Author Topic: Alembic Pre-Amps - Explanation (Read 187 times)

pts · « **on:** June 07, 2006, 10:15:45 AM »

Thinking of getting one, but I'm not very technical and don't understand the promotional copy. Can somebody explain to a novice in straightforward language: How exactly do Alembic pre-amps improve tone, and what makes them better than the competition?

I know the difference between lows, mids and highs, and the difference between fundamentals and actual notes, but that's about it.

I use a GK800RB biamp powering a 1x18 and 4x10 - which model is best for me?

ghunter · « **Reply #1 on:** June 07, 2006, 10:57:53 AM »

I'm not speaking as an Alembic preamp expert, but as someone who has heard a lot of preamps in my time (including a few Alembics).

Adding an external preamp to your GK head will give you a different set of tone shaping controls than what you currently have - even when set flat an external preamp will color your tone. You may or may not find this to be better than plugging straight in to your GK.

I'd bet that you like your overall tone otherwise you wouldn't have spent the money on a rig like that. What is it that you're missing that makes you crave a change?

bigredbass · « **Reply #2 on:** June 07, 2006, 07:33:53 PM »

PTS, think of a cascading chain:

Bass-preamp-power amp-speaker(s)

In your cureent setup, the bass pickups generate a small voltage that goes up the cable to your GK head.

The end of the GK head with the input jack and all of the gain/tone controls/filter switches, etc. actually IS the preamp. It takes the small voltage from your bass, adds tone control, effects, etc., then hands it off to the power amp section of your GK head, which then sends AC current down the speaker wires to your cab. In any bass head, you actually have a preamp section and a power amp section, combined in the one box.

The ALEMBIC preamp originally was an outgrowth of a mod that ALEMBIC did to amps for the Bay Area bands back in the Summer of Love: Take their Fender amps, make an output at the end of the preamp section (skipping the power section) and using it to drive outboard (read bigger and more hifi) amps (typically MacIntosh or Crown) for more and better sound. They eventually revised the design, and built it into the separate, two space rack box, and voila, the F2B was born. It's basically a stereo version of a Fender front end to drive both channels coming from the Series Basses, which have stereo output.
Hooked up to a typical stereo power amp and cabinets for each channel, and you were off to the races.

More than anything else, the big difference is TONE. The F2B is one of the classic distillations of tube tone, and time-honored and revered classic. It would just sound DIFFERENT than your GK. I suppose you may be able to use it through an effects loop, but it possible you would plug your bass into the F2B and plug the F2B's output into a 'Power Amp In' jack if your particular GK is so equipped. In which case it would sound a LOT different. Whether it's a sound for you or not is up to your ears.

On the other hand, once you had it, you could also pick up a power amp (lots of our friends here swear by QSC) with it's own crossover (or buy an F1X, basically a mono F2B with its own crossover built in) and drive your 118 on the low pass, the 410 on the high. You'd then have one of the highest tone and performance bass rigs possible, and then wonder who's gonna buy this old GK head !

J o e y

pts · « **Reply #3 on:** June 08, 2006, 04:27:22 AM »

Yes, I've played around with the GK's preamp section (why would a bassist want a low cut anyway?). But I'm increasingly just leaving everything flat, and wondering, is that all there is? Don't get me wrong, it's certainly better than my previous amps. Overall, I guess I just wanted more clarity and note definition, especially at the higher output levels, while still getting enough low-end rumble.

ghunter · « **Reply #4 on:** June 08, 2006, 07:51:56 AM »

If you're playing through a 2x10 cab (or smaller) that doesn't have good low-end extension you can cut the lows and give the mids more clarity. I can also see acoustic basses potentially wanting a low-end cut too, but I can't see an acoustic bassist using GK

It sounds like you really just need a better EQ in your signal chain, and although you could get it from a preamp you would save a lot of money (or get a better EQ) by getting a dedicated EQ, perhaps a tube EQ if you want to warm the signal a little.

Also check out the Alembic SF-2 Super Filter. It's different than an EQ, but maybe that's what you're after. This image will give you a good idea of what the controls do:

Also note from that pic that the F-1X won't give you that much more control than what you have now, but it will definitely change your tone.

olieoliver · « **Reply #5 on:** June 08, 2006, 08:05:38 AM »

How are you running your gains (channel and master volumes) Peter? You'll get a much cleared sound from a GK head by running you master much higher than the channel gain. I used a 400rb through 2 4x10 hartke cabs for years and I always got complements on my live sound. Crisp, clear notes and thunderous bottom end. So I know the head you have is capable of getting the sound you want.

pts · « **Reply #6 on:** June 11, 2006, 04:11:32 PM »

Yes, I've tried both - high gain, low master, and vice versa. I do prefer the latter, and used it on Friday at a gig. Should have mentioned this earlier, but I'm currently playing a Fishman'ed acoustic bass guitar while waiting for my Essence 5 to get shipped, so perhaps I'll hold off on any gear aquisition thoughts till it arrives.

bigredbass · « **Reply #7 on:** June 11, 2006, 06:28:11 PM »

I would DEFINITELY wait and address your amp questions with a bass with regular pickups: Piezo-bridged acoustics (and ABGs) present and entirely different output to an amp! They can make a lot of amps go nuts as the piezo/acoustics generally have MUCH hotter output and higher impedance than a magnetic pickup.

J o e y

davidravenmoon · « **Reply #8 on:** June 19, 2006, 01:27:11 PM »

I owned an 800-RB for many years... bought it back in the '80's when they came out, and sold it just a couple of years ago.

GK has somewhat ugly EQ center frequencies in my opinion. I was never able to get the tone of the amp out of my way, and eventually used a separate rack mount preamp (not an Alembic...) which I felt improved the tone.

This is kind of an issue I have with amps in general lately... they all color the sound too much.

Of course if you like the tone of the amp, thats fine. I got tired of it after a while.

So you might like a different preamp.

johnnybassboy · « **Reply #9 on:** June 24, 2006, 03:02:57 AM »

I am fortunate to have a few combinations of heads (mostly racks), cabs and basses. This allows me to adjust to the sound, volume, style, and equipment size requirements of most gigs. Cab wise, I have Acme, Accugroove, Eden and Jbls. Preamps are Alembic, SWR, Roland, and Symetrics. Poweramps are Carver, Stewart, and QSC. I also have an OLD Sunn 1200S Tube head... although I haven't used it in some time... I hate to get rid of it though. It's like a 2000s head, but with a better (IMO) preamp.

I find I often like to use the Alembic preamp with the Accugroove speakers the best. The reason is that the Accugroove are the flattest in response. The Alembic CANNOT be made to be flat (unless you do a simple mod), but instead is excellent at removing excess mids. The Acme cabinets already have quite a scoop in the midrange, and can be run flat. If I combine the Alembic and the Acmes however, I find I have to boost the mids on my bass, as the sound is a bit too sucked-out for most situations unless I do.

And in case you're wondering, yes, my wife doesn't like all my gear. But I play in SO many different venues and I find speakers are the critical interface with the room. Bass players (IMO) are wise to remember we actually are playing the room.... the room interacts with our sound as much as anything else. You can have the most happening sound at home or your last gig, and just not come-across in the next place if you don't take into account the sound of the room.

pauldo · « **Reply #10 on:** June 25, 2006, 06:32:27 AM »

Peter,
You may want to try running the 800RB in 'full' mode. I have had an 800RB for many many years and run it through a Hartke 2 x 10, and a Mesa 1 x 15. Depending on the venue's size and shape I will either run bi-amped or in full mode. Try it and listen, see what you think.

As far as EQ, my Distillate has such a large tonal pallete that my 800 RB is set flat and I may use the mid-cut. Again the venue's size and shape may dictate a 'slight' EQ tweak but 95% of the time my EQ is set flat.