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peavey Classic Series 60/60. When were they built?
Old 23rd August 2018
  #1
peavey Classic Series 60/60. When were they built?

Hi Folks
Just sealed a deal on an old Peavey Classic Series 60/60 Tube Power Amp Rack and wondering when they were manufactured? Any ideas?
Old 23rd August 2018
  #2
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fireberd's Avatar
11/1989 according to when the manual was published.
Here is the link to the Peavey manual.
https://assets.peavey.com/literature...s/80301119.pdf
Old 23rd August 2018
  #3
Thanks Fireberd, appreciate it!
Old 21st September 2018
  #4
Here's some info about the Peavey Classic Series 60/60

Hi guys

I've collected what I can find about the Peavey Classic Series 60/60 and documented it in a comprehensive blog post. Plenty of pic's from inside the unit, downloads (manuals/schematics etc), controls and more. Hope someone will find this useful.
If anyone has additional info I can include please let me know.

Peavey Classic Series 60/60 - Under The Hood - Mooselander.com


Thanks, appreciate it.
Old 21st September 2018
  #5
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I suspect that date of 1989 for the manual was a record of a revision since I am certain the 60/60 rack unit existed as early as 1985-6. I was employed by a large retail Musical Instrument outlet and saw those amps then and a few, very few I should add, came across my bench. It was and is a decent amp and came from a time when savvy ol' Hartley was finally beginning to lose his well-documented bias against tube amps. Nevertheless he, being the salt of the earth savvy gent that he is, was swayed by his Sales Department which while partly responsible for the evolution into understanding that tubes do indeed offer something SS can't also made him push design to deliver hot bullet points like wattage numbers pushed high by skirting the very boundary of Class B where things get nasty.

As a result I think the 60/60 would benefit greatly from a qualified tech either adjusting the bias for a warmer, more dynamic sound either by resistor substitution or better, by altering the amp for adjustable bias especially considering the difference in available tube quality from 30 years ago.

BTW nice job on both mounting the amp and the website.
Old 21st September 2018
  #6
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They made a 50/50 and a 120/120 as well,the 120/120 was brutal cranked.
Old 21st September 2018
  #7
Thats great info guys, I thank you.

Enorbet2, can I ask permission to update my blog with your post? Seems to be right on the ball and solid advice. It's become my go-to power amp in the studio now. I will certainly be looking into the possibility of an adjustable bias mod in the future. First up though, gotta change that cooling fan.
Old 22nd September 2018
  #8
Quote:
Originally Posted by enorbet2 View Post
especially considering the difference in available tube quality from 30 years ago.
I don't understand this - tubes, especially output tubes, really suck compared to quality tubes from 30 years ago.
Old 22nd September 2018
  #9
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Quote:
Originally Posted by simhaw View Post
Thats great info guys, I thank you.

Enorbet2, can I ask permission to update my blog with your post? Seems to be right on the ball and solid advice. It's become my go-to power amp in the studio now. I will certainly be looking into the possibility of an adjustable bias mod in the future. First up though, gotta change that cooling fan.
Of course and the answer is "yes"
Old 22nd September 2018
  #10
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Regarding mods to adjust bias levels in Peavey amps, John said

Quote:
Originally Posted by John Eppstein View Post
I don't understand this - tubes, especially output tubes, really suck compared to quality tubes from 30 years ago.
I think that's close to self-explanatory in that quality in general as well as quality control has suffered compared to what was commonly available in the 80s and earlier. The ability to adjust
operating characteristics via bias adjustment translates into longer life and/or better tone and dynamics ie: making the best of a sad situation.

I'm sure you're aware that many manufacturers built amps that ran tubes at higher levels than, for example, what tube manuals claimed was max levels. Back then they could take it or at least some could. Additionally consider how 6550s even back then were said to be subs for KT88s when they were not at all interchangeable. You could generally put a KT88 where the design was for a 6550 but it was/is risky to place a 6550 in an amp actually designed for KT88s. One way to accommodate swapping out is bias control.

Granted a self-biased output where the bias voltage is in direct proportion to the actual operation parameters of the tube is a great way to go but given a B- supply, IMHO it needs to be adjustable. Tube variation only makes that more important.
Old 1st April 2019
  #11
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Quote:
Originally Posted by simhaw View Post
Thats great info guys, I thank you.

Enorbet2, can I ask permission to update my blog with your post? Seems to be right on the ball and solid advice. It's become my go-to power amp in the studio now. I will certainly be looking into the possibility of an adjustable bias mod in the future. First up though, gotta change that cooling fan.
Inspired by you post I reconnected with my very old friend, passed down to me around 1995(?!).

Any recommendations more than welcome!!

Peavey Classic 60/60 - cleaning/refreshing/upgrading?! - diyAudio

Cheers
Old 1st April 2019
  #12
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enorbet2's Avatar
Quote:
Originally Posted by Slicklickz View Post
They made a 50/50 and a 120/120 as well,the 120/120 was brutal cranked.
Yes the Peavey 120/120 was indeed brutal but this was the time when guys like Steve Lukather were using one or more Mes Strategy 400s w/ 12 x 6L6's. Now THAT's Brutal!
Old 4th April 2019
  #13
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hi all,

Any comments regarding upgrade to the sound if the amp is used for music? (not a guitar etc/live)

- Get new tubes?! What do you think? JJ?Sovitek? I have no idea!

- Any comments for audio upgrades related output transformers? The specs are 40hz-20k even though I remember the sound very full and low. but and audio upgrade will be super Wellcome.

Thanks
Old 4th April 2019
  #14
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noah330's Avatar
By the teal graphics I would say 89**** if I had to ballpark it.
Old 5th April 2019
  #15
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enorbet2's Avatar
Quote:
Originally Posted by Varoudis View Post
hi all,

Any comments regarding upgrade to the sound if the amp is used for music? (not a guitar etc/live)

- Get new tubes?! What do you think? JJ?Sovitek? I have no idea!

- Any comments for audio upgrades related output transformers? The specs are 40hz-20k even though I remember the sound very full and low. but and audio upgrade will be super Wellcome.

Thanks
While it might be useful to try different tubes you are going to be up against a basic issue that most amps designed for guitar for the most part are quite different from those designed for program material. There are exceptions like those of the era of UltraLinear Fenders which most guitar players dislike and non-player engineers appreciate, but even those are designed with the wide dynamic range of live guitar output as opposed to the far weaker range of recorded material.

I have several old Eico, Dynaco, and Heathkit tube amps designed for program material and have had the pleasure of witnessing some super power tube amps like Mesa Barron and Carver designed for such work and those do sound like angels singing but the last two can double as space heaters.

If you know a qualified tube tech and are really serious about using this for recorded music playback I'd have him give you an estimate on modding for that purpose. At the least I'd estimate useful mods will start at twice the cost of a set of good power tubes, but the effect could easily be 10 times as great, even for just rudimentary re-design

Hmmm now that I think on it a little longer it might be possible to alter just the negative feedback and input sensitivity to achieve a fairly profound improvement for near the cost of a set of tubes from the right guy.
Old 5th April 2019
  #16
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Quote:
Originally Posted by enorbet2 View Post
While it might be useful to try different tubes you are going to be up against a basic issue that most amps designed for guitar for the most part are quite different from those designed for program material. There are exceptions like those of the era of UltraLinear Fenders which most guitar players dislike and non-player engineers appreciate, but even those are designed with the wide dynamic range of live guitar output as opposed to the far weaker range of recorded material.

I have several old Eico, Dynaco, and Heathkit tube amps designed for program material and have had the pleasure of witnessing some super power tube amps like Mesa Barron and Carver designed for such work and those do sound like angels singing but the last two can double as space heaters.

If you know a qualified tube tech and are really serious about using this for recorded music playback I'd have him give you an estimate on modding for that purpose. At the least I'd estimate useful mods will start at twice the cost of a set of good power tubes, but the effect could easily be 10 times as great, even for just rudimentary re-design

Hmmm now that I think on it a little longer it might be possible to alter just the negative feedback and input sensitivity to achieve a fairly profound improvement for near the cost of a set of tubes from the right guy.

Hi, I have an ok lab with test gear (scopes/PS etc) so I was thinking of doing everything DIY (I have done some HAM radio things too so Im not a complete jerk). I also have a metal/wood workshop with CNC and other robotic toys so I can do some chassis work too.

What would be the mods that you would propose? (simple to more complicated maybe?) Im all ears!

EDIT: regarding new tube, I have seen review that the JJs are good.

Last edited by Varoudis; 5th April 2019 at 03:09 PM.. Reason: edit
Old 5th April 2019
  #17
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Quote:
Originally Posted by Varoudis View Post
Hi, I have an ok lab with test gear (scopes/PS etc) so I was thinking of doing everything DIY (I have done some HAM radio things too so Im not a complete jerk). I also have a metal/wood workshop with CNC and other robotic toys so I can do some chassis work too.

What would be the mods that you would propose? (simple to more complicated maybe?) Im all ears!

EDIT: regarding new tube, I have seen review that the JJs are good.
Nice! The first thing you need to do is verify the output range of your preamp. The Peavey requires a minimum of 1.0vrms to achieve full output and most commercial HiFi gear preamps put out about 0.10-0.40 vrms iirc while Pro gear puts out 1.0-1.4 vrms. So you will need a clean gain stage added if you're using a commercial preamp. If your preamp is Pro then the requirement is met and no mod is needed.

The amp includes a filter that rolls off lows with the "knee" at 40Hz and at a slope of 18db/octave that is unacceptable for HI Fidelity program material so it should be removed.or dropped an octave.

I note that Frequency Response is +0, -3 db @55 watts from 40-20KHz and I suspect the 3db down is on the low end unless the negative feedback loop is compensated with a cap to allow greater cancellation in the highs. I can't recall and I no longer have a schematic but if one was in front of me it would be easy to check that 1) no excessive hi freq filters were being employed (often done on instrument amps to reduce the likelihood of ultrasonic oscillation) and, 2) all coupling caps were full range, basically at least 0.1 mfd or larger.

For good measure I'd double the value of the filter caps, all of them if possible, but at least the first two stages.

Without altering the circuit any further this should be a rather profound improvement but the input level situation is essential to resolve first. To do any more I would need the amp or a schematic and so would you.

Good luck! Sounds like a fun and worthwhile project. I love how my 2 Eico 60 watt tube power amps sound and the Dynaco Mk III 60 is even better. I'll injclude the Dynaco schematic so you have a decent guideline to show the differences.Mine have been modded with substantially increased capacitor values and the S/N ratio is superb. The 1K resistors at the power tube grids are replaced with 1% tolerance metal film versions as are the two 100K bias supply resistors between pints 2-1, and 2-3..

Old 6th April 2019
  #18
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@ enorbet2

Sorry I posted with the assumption that you had the schematic from previous posts:
Peavey-Classic-60_60-schematic.pdf
Here it is.

1) Ill measure my pre but its not "pro" a normal Denon one with "preouts". I have built a tube pre (Nutube) but I don't want to mix the two. I'd like indeed a clean pre stage.

2) From the schematic Im not sure where the low filter is. Maybe the schematic helps?

Do you see points in the schematic I need to focus regarding all your comments?

BTW!! my first step is to troubleshoot the channel imbalance it has. Its around 10-15% but Ill scope it on Sunday probably.

The amp is all original and passed down to me around 1995, some time after my dad got it new I believe. I remember the imbalance for some time before I left it back in my old home around 15 years ago. Now I;d like to give it all the love I can.
Old 6th April 2019
  #19
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Quote:
Originally Posted by Varoudis View Post
Sorry I posted with the assumption that you had the schematic from previous posts:
Peavey-Classic-60_60-schematic.pdf
Here it is.
Thanks. I once had the schematic back when I did a stretch as a "hired gun" for music stores and when it first came out I was curious about how Hartley was evolving with tube design so I checked it out pretty thoroughly and had decent , if somewhat vague, memory of it's design and construction.

Quote:
Originally Posted by Varoudis View Post
1) Ill measure my pre but its not "pro" a normal Denon one with "preouts". I have built a tube pre (Nutube) but I don't want to mix the two. I'd like indeed a clean pre stage.
That should be easy since you only need a gain of ~10 and a single 12AX7 stage can easily deliver 30 but that should probably be job #1 . Level matching is essential.

Quote:
Originally Posted by Varoudis View Post
2) From the schematic Im not sure where the low filter is. Maybe the schematic helps?
I'm not actually sure I see it either, partly because it could be distributed between the (somewhat complex rendering of the feedback loop with it's branches into the Line Outs) negative feedback loop and the natural and cumulative attenuation due to the 0.047 coupling caps. Notice the couplers on the Dynaco are .22 and for good reason - strong low freq transmission

Quote:
Originally Posted by Varoudis View Post
Do you see points in the schematic I need to focus regarding all your comments?
Yes and I've already mentioned them. Increase the values of the coupling caps and the filter caps and do some checking around the feedback loop for any fixed high frequency emphasis and eliminate that if present..There's more following your next question.

Quote:
Originally Posted by Varoudis View Post
BTW!! my first step is to troubleshoot the channel imbalance it has. Its around 10-15% but Ill scope it on Sunday probably.
Using high quality coupling caps and replacing any matching resistor values with 1% tolerance resistors is wise even if the originals were 5%. In fact, as cheap as metal film reistors are I'd even replace the originals if they started as 1%. That will make anything else you do for balance that much easier.

Quote:
Originally Posted by Varoudis View Post
The amp is all original and passed down to me around 1995, some time after my dad got it new I believe. I remember the imbalance for some time before I left it back in my old home around 15 years ago. Now I;d like to give it all the love I can.
It's a decent amp and especially with the price of Dynaco MK IIIs hovering close to $1000 for one monobloc it should be very cost effective if you spend wisely and work carefully.
Old 6th April 2019
  #20
RiF
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I have a Peavey Classic Series 50/50. Sounds great. Seems to have more features than the 60/60 like Resonance, Presence and Level controls on the front.
Does anybody has a clue about when they were built?
Old 21st April 2019
  #21
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Peavey Classic 60/60 - Replace the 1M feedback resistors (R53 and R58), with 250K resistors. This will increase the negative feedback and reduce the gain, but turn the amp into one of the sweetest tube amps I've ever heard.
Old 9th May 2019
  #22
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Quote:
Originally Posted by Enzo911 View Post
Peavey Classic 60/60 - Replace the 1M feedback resistors (R53 and R58), with 250K resistors. This will increase the negative feedback and reduce the gain, but turn the amp into one of the sweetest tube amps I've ever heard.
Hi,
Thank you all for the feedback.
I have updated the output tubes with JJ and the balance is good.
I did some manual frequency response measurements (signal gen and a scope) and I found the the original 12ax7 give a better response than using new 12ax7 and new 6L6 (all JJs).

One thing I don't know yet is if all caps are ok. I need to test full (or near full) power to see if I have any leaks. B+ etc and other voltages seem OK though.

I have only push it up to 20-22Vpp (not RMS) into 8ohm dummies.

Ill probably change all coupling caps.

Enzo, (firstly, are you Enzo Campagnola? I've been looking at your work with this amp!).
Ill do your mod and see. Have you tested anything on a spectrum analyser maybe after the mod?

Thanks a lot
Old 9th May 2019
  #23
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btw any idea of the output transformer specs?!
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