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daflewis

A.C.G. bass pre-amp

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this is a review that i wrote for the site when it was bassworld, been meaning to copy it over for a while, so finally.....

I’ve had this preamp fitted to my 1989 Warwick thumb 5 string fretless for about a year now, (and have also recently had one added to my Parker Fly 5). I think most of us have probably read the thread where the idea for a “Wal” style filter based tone control system has been discussed between Alan, John and various members of bassworld/talkbass/basschat, and, indeed, this is where I first heard about the idea.
My thumb has EMG pickups and always had a good full sound but I felt that it lacked the ability to growl in the way made popular by people like Pino Palladino; I certainly felt that there was more “wood” in there somewhere.

The fitting

The pre-amp was designed for a.c. guitars by John East, an electrical engineer/wizard who is based near oxford. The story goes that john had mentioned to Alan that he was toying with the idea of a filter based pre-amp and Alan said he would be interested in trying it out in his basses. Well, time passed (quite a lot of time, I believe) and eventually john admitted that he would probably never actually get round to finishing the pre-amp so Alan threw some money into the equation and commissioned john to make the pre-amp exclusively for a.c. guitars. (Good move Alan!!).
The pre-amp uses four stacked pots (which we’ll come to later) and my thumb only used three pots necessitating the addition of an extra hole in my beloved bass! This was my one real concern in the whole affair (no pun intended) but Alan put me in touch with john who lives about an hour away from me and he was good enough to arrange for a luthier to do the necessary. As long as you have the right number of “pot holes” on your bass you can fit the pre amp yourself as it has been designed so that no soldering is required.



The pre-amp

The controls are very intuitive, give it a few days and you’ll hardly think about it though the huge range of sounds will keep you twiddling for months!
The first pot is; inner knob – volume, outer knob – pick up pan. Nothing new there…
The next two can be thought of as (for each pick-up) inner knob – boost (0 - +12db), outer knob – frequency (70Hz. – 3kHz.) SORT OF…. These two controls are where the magic is and deserve a wider explanation. The frequency control is actually a low pass filter so when the control is fully counter clockwise only the very lowest frequencies are allowed to pass through and when fully clockwise the full spectrum is allowed through. The boost control puts a spike in just before the drop off point set on the low pass filter.
The final pot is; inner knob – boost (-inf. +18db), outer knob – treble frequency (4kHz. – 10kHz.)Because the tone controls always let through low end but not always top, you can use this to compensate for any lack of treble.





In use

I described the two filter controls as frequency and boost earlier and that’s because this seems to be the easiest way of thinking about how to use them. If you set the boost quite high and sweep the frequency control it is a bit like a wah pedal but with a much greater frequency range; that may give you an idea of how much control there is over your sound (x2 of course, one for each pick-up).

two examples (sweeping the frequency with the boost on full):

[attachment=1742:BRIDGE01.MP3]
[attachment=1741:NECK01.MP3]

As a quick start, I have found that what I tended to do was set the neck pick-up to just let through lower bottom end and use it as a sweepable bass tone control, then set the bridge pick – up to a higher frequency and use it as a sweepable mid tone control, this means that the pick up pan suddenly becomes the most powerful single knob tone control I have ever used, though this grossly simplifies the actual tone shaping at your disposal.

example with bridge pickup as mid and neck pickup as bass then panning between using a general setting (not full boost)

[attachment=1744:PAN01.MP3]

The range of tones is enormous, almost bewildering, and this brings me to one (very small) minus point. The tiniest movement of the frequency control, especially in the 500Hz to1kHz (ish) range makes an enormous difference to the sound (with suitable boost) and this means finding the right spot can be a bit fiddly. Having said that, this is simply a function of the enormous flexibility of the system, so I guess you can’t have your cake and eat it!
The treble control is also a lot more powerful than one would think. If I want to dial in a wal sound then I will have the treble boost off (I can only assume that the wal basses do not have this in their filter system), a fairly heavy pan to the bridge pickup and a fairly high boost in the mid range giving that classic honky/nasal pino style sound; but to get a different and more balanced sound just add a little top end and everything just seems to even out to a good standard usable sound, so a lot of knob twiddling is not required.

example of a general sound with treble off then turned up to full and sweeping the frequencies then turned down again. (a more subtle change but in practice very powerful)

[attachment=1743:TREBLE01.MP3]

and finally a general sound that i use quite a lot.

[attachment=1745:GENERAL1.MP3]

In conclusion

Just about any sound is available, from the lowest thumping reggae to the clankiest rickenbacker and beyond with never a hint of hiss or other noise; which with up to 18db of boost in the 4-10kHz range is remarkable, and I found that using less boost doesn’t just give less of whatever sound is set on the frequency control but seems to send you off in subtle new directions - I have never found a pickup pan to be so powerful! It’s a beautifully made bit of kit and very light on power consumption – eight shows a week and the battery lasted for over two months before dying on me!
This is the best £200 (just over $400 in the U.S. at the moment) that I have ever spent on sound.

I’m based in Bedfordshire and am currently working at the Apollo Victoria Theatre in London with the show Wicked, so if anyone would like to hear and/or try this for themselves p.m. me. I’m sure we can meet up – it’s such a great bit of kit I think everyone should have one!

Edited by daflewis

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Good review, but is there any chance of you making a recording simply holding a note and twiddling with each knob so I could hear exactly what it does?
I am getting a bass made for me that will have one single coil P-Bass pickup in it, and I was going to go passive until I heard about this preamp, but for the $400 Canadian I will pay for it, I would like to hear it before I decide.

-Micah

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thanks Micah, glad you liked it.

i've been thinking about adding some sound clips - asked kiwi and ped for some advice in the "suggested format" thread at the top of this section.

your request will help me pull my finger out, i should have some time on monday, hope that's soon enough to be of use to you.

not sure how the preamp will work with your new bass as the two filters work off separate pick-ups, though i'm sure john (east) could give you some advice....

sound clips to follow...... :huh:

promise! :)

daf

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Thanks for the clips - that helps a lot.
I was thinking about putting it into my upcoming bass (a Warmoth built single coil p-bass) but after thought, I have changed my mind.
My current bass is an Ibanez SR405, and when I get my new bass I am defretting the Ibanez, and I think I will get this preamp and put it in there.

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that sounds good, i think that the preamp is particularly well suited to fretless - the ability to dial in that "growl" is, perhaps its greatest asset.

daf

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[quote name='bassninja' post='44978' date='Aug 13 2007, 08:10 PM']I'm loving that...[/quote]

cheers mate. :)

appreciate the comment.

daf

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Thanks for putting up those sound clips.

Now I definitely know that this pre-amp is what I want. I'll be ordering one for my Buzz at the end of the month. Just got to check there's enough room for all the bits...

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[quote name='BigRedX' post='45061' date='Aug 13 2007, 11:08 PM']Thanks for putting up those sound clips.

Now I definitely know that this pre-amp is what I want. I'll be ordering one for my Buzz at the end of the month. Just got to check there's enough room for all the bits...[/quote]

hi red,

you're welcome, i remember your supportive comments after the original post on bassworld - thanks.

i think this would be quite something in a pedulla;
heard one for the first time recently and thought it had a great sound that this could only add to! :)

if you need any help with measurements etc. or would just like to try it out for yourself please get in touch.

cheers,
daf

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Lovely! Great review, and I really enjoyed the sound clips.

Cheers
ped

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cheers ped, and thanks again for the advice about sound clips.
now i see how much file space is available for uploads i might try and make the sound clips a bit more comprehensive - i feel like i've only just scratched the surface of the tones available!

cheers,

daf


p.s.
hope things work out o.k. for you, sounds like you're having a tough time at the moment.

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Yeah 500MB isn't too bad is it! The bass sounds really nice, the pre amp sounds like it really brings out the blooming fretless tone from it even more than normal.

Cheers for the thoughts matey, things are getting better having sold some gear but the government side of things is just laughable, it really is.

ped ;0)

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yeh, 500mb gives a lot more room than i expected (as long as you don't use wav files i suppose!)

the preamp has surpassed all my expectations. my warwick thumb has always been a bit special, i've had it for 17 years now and it has been my first bass pretty much all that time, so drilling that hole and changing the preamp was quite a big decision, but it certainly worked out for the best!! next time i'm over seeing john east in oxford i'll give you a shout and bring it round.

i've seen the adds in the for sale section, it must be tough selling off such lovely instruments, but i'm sure everyone would give you first refusal to buy them back when things sort themselves out. - those bachuus look and sound great - rather tempted by the black one myself actually......

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Cheers matey, the Jazz went to a friend on here and I do indeed plan on having it back one day - as with the 24F.

In the meantime I will add the ACG to my list!

ped

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hey daf, i'm putting the acguitars pre and the q-tuners back in, as i need a bit more "aggressiveness" in the mid department to compliment the piezos. nice review, m8 :)

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[quote name='m0reilly' post='45124' date='Aug 14 2007, 03:05 AM']hey daf, i'm putting the acguitars pre and the q-tuners back in, as i need a bit more "aggressiveness" in the mid department to compliment the piezos. nice review, m8 :)[/quote]


thanks michael,
shame you can't quite cram all the electronics in and have both!
that said since i've had the ac pre fitted in my parker fly the piezo has been completely redundant!

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[quote name='ped' post='45107' date='Aug 14 2007, 01:08 AM']I do indeed plan on having it back one day - as with the 24F.[/quote]

yeh, it seems like a lot of basses on here are kind of communal anyway! :)

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Damn! Damn! Damn! Damn!

I hate, hate, hate, hate hearing people play fretless when it sounds this good. Now I have to go out and buy a fretless... again (never can stick at it)!

Is it possible to have too much choice with a preamp like yours? By that I mean do you find yourself tweaking or heaven forbid inadvertently grabbing the wrong setting mid-number? With the standard B/T controls on my Warwick I find it's very easy to dial in the sound I want but past experiences of basses with a lot of extra control (Wal in particular) can leave me exacerbated. As I type this I realise I'm seeking justification with myself for changing the pups/preamps on a couple of my basses, I'm sure if I persevere with whatever I install I'll become accustomed. Ignore me :)

Seriously though, nice review.

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[quote name='warwickhunt' post='45387' date='Aug 14 2007, 07:12 PM']Is it possible to have too much choice with a preamp like yours? By that I mean do you find yourself tweaking or heaven forbid inadvertently grabbing the wrong setting mid-number? With the standard B/T controls on my Warwick I find it's very easy to dial in the sound I want but past experiences of basses with a lot of extra control (Wal in particular) can leave me exacerbated. As I type this I realise I'm seeking justification with myself for changing the pups/preamps on a couple of my basses, I'm sure if I persevere with whatever I install I'll become accustomed. Ignore me :huh:

Seriously though, nice review.[/quote]

oh yes!! :huh: particularly as i have the same pre-amp in my parker with a diferent control layout! :)

actually the biggest problem is catching one of the filter controls with my strap when i pick it up off the stand; as the smallest movement changes things so much - i put down a warwick and pick up a rickenbacker!! :huh: (hmm, fretless ricky... that's something ive never seen... :huh: )

that said, don't let that put you off, the trade-off is so worth it!...(sorry, i know that's not what you wanted to hear :huh: )

oh, and thanks for the compliment, by the way. :huh:

cheers,
daf

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another one here to say, great review. easy to understand (no babbling) and useful soundclips.

in fact, it was a little TOO good. i need one now....

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[quote name='wotnwhy' post='46014' date='Aug 15 2007, 07:33 PM']another one here to say, great review. easy to understand (no babbling) and useful soundclips.

in fact, it was a little TOO good. i need one now....[/quote]

thanks, it's nice to know it makes sense! i did wonder if i was "going into one" when i wrote it! :)

you know, i'm beginning to think i should be on commission! ^_^

only joking alan!! :huh: :huh: :huh: :huh:

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[quote name='skelf' post='46175' date='Aug 15 2007, 10:29 PM']I was beginning to think the same thing.
Alan[/quote]

thank you alan, for making available a most wondrous pre :)

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That's a brilliant review there daf. I'm pretty excited as my ACG isn't far away from being ready. Hmm... you've got me thinking, my Warwick fretless already has 4 holes in it :)

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