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Calling all ACG filter preamp users!

Bright Midnight

Bright Midnight

Oct 5, 2010
1,261
1,230
Belgium, Flanders
#1
Not really a question but rather an itching desire to hear your impressions on this preamp. Write down what you think are the pro's and the con's. I'm leaning much toward the ACG for my first build. It seems a big leap forward from regular preamps and I'm dying to get my bass fitted with one!

Fire away! :bassist:
 
#2
I put one in a G&L L2000 (I do believe I was the first lol) and while I did like it, I am not sure if I would do it again. On a gig, the preamp was difficult to adjust IMHO. The HPF was way too harsh and I didnt use it at all and if I needed more lows it tended to wipe out everything else (including mids) Overall the bass sounded good once I found a sweet spot, but there are lots of times when you have to adjust to a room and thats where I had issues with it. YMMV.
 
#3
I have found it to be a very useful preamp. I have it in a Warwick Corvette with EMG JX pickups. The preamp gives me at least 6 useable tones of which I use at least 3 in a gig.
My experience is not that like the poster above. I have tons of mids. It all about setting the preamp up right. I love it and will keep it in this bass.
The cons for me aren't that bad. It takes a bit to truly dig in and get all of the different sounds that are possible. After messing with it enough though it becomes second nature to dial in the EQ that you want.
 
#4
jgroh said:
On a gig, the preamp was difficult to adjust IMHO. The HPF was way too harsh and I didnt use it at all and if I needed more lows it tended to wipe out everything else (including mids) Overall the bass sounded good once I found a sweet spot, but there are lots of times when you have to adjust to a room and thats where I had issues with it. YMMV.
Click to expand...

How come the HPF sounded too harsh? From what I read in the ACG manual the peak control on the HPF works like the resonance control on a synth filter. Cutoff on a filter is pretty straightforward, but adding resonance is more sensitive. It yields the sonic treasures though, but only if handled with a bit of care. I suspect the ACG preamp works similar and turning open the peak control on the HPF boosts the higher frequencies up to where they become harsh sounding. In what way did you use the peak control on the HPF? Just curious because I know how easily resonance can destroy a basically good sound. Thanks for the input, will keep it in mind!
 
#5
The HPF to me is an instant stingray-ifier. Not harsh per se unless you go too extreme with it. To me, adding a bit of bass to the signal isn't about cutting the filter all the way down to the frequency that you're looking for, but just cutting back the higher frequencies a little more, just a little.

I keep my HPF off, LPF wide open or slightly less than that, no boost. Gives me exactly the tone I want.
 
#6
On my bass, the HPF was completely off. Peak control was off. If I turned it up at all it made the bass sound like a six string guitar. If I turned the LPF just a notch too much, it was like I instantly grew dreadlocks, wore a beany, and was transported to jamaica =) I have talked to lots of other people that said it worked great in their bass, and like I said I had found a sweet spot, but I preferred the stock G&L preamp.
 
#7
Hi
The high pass filter does not have a peak control. The lower ring controls the frequency of the filter cut off. The upper ring is a gain control. This allows you to remove the high pass filter from the signal chain. Also bare in mind that the high pass filter has the most noticeable effect on the sound when filly backed off. In this position it lets through the lowest frequencies that the filter allows. So you have frequencies as low as 1kHz which if then boosted a lot could sound pretty harsh. If you also have the lowpass filter open in the same range and then boost it with the upper ring you are going to be really boosting in a narrow area. As you open up the high pass filter it removes the lower frequencies progressively until you have only the real top end. There is quiet a big overlap between the two filters this allows you to use either in certain frequencies to make the pre-amp more flexible but if used both in the same range it will be possible to come up with less than ideal sounds. However as with all these things someone may well want that sound.

The upper ring on the low pass filter does add boost to the frequency cut off set by the lower ring forming a peak round the cut off.
 
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#8
I have only had mine installed for a couple of days. It is staggering. Paired with Delano pickups it is amazing in its tonal range. I wish I could offer a more informed opinion. I can say that the first impression is that this it one of most important pieces of gear ever conceived. The customer service at ACG is phenomenal. Alan gives a level of personal attention that is not the norm in this day and age. I will post a proper review after some gigs.
 
#9
The ACG (and other filter-based preamps, like Wal and Alembic) does require a different approach than the traditional 2- or 3-band boost/cut.

I have a lot of experience with the Wal preamp, but I'm still sorta getting used to the ACG preamp. With both, though, my basic approach is to treat it like a "supercharged" passive tone control. I tend to use the cutoff frequency on the LPF to decide how bright or dark I want the overall tone to be. Used in that way, it feels and sounds very natural.

I generally leave the boost off (all the way counterclockwise) on both the LPF and the HPF unless I'm going for some specific effect, but it's a case where I have a few specific settings I like to play with. It's not quite as easy to do minor tweaks with the boost settings on the ACG as it is on a traditional 3-band, but it offers some settings that simply aren't possible with the traditional EQ.

One thing that confuses people, I think, is the center detent in the boost control for both the LPF and the HPF, which is not "flat" but "boosted halfway". Also, I find myself missing the numbers on the Wal knobs, which made it a lot easier to reproduce specific cutoff frequency settings. But the ACG has more overall flexibility than the Wal EQ, with variable boost instead of a single on-off boost setting, and a high-pass filter control with wide or narrow frequency range and variable boost instead of a "pick attack" with a narrow frequency boost and a single (adjustable) on/off boost setting.

It's not something that will work for everyone. It's really easy to get a wide range of tones from bright to very dark, with an infinitely variable amount of "midrange honk". But if your preferred tone is basically a "flat" sound with a little bit of bass boost, that's not really something you can do.

Mike
 
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#10
Im not saying the preamp wasnt great, because it is and I used it to record and it sounded very good. Live is where I had problems with adjustments. Some gigs didnt require much adjustment and I was good, but alot did...maybe a little less/more lows, mids, etc without changing the other frequencies, if that makes sense. All in all it was very cool but it is not for everyone like mikezimmerman says above.
 
#12
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Starts out with treble filter off and bass filter wide open. Eventually you hear the treble filter pulled in for a moment. Treble filter back off again, and I do the same riff over and over, gradually bringing the bass filter down from wide open. Then I boost the heck out of the low filter and make some uh...wah sounds with it. Then some more fiddling with the treble filter.
 
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#13
Nice, keep the posts coming!

I would also like to hear how you owners feel about the passive tone knob! I'm thinking it makes a nice addition to a sculped active sound, especially with those filters, dialing in some passive tone to further shape the tone. I'm guessing that it is best used subtly?

:hyper: Me want one! NOW!
 
#14
I don't have the passive tone knob on mine. As I said, I tend to treat the ACG as a "supercharged" version of the passive tone, so I honestly don't know how much use an additional passive tone knob would be. After all, the passive tone simply cuts frequencies above a certain cutoff frequency (based on the capacitor value), and you've already got a LPF doing the same thing in a more flexible way.

Maybe someone who has an ACG with the passive tone can chime in about how they use it?
 
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#15
Oreomeister365 said:
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Starts out with treble filter off and bass filter wide open. Eventually you hear the treble filter pulled in for a moment. Treble filter back off again, and I do the same riff over and over, gradually bringing the bass filter down from wide open. Then I boost the heck out of the low filter and make some uh...wah sounds with it. Then some more fiddling with the treble filter.
Click to expand...

Thanks for your demo. Gives me an idea of the extremes this preamp is capable of. I hear this preamp has a broad range and it's pretty sensitive, right? Seems like it's gonna take some homework to get the most out of it, but it'll be worthwile!
 
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