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DB750 EQ

Discussion in 'Amps and Cabs [BG]' started by EricF, Apr 21, 2009.


  1. EricF

    EricF Habitual User

    Sep 26, 2005
    Pasadena, CA
    The Owners Manual for the DB750 indicates a 12dB boost for each of the EQ controls. By this description, it would mean that "flat" is with all EQ knobs all the way left. Is this correct, or did Aguilar leave out some info?
     
  2. KJung

    KJung Supporting Member

    No, they are standard +/- 12db. I have no idea if noon is truly flat, but that's the 'starting point to get the designer's inherent tone of the amp'... i.e., the 'neutral' setting.

    Here's the spec from the site:

    EQ Section: Tube-driven shelving type treble (+/ - 12dB @4kHz), mid (+/ - 12dB @ 400Hz), and bass (+/ - 12dB @ 40Hz) controls.
     
  3. Ryan Mohr

    Ryan Mohr

    Oct 23, 2007
    I have been confused with how this differs from the new DB 751 besides a different center frequency for mids. This is what it says for the DB 751 on the Aggie site:

    Sorry, I just don't understand the difference.
     
  4. KJung

    KJung Supporting Member


    The main difference that I can see is that the EQ section is no longer tube driven (that's why they list one less tube in the specs of the 751 versus the 750, if I'm understanding this correctly). I assume this allowed them to use some common parts with the AG500 in the EQ section, and also to lower the cost of manufacturing.

    I have no idea if DB750 lovers will find this an improvement or not.
     
  5. EricF

    EricF Habitual User

    Sep 26, 2005
    Pasadena, CA
    Thanks for clearing that up. I missed the +/- on the site. I went straight to the manual which only says boost.
     
  6. Ryan Mohr

    Ryan Mohr

    Oct 23, 2007
    Oh I see, would that yield a "less tubey" tone?

    I still don't see why it offers "greater EQ control" though.
     
  7. KJung

    KJung Supporting Member

    I don't either. I know the current DB750 tone controls are pretty limiting, but I always attributed that to the center frequencies and the simple three band. I have no idea what impact taking that tube out has on the tone of the amp.

    I'm sure we will get some posts about the new 751 soon, and that should clear things up a bit.
     
  8. coyoteboy

    coyoteboy easy there, Ned Supporting Member

    Mar 29, 2000
    Sactomato, CA
    If I remember reading correctly, D.B. posted that the one fewer tube in the 751 was in fact the driver tube for the power section, that the 751's circuit didn't require it.
     
  9. KJung

    KJung Supporting Member

    That could be. I was interpreting the change in the EQ description on the website. The 750 says tube driven, but the 751 does not. So, not sure. I guess the only thing that matters is how it sounds. I guess the new one is a little less expensive, and unfortunately about the same weight.
     
  10. Aguilar/Dave B.

    Aguilar/Dave B. Aguilar Amplification Commercial User

    Nov 8, 2003
    New York City
    President: Aguilar Amplification
    The tone stack is the same on the DB 751. The preamp tubes are the same.
    The 12AU7 was not neccesary to the circuit. After a lot of listening, we felt we could get rid of that tube without any sonic effect except for the benefit of getting rid of a lot of microphany and hiss.

    What is different in the EQ is the addition of an active element that makes the midrange eq work. Now you can separately eq the mids and bass.

    The DB 751 actually does feel a little lighter. The real weight of the DB 750 is 46 lbs. We now have a real shipping scale. Back in the day we probably used a bathroom scale (sorry) The 751 is 42 lbs.

    I hope this is helpful and answers some questions.

    Dave B.
     
  11. Aguilar/Dave B.

    Aguilar/Dave B. Aguilar Amplification Commercial User

    Nov 8, 2003
    New York City
    President: Aguilar Amplification
    The tone stack is the same on the DB 751. The preamp tubes are the same.
    The 12AU7 was not neccesary to the circuit. After a lot of listening, we felt we could get rid of that tube without any sonic effect except for the benefit of getting rid of a lot of microphany and hiss.

    What is different in the EQ is the addition of an active element that makes the midrange eq work. Now you can separately eq the mids and bass.

    The DB 751 actually does feel a little lighter. The real weight of the DB 750 is 46 lbs. We now have a real shipping scale. Back in the day we probably used a bathroom scale (sorry) The 751 is 42 lbs.

    I hope this is helpful and answers some questions.

    Dave B.
     
  12. EricF

    EricF Habitual User

    Sep 26, 2005
    Pasadena, CA
    Thanks for your input, Dave. Based on your comment, it would appear that the bass and mid EQ controls on the 750 effect each other, but the active EQ on 751 has eliminated this interaction. Is this correct?
     
  13. KJung

    KJung Supporting Member


    I'm still a bit confused, since the 750 also had a +/- 12db midrange control centered at, I believe, around 400hz. So, not sure what 'active' means relative to that.

    Maybe what you mean is that the higher center mid EQ point on the 751 does not sit on top of the bass control as much as the 750's mid control? That would make sense to me.

    Was the 12AU7 'driving' the power amp, or was it associated with the EQ circuit?

    Just curious, since the specs make all this a bit confusing, especially the 'now the EQ is active' when you listed the previous EQ as +/-.
     
  14. Aguilar/Dave B.

    Aguilar/Dave B. Aguilar Amplification Commercial User

    Nov 8, 2003
    New York City
    President: Aguilar Amplification

    Hey Kjung,

    The center point on mid eq is higher than the 750; but we've also added a circuit to the tone stack that allows the mids to adjusted. The eq works better now. You can get lows without mids, mids without lows, the highs are more flexible. It is still a passive tone stack; but it is more usable.

    In our marketing we are trying to get across that we've added an active element (transistor) to the tone stack for greater control. I think when we said "cut and boost" some people inferred a completely different tone circuit to some. Maybe we'll revise this copy for clarity.

    The DB 750 always had a transistor driving the power section. The 12AU7 was largely redundant, as it is also in that area of the amp.
    It was not associated with the EQ.

    I hope this is helpful.

    Dave B.
     
  15. KJung

    KJung Supporting Member

    Cool! Yeah, your wording is a little confusing.... mids with lows, etc.... I still don't know what that means (mabye the Q changes as you increase or decrease the mid control or something?). And, with my limited understanding, a passive tone stack is cut only, not cut and boost.

    Just FYI, but from your specs, the description between the 750 and 751 implies that the main difference (besides the center freq of the mid control) is that it is no longer tube driven (which is obviously not the case).

    Since I found the mid control of the DB750 it's weakest point, if you could put the improvement into accurate language, I think that would be a positive bit of news for some!

    Even though I still don't personally understand the difference, it sounds like an improvement, which is all that really matters:)
     

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