Genz Benz GBE 750 tube options +

Discussion in 'Amps and Cabs [BG]' started by etherealme, Jul 5, 2020.


  1. etherealme

    etherealme Supporting Member

    Jun 26, 2007
    Louisiana
    Hi all.

    So, I have poked around here for a bit for something related to my question before posting.
    I really love the sound of my GBE 750 and have been using it for years with various cabs. Right now I am running a 1x15 Faital speaker (800w) and another 4x10 Faital cab to the same effect. I just don't find that I like the grind or warmth the tube gain produces so I run the tone really clear.

    Have any Genz users tried switching out their tube in the preamp for a different "color" tone with any success? Does this sound like a feasible idea for changing the colorization of that preamp?

    I don't want anything drastic. I do find I like the natural clear tone this amp is voiced with but have never achieved a grit tone I dig though most people that stick with the Genz GBE rave about the tube preamp which I have never cared for when gain is applied and it's being driven.
    A month ago I used an Ampeg Pf-800 and got some wonderful grit from the gain stage on that amp which was surprising since it's a class D. It was subtle but more a pleasing voicing. Hope that helps with the sound I am chasing. Any 12AX7 tubes that would give more usable grit? Not a "fuzzy buzzy" overdriven thing, that's why I mention the Ampeg tone.

    On the Genz I usually run everything flat, EQ at 12 with the gain up at 10:00 and the master between 8 and 10 only. I may roll off the high knob a quarter to 9:00 depending on the bass used. I don't care for the eq frequencies or I find them unusable at any rate.
    It's a great reliable, very loud amp so I don't want to just dump it for something else.

    Thoughts welcome. Thanks!
     
    Last edited: Jul 5, 2020
  2. You can try one of the many drive type or preamp type pedals that are out there to change the tone to your desires quick and easily and keep that amp as good clean power.
    The Sanamp, the Ampeg SCR-DI or the VT-Bass will hep get you there.
     
    etherealme likes this.
  3. etherealme

    etherealme Supporting Member

    Jun 26, 2007
    Louisiana
    I have a Tech 21 Sansamp GT2 on the way as we speak, so that is reassuring. What if I just have never liked the "colorization" from that 12AX7 in the gain stage of the amp though? Could I try to get some different voicings via change out of the tube? Or is there just a nominal difference to be had?
     
  4. Not sure how the tubes effect in this amp, lets ask the guy who designed it.
    Mr. @agedhorse, help please.
    Thank you.
     
    etherealme likes this.
  5. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    The differences are going to be quite subtle between preamp tubes, MUCH less than I think you are looking for.

    The PF-800 doesn't have a tube preamp, so maybe what you are looking for is an entirely different voicing rather than a different tube?
     
    wave rider and S-Bigbottom like this.
  6. etherealme

    etherealme Supporting Member

    Jun 26, 2007
    Louisiana
    First off, I feel honored to be given such focus and let me say thanks in advance.

    To attempt to clarify, I love the Genz for what it does clean. I would like to have been able to utilize the tube preamp for what I assume it is designed for in giving the tone some variation when warranted. Even though the Ampeg class D mentioned does not have a tube preamp, I am assuming the gain section of this amp was designed to model something like it when pushed.
    What more can I do to make the GBE 750 preamp more versatile rather than using it as a flat reproduction of my bass? I don't like what sounds it produces when the gain of the tube preamp is turned up so I thought that could lie in the tube characteristics / manufacture.
     
  7. hasbeen

    hasbeen Commercial User

    Sep 23, 2004
    Vice President, KMC/JAM USA: Distributor of Ashdown amplification
    Can you explain either what you don't like about the tone when it is tuned up or explain what tone you're looking for. Are you looking for overdrive? If so, that isn't what it was designed for.
     
    S-Bigbottom, etherealme and agedhorse like this.
  8. etherealme

    etherealme Supporting Member

    Jun 26, 2007
    Louisiana
    No, I am not looking for an overdriven tone. Realize and understand I have owned this Genz amp for over 12 years now. It's just not a pleasant voicing to me. I always have run the amp super clean with very little gain dialed in and never utilize the eq either so I am just looking for different options for versatility rather than basicaltt a big virtually clean power amp with no other function.
    It doesn't really warm up the tone - it just sounds like unpleasant muddiness and clipping (though it's not sending a clipping light.)
    I was just trying to get more variation out of the amp. Why load it with a tube preamp that has zero applicability.
    The Ampeg despite being a class D amp just had a warmth I was seeking yet, WITHOUT any tube preamp, so that was shocking.
     
  9. BassmanPaul

    BassmanPaul Inactive

    You seem to be misunderstanding what a tube does. Adding a tube stage is not for adding distortion or drive. It's to provide a tonality that the designer feels applicable to his/her amplifier design.

    You have owned this amplifier for more than twelve years but have never been happy with it. Thats fine - one particular amplifier will not please everybody. Why not just sell the thing and buy that Ampeg that has the sound that your are seeking??

    Why would it be shocking that a Class D amplifier be warm?
     
    hasbeen likes this.
  10. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    The amps have 2 entirely different voicings. If you don't like the GBE-750's voicing, there's nothing you can do to change that aside from using the eq and tone shape filters (which I assume you have tried in the past 12 years).

    If the amp doesn't work for you, sell it and find something that does. Changing the tube isn't going to get you there... or even close.
     
    hasbeen and BassmanPaul like this.
  11. etherealme

    etherealme Supporting Member

    Jun 26, 2007
    Louisiana
    Ok, fine. I'll bite. What does a tube DO then?

    I'm just trying to find out what characteristics would come about in changing the preamp tube. All kinds of preamp tubes have tonality in their manufacturing characteristics. The GENZ is great; it's fine. I never said I didn't like it. I have played all over the place with it. You're trying to say changing the tube isn't going to change a thing? People change their amplifier tubes all the time because different components render varying alternative sounds.
     
    Last edited: Jul 15, 2020
  12. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    As the designer of said amp, changing the tube will result in very subtle differences. Nothing that would change anybody's opinion either way about the amp.
     
  13. etherealme

    etherealme Supporting Member

    Jun 26, 2007
    Louisiana
    Fair enough. I guess I AM after all, quite attached to the Genz as I have identified with it's tone for many a year so my original inquiry was based on fear of parting with an old friend that has been a solid work horse. It's as reliable as it gets and the low end boost is a hell of a feature running out of 15s.

    I guess I was presented with a surprisingly punchy more midrange, unexpected tone that I was wondering if I could achieve somewhat close results by modifing a known component of the GENZ. I accept intended results not being in the spectrum of what the tube is going to affect. Just searching for options rather than going chasing GAS by dumping amp after amp after amp etc....
     
  14. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    Try some different amps.
     
    BassmanPaul likes this.
  15. Wasnex

    Wasnex

    Dec 25, 2011
    I don't have a GBE750, but I do have a GBE1200 which I suspect has pretty much the same preamp design. Maybe @agedhorse will confirm or correct this assumption.

    I also have quite a bit of experience rolling tubes.

    First I will say I agree that rolling tubes is unlikely to have a major effect on the voicing of the amp. In my experience, trying different tubes may make no difference at all, or it may make a subtle change. Sometimes the subtle change can be enough to impact how you feel about an amp though, so it can be worthwhile in some amps, and totally pointless others. I have not rolled tubes in my GBE1200, and I don't think the tube channel sounds particularly tubey by itself, although it does sound a bit less focused than the FET channel.

    My GBE1200 may be my favorite amp at out 28. I find that it is very easy to dial in, and to be honest the amp's voicing is very close to what I like without any major tweaks. By nature it is a very clean and smooth sounding amp IMHO. It also has a lot of slam without getting muddy.

    In order to get it to sound a bit more tubey I use the "Mix" feature, which engages both preamp channels simultaneously. I set the basic tone that I want with the FET channel and then use the tube channel with some very aggressive EQ to get the tubey feel, and maybe a bit of grind.

    I suggest experimenting with the Gain and tone controls on the Tube channel one at a time. Really crank up one of the tone controls and then advance the Gain until the channel is barely breaking into OD when you pluck hard. Next set the Volume on the tube channel to get the desired blend with the FET channel. Once you get a feel for how the individual tone controls work with the gain, adjust to taste.

    Keep in mind you're really just adding enough of the Tube channel so the frequency range that is peaked by the tone controls is poking through over the basic sound you have dialed in with the FET channel. This helps you to dial out any harsh distortion. Don't be afraid to peak one tone control and dip another if necessary to get the sound you want. If I remember correctly, the tone controls come after the tube stage, so the tone controls are not determining which frequency band breaks up, rather they are shaping the signal after the distortion is developed.

    I don't know exactly how the tube is used in GBE circuit or how it is tuned, so I don't know how or if it will respond to different tubes. I have done some experiments with 12AX7s that were pushed into OD and my favorites were the Chinese version of the Gold Lion ECC83 and also some Chinese 12AX7Bs that I bought from Antique Electronic Supply. Both tubes sounded very similar, and the Gold Lion was just slightly better in my opinion. I like the Russian B759 version of the Gold Lion better for clean circuits. Keep in mind that tubes respond to circuit conditions so there is no guarantee that the tubes I am suggesting will be great in the Genz Benz. They may sound a little better, they may sound exactly like the tube that is already in the amp, or they may sound like crap.

    In my experience the preamp drive produced by most amps is pretty resistant to change. If you want a drastically different sound, I suggest trying various pedals. If you want a different voicing overall, try a different amp. A different tube may help, but I would not expect a major change.
     
    Omega Monkey, etherealme and TonH like this.
  16. TonH

    TonH

    Jan 26, 2011
    The Netherlands
    Like Wasnex says, use the Mix feature and cut the low mids (250Hz) on the tube channel.
     
  17. hasbeen

    hasbeen Commercial User

    Sep 23, 2004
    Vice President, KMC/JAM USA: Distributor of Ashdown amplification
    Apologies, but I'm not understanding your comment above about "punchy more midrange". Are you saying that amp has too much punch or not enough?
     
  18. turcmic

    turcmic Supporting Member

    Jul 30, 2006
    Montreal, QC
    I understand your feeling. I bought a Shuttle 6.0 10-15 years ago (I had a GBE750 prior to that) and it’s been my only amp since until I wanted something different. I did change the tube but as AH mentioned, no significant change in tone. During all these years, I bought effect pedals to alter the tone based on the things that were required for my gigs. For example, I used a Sansamp for an emulated tube-like sound to my satisfaction.

    I went full tubes last year when I bought a SVT (that thing is loud!) and more recently a V4 (guitar equivalent of a V4B but sounds really good with bass).

    So, different tools for different sounds. The Shuttle is more flat and reproduce whatever you put in it, and that’s exactly what I want from it. I love its versatility. The tube adds warmth but is not intended for grit. I will never replace it. On the other hand, Ampeg has its own sound. I like to think of them as a part of the signal chain « before amplification ». It simply adds to the tone and can generate grit that make you feel so good. I also bought a Countryman DI to send the tube tone to FOH. I bring the amp that fits the gig. For the corpo gigs, Genz-Benz without hesitation. For rock gigs, Ampeg tubes all the way. Best of both worlds.

    My suggestion is to try with pedals first to see if you dig the tube tone and start looking for a deal on a full tube amp to add to your arsenal.

    Anyway, you cannot escape from GAS and you know it lol!
     
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  19. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    The GBE-750 and 1200 use the same preamp.
     
    Wasnex likes this.
  20. BassmanPaul

    BassmanPaul Inactive

    No attitude and certainly no snarkiness was presented - just facts. Grandstanding? I don't think so! No single amplifier can suit every player out there. The Genz is a great amplifier - just not for you. Time to move on.
     
    hasbeen and agedhorse like this.
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