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Double Bass Clarus SL Questions

Ben Rolston

Ben Rolston

Supporting Member
Aug 30, 2006
752
548
Brooklyn, NY
#1
So for the past year-ish I've been using a Genzler Magellan 350 with a Felix into various cabs (with a full circle, then a Yamahiko). Recently, since moving to NY and using a variety of house amps, I've been feeling like I want to hear just Felix but the Magellan doesn't have an effects loop (it does have an aux in, but that seems to result in a much lower volume ceiling). This logically points towards a power amp set up or a powered speaker set up; I know many others have gone this route. Before going down that road I thought I'd get a Clarus SL on trial from Gollihur, and wow I really like it! I thought I'd use it just a power amp, with the preamp input as a backup, but honestly it sounds pretty great without Felix (at @SamuelHarris 's recommendation).

So here are my questions:
  • Has anybody else found the Clarus- SL (or acoustic image amps in general) to be more feedback prone than others? The amp really seems to pick up and emphasize a problem afterlength note on my bass. In general the response from the amp feels kind of "gained up" or even a little compressed, kind of nice because I think more nuance will show through BUT not if there's feedback :(
  • Any advice about setting the gain structures on the amp? I'm very used to having a clip light on the preamp stage. Obviously using my ears to listen for clipping comes first, but I find that sometimes low key clipping is hard to distinguish from bass buzz, cabinet buzz, environment buzz, etc. I know with the Aguilar Tone Hammer for instance you can't really clip it, any chance AI is similar? (Interestingly the manual suggests starting with the master volume at noon, and adjusting the input volume from there to get a stage sound).
  • Finally any ideas why these amps, Clarus SL and SL - R, are the only AI amps to feature a 10 Mohm input? It makes a HUGE difference in my experience with the Yamahiko, and I assume other pickups too -- though maybe not?? Full circle definitely benefitted from the high impedance on Felix. I've spent a lot of my bass playing life thinking I didn't like the AI house sound because of the old style cabinets and now, im realizing, the input impedance.
Even if I end up going with a power amp, this is a REALLY cool piece of gear!
 
#3
tombowlus said:
I am a big fan of AI products, in general, and the Clarus-SL, in particular. I have not had any issues with it being more feedback prone than other amps.
Click to expand...

As am I, especially if you're trying to navigate the New York Subway's. Personally, I think the Grace Felix has one of the clearest, if not the clearest EQ section I've ever experienced. I use it in combination

with a MAS 1/8. It's astounding. Just my take though, you could get a Claris SL and the Upshot and be very compact, whether it would sound as good or not is a matter of opinion. I guess if I were competing in

that environment, I'd want the best sound possible out of the smallest rig conceivable. I think the Clarus-SL sounds great, and combined with the MAS 1/8 you have a real winner.

Ric
 
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#5
The Clarus SL and SL-R retained the dual 1/4" inputs, one for 1M and one for 10M, from the older Series I and II designs.

All other AI models lost this feature when the company switched to combo jack inputs (Series III and Series IV) which are only 1M. That includes the two channel SL2, because there's no room on the front panel for the extra jacks.

As far as gain structure, I usually run the master full on and adjust overall volume from the gain control. I've never run the gain up to 12:00 on my AI amps (Contra III, Coda III)...usually 9:00-10:00. If the gain at 9:00 is too much with the master full on, I back off the master to suit.

As far as feedback control, the HPF takes care of that for me.
 
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#6
When I chatted with Rick Jones at last years ISB convention, I believe he mentioned that they found a way to integrate switchable input impedance

into the new front end architecture of the the Claris SL and SL-R. Incidentally, this is nothing new, my Ampeg B-15N(C) has different input impedances on each

of the three inputs. The Channel 1 inputs are 1 Meg Ohm and 5.6 Meg Ohms while the Channel 2 input is 2.2 Meg Ohms. This is one of the reasons that the

B-15N's sounded better with Piezo Pickups. For most pickups, 1 Meg Ohm is just fine, the one exception I'm all to familiar with, is the Fishman BP-100. It

has to be loaded at 10 Meg Ohms to even sound passible. I know this because all the Walter Woods amps were set at 1 Meg Ohm, and you still needed the

Fishman Pre Amp to get them to sound decent.

Ric
 
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#7
Ric, I'm definitely thinking about the upshot. The 18 is doable, but the upshot is half the weight :woot:

Cool to know some of the history behind the impedance choices from AI. I think the Realist and the Full Circle still benefit from higher impedance than 1 M-ohm, though maybe not the 20 M-ohm of Felix-- so I appreciate that the Clarus has them.

brianrost said:
As far as gain structure, I usually run the master full on and adjust overall volume from the gain control. I've never run the gain up to 12:00 on my AI amps (Contra III, Coda III)...usually 9:00-10:00. If the gain at 9:00 is too much with the master full on, I back off the master to suit.
Click to expand...

Interesting!! I've always set and left the preamp gain and used the master for volume control, I wonder if there are any benefits / drawbacks to either approach. I would assume that on poorly designed amps you'd get some hiss from running the master full open, but maybe AI's got that covered.
 
#8
If you set the master to a very high value and the gain low, that signal to noise ratio is low, meaning there is more noise amplified than needed. Not a problem with a silent amp, but if there is something noisy I cannot recommend that.
On the other hand setting the gain short before clipping can give you a distorted sound if you play louder than when you have checked the level and set the gain, so better turn back the gain a bit and set the gain when playing the low strings as loud as you can imagine you can do and would never play during a performance. Not nice during the soundcheck ...
Then only use the master volume to set the volume level.
If the preamp distorts before the gain limit is reached, a lower gain with higher master make it cleaner but also more noisy. Depends on the noise audible when not playing the bass.
But I cannot recommend adjusting the gain for volume because you have no control over the overdrive indication during playing your stuff and maybe set it too high by accident.
 
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#9
Ben Rolston said:
Ric, I'm definitely thinking about the upshot. The 18 is doable, but the upshot is half the weight :woot:

Cool to know some of the history behind the impedance choices from AI. I think the Realist and the Full Circle still benefit from higher impedance than 1 M-ohm, though maybe not the 20 M-ohm of Felix-- so I appreciate that the Clarus has them
Click to expand...

Ben,
Gigging in New York, it’s likely that the Clarius Sl and Upshot will be your best bet. Input impedance, is only part of the picture, since the first stage of the preamp greatly effects the timbre of the bass. My Walter Woods at 1 Meg Ohm sounds better with the Realist, than most other amps that I’ve used. Acoustic Image amps are much the same, their preamps work in conjunction with the input impedance. My current pickup works best at somewhere between 2-5 Meg Ohms.

Ric
 
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#11
I’ve not found my Clarus SL to be feedback prone. Quite the opposite—and I’ve playe some loud blues gigs with this set-up. I run my master at about 3 o’clock and gain to suit. I should note that an HPF-2 is at the front of my signal chain, followed by a Sansamp ParaDriver DI, then the Clarus.
 
#12
Marty Forrer said:
Feedback with an upright always comes from too high a gain level. Set the master on full and use the gain as your volume control.
Click to expand...
An overdriving gain can easily lead to feedback, but setting the master to full is kind of overkill. Just reduce the gain a bit and enlarge the master setting and then use the master only to change volume.
 
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#13
I just ordered a pair of MAS 18 speakers. Been playing EB since 1975, just bought a used Eminence EUB. I am looking at a Clarus SL...will the 350 watt(8 ohm) and 650(4 ohm) push these speakers without losing headroom? I don't want to buy a Felix either, will the Clarus do the job ok without it? Also considering the Quilter BB800, but wonder if the eq section is versatile enough? Any feedback would be greatly appreciated. PS: Most of my gigs will be with one MAS 18 and I have a killer EB setup so won't need to double with this one.
 
#16
Marty Forrer said:
Feedback with an upright always comes from too high a gain level. Set the master on full and use the gain as your volume control.
Click to expand...

In my experience this only works well with older analog like the Walter Woods MI series amps. Those amps are designed to run the master volume wide open and increase the gain at the preamp. Newer amps like the Acoustic Image are designed differently, these amplifiers have the user run the poweramp volume somewhere between 50 to 70% adjusting the preamp volume.
If I run my newer amps power section wide open they will most likely feed back.
 
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#17
Keithunem said:
I just ordered a pair of MAS 18 speakers. Been playing EB since 1975, just bought a used Eminence EUB. I am looking at a Clarus SL...will the 350 watt(8 ohm) and 650(4 ohm) push these speakers without losing headroom? I don't want to buy a Felix either, will the Clarus do the job ok without it? Also considering the Quilter BB800, but wonder if the eq section is versatile enough? Any feedback would be greatly appreciated. PS: Most of my gigs will be with one MAS 18 and I have a killer EB setup so won't need to double with this one.
Click to expand...

This is of those things that always comes up with one speaker 8 ohm vs a pair of them. That’s why I went with a powered 1/8 but their more expensive.
 

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