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Author Topic: NPD - Mesa Boogie V-Twin Preamp  (Read 6023 times)

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Systematic Chaos

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NPD - Mesa Boogie V-Twin Preamp
« on: Time Format »

just found one in a Tokyo 2nd hand / pawn shop for 80$ and couldn't pass.....
Mesa Boogie V-Twin preamp pedal.... 2 1/2 channels all tube/analog, hand-built like a tank :

It's definitely not an ultra high-gain preamp but it does everything up to hard-rock/metal and it takes an OD pedal up front real well (tried it with a Maxon OD808 and an MXR GT-OD).
It still had the original Mesa 12AX7 Russian 2 (aka EH) tubes in but those had reached the end of the musical life-span.
Found some NOS Groove Tubes GT12AX7M (!!!!) in a music shop and now this baby shines
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rnolan

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Re: NPD - Mesa Boogie V-Twin Preamp
« Reply #1 on: Time Format »

Very cool SC  :thumb-up:
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MarshallJMP

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Re: NPD - Mesa Boogie V-Twin Preamp
« Reply #2 on: Time Format »

I wonder how you do it  ;D you always find great deals.  :thumb-up:
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Samuraipanda

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Re: NPD - Mesa Boogie V-Twin Preamp
« Reply #3 on: Time Format »

I had one for a year, the 2nd version. Good sounding and I should have kept it. $80 ?????
I sold mine for $325 and I've seen them on CL for $400+

I thought it was a bit flubby in the low end but didn't really take a lot of time trying to add an eq pedal to it to see if I could tighten up. I got it around the same time I picked up the 3.666 mod MP1 and I spent much more time tweaking that.  :homer:

Great deal!

Let me know if you can find any Washburn KC100 guitars over there... I would love to get a third.
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Systematic Chaos

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Re: NPD - Mesa Boogie V-Twin Preamp
« Reply #4 on: Time Format »

I had one for a year, the 2nd version. Good sounding and I should have kept it. $80 ?????
I sold mine for $325 and I've seen them on CL for $400+

I thought it was a bit flubby in the low end but didn't really take a lot of time trying to add an eq pedal to it to see if I could tighten up. I got it around the same time I picked up the 3.666 mod MP1 and I spent much more time tweaking that.  :homer:

Great deal!

Let me know if you can find any Washburn KC100 guitars over there... I would love to get a third.

It is indeed flubby on the low end, but a TS-Type OD up front takes care of that and the result is 100% Boogie Mk-meets-Recto.
I nevertheless attached the schematics...maybe MJMP can point out if theres potential for some possible mods part-value wise to tame the low end flub and tickle some more gain ;-)
 
There are some Washburn KC100 guitars on the used market here, average going rate on them 90-150$. Problem with getting them to your doorstep is CITES....
Thatś easier with the Ibanez Pro Line series you asked about....those are ebony or maple fretboards. A good used 1996 PL5510 e.g. goes for roughly 300$
« Last Edit: Time Format by Systematic Chaos »
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MarshallJMP

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Re: NPD - Mesa Boogie V-Twin Preamp
« Reply #5 on: Time Format »

Ok I'll have a look at it!
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Samuraipanda

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Re: NPD - Mesa Boogie V-Twin Preamp
« Reply #6 on: Time Format »

$90-$150 ???? Wow!!!
I've had offers of $1200-$1500 each for my KC100's here in the states. I thought the bans on Rosewood sales were limited to just raw wood or new production. Can you PM me some of the listings?
I might try to figure out a way to get them here at those prices. 
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MarshallJMP

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Re: NPD - Mesa Boogie V-Twin Preamp
« Reply #7 on: Time Format »

SC, I saw it has 2 channels, a clean and a dirty or am I wrong, I'm guessing you want to alter the dirty channel?
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Systematic Chaos

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Re: NPD - Mesa Boogie V-Twin Preamp
« Reply #8 on: Time Format »

SC, I saw it has 2 channels, a clean and a dirty or am I wrong, I'm guessing you want to alter the dirty channel?
MJMP, thanks for tyour reply and taking the time!!

It actually has 2 1/2 channels. Channel 2 can be switched (see the black switch in the middle of the pedal) from a low gain "Blues" to the high gain "Solo". I be interested in slightly altering/tightening up the dirty channel.
I'm nowhere near you in reading schematics but my take is that the initial dist/gain is produced by a TL072 going into an array of clipping diodes. I already though of maybe a 2604 instead of the TL072 to make that a bit more organic....
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Hanneman213

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Re: NPD - Mesa Boogie V-Twin Preamp
« Reply #9 on: Time Format »

Probably the seller thought that this was a AM radio.
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MarshallJMP

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Re: NPD - Mesa Boogie V-Twin Preamp
« Reply #10 on: Time Format »

SC, I saw it has 2 channels, a clean and a dirty or am I wrong, I'm guessing you want to alter the dirty channel?
MJMP, thanks for tyour reply and taking the time!!

It actually has 2 1/2 channels. Channel 2 can be switched (see the black switch in the middle of the pedal) from a low gain "Blues" to the high gain "Solo". I be interested in slightly altering/tightening up the dirty channel.
I'm nowhere near you in reading schematics but my take is that the initial dist/gain is produced by a TL072 going into an array of clipping diodes. I already though of maybe a 2604 instead of the TL072 to make that a bit more organic....

SC, I send you an email with some things to try out, if you like them you can post them here.
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Systematic Chaos

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Re: NPD - Mesa Boogie V-Twin Preamp
« Reply #11 on: Time Format »

Got it MJMP, thanks.
Here's for all:
Well you could lower C22 and C23 to roll off some bass freq, or C24 (I would start with 1µF and go from there.
 
Gain wise, there is a lot to begin with (around 2000x with the opamps), you could raise R28 to get more. But you need to be carefull that the noise doesn't get too high.
 
You can also play around with the diodes, replacing them with led's.

I'll tinker around with it during my summer leave and I'll let y'all know

Short Qs:
- Do you mean C22, C23 and C24 altogether (C24 has polarity, right?) Any special recommendations on type/brand/value?
- By how much should I raise R28 to get just a tad bit more gain?
- Do you think I'll get some improvements if I swap U4 (TL072) for an OPA2604?
- Clipping wise I actually prefer the softer clipping Silicon diodes over LEDs...
« Last Edit: Time Format by Systematic Chaos »
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Dante

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Re: NPD - Mesa Boogie V-Twin Preamp
« Reply #12 on: Time Format »

Got it MJMP, thanks.
Here's for all:
Well you could lower C22 and C23 to roll off some bass freq, or C24 (I would start with 1µF and go from there.
 
Gain wise, there is a lot to begin with (around 2000x with the opamps), you could raise R28 to get more. But you need to be carefull that the noise doesn't get too high.
 
You can also play around with the diodes, replacing them with led's.

I'll tinker around with it during my summer leave and I'll let y'all know

Short Qs:
- Do you mean C22, C23 and C24 altogether (C24 has polarity, right?) Any special recommendations on type/brand/value?
- By how much should I raise R28 to get just a tad bit more gain?
- Do you think I'll get some improvements if I swap U4 (TL072) for an OPA2604?
- Clipping wise I actually prefer the softer clipping Silicon diodes over LEDs...



AaAAAAaaaaannnnnddd, right about here is where I get that look on my face like I need to droooool cuz I don't understand -SQUIRREL!- what's going on and -PRETTY BIRD!- I kinda have that blank look on my face like -BAHAMAS!- I'm somewhere else

R28, opamps, softer clipping Silicon diodes?!?!

SORCERY!!
« Last Edit: Time Format by Dante »
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MarshallJMP

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Re: NPD - Mesa Boogie V-Twin Preamp
« Reply #13 on: Time Format »

Don't say that too loud or the internet inquisition will lock is up and torture us  >:D
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Systematic Chaos

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Re: NPD - Mesa Boogie V-Twin Preamp
« Reply #14 on: Time Format »

Conclusion:
- changed R28 from 100k to 120k metal film
- swapped the TL072 (JRC072D) to a BurrBrown OPA2604AP
- lowered both C22 and C23 from 1µF to .33µF Mallorys
- lowered C24 from 22µF to 2.2µF Panasonic Gold

This thing delivers! You still have to use an OD set to Clean Boost settings up front to tighten it all up and make it sing....but then so it does.
The lead Channel is a mix between Recto and Mk, the Blues Channel is a Californian flavored Brown sound and the Clean Channel is dead on Blackface.
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