Taming the Peavey "Nasties"

Tube or solid-state, this section goes to eleven!
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Post by SG6505 »

Thank you för the tip. Can you describe the benefits of a OT upgrade?
I know it's subjective but I would apprechiate it very much.

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moltenmetalburn
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Post by moltenmetalburn »

alright i will attempt to describe IMO the benefits/tone difference.

(no flaming from anyone here, this is my opinion only, no to be misconstrued as fact.) [smilie=rlp_smilie_003.gif]

Ive put new OTs into two 5150s, a 5150+, and a krank revolution 1 personally.

The amplifiers all received similar benefit, which i would call increased harmonic complexity, way difficult to explain but the distortions that you hear are far more pleasing to the ear, less harsh, not actually smoother sounding but pleasing, probably due to increased second order harmonics. I found myself playing bar chords over and over just to let them decay into feedback so I could listen to the distortions occurring. really nice. extra sparkly.

I found the Bass to be much tighter and fuller and the amps seemed to lose a little bit of gain but for far better tone.

I kept finding myself using lower gains settings than previously to really allow the tone of the instrument through the distortion, the interesting thing is even though im using less gain than before and the amp seems capable of a slightly less amount of gain i still have the same feel going on. doesn't seem under-distorted for thrash riffing. (if thats your thing hehe)

My EQs SEEM to have more of an effect now.

note definition is unreal compared to the shit iron that was stock. if you ever played a Soldano SLO 100, and noticed how clearly each note rings true in a chord even under heavy distortion, thats what im expressing.

Now Im not saying every amp needs a tranny upgrade, Im sure there are some that wouldn't sound much different depending on the circuit, or already have hi quality iron already, but from experience the iron in the peaveys is terrible, and a higher quality tranny was a huge improvement.

some good transformer companies are:

mercury magnetics
Onetics
TMI
Heyboer

im sure others can chime in with many more.
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Post by SG6505 »

Thank you very much, I will definetly concider an upgrade. I'll look around and see what's available in scandinavia. I'm afraid shipping a 2-3(?) kg lump of iron from US to sweden is going to cost me. The only shop I know of here has "Marshall 100W" or "Fender Twin" OT's , no info if it's original parts or not. At least I hope I get to do the choke-upgrade this weekend

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Post by moltenmetalburn »

Lots of Scandinavians touring the united states these days, particularly metal bands, do you know anyone in a touring band? have em bring one back for you! If you don't sorry for the stupid idea, he he.
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Post by SG6505 »

Hi all

I performed the filter choke upgrade today and I must say it was another giant leap for ampkind. :applause:

The cleans became beautiful, real warm singing tube sound. I played my strat with a big silly smile for half an hour when testing right after the surgery.

I think the crunch and higains also benefited from the mod, but it is in the clean sound it really leaves it's mark.

The stock 6505 is a one trick baby indeed. But after theese simple and cheap mod I now have a really versatile amp that does it all, from singing cleans over broken up crunch to roaring deathmetal.
I think I will stop here with the mods of this amp. Saving the OT upgrade for later. I do not duobt that the amp will benefit from an upgrade, but I am so pleased with how it sounds now.
Thank you again everybody for the tips getting my amp come alive and show it's hidden soul.

:thumbsup

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Post by moltenmetalburn »

Awesome! Im glad you found inspiring sounds in your peavey!
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Post by SG6505 »

I have found a company in Sweden that sell Hammond transformers at reasonable prices. Do you know if they are any good? Would it be a major upgrade compared to stock?

Thx

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Post by bajaman »

I performed the filter choke upgrade today and I must say it was another giant leap for ampkind.

The cleans became beautiful, real warm singing tube sound. I played my strat with a big silly smile for half an hour when testing right after the surgery.

I think the crunch and higains also benefited from the mod, but it is in the clean sound it really leaves it's mark.
Thanks for listening to my pleas :wink:
In my opinion the missing filter choke is THE secret ingredient for a god clean sounding tube amp - we can always make a tube amp sound dirty with overdive/ distortion pedals, but it is not so easy making a grungy amp sound clean.
ALL the best sounding amplifiers from the 60s and 70s used filter chokes in their power supplies - The VOX AC30, Th e Marshall SuperLead and The Fender Twin Reverb to name a few. :thumbsup
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Post by SG6505 »

bajaman wrote:
Thanks for listening to my pleas :wink:
Thank you for emphasizing this.

Since I started building audio amps I've been surprised when I discovered how much of the tone and character that comes from the power supply. In my first attempts i only looked at the preamp. Filter chokes are going to be mandatory in all my future builds. I am planning to finish my marshall clone in the coming weeks and I will definitely bless it with a choke.

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Post by bajaman »

:thumbsup
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Post by JonnyPerez »

Hello! I've been modifying my Peavey 6505 amps for like 3 years, but never did anything about the choke filter or the bias mod.

Please forgive my ignorance, I've stepped away from modding and anything technical since january 08 and did a sort of brain dump.

1. Soulsonic, I do believe you may remember me asking you about Peavey mods on the DIYstomboxes forum a couple years ago. It was extremely informative to say the least! But since an account no longer exists for me, nor does any chance of getting a new one, I found this forum in hopes of getting some clarification.

2. Where does the choke filter go? I don't quit understand. I know as much as it replaces a resistor and how it affects the tone, but can't eyeball where it's supposed to go.

3. My amps need to be properly biased, I never realized it until today. How do I go about fixing this "lack of bias" situation?

Thanks alot!

BTW, I love this forum. I'm so sick of the bullshit (mojo) everywhere else on the web. It's the main reason I gave up building pedals and such.
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Post by SG6505 »

2: It is the first resistor in the power supply. Unfortenatlely the 5150 schems I have found does not show the power supply, but look at any old fender or marshall schematic and you will find a choke in series with the rectifier right after the first filter cap(s). Visually you recognize it as it is a very big black resistor on the power amp board.Image

3:The bias mod is well documented on the web, I followed the instructions on blueguitar

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Post by JonnyPerez »

GOT IT! I will do as such when I get home. For some reason I got lazy and didn't look about the google machine.
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Post by iwantmypie »

my triode electronics choke should be here tomorrow and i look forward to performing surgery to my mace again. i noticed bajaman recommended both a fender twin and marshall super lead choke and i ended up going for the twin choke. i believe it's 90mA and 4H. hopefully it's a good fit and i don't regret not getting the marshall choke. i'll let you guys know how it turns out...hopefully for the better :popcorn:
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Post by soulsonic »

Welcome, Jonny!
I'm glad you found the info you needed, and I'm glad you found your way here!

Besides the filter choke, you should also seriously consider replacing the screen grid resistors if they're the "standard Peavey" 100ohm values. Sorry, I'm not as familiar with the 6505 as I am with the 5150... if they are the 100 ohm ones, the amp will definitely be happier if you replace them with some nice 470 ohm 5 watt ones. That's one of the things I did to the Butcher at the beginning of this thread and it definitely helped it.
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Post by bajaman »

you should also seriously consider replacing the screen grid resistors if they're the "standard Peavey" 100ohm values
+1 :thumbsup
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Post by SG6505 »

The 5150 and 6505 are identical, just different names due to EVH beeing the owner of the brand "5150" as I am informed.
The 6505 has 100 ohm screen grid resistors and on side two of this thread I review the positive effects of swapping them to 470 ohms and setting the bias hotter on my amp.

Big up to Soulsonic and Bajaman and everybody else for for providing these tips. :hug:

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Post by iwantmypie »

sooooooo i finally stuck the choke in and i have nothing but good news to report. i haven't gotten to do much testing but there is definitely an increase in clarity when set both clean and dirty. the bass seems a little tighter but not as much as i thought i would get. i still have some more testing to do but while the differences are subtle, they are there and they are good. i think i might get some new filter caps for my peavey. i don't think most of the people in this thread would have to do it since their 5150's are all fairly new and not in need of new caps but my mace is 31 years old approximately and it looks like the caps are original, all wire-tied down to the board :lol:
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Post by DougH »

Here's a good article on tube screen circuits: http://www.webace.com.au/~electron/tubes/screens.htm

You can get away with smaller screen resistors for beam tubes *if* the power supply is designed correctly.

I just bought a Peavey Windsor because I couldn't resist $400 for a 100W half-stack (including 4x12). Overall, it sounds pretty good. My main complaint is it doesn't clean up very well because they put that stupid slo/rect/5150 "clipper stage" in the 4th stage of the preamp. All it does is compress the crap out of the signal. That's going to get converted to a buffer to drive the tone stack, which should help that a lot. I may revoice the tone stack into a standard marshall tmb too. Although it can be dialed in to sound good, it is voiced on the trebly side.

Looking at the schem, overall there are some nice reliability features- 4 or 5 individually fused circuit sections, diode protection of the output transformer, and so forth. But then they put 700 ohm screen resistors on EL34 pentodes (???). I don't understand that. I've heard stories of some Peaveys where they "will only work with certain brands of EL34's". Well, no wonder... Those will get changed to 1K's and I'm going to bias it (it is adjustable fixed bias) and make sure I'm happy with the preamp voltages as well. It's not a bad amp out of the box (esp for the price) but with a few simple tweaks I think it can be much better.
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Post by andersom »

Hello all,

I have an old (30years) Peavey Deuce VT, i'm wondering if these mods will work for this amp?
here's a schematic of an Deuce (not VT): http://schematicheaven.com/newamps/peavy_deuce-b.pdf
Does anybody know if can make these changes?

Whats the best thing to do?
* change the choke (what one is good for this old buddy? Marshall or Fender) http://www.tonefactory.nl/shop2/advance ... ke&x=0&y=0
* change the Screen Grid resistors in the Deuce to 470 ohm 5 watt resistors (cant find the 5 watt version) http://www.tonefactory.nl/shop2/advance ... &x=32&y=14


I put 4 new EH 6L6GC Matched Quad in the amp which made a big diffrence
Thanks in advance, i really love this forum i learn everyday :)

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