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Author Topic: NAD 90s Carvin Tube 100  (Read 9978 times)

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Systematic Chaos

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NAD 90s Carvin Tube 100
« on: Time Format »

Did I mention that you gotta love Japan  ;D ;D ;D

Just scored a '93 Carvin Tube 100 off Yahoo Auctions here in Japan for a blasting 85€.
Nice 2U rack poweramp from the early 90s with the even nicer feature of a 120/240V switch.
Other than that it's a basic 2x50w stereo tube poweramp. Gotta check how it sounds once it's delivered.
I'm not too fond of EL34 sound though....gotta wait and listen.

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rnolan

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Re: NAD 90s Carvin Tube 100
« Reply #1 on: Time Format »

Hey SC, great score, I'm pretty sure you'll like it.  I suspect the new version which I have is very similar, they put the presence knobs on the front but apart from that it looks the same(ish), now mine can run 6L6 (which is how it came) or EL34, may be so can that one ?
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Systematic Chaos

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Re: NAD 90s Carvin Tube 100
« Reply #2 on: Time Format »

I’ve briefly compared the schematics and there’s quite some differences. My “old” one seems EL34 only. Big win though is the voltage selection switch so I can use it both here and in Europe.
Everything else is pretty straight forward and simplistic. Maybe the circuitry can be modded to accept 6L6/5881....will have to check with MJMP on that

http://carvinimages.com/schematics/Tube100%20Output%20Schematic.pdf
« Last Edit: Time Format by Systematic Chaos »
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Harley Hexxe

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Re: NAD 90s Carvin Tube 100
« Reply #3 on: Time Format »

Great find SC!  :thumb-up:

    I see the Presence knobs on the back of it for each channel.
    Don't they run 100V in Japan?

    In any case, what I was looking for on the back and don't seem to see, is a voltage bias for tube replacement. Hopefully there is one on the inside on the PCB. That would definitely cut the cost on a tube change.

    Who knows? You might like the tone of this one with EL34's.
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rADAr

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Re: NAD 90s Carvin Tube 100
« Reply #4 on: Time Format »

This is a what I currently have with my AXE-FX II. This early version can only use EL34 tubes, I think. It sounds good to me, but I find the clean sounds can be a little lacklustre - after having owned the Mesa 2:90 with 6L6's for comparison, that is. Enjoy, look forward to hearing how you like it...!
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MarshallJMP

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Re: NAD 90s Carvin Tube 100
« Reply #5 on: Time Format »


Everything else is pretty straight forward and simplistic. Maybe the circuitry can be modded to accept 6L6/5881....will have to check with MJMP on that

http://carvinimages.com/schematics/Tube100%20Output%20Schematic.pdf

Let me know if I can help out.
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Systematic Chaos

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Re: NAD 90s Carvin Tube 100
« Reply #6 on: Time Format »

Great find SC!  :thumb-up:

    I see the Presence knobs on the back of it for each channel.
    Don't they run 100V in Japan?

    In any case, what I was looking for on the back and don't seem to see, is a voltage bias for tube replacement. Hopefully there is one on the inside on the PCB. That would definitely cut the cost on a tube change.

    Who knows? You might like the tone of this one with EL34's.

Yeah, JPN is 100V but there's lots of US-Voltage gear operated and running here with no problems.
While rechecking the schematics there's bias pots for each side (l & r), so no biggie re-biasing after a tube change.
I've modded various Boogie fixed bias amps in the past so even if this would've been fixed I would've had no headaches with it ;-)


Everything else is pretty straight forward and simplistic. Maybe the circuitry can be modded to accept 6L6/5881....will have to check with MJMP on that

http://carvinimages.com/schematics/Tube100%20Output%20Schematic.pdf

Let me know if I can help out.

@MJMP: Thanks bro! I was wondering if there was a way (maybe by tinkering with/modding the circuitry) to run 6L6/5881 tubes in the amp. I've linked the schematic above and attached all revision schematics...
Will post gut-shots once I have the amp on hands
« Last Edit: Time Format by Systematic Chaos »
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Harley Hexxe

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Re: NAD 90s Carvin Tube 100
« Reply #7 on: Time Format »

Hey SC,

     Tell me you are at least going to check the amp out as is with your rig before you start tinkering with the circuitry.
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Systematic Chaos

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Re: NAD 90s Carvin Tube 100
« Reply #8 on: Time Format »

No worries Harley, I’ll give it a thorough check. But there’s a reason I’ve ditched all EL34 based poweramp stages in favor of 6L6/5881 ever since. The only exception is when running 6L6 in Class AB and 34 in Class A simultaneously (Boogie Mk SimulClass)
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Harley Hexxe

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Re: NAD 90s Carvin Tube 100
« Reply #9 on: Time Format »

Hey SC,

     If you don't mind me asking, what's the reason?
     I've been using 6L6 power tubes for years, and I feel the need to try something different, so this is why I went with the power amps I have now. I'm definitely getting a pronounced, and articulated bottom end response from these with a nice midrange, so I'm pretty happy with them.
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MarshallJMP

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Re: NAD 90s Carvin Tube 100
« Reply #10 on: Time Format »

Well looking at the schematic you should be able to put 6L6's in it. Bias range goes to -57V so that should be enough for 6L6's.Heater current is less with 6L6's so that should be a problem either. Raa is a bit higher with 6L6's but not much so should be a problem either.
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Systematic Chaos

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Re: NAD 90s Carvin Tube 100
« Reply #11 on: Time Format »

Hey SC,

     If you don't mind me asking, what's the reason?
     I've been using 6L6 power tubes for years, and I feel the need to try something different, so this is why I went with the power amps I have now. I'm definitely getting a pronounced, and articulated bottom end response from these with a nice midrange, so I'm pretty happy with them.

No problem asking....
My preferred sound typology is Boogie Mk (IIC+, IV) which is mid heavy by itself. I tried it paired (Studio Preamp, Quad Preamp, Triaxis) with various EL34 power stages and it simply sounded meeeh. For my tastes it works best with either pure 6L6(W)GC, 5881 or in SimulClass mode (2:90, 295).
Since I don't gig out that often atm (mostly Madison Square bedroom and only some "Open Stage" events and maybe a hired hand job every 2-3months) I left the big WOMS in Germany in storage and only took the AxeFXII with me to Tokyo....(I nevertheless gave in to GAS and got myself a JP2C head).
Main aim for the Carvin Tube 100 now is ti pair it with the AxeFXII...and for that I wanna keep it as clean as possible, which is where the 6L6 excels over the EL34.

Well looking at the schematic you should be able to put 6L6's in it. Bias range goes to -57V so that should be enough for 6L6's.Heater current is less with 6L6's so that should be a problem either. Raa is a bit higher with 6L6's but not much so should be a problem either.

Thanks for that quick reply...I´ll give it a go once I've checked how it sounds with the EL34. Re-checking the schematic I couldn't find an Input 12AX7, just 2 PIs, correct?!
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Harley Hexxe

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Re: NAD 90s Carvin Tube 100
« Reply #12 on: Time Format »

Hey Sc,

     So basically, you are thinking about upgrading this old Carvin to the specs of the newer ones with no amp character added to it, if I'm following you correctly.
    It seems you prefer that 6L6 punch over the softer EL34 compression.
    I was looking for a Simul-Class power amp because I kind of get the impression that you can get the best of both worlds with those, depending if you run Class AB or Class A. I could be misunderstanding that difference in those amps though. In any case, I'm going to be sticking with tubes for the power section whenever it's reasonable to do so.
   I'll still keep the B200S for situations where the tube amps would be too much.
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Systematic Chaos

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Re: NAD 90s Carvin Tube 100
« Reply #13 on: Time Format »

With the SimulClass amps I had I only used them in SimulClass, running AB and A simultaneously. It adds something to the sound that’s hard to describe...more complexity.
Check out a 2:90 if you get the chance and you’ll know what I mean.

With this Tube 100 I am just trying to find easy workable possibilities if I come to the conclusion that the EL34s won’t do it for me. Dropping a quad of 6L6s in there and just re-biasing sounds easy enough  8)
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Harley Hexxe

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Re: NAD 90s Carvin Tube 100
« Reply #14 on: Time Format »

Okay,
   the 2:90 is basically two 6L6 power amps side by side, correct?
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