Grateful Dead Music Forum

Hey yall. My trusty Mosvalve has finally bit the dust and as much as I liked it, I don't want to risk buying a used, out of production amp again. I'm trying to find an affordable ($400 ish max) power amp that offers the same input/output set up as the Mosvalve 962 but I'm not having any luck, so hoping that the collective wisdom here can point me in the right direction.

Basically, I need a power amp that uses one 1/4" TS input (line coming from the pre amp) that offers TWO 1/4" outputs for speakers (so, connecting two separate 8ohm speakers via 1/4" speaker cables).

I've looked at the ART SLAs but I cannot for the life of me confirm (even after calling Sweetwater and picking their brains, also emailed ART but no reply as of yet) whether or not the amp would power two speakers connected separately if I'm only hooking up a pre amp into one channel.

Thanks in advance for the help here.

There are at least two options. Are you using two separate speaker cabinets?

1. Use the bridge mode. One input signal from your preamp, the power amps combine to have one output. Two 8 ohm speakers are connected in parallel to provide the minimum 4 ohm load (or series for 16 ohms with a little less output power). You need to connect the speakers across the two red binding posts. If both speakers are in the same cabinet, wire them in parallel. With this method, both speakers are driven the same, you can’t adjust the volume of each speaker independently.

2. Use stereo mode. If you have just one preamp output, I think you can jump both inputs of the SLA-1 together. If your preamp has an XLR output, connect to the CH1 input, use a 1/4 inch cable between the SLA inputs. Connect one speaker to CH1 and the other speaker to CH2. The volume of each channel can be controlled independently. If you only have a 1/4” output from your preamp, you need an XLR cable with male connectors on both ends for the jumper.

I don’t recall your preamp setup, can you tell us everything you are wanting to connect? That could narrow down your best choices.

I use a Sarno Revelation preamp into an SLA-2 using a 1/4’ cable and running in bridge mode. I made a speaker adapter using banana plug to 1/4” jack using 14 gauge wire. Since the SLA-2 bridged is over 500W, I turn down the CH1 attenuator knob to not exceed my speaker rating. I think full output on mine is 560W bridged at 8 ohms. You can find a chart or calculation to determine how far to turn down. The attenuator knob is marked in dB, so X watts below 560W converts to dB = your knob setting.

Again, provide more details about what you have and what you want and I can help. The SLA amps sound good with a Jerry type preamp.

Hey Boogie,

Thanks for the reply. So my set up is similar to yours- I'm using a Sarno Spectrum as the pre amp in this case (single 1/4" TS output running to whatever power amp I would use).

All of my speakers are in single cabs, and they're all 8ohm speakers. So ideally, I'd be using the SLA to power 2- 1x12" 8ohm speaker cabs. I'd prefer to use speaker cables with 1/4" jacks on both ends, but I do have a set that has banana jacks that I could use in this case to hook up to the SLA.

What I liked about the Mosvalve was that it gave me the ability to connect the separate speaker cabs and control the volume in each separately. I play venues sometimes that only require a 1x12, but I usually bring along and hook up a backup speaker just in case something goes wrong. With the Mosvalve, I could have the backup speaker hooked up and ready to go but with its volume set at 0.

From what you describe, it sounds like if I want to run the SLA like this I would also need to choose "stereo mode" on the SLA and invest in a custom cable (one end 1/4" TS to connect to the Spectrum, and two XLR male connectors on the other end to connect to the SLA). Any idea what the output wattage would be if I were to go this route? I usually bring a JBL K120 and an E120, so the speaker wattage would range from 70ish to 300 watts.

Each channel of the SLA-1 is rated at 100W, so 3dB down from full output is about 50W. You wouldn’t have to turn down the SLA-1 much. Unless you are playing really loud, you can adjust gain down as a safety factor.

Another option for connecting things is a Y adapter cable with three 1/4” jacks. Single side from the Spectrum, the Y end to each channel’s input. You can ask Brad to be sure. The SLA-1 input impedance for the 1/4” jacks is 22K ohms, so 11K ohms seen by the Spectrum's output. Another way is to buy a 1/4” A/B/Y box. Many are active ($100 to $350) if the split signal needs to be buffered.

It is easy to make banana plug to 1/4” jacks for the speaker outputs. Then you can use standard 1/4” speaker cables. And make a plate or other mount in your rack for those speaker jacks.

Got it. Thanks for the input. I’ve got a splitter box and also speaker cables with the banana jacks already so I think I’m good to go.

Rip, Mosvalve. You served me well.

I am using a SMS CTP into a ART SLA-1. I love the tone. Its a light weight setup. You can find ART makes more powerful models of the SLA series. But i found 100 watts cranked into two JBL E120s makes the sound i want.

And I'm using an SMS Classic Pre into a Carvin DMC200L. In their Gator short rack case, the whole kit and caboodle weigh about 16 lbs.

Tubeworks = Class AB
Many modern amps = Class D

I've yet to find a Class D that I like as much as my TW. It just feels better.

Orange Baby 100 is Class AB, I'd likely try that if I needed something new.

When not playing through my Quilter, I use an Alembic F-2B into a Carvin DCM200L. I jumper channel A to channel B on the F-2B. the two separate channels then go through the Carvin and each to its own 1x12 loaded with a JBL K120. I tweak one JBL to accentuate highs and the other to accentuate lows. I then adjust the relative volumes in relation to each other.

Bill, tgo

@Tacosauce - did you get an SLA-1 power amp? If yes, how does it sound? This amp is Class AB

Also my ART SLA-1 is setup where i can control the speakers in my 2x12 individually. So for live shows for example, i have the bottom speaker mic'd by the sound guy. But if i need more stage volume, i can adjust just the top speakers volume and i dont mess up the mix for the sound guy. I make friends with the sound guys now

They make a SLA-2 and SLA-3. But im telling ya right now, the SLA-1 is plenty. Im using a 2x12 with JBL e-120s. Along with the SMS CTP, i am living the high life tone wise

I have a Furman unit in my rack setup. This is a MUST if your gigging out a lot. Power conditioner is a must.

Hey! I cannot recommend highly enough the Carvin TS-100. Yes, it’s tube, but it’s voiced to be very hi-fi. I recently upgraded all the caps, biased the power tubes a touch cooler, and added NFB trim pots in the back- this allows you to really tune the amp to the speaker and preamp. I honestly think it sounds better than the mc250 in side by side comparisons. I think this is an overlooked option for pairing with a CTP or a Spec. Plus, you can play with different tube sets in both the power and phase inverter spots.

Your Carvin looks like a fine unit.

And it's nice to see there's been more action (new posts) here of late!

Should add also that that the Carvin TS100 is class AB and you can run one speaker off of each channel and control the mix for the two as I do with two K120’s, one original cone and one recone. Super helpful especially with the added NFB trim for each side.

msalata wrote: ↑Wed Dec 17, 2025 4:55 pm Should add also that that the Carvin TS100 is class AB and you can run one speaker off of each channel and control the mix for the two as I do with two K120’s, one original cone and one recone.

It's how I'm using my Carvin DCM200L: each side drives its own SSP 1X12, one with a K120, the other with a Celestion Neo Copperback (which I installed after selling the E120 I had in it beforehand; the E120 sounded fine but I am so done with 18 lb. speakers).