NAD vibrolux

Discussion in 'Ampage Area' started by cowmoo, Oct 22, 2020.

  1. cowmoo

    cowmoo Country Gent

    Aug 19, 2011
    North Wales
    831C2AC3-69B6-46C9-A2CC-0975F0AAB612.jpeg 78879864-5810-4BA7-B781-55E53C69525A.jpeg 9FB9CB2A-4AA3-46E0-803F-02A53B9A2157.jpeg 76952D31-8D5F-414B-B4A6-AEFC5EE303A7.jpeg Just picked this up for £600.
    It’s in good nick.
    Got the factory standard white noise issue.
    Sounds just like i expected otherwise.
    Not sure how old it is?
  2. cowmoo

    cowmoo Country Gent

    Aug 19, 2011
    North Wales
    Not had chance to crank it yet, probably won’t for a while but even at low volume the crispness in the response (is that a term?) makes it so much more giving than the bassman, which sounds more reluctant to give you an easy ride.
    It’s really noisy though, and i’ve already prepared myself for the possibility of purchasing the Fromel mod kit.
    Tremolo is very noisy with the reverb on.
    I tried the bassman through the two Jensens by disconnecting the vibrolux and it was much nicer than the 2x12 v30 cab, so that reinforces my 2x10 cab build plans for that.
    Noise aside I like it so far.
  3. speedicut

    speedicut Friend of Fred

    Jun 5, 2012
    Congrays cowmoo, I love my 69 Vibroluxe.
    I had mine rewired and it sounds great... no noisier than my Twin
    cowmoo likes this.
  4. Tele295

    Tele295 Country Gent

    The CVR circuit had a noise issue because it has no negative feedback loop (unlike a vintage Vibrolux Reverb or Twin). I’ve heard that installing a NFB loop will reduce the noise.
    MKunie, Groutsch and cowmoo like this.
  5. cowmoo

    cowmoo Country Gent

    Aug 19, 2011
    North Wales
    Yes, i’ve been reading up on the mods for this but am a bit wary as there is a lot of caution about the tracks being very thin and flimsy on the boards.
    The hiss i could live with but when the tremolo intensity is raised it becomes annoying!!
  6. Tony65x55

    Tony65x55 Gretschified

    Sep 23, 2011
    The 'Shwa, Ontario, Canada
    I knew you'd like the Bassman through the 2x10" Jensens. :)
    pmac11, MKunie and cowmoo like this.
  7. Byron

    Byron Synchromatic

    Sep 4, 2009
    Oo, oo, ooooh! Like that! And I'm a big believer in 10" speakers, shout it out!
    cowmoo likes this.
  8. hcsterg

    hcsterg Friend of Fred

    Feb 13, 2012
    @cowmoo ; this (apparently well-known) issue can certainly be corrected, right ? o_O

    But as I never saw a VR RI coming in for repair/service, I can't tell... :oops:

    MKunie and cowmoo like this.
  9. cowmoo

    cowmoo Country Gent

    Aug 19, 2011
    North Wales
    Indeed! There’s a response in this sound i don’t get from the bassman and 2x12 v30’s. It feels alive when played even at low volumes. My Gretsch actually has a twang now!! I’ll probably keep the bassman but the 2x12 v30 cab is a goner!! :D
    It’s the way i’m heading mate. I’ve been waiting for a baffle to be made( i could have done it myself a dozen times by now) for a 1x12 conversion for the bassman or i’m going to get a 2x10 combo cab made for it thanks to a kind chap on here.
    I believe so, there are simple mods to make it have lush reverb a nfb loop and eliminate hiss. I’m worried my soldering iron may be too aggressive so need a new one before attempting them!!
    hcsterg likes this.
  10. Ricochet

    Ricochet I Bleed Orange

    Nov 13, 2009
    Monkey Island
    Congrats, nice pairing with the Phoenix!
    MKunie and cowmoo like this.
  11. Lucky Jim

    Lucky Jim Electromatic

    Oct 16, 2020
    Kent, England
    There was one for sale in Telford a few weeks ago for £1k so you did well at £600. It makes the cost of having the noise issues fixed more palatable. Love that Gretsch btw :cool:
    cowmoo likes this.
  12. cowmoo

    cowmoo Country Gent

    Aug 19, 2011
    North Wales
    Yes i’d spoken to the seller when it was up at 11 or 1200, so glad i didn’t act in haste.
    Looking at the Fromel kits they’re about £80. (A few reaistors and caps)
    I will talk to my friend and i’m sure he’ll tell me what to replace with locally sourced parts.
  13. cowmoo

    cowmoo Country Gent

    Aug 19, 2011
    North Wales
    image.jpg Got it opened up now.
    Looks good so far. someone has had it apart but been kind enough to leave placement tags on the cables!!
    I was going to squirt the crackly pots but i’ll leave that until mod time because of those poxy boards!!
  14. cowmoo

    cowmoo Country Gent

    Aug 19, 2011
    North Wales
    I bet there’s a kit to ptp wire this!!
    Tele295 likes this.
  15. swivel

    swivel Country Gent

    May 13, 2018
    Buy an AB763 eyelet board and some good wire and convert that amp to PTP! Just re use the pots after taking that PCB off of them.
    I did a Deluxe Rev RI years ago, it wasn't too hard to do.
  16. Axis39

    Axis39 Country Gent

    Jun 2, 2008
    Beaumont, CA
    The problem with this is it's not exactly an AB763 amp. It is the beginning of the ab763 amps. It is actually based on the 6g16 Vibroverb circuit. It's a brownface amp in transitional clothing.

    I haven't gone component to component on the circuit. I do know there are a number of EQ and tone shaping values that are different, though the gain structure is similar, to the blackface amps. But, the tremolo is the biggest difference. This amp has bias vary trem and blackface amps (other than the Princeton) had the optocoupler bug trem.

    I have a '63 Vibroverb Reissue, which is the predecessor to this amp. It's a little cleaner, and no hiss... Due to the NFB mentioned earlier in this thread. Love that amp. Not sure I will ever sell it!
    pmac11 likes this.
  17. cowmoo

    cowmoo Country Gent

    Aug 19, 2011
    North Wales
    So they are real pots under the pcb? Cool.
    I was looking for a vibroverb, but they were all holding out the prices, there were used Rift vibro35’s for similar money and they are ptp but all this lockdown crap we’re having put paid to collecting amps.
    I thought this was opto trem unlike the VV?
    This sure makes some clickety clack sounds as you ramp up the intensity!!
    I did notice there was a 12ax7 in v3 not the required aT7

    may have misunderstood about tremolo
    Axis39 likes this.
  18. swivel

    swivel Country Gent

    May 13, 2018
    Yeah, true if you want to keep that architecture. I wonder how hard it would be to duplicate in that chassis? So it has Bias Vary like the Princeton? Not the tube trem like a brown Super?

    The DRRI had real pots, but they are direct soldered to the narrow PCB. However, I just unsoldered and wrapped a wire around the solder points and they were smooth and quiet. Some people replace them and driill out the faceplate and chassis. But frankly those pots, although small body, were just great ....and smooth compared with my vintage BF amps!
    Axis39 and cowmoo like this.
  19. swivel

    swivel Country Gent

    May 13, 2018
    I should add in here: Converting an amp isn't for everyone, and if your amp works fine and you like it ... dont! I don't want to promote this too much except for the person who likes to tinker! :eek::rolleyes::D
    Axis39 and cowmoo like this.
  20. cowmoo

    cowmoo Country Gent

    Aug 19, 2011
    North Wales
    I like to tinker, but if i can get it to have less hiss, bigger reverb, smoother tremolo and add nfb and maybe a bias pot with this board in i’ll gladly leave it.
    The first 3 are addressed with the Fromel kit.
    Theres a few results i can follow for the other 2 on the wide wide world of web!!

    ...but i’ll probably get stuck and start a ‘how to’ thread here !! ;)
    Last edited: Oct 26, 2020
    Axis39 likes this.
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