FS ALEMBIC F-2B STEREO PREAMP

[singlemalt]

$400 plus buyer pays freight.

Best guess is mid '80's. Black face, red knobs, blue rack ears. Very good condition.

Channel A totally stock, works perfect. Channel B has some mods to boost midrange and treble. A huge tone machine. Like adding a tube amp without all the weight.

The word everyone uses is "organic" sounding. I love it but I'm downsizing gear.

I'll post pictures ASAP.

Thanks

[singlemalt]

Okay, here are some photos.

As far as the modifacations to the B channel, without getting too technical, or technical at all: I like it. I've got two distinct palettes to choose from. Both sound great. The B channel mids and highs can be boosted, and I ended up using this channel more.

You can run each channel separate thru individual outputs or mix the two together.

As you can see this unit is in very clean condition. There was a small discoloration/blemish on the bottom that scraped off. It came with the two prong plug, I understand that that was how they built them.

Quiet and clean, with great presence and warmth.

Hope that helps.

[pfschim]

so, with this preamp, I could plug one bass into either channel, A or B, then use the dual outs to run 2 channels of a poweramp ?

i.e.

bass into -- ch x (A or B)
--- pre out a to input a on poweramp --- ch a out to cab a
--- pre out b to input b on poweramp --- ch b out to cab b

I am interested, but want to make sure this is how it can work.

what I am considering is this pre into a 2 ch QSC, into two Accugroove Tri 115L's.

let me know

[4Mal]

An F2B has A, B and A+B outputs. You can set it up as ...

1. Dual Mono, 1 side of the pre to one side of a power amp
2. Cascade (for the gainiacs amognst us) A ==> B == Power amp
3. Mono Only (how I used mine) A and B are summed to a single output. I found that useful for
- gain balancing my effects chain with my dry signal. effects often end up sucking down some bass and either robbing some volume or increasing it. Use the channel Vol & Tone stack to restore that and now your Dry and Wet signals come down the line iwht about the same impact. Very cool for live use.

- gain balancing 2 basses with very different output levels. Dark Star P and Passive J. I kept them both wired on stage and could swap basses in between songs without touching a volume control and potentially messing up the mix. Also very helpful for me at the time.

[Passinwind]

Originally Posted by singlemalt

As far as the modifications to the B channel, without getting too technical, or technical at all: I like it. I've got two distinct palettes to choose from. Both sound great. The B channel mids and highs can be boosted, and I ended up using this channel more.

I did the mods when I briefly owned this F2B. I also did a cap job on the power supply at the same time, since this is a mid-80's vintage piece. I will reverse the channel mods back to stock configuration before the unit ships if desired, on my nickel. I asked singlemalt to try the mods for a while and he's never asked me to change 'em...

[4Mal]

Originally Posted by pfschim

so, with this preamp, I could plug one bass into either channel, A or B, then use the dual outs to run 2 channels of a poweramp ?

i.e.

bass into -- ch x (A or B)
--- pre out a to input a on poweramp --- ch a out to cab a
--- pre out b to input b on poweramp --- ch b out to cab b

I am interested, but want to make sure this is how it can work.

what I am considering is this pre into a 2 ch QSC, into two Accugroove Tri 115L's.

let me know

After a re-read... there are a couope of options

1. set the QSC for parallel mono. I believe that the input attenuators are still active on both sides of the QSC.

2. If you were looking for 1 bass being able to control the volume on each cab, then you could plug the bass in to Alembic CH. A Then Jump from the #2 input on A to #1 on B using a jumper cable* Then senfd A out to A in on the QSC and B out ot B in.

* It is possible that the jumper cable will have to be wired to flip the phase. No big deal if so...

Passinwind will know more about that phase action than I for sure. IIRC there is a slight gain reduction when jumping the channels like this so the Volume on B will be up a little higher than A. This is actually a pretty standard procedure for guitarists using Fender tube amps. I believe it was Passinwind who turned me on to this. In that case it was almost using the jumper as an effects loop. I put a lexicon rack unit in between the Ch A #2 and Ch B #1 inputs. it was ... way trippy! and worked like a charm! I was thinking 'Careful with that Axe Eugene!' in no time.

Hope that helps

[singlemalt]

Thanks guys for having my back.

I need all the help I can get with this stuff.

Looks like I barely scratched the surface of what the F-2B will do. I had ideas for using the two channels to capture bass and drum machine mixed together with my looper to set up a bit to solo over, but I'm a ways from taming the looper.

I simply used the mix output to amp, and selected A, B or bridged depending on what sounded good in the room. It made the GK sound great, breathy and warm, organic. I could fine focus the sound like crazy.

As far as mods to Channel B, in tech terms, I liked it. Nice to have that choice of flavors rather than two identical circuits, and after a bit I used the B channel more.

Thanks for the offer Charlie, we'll see if whoever buys this wants to have the modded option or if they want it stock.

Looking forward to the Hood River get together. We'll miss ya at Mal's underSTOCK party.

We missed you at Chips last night, it was great fun. My 606 kicked ass.

[singlemalt]

Bump and a link to some reviews here on TB and other places. David Gilmour's secret tone machine.

http://www.talkbass.com/reviews/show...uct/446/cat/26

http://www.alembic.com/prod/f2b.html

http://reviews.harmony-central.com/r...be+Preamp/10/1

http://www.gilmourish.com/?page_id=71

http://www.basscentral.com/alembicbass/preamps.shtml

This unit can be put back to stock. Its not something I would do for myself as I prefer the modded channel.

Thanks Charlie for your generous offer.

[singlemalt]

bump for the weekend

[LarryR]

Can anyone talk on how well this would work with a Walter Woods stereo amp?

[gnergaard]

Originally Posted by Passinwind

I did the mods when I briefly owned this F2B. I also did a cap job on the power supply at the same time, since this is a mid-80's vintage piece. I will reverse the channel mods back to stock configuration before the unit ships if desired, on my nickel. I asked singlemalt to try the mods for a while and he's never asked me to change 'em...

Thanks for posting on this add, passinwind. About the mod to channel B- can you tell me more about what was done? Was it a mod to the preamp stage or to the tone stack?
If I purchased this unit, but I wanted to try the modified channel B, would you be able to tell a competent amp repair tech how to return channel B to stock, i.e.: remove the mods?

Also- perhaps you could tell me- is it possible to modify these Alembic F2b preamps further and add a DI output with a Jensen transformer? have you ever tried it? Know anybody who has?

Thanks,
Greg

[singlemalt]

Sold, thanks very much everybody.