Technology! Progress! Solid State!

[xtian]

My band sent me home with our two rackmount amps from our PA system to clean the pots and check them out. Opened them up, and both have extremely leaky power caps. Crap.

So I look up what replacements will cost, to compare with the cost or repair, right?

CURRENT amps: TWO of QSC MX1500A. 500 watts per channel (FTC) into 4 ohms. Total weight for four channels is 84 pounds. Cost for repair is roughly $340, retail.

CANDIDATE replacement: Behringer iNUKE NU4-6000 (FOUR CHANNEL AMP!). 860 watts per channel into 4 ohms. Total weight is 12 pounds. Cost is $350. Three year warranty.

No fucking contest.

[Leo_Gnardo]

I send people home with their (unfixed) solid state amps all the time. And try to avoid having people bring them here in the first place. You're right, at today's replacement prices, there is no point in repairing, it will cost the same or more than a new amp. The ones people want me to fix are in facilities where "someone" decides to play Big Disco DeeJay when nobody else is around, cranks up the volume, mysteriously next day amps are ka-poot. Knowing that, another good reason to refuse the repair: freshly repaired amps will be subject to the same abuse. When they fail, crustomer will want their money back. I refuse to get on the idiots-delight merry go round. Let 'em buy new amps and blow 'em up one after the other: an idiots-delight game I don't have to participate in.

Can't say much about Behringer's - ahem - reliability. But the price is sure attractive. Even if you swapped out QSC old for QSC new I'm sure you'd still be getting a bargain.

[vibratoking]

I must be missing something. Why is this a SS problem? Or is it a SS problem?

The power ratings are always dubious to me. Without knowing how it is measured the quoted rating is meaningless.

I am under the impression that Behringer reverse engineers designs from other companies. Which is why they can offer products so cheaply. If that is the case, I don't feel very good about giving them my money. That being said, I own a couple Behringer products and they have performed well.

I'd be tempted to close it up and use it to failure before discarding it.

[Structo]

I believe most PA amps now are D class, which means a light powerful amplifier

[M Fowler]

I run Carvin PA mixer and Power Amps great prices.

[xtian]

The only issue with these QSC amps is reliability--don't want them to fail during a gig. Likely they will improve in performance with a recap!

Trying to do cost vs. benefit evaluation.

[boots]

I agree about repairing solid state amps for people. You might as well pay the customer to work on their amp, cuz you sure won't end up making any money on the repair! You'll probably end up leaving some of your own parts in the unit before throwing up your hands in disgust and giving it back unrepaired, at no charge.

Still I end up getting talked into working on that crap, even though I keep saying I will only do custom builds from now on....

My worst experiences have been with Peavey, but most all brands of "consumer electronics" grade crap are a nightmare to work on.

[briane]

SS repairs are charged by the hour + bench fee, while tube amps are bench fee + diagnosis and a set fee upfront to repair.

makes it easy - always make money.

almost all see there is no value in the repair of SS when their paying hourly.

I aint no damn chump for an uneducated customer to whine to - go down to the pound if your a whiner!

[schaublin65]

Hi,

if you can recap an old SS power amp yourself and don't mind the weight issue it's possible to do OK.

If you have to pay bench fees it's a different story.

QSC are easy to get information from and have a good forum with tech support. The old ones are simple and well made. I like them

Peavey are good for schematics but their forum is less useful I think.

Hartleys Law is often believed to state that the worse a thing sounds the harder it is to kill. I think this is a little unkind. The dollar a watt CS800 runs at 10 cents a watt here in Ireland now. I just bought one for my nephew for his first PA. He is 17 and well able for the weight!

In Europe the T Line Pro amps are highly regarded for modern chinese productions.

Take care...

John

[cbass]

Ive managed to repair several couple were pretty straightforward couple wasd a real bitch . I dontvrepair amps for a living so I looked at it like a learning experience

[Leo_Gnardo]

Hartleys Law is often believed to state that the worse a thing sounds the harder it is to kill. I think this is a little unkind. The dollar a watt CS800 runs at 10 cents a watt here in Ireland now. I just bought one for my nephew for his first PA. He is 17 and well able for the weight!

I subscribe to another corollary that goes something like: the worse the quality of a device, the more fasteners will need to be undone to get inside to fix it.

I made my first good PA with a Peavey CS800 and CS400. Sounded great & very reliable. Also didn't wreck speakers because of the DDT limiting circuit, pure genius for the day. Heavy though, just back breakin'. With a little dusting-out every so often, no reason those amps can't last 40-plus years.

I wouldn't pass up fixing a nice old McIntosh, Crown, Phase Linear SS amp. Very simple compared to some modern ones, also made with real-size components, no flea-size circus-mount parts. Like the tone of some of these old classics too. I think the SS manuf's made a wrong turn when they started to overcomplicate the circuitry & miniaturize it besides. But that's from my POV, a fixit technician. Their POV = make it cheaper faster bigger, who cares now about reliabilty and tone, what's that?

[John_P_WI]

Have to agree with you Leo. A number of years ago my original 1980 polytone minibrute V stopped working, it was a great clean practice amp. This past weekend I decided to tear into it. After taking a zillion screws out and pushing all of the combo fiberglass insulation out of the way to reveal the power amp it was obvious a fuse was blown. Replacing the fuse and running it at 20v through the variac resulted in a terrible hum and a sawtooth wave form on the 'scope. Yeah, you guessed it measuring B to E and B to C on the power transistors showed they were shorted... Long story short, simple SS amp, with no schematic - and was able to diagnose in less than 10 minutes.

Now... If I could only have found substitution parts for the obsolete driver and power transistors in as short of time. Progress definitely made finding the replacement parts difficult... nevermind the screw terminal 8200 uF x 50 v electrolytics that are unobtainium

[schaublin65]

Hi

"I subscribe to another corollary that goes something like: the worse the quality of a device, the more fasteners will need to be undone to get inside to fix it."



I have a digital projetctor with a water damaged SMPS here that must have a hundred screws in its "box"

Thankfully we have digital cameras now.

Get off my lawn???

Take care

John

[matt h]

(deleted)

[vibratoking]

I subscribe to another corollary that goes something like: the worse the quality of a device, the more fasteners will need to be undone to get inside to fix it.

+1 Nothing to do with SS vs tube, butI have one of these mixers. Not bad when it works properly. It suffers from a crappy ribbon cable connection problem. Take off EVERY knob plus some screws to get inside. Next time I'm going to rip out the connectors and solder them all instead.