Peavey Bandit 65 mods, anyone have any good mods?

[Slobrain]

Hi, I did eventually complete this work and actually did a whole load more to my Bandit 65. Good news is that they more or less used an identical preamp on many amps so these changes could (at your discretion) be used on the VTX. The final result was, to my ear, a real improvement on the original design. Cause I am a bit daft (and frankly obsessive) I even picked up a second Bandit 65 locally for £20 and used it to A/B the mods. Now I'm probably biased on this so I asked a couple of other guitarists to see what they thought and one went as far as to buy the un-modded amp from me in order to make similar changes himself.

Of course, your mileage may vary but the mod list and original schematics schematics for reference are attached.

Component, Change, Effect
CR3, Single OA91, Assymetrical clipping of overdrive
R5, 470 up to 680, Increases diode clipping to reduce 'railing' of next stage. Sims showed that for high output guitar pickups,the first stage had inadequate headroom without this mod.
C6, Change to 330n, Additional Bass cut in full Sat mode which prevents the really buzzy breakup that occurs when the signal is reduced to a pure square wave. This was really prominenet with my Tele on the bass strings
C5, Change to 15n, Move 'Bright' to slightly higher freq. his made the amp 'sparkle' rather than shout (IMHO).
CR6, 1N4148 x2 series, Less harsh clipping (already implemented on the VTX)
CR5, 1N4148 x2 series, Less harsh clipping (already implemented on the VTX)
CR5, Parralel 100n cap shorting both dioeds to GND, Less high freq from distortion at full Sat. I used a panel mounted switch to select/de-select this feature). This really improved the Sat tone.
C10, 1u, Not essential, just tightens up clean channel
C11, 15n, Move 'Bright' to slightly higher freq. his made the amp 'sparkle' rather than shout (IMHO).
C17, 180p, Slight 1kHz 'scoop'. Or 220pF for less 1kHz cut
C18, 33n, More bass (post distortion stage)
R18, 47mH and 470R, Series Ind and Res in parallel with R18 gives addition mid 'bump' at full gain
C25, 20n, More high boost at full 'Presence'
R46, 1k, More high boost at full 'Presence'
C23, 10n, More high boost at full 'Presence'

All these mods had an effect but I was particularly pleased with the 100nF short of the SAT clipping diodes, and improvements to the Presence and Bright controls.

I also ultimately upgraded the speaker to a Jensen C12K (which is superb) but the sound was still hugely improved with the original Scorpion.

I should add that playing around with alternative op-amps yielded no discernible results (to my ear).

The mods sounded good with both my Tele 27 Custom RI and Gretsch P90 hollow body.

[ATTACH]33097[/ATTACH]

Cheers,

iep

I guess were in an age now that we can use a PC simulator program to actually help somewhat redesign certain amps to make them better. Not sure what the Peavey engineers were using back in the early 80s but This gives me hope for modding a few of my Peavey amps now.

I do want to ask iep, what style music are you playing thru the Bandit 65? Reason I ask is that I'm more a rock and metal guy.

Thanks

[iep]

Hi Slobrain,
I did try to make a recording using my iPhone when I had both the modded and original Bandits but the mic really isn't good enough to differentiate the tonal changes. You just end up hearing the room acoustic.

I can try to give a better description of the overall change though.

1. My aim was to get rid of the shouty/barky nature of the amp. I wanted more of a fender sparkle. I always thought the normal tone was a bit dull and the 'bright' setting was too harsh. Changes to the 'bright' setting were aimed at taming the mid and adding slightly more high frequency.

2. Similarly, I usually found myself running the amp in 'normal' (non bright) with the presence set very high. So, I modded the presence control to have a bit more boost at maximum and (similar to bright mod) a little less high/mid boost.

3. The use of asymmetrical diodes in the pre-gain circuit (not Sat circuit) worked with the mod to R5 increase their clipping effect. As I say, in stock format, it was possible to run this stage so the op-amp clipped which gives the nasty hard clipping distortion that no-one cares for. I like this tone for classic rock stuff. The addition of the Inductor and resistor in parallel with R18 served to give a mid bump at full pre-gain. This was an attempt to ape the mid boost of the tube screamer. Granted, the result is no tube screamer but it is better than stock.

4. Series clipping diodes in the Sat circuit increase the output of the preamp at full Sat (as swing is limited to 1.4Vpk rather than 0.7Vpk). This still allows plenty of 'gain' but with a bit more of the original guitar tone to make it through as the waveform is less clipped. I fairness, PV worked this out for themselves in subsequent designs. I think the Bandit was among the first to use this pre-amp. The switched 100nF cap in parallel with the clipping diodes makes for a nice creamy tone at full sat rather than the nasty buzz tone.

I don't think I have made a 'better' amp than the original. I.e. I am no smarter than any of the guys who did the original design. All I ave done is attempt to modify the tone for modern tastes. I'm pleased with the result. If the original design had been poor though, there was not way a few small changes like these would make so much of a difference.

As for style of playing, I play rhythm guitar in an indie/rock band. Main guitar for this is my Gretsch hollow body with P90 pickups. That said, the changes I have made to the amp allow a nicer scooped tone if Presence is run high and the Sat tone is also much nicer so I reckon it would be an improvement for metal too.

Hope that helps,

iep

[patlaw]

iep, where do you find OA90s? What other germanium diodes would be useful for this application? 1N34? 1N60? I shudder to think how many I threw away years ago. Then again, the current manufacturing processes for germanium semiconductors should cause them to be better parts than the old ones. That's the theory, anyway.

[J M Fahey]

Any germanium you can get will do.

And I doubt any are made anymore, last batch (say, from 1980 something) will still last years or decades, given the level of consumption.

So all should actually be NOS, even if not so labelled.

[Slobrain]

Hi Slobrain,
I did try to make a recording using my iPhone when I had both the modded and original Bandits but the mic really isn't good enough to differentiate the tonal changes. You just end up hearing the room acoustic.

I can try to give a better description of the overall change though.

1. My aim was to get rid of the shouty/barky nature of the amp. I wanted more of a fender sparkle. I always thought the normal tone was a bit dull and the 'bright' setting was too harsh. Changes to the 'bright' setting were aimed at taming the mid and adding slightly more high frequency.

2. Similarly, I usually found myself running the amp in 'normal' (non bright) with the presence set very high. So, I modded the presence control to have a bit more boost at maximum and (similar to bright mod) a little less high/mid boost.

3. The use of asymmetrical diodes in the pre-gain circuit (not Sat circuit) worked with the mod to R5 increase their clipping effect. As I say, in stock format, it was possible to run this stage so the op-amp clipped which gives the nasty hard clipping distortion that no-one cares for. I like this tone for classic rock stuff. The addition of the Inductor and resistor in parallel with R18 served to give a mid bump at full pre-gain. This was an attempt to ape the mid boost of the tube screamer. Granted, the result is no tube screamer but it is better than stock.

4. Series clipping diodes in the Sat circuit increase the output of the preamp at full Sat (as swing is limited to 1.4Vpk rather than 0.7Vpk). This still allows plenty of 'gain' but with a bit more of the original guitar tone to make it through as the waveform is less clipped. I fairness, PV worked this out for themselves in subsequent designs. I think the Bandit was among the first to use this pre-amp. The switched 100nF cap in parallel with the clipping diodes makes for a nice creamy tone at full sat rather than the nasty buzz tone.

I don't think I have made a 'better' amp than the original. I.e. I am no smarter than any of the guys who did the original design. All I ave done is attempt to modify the tone for modern tastes. I'm pleased with the result. If the original design had been poor though, there was not way a few small changes like these would make so much of a difference.

As for style of playing, I play rhythm guitar in an indie/rock band. Main guitar for this is my Gretsch hollow body with P90 pickups. That said, the changes I have made to the amp allow a nicer scooped tone if Presence is run high and the Sat tone is also much nicer so I reckon it would be an improvement for metal too.

Hope that helps,

iep

Hey iep,

Yes, I can understand trying to use a iphone or similar to record with... they are decent but not that good. I do want to thank you for the work you have done with the Bandit. I really wanted to finish getting my electronics degree back in 89 to do stuff like you have but sometimes things are just not in the cards. I do electronics repair but I don't know how to engineer circuits. I know tubes amps pretty darn good as I did a lot of modding back in the 90s but that was also with the help from the guys at the old Ampage forum. I built SLO 100 clones too and can build a tube amp.

I think for what the bandit is its a good amp for any club use. even recording too. after all the tone one chooses to use is in the ears and the desired use. Heck, Tony Iommi used a small amp with a ripped speaker to record his lead on the song Paranoid...

Over all I like to repurpose stuff when possible and I think there are a lot of good old amps that can be done with. All the new stuff coming out are just twists on old designs.. accept the modeling stuff which can be good or bad depending on the use. I find its mostly musicians that are critical to sounds. Back in my club days I used SS amps and tube amps and really no one in the bars or clubs ever really knew the difference except other guitarists.

Cheers

[Slobrain]

I took apart a MXR distortion + in 1990 and built a clone from that so hopefully I still have some of those old germaniums laying around to try... Of course there is always EBay... I was thinking that the MXR distortion + was actually a good pedal, too bad no one ever re-engineered it to make a better Distortion +... or maybe they did and I just didn't know they did...

[patlaw]

Any germanium you can get will do.

And I doubt any are made anymore, last batch (say, from 1980 something) will still last years or decades, given the level of consumption.

So all should actually be NOS, even if not so labelled.

I have no idea if germanium diodes are still in production, but a LOT of research using germanium in semiconductors is going on at the university level, primarily involving a mixture of silicon and germanium.

[J M Fahey]

I took apart a MXR distortion + in 1990 and built a clone from that so hopefully I still have some of those old germaniums laying around to try... Of course there is always EBay... I was thinking that the MXR distortion + was actually a good pedal, too bad no one ever re-engineered it to make a better Distortion +... or maybe they did and I just didn't know they did...

Oh, they did go on ... but you know Guitar players are so stubborn and absolutely refuse to use anything if [insert Guitar God Name here] didn't use itbefore.
No kidding.

Here's the very good MXR Distortion II :





but by then the Japanese broom had swept the American pedals away.

The last nail in the coffin was that many Guitar Gods did use Japanese pedals, as we all know.

EDIT: here's Distortion 3 .

It heavily borrows from Japanese, (think Boss) : the typical single bipolar transistor input buffer and the Tube Screamer type tone control.

[iep]

Hi Slobrain,
As you already said, eBay is your friend. That is where I get all my weird electronics components.

BTW, hooked up the bandit pre-amp to the power amp input of an old PV Classic VT 212 that I am repairing today. Sounded damned good.

Cheers,

iep

[Slobrain]

I bet that distortion II would sound better with a redesign removing the resonance and filter and adding a bass-mid-treble type eq to it. Cool looking pedal... I still have 2 Ibanez Distortion chargers from the late 80s. Waiting for the prices to go thru the roof to sell them on Ebay... they are good sounding pedals but I just don't use them any more... Sort of like a higher gain tubescreamer, kinda Van Halenish too.

[Silvertone Jockey]

I just received these 10x GE 1N60 Germanium Diodes NOS Fuzz Guitar Pedal Effects Crystal Radio NTE110A $5.99

10x GE 1N60 Germanium Diodes Fuzz Guitar Pedal Effects Crystal Radio NTE110A | eBay

[J M Fahey]

I bet that distortion II would sound better with a redesign removing the resonance and filter and adding a bass-mid-treble type eq to it. Cool looking pedal... I still have 2 Ibanez Distortion chargers from the late 80s. Waiting for the prices to go thru the roof to sell them on Ebay... they are good sounding pedals but I just don't use them any more... Sort of like a higher gain tubescreamer, kinda Van Halenish too.

Same here.

Both mods to original pedal make it bass heavy .... way too much.

Filter comes straight from RAT ... with the difference it does not have the RAT pre distortion high boost, and resonance stinks of trying to give kids with small amps the chest pounding only a 4x12" has .

Both will make it muddy and farty.

Now if you set both controls off, pedal becomes a distortion+ on steroids.

I remember a similar pedal, think was the TC Electronics version, which was basically the same but very well made, and included a compensated XLR out, so it could be carried in the gig pack as a backup and worst case plugged straight into PA with very acceptable results, and using any crappy amp available as onstage monitor.
Cool pedal.

[Leo_Gnardo]

I just received these 10x GE 1N60 Germanium Diodes NOS Fuzz Guitar Pedal Effects Crystal Radio NTE110A $5.99

These days that's an excellent price. Ge are a bit sensitive to heat. Good idea to use heatsink clilp when soldering-in.

[goldtop5]

I used to own a Peavey Bandit 50w that sounded pretty good back in the day (mid to late 80s). I would set it clean and used stompboxes to get a good sound. The PA carried it the rest of the way. It got stolen and I never saw it again. But once you go to a tube amp, you'll never go back (in live applications). Here are my amps over the past 3 decades in chronological order: Peavey Bandit, Peavey Century, Marshall Valvestate vs100, Marshall JCM2000 dsl100 (sold it, and I'll guess most of you know why), Soldano SL-60, Fender Prosonic combo, Peavey classic 30, Peavey classic VTX, and a Marshall Vintage Modern 2466. Tube amps just sound better, especially when you turn them up. A solid state amp will break down and sound muddy when you crank it. One thing I have to give to the old Peaveys is that they were built to last forever. The old circuit boards were flexible. I'm sure someone out there is enjoying my once old faithful workhorse!

[noizreduxion]

Hi. Just wanted to thank you iep for sharing that dope mod you made on the Bandit 65. I have almost followed every steps except for C18 wich appeared to already be 33nF on my board plus I also replaced all other electrolytic capacitors by new ones.
The amp sounds far better now, got a little more crontrol on the whole volume boost but mostly as you said it now "sparkles" more than it yells.
I use this amp along with my recently retunned Rhodes stage piano I am actually learning playing on. I could not offer that holly grail Fender Twin Reverb for now so I went with this Bandit 65 that used to belong to my father and it sounded no so bad soon as you didn't push distortion stage.
Most issues that appeared to my ears are now gone with your mod, more clarity when pushing highs instead of high-mids yelling, basses seam a little more rounded, less compressed I would say, Lovely for a solid state amp. I am still running with the Scorpion speaker in it but I guess the next step will be speaker swapping. Once again thanks a lot for this great mod mister !!