circuits. I must say I loved the crunch channel then, but the 'clean channel' sucked, so I undid it. I need to contemplate this some more to arrive at a situation where I can get the best of both worlds if possible without invcolving unnecessary complexity of departures from 'stock fender values' in V1A and V1B.
Building a better world (one tube amp at a time)
"I have never had to invoke a formula to fight oscillation in a guitar amp."- Enzo
Steve, they have not changed the circuits inside those amps. They added the tube guards to satisfy customer feedback. That 15 sounds nice, especially in the larger cab the DB lives in.
Education is what you're left with after you have forgotten what you have learned.
Steve, they have not changed the circuits inside those amps. They added the tube guards to satisfy customer feedback. That 15 sounds nice, especially in the larger cab the DB lives in.
Thanks- I was going to ask you about that. I had a theory about the early Classic 30 prototypes: I was thinking that James Brown was using a Vintage 30 speaker when he voiced the amp, but when it went into production of course Peavey had to use a less expensive speaker...
That would not necessarily be a mistake- a lot of people are going to upgrade the speaker in any amp that they buy, often with a Vintage 30, so why not go for it? (The supporting argument for that theory is that so many people have been very happy with the amp once they replace the speaker with a Vintage 30.)
The Delta Blues has a such a full clean sound and when you turn down the volume it still sounds really full.
Of course over the past 13 years the tubes shipped with the amps have changed- were they using Sovtek 12AX7WA's back in 1994 when I got my Classic 30? That is one of my least favorite tubes...
Steve Ahola
P.S. So they are still making these amps in Mississippi? Wow- a real power cord that doesn't get unplugged and lost... a dying breed!
EDIT I just checked the tubes and they are JJ's. I tried swapping out the preamp tubes with various Groove Tube/Mullards but went back to the stock tubes. Except I did put in a Sovtek 12AX7WB for V2, which smoothed out the overdrive a bit (as always- I love those tubes!)
For some reason this amp works really well when you turn down the volume on your guitar- even at low settings it has a really full sound (with my other amps its kinda like the guitar gets swallowed up when you turn it down). I think it is that 15 inch speaker and that huge cabinet!
FWIW I am playing PRS SE's with humbuckers and P-90's these days- when I did all of the Classic 30 & 50 mods 10 years ago I was pretty much playing strats and teles. (I'd test my mods with my Les Paul but it was not my guitar of choice back then.)
Thanks- I was going to ask you about that. I had a theory about the early Classic 30 prototypes: I was thinking that James Brown was using a Vintage 30 speaker when he voiced the amp, but when it went into production of course Peavey had to use a less expensive speaker...
Hi Steve,
I've done extensive mods to my C30 following your documents (I have to say I concentrate myself on the clean channel, at some point I gave you a list of what I've done).
For the cone I've tried a Celestion G12M, a Vintage 30, a Jensen C12R and finally a Jensen C12K, which is the best one to my ears.
The vintage 30 was... the worst the mids were muffled, the bass overlapping and the highs strange, like putting a tent over the amp.
Of course it's just a matter of personale taste, what it's bad for me could be the holy grail for someone else.
ciao
Marcello
Hi Steve,
I've done extensive mods to my C30 following your documents (I have to say I concentrate myself on the clean channel, at some point I gave you a list of what I've done).
For the cone I've tried a Celestion G12M, a Vintage 30, a Jensen C12R and finally a Jensen C12K, which is the best one to my ears.
The vintage 30 was... the worst the mids were muffled, the bass overlapping and the highs strange, like putting a tent over the amp.
Of course it's just a matter of personale taste, what it's bad for me could be the holy grail for someone else.
ciao
Marcello
For all the bad rap those Recoton "Jensens" get there sure is quite a few ppl out there who swear by them. I have a customer who recently dumped all his Celestions in favor of the C12N.
The farmer takes a wife, the barber takes a pole....
Comment