SR-400 to Beta Lead 212?

[BornInSinn]

Hi All, I'm new here and could really use some advice - I've searched all the forums and come up empty - and it'd be much appreciated!

I have a Beta Lead 212 combo and recently acquired an SR-400 "Sound Reinforcement" powered mixer. I'm in the process of finding a cab to run the SR-400 through on the regular, but I also know that both the Beta Lead and the SR-400 are rated at 100w@4ohms, so I was wondering if I could disconnect the 6" cable from the Beta's head to its internal speakers (which I assume are 50w/@8ohms, wired in parallel?) and patch in the SR-400? Or will going from stereo to mono burn something out?

Any suggestions would be much appreciated, as would any other info anyone happens to have on the SR-400. There's a real paucity of info about it available, near as I can tell.

[Isaac]

I'm not quite sure what it is you want to do. If you want to run the SR-400 into the Beta Lead's speakers, then I don't see a problem, provided you disconnect the Beta Lead, as you said. Which one are you thinking is stereo?

[BornInSinn]

Hi Isaac,

Thanks for responding! Yeah, I was hoping to use the Beta Lead's speaker's (bypassing it's amp entirely) with the SR-400. The SR-400 is stereo I think because it has two speaker outputs (though they aren't marked left and right, for what it's worth) and they guy I bought it from warned me that going from stereo to mono could cause the amp to overheat (though he didn't seem 100% sure about that). But it sounds like you're saying that shouldn't be a problem, so maybe I'll just give it a shot. Thanks again!

[Isaac]

I think the guy you got it from was mistaken. I see no indication that it's stereo. No left/right masters, no left/right outputs, no pan pots on the channels. It's mono, for sure. If you check, you'll find that the two speaker outputs are in parallel.

[BornInSinn]

Update:

You were right, Isaac - I ran the SR-400 out to the speaker input on the beta lead and it worked like a charm, thanks!

Unfortunately, however, that test was diagnostic for another problem that literally just came up yesterday. I realize it's a slight change of topic, but seeing as I'm the OP, I was wondering if you might be willing to offer some more (very helpful!) advice?

So yesterday I got my new (to me) ART MP Studio tube preamp. I was running it through the A accessory loop on the beta lead and everything was fine - the tone was noticeably warmer and 'tubier', the levels seemed fine, there was no clipping, etc. - when all of a sudden my finger hit the +20dB gain button, and the beta lead made a noticeably unhappy noise. I turned off the amp and the preamp (I think perhaps in the wrong order?) and hooked my guitar straight up to the amp. When I turned it on everything seemed fine at first, but then I noticed that whenever I played a louder note or hit a chord with any amount of reasonable force, the signal began to stutter and distort and there was a noticeable drop in volume for a second, then it returned to normal. I also seemed to be getting a low grade hum last night right after it happened, but when I tried it out today the background hum was gone, although the volume problem was still there. I'm not sure whether it's a problem in the preamp or the power amp or what. I know it's not the speakers -- they worked fine with the SR-400 -- and I get the problem in both channels now, not just A.

In any case, if you or any of the other knowledgeable folk around have any thoughts about what the problem might, I'd sure appreciate any input/advice/terrible news. I only got the beta lead 2 weeks ago - my first "real" amp, that I bought myself, with my own money and everything - and I love it so much! I'd hate for it be shot or effectively totaled...

TL;DR: Preamp fried my beta lead and now I can't play power chords - help!

[Isaac]

First step is to isolate the problem. The problem is present when using just the Beta, so we can be pretty sure that it's in either the preamp or power amp of the Beta. I know, it seems obvious that it's the power amp, but it's best to make sure. Run the Beta preamp into the SR-400 power amp, then to the speakers. I expect the problem will not be present. Run the SR-400 preamp out into the Beta power amp. The problem should come back. Those tests, if they come out as I expect, will prove that the problem is in the Beta power amp. If so, you're going to need a technician.

[BornInSinn]

Hi Isaac, thanks again for all your help! I ran the tests you suggested and the beta lead sounded fine through all of them. In fact, it seems pretty much back to normal - I just finished playing through it (i.e., guitar to beta lead) and didn't get any of the volume drops or distortion. I recall a few weeks ago the beta lead was having a similar problem during normal play (no tube preamp business or anything) so I stopped for the night and it was fine the next day. When the problem didn't go away overnight this time I figured it must be something else, or at least the straw that broke the camel's back of the old problem.

So now I'm obviously happy my amp is back in fighting shape, but I'm wondering whether there's not still a lingering problem that might one day, if unchecked, turn into a serious (and non-self-healing) problem. Any thoughts about what could cause this? Since I feel like I escaped a hefty amp repair bill, I'm going to take it into my local shop for a once-over, check-up, but if you have any suggestions/ideas I'd love to hear them.

In any case, thanks so much for all your help!

[Isaac]

I'm not familiar enough with the circuitry of the Beta to even hazard a guess, but maybe someone else here can make a suggestion.

[BornInSinn]

No worries, thanks so much for all your help!