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If you guys could spec your own preamp, what would you want?

Discussion in 'Amps and Cabs [BG]' started by Angus, Apr 24, 2009.


  1. Angus

    Angus Supporting Member

    Apr 16, 2000
    Palo Alto, CA
    Hey guys,

    I'm starting a new project designing a preamp. I've built a number of onboard preamps lately (both filter and EQ types), and have decided for fun that I'm going to design a really proper rackmount preamp.

    So, I'm curious for some ideas of what YOU would do- I know what I'd do, but perhaps a few of you will have features that might be interesting to implement.

    I'm not going to do any onboard effects, as generally speaking I hate effects. I'm finishing up a compressor right now, but beyond that I don't have much interest in effects.

    Beyond that, anything goes. Solid state? Tube? Filter-based (unusual for a rackmount pre)? EQ (what type, where, how much, how many, etc)? And on and on.

    So...what would YOU want if you could spec one? I appreciate the input!
     
  2. PICK

    PICK

    Jan 27, 2002
    Sydney, Australia
    Mids @ 250 would be one thing i would want. It's a nice frequency IMO.
     
  3. TheMutt

    TheMutt Guest

    Apr 28, 2007
    - Tube/SS/mix of both preamp operation
    - Two channels
    - Parametric 5 band EQ (low, low mid, mid, high mid, high) with frequency sweep for each band for each channel
    - Global graphic EQ from Low B up
    - Gain control for each channel
    - Tube/SS/mix of both DI out w/ stereo/mono operaton (for DI of crossover/fullrange signal) and ground lift (believe it or not, some amps do not have this feature)
    - Tube/SS switchable compressor
    - Mute/standby switch
    - passive/active input or pad(s)
    - built in crossover with balance/frequency controls
    - Footswitchable between Tube/SS features, channels, comp on/off, graphic eq on/off, mute on/off

    Essentially the ultimate end-all-be-all preamp. So start making it so I can buy one! :D
     
  4. PaperbackRyder

    PaperbackRyder Supporting Member

    Apr 21, 2007
    Maynard, MA
    I would have no on board effects either...but it would be designed to function with both EB and DB (mic and/or pup)...
    Two channels -
    1st would have switchable input impedance for either a passive electric or a piezo pup, plus EQ similar to either the Read Purity or Mesa Walkabout.
    2nd would have a combo jack for either a mic or a hi-z piezo, with lo-pass filter, variable phase, notch filter and semi parametric eq.

    Hey whatever can sound like an SVT or a Woods/VL208 with the flip of a switch or twist of a knob, is ok by me y'know....as long as we're dreaming.....:hyper:

    =JR=
     
  5. Bassmec

    Bassmec

    May 9, 2008
    Ipswich UK
    Proprietor Springvale Studios
  6. Eminor3rd

    Eminor3rd BLAAAAARRGGHH!!

    Feb 10, 2008
    NYC
    Definitely semi- or fully-parametric EQ
     
  7. NickyBass

    NickyBass Supporting Member

    Nov 28, 2005
    Southern New Jersey
    Honestly, I would just like to see a good, high quality point to point solid state preamp with only one in, one out, volume, treble and bass.
     
  8. mr.redpants

    mr.redpants

    Feb 6, 2002
    Philly
    whatever Jack Read says ...
     
  9. PICK

    PICK

    Jan 27, 2002
    Sydney, Australia
    Ok, seriously. All i would "need" to be happy would be an Eden with gain, enhance and master. Throw in Treble and Bass for good measure.
     
  10. HogieWan

    HogieWan

    Feb 4, 2008
    Lafayette, LA
    hi and lo shelves
    3 band parametric
    switchable/sweepable hi and lo pass filters

    clean SS and overdrive tube channels (tube channel could be jFETs to keep voltages lower)
     
  11. ehque

    ehque

    Jan 8, 2006
    Singapore
    No knobs. Plug in and play would be really nice. Along the lines of REDDI.
     
  12. Steve

    Steve

    Aug 10, 2001
    The oddball stuf that most don't have

    1. Highpass filter
    2. multiple balanced outs so you can drive a power amp balanced without loosing the DI
     
  13. -Useful gain knob. Don't make me have to turn it up all the way to get a good signal; conversely, don't put all the heat in the first 1/4 turn of the knob. I should be getting a 'proper' signal about halfway up. Below that should be some good attenuation for hot basses; above that I should get some gain and gank. Give it thickness! Don't just overload and give me nasty digital clipping. Thicken things up with some even order harmonics as I crank up the gain.

    -Filter section. A LPF with resonance would be fantastic for getting thick dub or synth tones.

    -sweepable mids. I don't want to click, or pull down sliders. I should be able to crank the Q and then sweep through to find out where the best place for my mids are.

    -adjustable input impedance; maybe just a 2 or 3 way switch.
     
  14. gerryjazzman

    gerryjazzman

    Dec 31, 2006
    New Jersey
    Let the others post what they DO want. Thought I'd chime in with what I would NOT want that seems to be designed into many preamps. Don't pre-voice the preamp at all :spit:. The preamp should NOT have a particular sound to it if you don't want it to. Never understood why manufacturers like to do that. I've seen evidence of it in many schematics that I've looked at. Little funky fixed filters or tone shaping networks buried in there. Maybe it's a way to appeal to a particlar genre of player and keep the design and controls simple. But then it tends to be a one-trick (or maybe two-trick) pony. In other words it should easily do flat. You should be able to do a design that's flexible enough to get whatever sound you want (punchy, smooth and round, warm, good slap tones, grungy, clean as a whistle, hi-fi, etc. etc.) at your choosing.
     
  15. why PTP? it doesn't affect the sound just makes the amp easier to service and is VERY impractical with solid state equipment.

    i'd want a all valve pre with a input and master volumes a baxandall tone stack, with mid range cut/boost and a valve driven DI / effects loop.
     
  16. Sandu

    Sandu

    Oct 23, 2007
    Bucharest, Romania
    I'm actually spec'ing out my own preamp and having a local whiz build it (hopefully). I sent him a rough sketch of what I want, but it's still open for discussion as it's still a little unclear to me as to what's doable, what's useless and what's unnecessarily complicated, as I'm waiting for his reply, so I'm gonna watch this thread carefully. So far I sketched out the following:

    -Full tube, but now I'm thinking switchable tube or SS for the clean channel
    -2 channels, clean and overdrive. The clean channel will probably benefit from the tube/SS switch. There'll be a semi-parametric eq (still deciding of number of bands and freqs). I may add an FX loop to the clean channel alone, with an on-off switch, 'cause I want to keep global, constant effects like compression, looper or whatever in the "main" fx loop.

    The overdrive channel will blend a second, separate clean tube signal and a tube overdrive signal, so no matter how much I turn up the OD, I can dial in clean low end from the clean channel, in a sort of bi-amping, only without a boatload of cables and stuff. I did it all the time in my recordings, so I want it for live sound as well. Experience tells me it will sound HUGE even with the gain cranked to max. For this to work properly, I'd need separate parametric eq's for each side of the signal and separate volumes, 'cause the overdriven signal will probably be louder than the clean one, and a blend knob wouldn't work that well (i find them to be less than accurate in getting the desired ratios, as well).

    After this there's the "main" FX loop and a true bypass graphic EQ, maybe 10 band. I'm still thinking whether I really need it or not, 'cause I don't see any reason in tinkering within the lo mid-hi mid range unless some effect or bass has weird voicing, so I'll probably downsize it to a low shelf-hi shelf combination, with sweepable freqs. Nothing annoys me more than a muddy mix, hiss, speaker farting and lack of headroom. Actually, I'll probably put the shelf controls in front of the FX loop.

    As for the knobs, switches, ins & outs:
    -input jacks for each channel, in case I want to jam with a guitarist at home. I'm thinking of adding an XLR in and having the guy build me an onboard buffer for one of the basses, with an XLR out, just for kicks. I'm curious as to how much signal loss occurs due to regular cables
    -an input pad, for active/passive basses
    -XLR & 1/4 jack send and return for the FX loops
    -dual parallel XLR & jack outputs (now I'm doing some research on the crossover thing)
    -true bypass for all eq's, maybe
    -mute/standby
    -ground lift
    -I saw a neat thing on a custom tube power amp: feedback, density and bias controls for the tubes. I wanna look into those as well, they noticeably altered the sound.
    -footswitch between channels, if possible: 1. clean channel, no FX, 2. clean channel + FX, 3. OD channel, then 4. tube/SS for clean channel and 5. Mute on/off

    I'm pretty enthusiastic about that OD channel... If it's doable, I could blend any 2 tubes out there, I could compare tubes a lot easier and faster, and if I add a tube/SS switch for the clean signal in here as well, that'll probably be my end-all-be-all preamp. 2 SS and 3 lamp preamps, all in one. I can't wait to hear back from the guy:hyper:
     
  17. Keep it simple:
    gain, low and high shelving, 2 or 3 sweepable mids, master vol.
    Effects loop, tuner out, XLR DI out switchable pre/post EQ
    wouldn't mind a built-in tuner and maybe a cigarette lighter :)
     
  18. stiles72

    stiles72

    Mar 20, 2009
    Albany IL
    Some weird bastardization of the following:

    - A 6sl7 tube preamp with a gain and master volume
    - The ultra low, ultra mid, and ultra high switches/settings from a B-100R
    - Bass and treble knobs/settign from the B-15R
    - The mid boost/cut knob/setting and frequency sweep from a Fender BXR 300C
    - XLR and 1/4 outs
    - Chrome chassis design with chicken head knobs
    - Some way of making the tube visible and easily accessible
    - Detachable power cord
     
  19. NickyBass

    NickyBass Supporting Member

    Nov 28, 2005
    Southern New Jersey
    I don't think it would be impractical if it only included the features that I wanted--two jacks and three pots.
     
  20. HogieWan

    HogieWan

    Feb 4, 2008
    Lafayette, LA
    kind of what I said, but you don't need a built in tuner (maybe the lighter though) you just need LOTS of individually buffered outputs.
     

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