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RH450 with a VT deluxe as a pre-amp

Discussion in 'Amps and Cabs [BG]' started by kmon, Jan 27, 2012.


  1. kmon

    kmon Supporting Member

    May 11, 2009
    Austin, TX
    anybody ever run a rusty box or a VT Bass, or any other preamp into the power-amp-in on an RH450?

    I was interested in trying this and bypassing the pre on the RH450 itself. Just a tonal experiment.

    I *think* I can do this but I'm ignorant on these matters. Any thoughts? Basically I want to use the RH450 as a power amp.

    Thanks!!!
     
  2. The short answer is yes, you can. Even they recommend using an RH450 as a slave to another one. It is clear from specs and signal flow diagram.

    What I don't know is what level you need to drive the power amp 100%. Specs say max level is +8dBu (some 2V RMS), but I don't know if a more moderate level is enough to take all power from these heads when the master control is at 100%.
     
  3. kmon

    kmon Supporting Member

    May 11, 2009
    Austin, TX
    yeah I saw the master/slave diagram in the manual and it looked like you could use it as just a power amp.

    not sure on the power amp input level...I'll see how it goes...thanks!!!
     
  4. I would be concerned about what you use as a preamp. From what I have read, they use a lot of preamping and compression to get their heads to sound like their advertised wattage. A power amp is a power amp. So you are just going to get the actual, lower wattage, power from the amp. You will have to make up for it with similar EQing and compression.
     
  5. newbold

    newbold

    Sep 21, 2008
    Toronto
    You *can* do it but I recall to this day what it was like to plug a VTBass into a TC Stacatto combo - bypassed, I got my ideal modern tone and then when engaged I got everything I love about Ampeg tone but with a great transparent compressor.

    On the other hand it might be amazing beyond words.
     
  6. kmon

    kmon Supporting Member

    May 11, 2009
    Austin, TX
    interesting point...yeah I had done some reading on the big to-do about the wattage they were claiming.

    I know the head straight up is loud as sh**...be very interested to see what it sounds like without the TC preamp magic
     
  7. kmon

    kmon Supporting Member

    May 11, 2009
    Austin, TX
    so you're saying I should try it right?? :bassist:
     
  8. Apparently all the post-compression (and "Advanced Power Management) comes AFTER the pre_OUT / Poweramp_IN.

    A few hours ago I asked in another post for confirmation that the "strong voicing" built into these amps (not the EQ or tube emulation or compression) is also built after the PowerAMP input. I suspect so from some freq. response measurements I did in the past.

    EDITED: This is the post and it partially address the original question:
     
  9. I would look at a Peavey IPR. Lightweight power amp with more than enough power. That would mean you have two amp set ups to use too.
     
  10. fraublugher

    fraublugher

    Nov 19, 2004
    ottawa, ontario, canada
    music school retailer
    I use an MXR M80 DI with my RH450 with and without compression successfully.
    It's a wierd new amp , in that the input stage uniquely levels any input you put in but at the same time I can still affect the output at the pre stage.
    I don't know the answer to your question.
     
  11. kmon

    kmon Supporting Member

    May 11, 2009
    Austin, TX
    thank you!! that seems to answer my initial question!!

    TB is incredible...
     
  12. fraublugher

    fraublugher

    Nov 19, 2004
    ottawa, ontario, canada
    music school retailer
    However, the modern tone people are complaining isn't available on the RH450 can easily be achieved with a pre-amp [like the MXR M80]
     
  13. kmon

    kmon Supporting Member

    May 11, 2009
    Austin, TX
    do you go straight to the power amp(bypassing the RH450 pre) or do you just plug into the front input like a regular pedal?

    if using the preamp do you have the RH450 EQ pretty flat or do you combine that with some M-80 EQing?

    I do like the M-80...haven't tried it with the RH though
     
  14. I suspect this is not 100% right:

    When you set spectracomp and tubetone to zero, all the possible compression (at high volume) should come from the "APM" in the power stage.

    The "lack of modern tone" in the 450 (not present in the 750, due to cut of highs) is most probably in the pre section. So you can overcome this with a different pre. I have the 750, so I can be as "modern" as I like when it comes to crystal clear highs.

    The part I am not sure is the high pass filtering around 60 or 70 Hz, I suspect it might be in the power section, which is odd but might be very convenient for certain applications.
     
  15. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    So if you defeat the pre, it doesn't become a 236w RMS amp again?
     
  16. That is kind of what I was getting at. I havnt read the thread posted above about where the voodoo comes in, pre amp or in the power stage...
     
  17. Yes I think so.
    This is as relevant, :)
     
  18. Please clarify...

    A.) Yes it does become just a 236 watt amp

    B.) Yes it does keep that voodoo compression
     
  19. fraublugher

    fraublugher

    Nov 19, 2004
    ottawa, ontario, canada
    music school retailer
    I haven't tried the effects loop yet so plugged in the front.
    For a modern tone i crank the highs on the mxr 100% and because I use a jazz bass the mids at 0-10% because the amp is mid heavy.
    Also I turn the low mid and mid on the amp to 9 oclockish
     
  20. fraublugher

    fraublugher

    Nov 19, 2004
    ottawa, ontario, canada
    music school retailer
    I read in the TC literature or maybe here on TB that one of TC's new feature's for digital amps was to eliminate the amps job of amplifying frequencies the human ear can't hear to make the amp more efficient.
    Of course I could be wrong ....again.:)
     

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