Hehe, just like they were in the 90s....
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Does the amp matter when bypassing the preamp?
- Thread starter HelpImaRock
- Start date
As much as I find the massive backing rig to be a cool feeling, I wouldn't mind this becoming the standard. Something like the Rolls PM50 and IEs might need to be standard on bassist's pedalboards, but I feel preamp pedal/rack unit MFGs would integrate something to make setup simpler. Similar to how nearly every recent bass amp also contains a DI out or effects loop.
I run a Mesa preamp/DI into the FX return of any amp I play. I've done this with a Fender Rumble 500 head and a Ampeg pf-500 head and my Rumble 500C combo. I could not hear any difference. It has been my experience that the CLASS D power sections of these amps sound the same. In my opinion, most if not all of the tone differentiation between SS CLASS D bass amps comes from the preamp. In the past I've used rack pre's (F1-X and SVP-pro) with different class AB power amps. I couldn't hear much if any difference.
While I'm sure differing power amps have differing sounds, one would tend to think that the power of a preamp EQ would easily overcome these subtle variations.
Isn't the effects loop before the EQ on the Little Mark II?
My live sound comes from my bass and an outboard pre as well, to FOH. For my stage amp I have the GK MB112 combo and the MBP powered ext cab, and thought "how cool would it be" to be able to just use my pre and the powered cab should the combo bite it. Very frustrating that according to GK, it will not work due their proprietary "chain" input thingy.
It makes sense to me that the speaker cabinet has a lot more impact on the final tone than the power amp does.
I have experimented some with this and the difference between various power amps is pretty small, but not zero. And I was comparing a lot of different class D heads that I think all use virtually the same ICE modules in the power stage.
I was using a Q-strip as my preamp.
- Feb 12, 2006
- 61,053
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- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
Almost certainly due to the preamp much more than the power amp.
Would love to do this, but we're a no-budget original band with half a PA for vocals in rehearsals.
My personal choice would be to use heads, mainly because power amps are largely rack width. I don't have any cabs that wide..
There are small form power amps, but they tend to cost about as much as a head anyway. I beat the drum a few years for small form power amps. There isn't really that much difference in street price to the end user in simply ditching the preamp section and offering a stand alone power amp in a cigar box size.
I'm ok with my bass to the front end of a head, so really I don't have a dog in the "fight". I'd say the differences are more on paper than in the real world. HPF, headroom, dsp, linear vs. Non-linear performance when pushed, etc being the most likely differnces.
There are small form power amps, but they tend to cost about as much as a head anyway. I beat the drum a few years for small form power amps. There isn't really that much difference in street price to the end user in simply ditching the preamp section and offering a stand alone power amp in a cigar box size.
I'm ok with my bass to the front end of a head, so really I don't have a dog in the "fight". I'd say the differences are more on paper than in the real world. HPF, headroom, dsp, linear vs. Non-linear performance when pushed, etc being the most likely differnces.
We didn’t have light weight neo speakers and class D power in the 90s . Powered cabs haven’t caught on and probably never will, and that’s too bad really. A pedal board and a powered cab is all most players really need.Hehe, just like they were in the 90s....
This is basically where I'm going. My setup is different, but what are the Helix and Fractal bassists doing?
In my experience, the preamp will make a much larger difference than the power amp to your desired sound as long as you don't have to push the power amp toward its limits. I would guess that IN GENERAL, most power amps are being designed to be rather neutral.
When deciding on two cabs, 4x10 on top of 1x15, I found that a clean class D amp works for me. If it fails I'll just get another clean power amp, very minimal, but I do want two channels, one per cab.
Once I get the tone I want (in an Oberheim GM-400, but whatever works, works), then balancing the cab mix directly with the power amp volume controls is fast and easy. I can do a similar thing with the active tone control on my bass, but not all basses have one. Adjusting dramatic changes in tone inside a multi-effects rack is fiddly, and rarely has the same scope for large differences capable of balancing to compensate for effects or proximity or resonance in a room.
There are so many variables that getting tone is tough, so I find it better to set the detailed stuff in the single device I use for what amounts to 'preamp', then have fast easy adjustments made for the context I put it in.
There are lots of preamps, so likely many ways to get a particular tone, so I think the division of preamp from power stage is likely to persist in the future longer and more consistently than any decision about cabs or no cabs. I think keeping a clean power stage together with a preamp is mainly going to persist only in devices that are aimed at being as small as possible.
Once I get the tone I want (in an Oberheim GM-400, but whatever works, works), then balancing the cab mix directly with the power amp volume controls is fast and easy. I can do a similar thing with the active tone control on my bass, but not all basses have one. Adjusting dramatic changes in tone inside a multi-effects rack is fiddly, and rarely has the same scope for large differences capable of balancing to compensate for effects or proximity or resonance in a room.
There are so many variables that getting tone is tough, so I find it better to set the detailed stuff in the single device I use for what amounts to 'preamp', then have fast easy adjustments made for the context I put it in.
There are lots of preamps, so likely many ways to get a particular tone, so I think the division of preamp from power stage is likely to persist in the future longer and more consistently than any decision about cabs or no cabs. I think keeping a clean power stage together with a preamp is mainly going to persist only in devices that are aimed at being as small as possible.
It might be ideal for controlling tonal balance, but I've only seen it used in studio monitors. Once you get a bass cab with high sensitivity, there's going to be some compromise in tonal balance to the point where exerting that kind of expensive control probably isn't worth it. A really good powered speaker uses a kind of servo that monitors motion in a speaker and used feedback to maintain linearity. In a musical amplification system it might be effective, and a lot easier and cheaper, just to maintain it on a short leash, i.e. use short heavy cabling to keep the amp's output able to tightly control the speaker as best it can without exotic mechanisms. Reducing resistance and inductance in that cable is critical for a tightly controlled sound, and the lower the cab's impedance, the truer this gets.
This is why I qualified my observations with “at reasonable levels;” I’d love to push the tube power section in my Buster! combo but that doesn’t happen anywhere near “reasonable”
the DDT circuit in my Mark IV would probably start affecting overall sound at some point, but again, not so much at reasonable levels.
Just adding my experience to the discussion. A few months ago, the preamp on my Genzler Magellan 800 just stopped working. Might just be an issue with the input jack, but it's hard to tell. Everything is hardwired to the circuit board, so I'd have to spend a good amount of money sending it out to their service center and getting it repaired (past warranty). In the meantime, since the poweramp still appears to be functioning normally, I am using the receive input on the back with my HXStomp. Plenty of preamps/amps/cabsims/IR's to choose from and I'm liking it so far. To avoid the cost of shipping/repairs, I might just keep using the Stomp. I did really like the preamp on the Genzler head, so I'm not saying that the usage of the Stomp as a stand-in is "better", but I'm enjoying how it sounds and I'll probably just keep it this way. Again, just my current experience as it relates to the topic.
I think the amp you utilize the power section via the effects return/line in/poweramp in/etc. patch points does matter. I have a bunch of rack mount preamps and preamp pedals that I've been doing this for years with and I notice a difference. For example, my Ashdown ABM 500 EVO II head has a very thick, muscular sounding power section whereas my GK MB500 has a very clear and transparent sounding power section. My Ampeg SVT3 Pro head has 12AX7 and 12AU7 preamp driver tubes in front of its MOSFET power section so that gives it somewhat of a tubey tone when I use the power section alone via the poweramp in or effects return patch points. The real sleeper of the bunch for this purpose is my Ampeg B2-RE head. The power section is voiced really well for several of my preamp pedals and rack mount preamps ... most notably my Sushi Box Underground Accelerator and Slampegg Bee Pre X pedals as well as my Tech 21 Sansamp RPM rack mount preamp. In addition, while its native preamp section is kind of "dry" sounding, it sounds absolutely wonderful when I run either my Ampeg Classic Analog Preamp or my One Control 360 preamp (Acoustic 360 emulation) into the B2-RE native preamp section. Used Ampeg B2-REs can be had pretty cheap. I got mine off of eBay as a brand spanking (N)ew (O)ld (S)tock USA version that had never been out of the original shipping crate for $150/shipped.
