I'm intrigued by these big rack mounted amplifiers with the handles :dbtu:
I'm seeing various models like the M-2600, IPS-800, CS-400....
Stupid question like always...what do/did people use these amps for ? I'm guessing it was to play loud music at an event like a wedding 💍💒 reception or keg party xP or maybe it was part of a band's equipment playing live ?
Anyhow another stupid question when I see rows of output transistors I wonder aside from being shorted which I guess would be very obvious and a big problem...do they fail in other ways?
For example if they have one channel with eight big outputs could it be the amp is slightly down on power because one or more outputs is not contributing? Like when you have a vehicle down one cylinder and you can feel it or hear it.
Every Power transistor has limits on how much Voltage it can withstand, how much current it can conduct and how much power (Voltage x Current) it can dissipate. The design of a power amplifier must take these limits into consideration if it is to operate without failure.
High power amplifiers use a number of transistors in parallel because of these limitations. If one of these transistors were to fail, the chances the amplifier will keep operating are fairly slim.
Bipolar transistors suffer from an additional limitation called "Second Breakdown". A transistor may be rated at 150 Watts, but at higher Voltages, they cannot dissipate that amount of power. They will fail. To get around this limitation, high power amplifiers use many transistors in parallel.
To see more about Second Breakdown, see this thread:
https://www.ssguitar.com/index.php?topic=4897.msg38561#msg38561
Also, power transistors are more likely to short than go open. A shorted power transistor will shut down the amp one way or another. And in the cases where one opens instead of shorts (or if it's emitter resistor opens), than the others in parallel with it have to do more work, and usually this leads to more failures.
Quote from: saturated on February 21, 2026, 02:08:06 PMwhat do/did people use these amps for ? I'm guessing it was to play loud music at an event like a wedding 💍💒 reception or keg party xP or maybe it was part of a band's equipment playing live ?
PA systems used to be a lot of non-powered speakers and racks of these big power amps.
The first powered speakers I'm aware of were powered subwoofers. Because they still used regular power transformers they were very heavy.
Once SMPS (switch mode power supplies) became more common, more and more speaker cabs became powered. SMPS replace regular power transformers with a very lightweight electronic circuit.
Most speaker cabs now are powered, but even stand-alone power amps now use SMPS, so they are also very light on a pounds-per-watt basis.
The downside of SMPS is longevity as they use a lot of capacitors that do not like heat and have a finite lifespan.
If you don't need mobility, the old power amps you can find are a pretty good bargain, especially if you find speaker cabs that are being junked because their amps are blown. :)
A person in Houston has this guy for sale $100
Thinking about getting it. I'm about 100 miles east of Houston but having a family get together on Sunday
Seems like a decent deal but idk
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I imagine most of these guys encountered in the wild have had rough lives :'(
Also no I deer 🦌 what the round sockets are xP
I think those round sockets are for transformers that are used when you use the balanced XLR type inputs. (I can't read what it says on the back of the amps.) This allows you to run a very long cable from a mixing board located in the audience to the power amps located on stage. They might also be special circuits that allow you to just drive sub-woofers.
Evidently, the round sockets are Peavey thing. They allow modules to be plugged in such as crossovers for different frequencies. And yes, supposedly, conversion from unbalanced to balanced. These things look like a metal can with pins.
Example someone posted in a forum. (https://www.diyaudio.com/community/threads/wanted-peavey-pl-2-balancing-transformers.38949/)
Give me any big rackmount amplifier; if it is a linear amp with a conventional global feedback loop, I will put current drive into that sucker and use it for guitar. 8)
Thanks guys :dbtu: :dbtu:
I certainly don't need it as far as geetar I been a bedroom wanker last thirty years xP
I could play music through it but I imagine it would vaporize any speakers :lmao:
However I desperately need some new stuff to work on and play with :tu:
Quote from: saturated on July 21, 2026, 05:37:25 PMI been a bedroom wanker last thirty years
Thats neither here nor there; you can be a bedroom wanker with a 1200W/ch thing into stereo 4x12 cabs loaded with 400W speakers. You keep it on the low most of the time and the neighbors barely know it exists.
I would expect $100 to be roughly market value for a power amp like this in working order.
If you need stuff to work on, you can probably find a broken one for free. :)
Thanks guys :dbtu:
About all I know at this point is
Check the emitter resistors xP
If it works fine $100 is a bargain and better than a free dead one which can become a bottomless money and time pit.
You can use it with a modeler into very inefficient speakers and still shake walls or for Sunday BBQ outside and annoy neighbours many blocks away. FUN!!!
Here in Argentina we get all kinds of imported stuff but then replacement parts or Factory Service becomes impossible because of 6000 mile distance and Customs/paperwork/exchange barriers so often stuff that dies ... dies.
Most (95%) of powered cabinets can not be repaired or their back plate amps can not be replaced (they cost more than a new one) so poor PA guys or small bands or Churches buy them for peanuts, junk the back plate amp, cover the humongous hole with a plywood rectangle and fit there a passive crossover (sometimes as simple as a 2.2uF polyester capacitor) and a couple Speakons.
Then they feed it from a boat anchor such as your Peavey , which are indestructible, or any "mystery" rack amp.
Believe it or not, end result is quite good, so you see a random mix of JBL, Yamaha, EV, RCF, Mackie, etc. cabinets stacked on both sides of stage, all powered by racks of old power amps.
Again, very usable.
You can build a serious PA setup for peanuts.
Old analogic mixer desks are also cheap, nobody wants them.