Double Bass Power Amps?

[Kenan]

I recently tried what you are suggesting with a less than successful outcome. I bought a Baby Sumo with the intention of using my pedalboard-mounted Subway Plus preamp to drive it. What I found is that it was lacking the headroom that I was expecting. I had several long pm/email chats with both the Sumo designer and Andy at Mesa and the short of it was that the combination was not a good one. The Sumo input is unbalanced, resulting in a signal loss. Others have used other preamps successfully with the Sumo, but I am not willing to change from the Subway pre as it does everything that I need (and very well, I might add) so I sold the Sumo. OP, if you want to see the long discussion (some of which is admittedly above my head) pm me and I'll send it to you.

I have had a similar experience running the Baby Sumo. I sometimes use it with a Fishman Platinum Pro in front. On really loud gigs, I have to have everything pretty much cranked to the max. Although it gets plenty loud, it doesn't FEEL like I'm cranking 600 watts. I assume that the Sumo is wanting a hotter signal, although that seems odd. Luckily I've always had just enough power so far, and the Sumo stays nice and clean even when dimed.

 

[Kenan]

It's quite a coincidence that this thread popped up as I was just thinking about this the other day. Since most amps tend to be voiced more for bass guitar than for upright bass, I was thinking it would make sense to plug into some sort of acoustic preamp and then plug that straight into a poweramp, then run that either through a bass cab or a PA speaker and cut out any sort of traditional bass head that would color the tone in potentially undesirable ways. I'm glad I'm not the only one considering this!

I agree with this way of thinking 100%. For upright, I typically use an acoustic preamp into a PA speaker. For electric, I use a more traditional bass rig. They are totally different things when it comes to amplification, in my opinion.

 

[Wasnex]

I have had a similar experience running the Baby Sumo. I sometimes use it with a Fishman Platinum Pro in front. On really loud gigs, I have to have everything pretty much cranked to the max. Although it gets plenty loud, it doesn't FEEL like I'm cranking 600 watts. I assume that the Sumo is wanting a hotter signal, although that seems odd. Luckily I've always had just enough power so far, and the Sumo stays nice and clean even when dimed.

It's not unusual to run the input control on a power amp wide open. This control is generally an attenuator rather than something that adds gain.

Sometimes it is necessary to dial a power amp's input controls down a bit for the best signal to noise ratio, but my impression is the Baby Sumo has a somewhat high sensitivity rating...meaning it needs a relatively hot signal to hit max power. Because of this, you probably need to run it wide open more often than not. I have seen quite a few threads were people had trouble pushing the Baby Sumo to full power, and many of them flip the amp in short order. Sometimes this occurs because the preamp is not really intended to drive a power amp...the output is not line level.

The amp output on the Platinum Pro is listed as 6dBv max. This is not a super hot signal. There are quite a few threads that suggest it struggles to drive a power amp.

 

[Maple]

Any love for the Demeter?

I have a MAS 1-8.5 that I use in low volume settings. But more often, I use a Demeter VTBP M 800D with an old Bergantino ht112. Either way, I usually have the Felix in front of those.
The Demeter makes everything sound good. I often rehearse in places that have a bass rig - for those, I bring the Demeter and use the house cabinets

 

[Ric Vice]

I have a question regarding power amps. Most of them I see are two channels. So people who use discrete power amps, what do you do with the second channel? Just leave it vacant or do you run it bridged for more power?

Ethan,
The Jule M700, Demeter, and Baby Sumo are all mono power amplifiers so
there’s no second channel to deal with.

 

[Drew Tanner]

Not mine, but there’s one of the rare Acoustic Image Focus SA power amps (600w) on Reverb right now priced lower than the Demeter or Jule amps, though a touch more than the Sumo. I have two of them and they sound remarkably good with the variety of preamps I’ve tried in front of them (Sarno V8, Grace Felix, SansAmp ParaDriver, Headway EDB2, etc.) driving a variety of cabs. And Rick Jones still services them.

 

[bherman]

It's not unusual to run the input control on a power amp wide open. This control is generally an attenuator rather than something that adds gain.

Sometimes it is necessary to dial a power amp's input controls down a bit for the best signal to noise ratio, but my impression is the Baby Sumo has a somewhat high sensitivity rating...meaning it needs a relatively hot signal to hit max power. Because of this, you probably need to run it wide open more often than not. I have seen quite a few threads were people had trouble pushing the Baby Sumo to full power, and many of them flip the amp in short order. Sometimes this occurs because the preamp is not really intended to drive a power amp...the output is not line level.

The amp output on the Platinum Pro is listed as 6dBv max. This is not a super hot signal. There are quite a few threads that suggest it struggles to drive a power amp.

I was one of those “flippers”. What I learned through my investigations (conversations with preamp designer and with Sumo reps) is that the bigger issue was a lack of a balanced input on the Sumo, resulting in a loss of input signal strength

 

[Ric Vice]

Not mine, but there’s one of the rare Acoustic Image Focus SA power amps (600w) on Reverb right now priced lower than the Demeter or Jule amps, though a touch more than the Sumo. I have two of them and they sound remarkably good with the variety of preamps I’ve tried in front of them (Sarno V8, Grace Felix, SansAmp ParaDriver, Headway EDB2, etc.) driving a variety of cabs. And Rick Jones still services them.

The Focus SA's were probably the first mini power amp around and have held up very well. Rick Jones told me that they only built @80 of them because they didn't sell.
Their more compact than the Jule M700. So if you can find one their a great alternative.

 

[ToneRanger]

Since I bought a Grace Alix I've been running it straight into the power amp stage of my Darkglass M900v2. So, I figured I'd simplify the setup by replacing the M900 with a GSS Baby Sumo. I'm very happy with the outcome - a compact package with ample clean power. The Grace has plenty of gain to drive to Sumo and the sound from both devices is crystal clear with absolutely no background hash. I'm enjoying the clarity, headroom and tonal flexibility of this combo, especially for acoustic Double bass.
Didier from GSS was very helpful with my queries, including adding a LED signal indicator free of charge.
The amp is not the finest piece of hardware I've owned (esp compared to the Grace & Darkglass) but seems robust enough. The main downside for me is that it can't go under 4 Ohms (for combining my 4 Ohm 210 with 8 Ohm 112) but I'll get by. I suspect this is a tradeoff for not putting in a fan, and I'm happy to not have that noise. The manual says not to run it in ambient temp above 40 degrees C - it remains to be seen whether that will be an issue on hot stages in a globally-warming Australian summer.

 

[ToneRanger]

BTW, I still have the Darkglass for sale if anyone's interested.

 

[ToneRanger]

The manual says not to run it in ambient temp above 40 degrees C - it remains to be seen whether that will be an issue on hot stages in a globally-warming Australian summer.
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Well, I'd only used the Baby Sumo at little cafe trio gigs until last weekend, when I was with a funky jazz quartet playing a small club without PA support, so I was pushing my rig fairly hard. The read peak light on the amp flashed a few times so I backed off a bit. The was no clipping distortion. Partway through our third set the amp shut down. Lights on but nobody home. Fortunately there was a spare QSC K10 I could grab to finish the gig. It was a fairly warm night but the venue was air-conditioned - I don't think the stage was more than 30 degrees C. So now I'm worried about whether I can depend on this amp through our summer.

 

[crd]

Well, I'd only used the Baby Sumo at little cafe trio gigs until last weekend, when I was with a funky jazz quartet playing a small club without PA support, so I was pushing my rig fairly hard. The read peak light on the amp flashed a few times so I backed off a bit. The was no clipping distortion. Partway through our third set the amp shut down. Lights on but nobody home. Fortunately there was a spare QSC K10 I could grab to finish the gig. It was a fairly warm night but the venue was air-conditioned - I don't think the stage was more than 30 degrees C. So now I'm worried about whether I can depend on this amp through our summer.

Thanks for reporting this. I've been thinking about one of these for a while and I appreciate the gig reports.