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Topics - SwamiRob

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Hey guys, just wondering if anyone could point me in the right direction of ways to do pretty basic tests on gear? Specifically whether something's mains input is working correctly? I've got an old Alesis compressor which uses an unusual mini jack style plug w/ DC, and compatible supplies are hard to find. I've got a power supply for it and also a noise gate from the same series which is also not working. Is there any straightforward way of using a multimeter to see if there's a break in the circuit that deals with taking mains power? I imagine this could be more straightforward on the power supply then either of the units! Thanks for the help!

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Hey guys, was just wondering if someone might be able to track down some OTT distortion I'm getting from the 2nd channel of my Lab Series?

The thing needed some attention after I'd got it and it was putting out a really inconsistent signal on both channels (although there was slot of noisy drive on the 2nd channel still) and I took it to a tech. I'd re socketed the reverb input/out from the board as it had all been disconnected. The tech managed to fix the power amp issues and there was now the ton of headroom you'd expect from a well made 70s 200w solid state amp. There was a weird feedback when you turned the master up, but so much volume that didn't matter.

Both channels now worked fine, but the connection to the reverb & distortion circuit had now been severed, reattaching it there was very very little volume from either the reverb or dry elements, and a really over the top clipping from the dry signal still present. Pretty much had to have the channel volume barely on to have lower gain clipping but nothing clean at all, although you could tell the signal sounded alot richer for going through that bit of circuit, as the sound is quite sterile without. Could live without it maybe as I can get round the reverb issue by splitting the signal and going through the footswitch, but that's predictibly noisy even with some signal boost from an EQ pedal, and also gets some nasty clipping when there's overdrive unless I really really full the signal (I know spring tanks get a LPF/HPFed signal to my knowledge, but it really doesn't sound right.

Got a new CA3094E for the distortion circuit, and the dry volume is better but not great, and there is now an increasing high/upper mid distortion signal that gets introduced as the master is turned up. The reverb however is now at a decent level with very little noise. I've messed with the distortion trim pot and that merely goes from very very distorted to extremely distorted. There is some breakup without the connection made to the circuit like it was when I got it back from the tech in a bit more of a controlled manner, just the overall signal seems like it'll be a tad warmer when it's working like it should, and the reverb sounds awesome.

Any ideas would be very appreciated! I can't find the listing from when I bought it, but they had mentioned that they had some unconfirmed reports it had belonged to some 80s metal band at some point, do not sure what might have been messed with!

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Looking for some guitar speakers with a bit of a mid scoop, definitely around the 400-500hz range where electric piano has a fair amount of mud, and a nice extended treble without too much upper mid harshness. Want something that's not too fizzy with overdrive, but considering a pedal with a clean blend so can keep the overdrive in the midrange with clean top & bottom end for better clarity, so hopefully extended highs for clean tone won't translate into fizz for overdrive! The most promising things I've seen are in the Jensen Jet range, as alot of them have that dip in the lower mid-midrange, and they also have a good power handling for my 200w LabSeries L11. Anyone got any good suggestions?

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Amplifier Discussion / LabSeries L11 power section repairs & spares
« on: July 20, 2020, 10:48:42 AM »
I've picked up a pretty battered L11 off eBay that I'm trying to get working for some electric piano. Was working ok other then the odd little sputter when I first got it (it was listed as probably needing a good service), when giving the thing a good clean out previous to it the reverb send/return socket has all the pins snapped off, and the reverb tank has a hook kissing off the transducer. Other then that it seemed to be able to get some decent volume without any problems other then the little random bits of noise that kept coming out that I figured could also be dirty pots. Second time I plugged it in to a 4ohm bass cab totally forgetting that it's 8ohm. Didn't use much volume but this time it sounded awful at anything other then minimal volume (until I worked out what I'd done...) making a horrendous farting noise. Same deal when I unplugged it and went it into a 8ohm speaker.

Not sure if the filter caps were ready to fail anyway and that's put them over the edge, or I've messed up some other element of the power section? Never ran an amp on the wrong impedance and don't know much about what it can damage, didn't think at all at the time as I'm so used to SS stuff being rated for at least as low as 4ohms.

I think I remember seeing that some obscure company makes output chips that are compatible with these (although my limited knowledge of output chips is that they tend to blow as quickly as a fuse and not gradually fail), but I'm a little concerned that there could be alot of components that are t going to be very easy to replace.

As a little aside if this ever gets revived to working condition - can anyone tell me a bit more about the compressor? The -/+ sides of it, is the plus side an upwards compression sort of effect/a downward expander/both/neither?

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