why are old school amps worth so much?

[tsmith1315]

Date would likely be very late 80's, their car audio line was speakers-only when I worked with the stuff in '86-'87. The manual claims "twin intelligent power supplies", but that's stretching it.

Claimed:
75WPC @8ohms,
125WPC @4 ohms,
160WPC @2ohms

TIP35 supply transistors and TIP142/147 darlington outputs, plenty of heatsink.

[amc32]

That is a terrible circuit board configuration for car audio. What secures the boards to the heat sink;Base,Emitter,Collector?

[tsmith1315]

Originally Posted by amc32

That is a terrible circuit board configuration for car audio. What secures the boards to the heat sink;Base,Emitter,Collector?

Like free-range chickens, the pcb's are happier and perform better if allowed to move around as they wish. The satisfaction of being unconstrained to fullfill their natural patterns of movement results in a more free-flowing electron stream. As a result this amplifer has a natural, open sound unlike any other I have experienced.

BCE's and all the wires and cable ties provide security that the boards won't stray into dangerous areas.

Incidentally, the toroid is a free-floating design, defying imagination by levitating in mid-air. (Actually there is a broken tie strap that must have once kept it close to the free-range power supply board.)

There is a hole in each end of the PCB's that appears to have been provided for mounting, but no provisions in the heatsink to complete the attachment process.

A little more detail is in the attachment.

And upon second look, the "twin supply" is outright **. One 4093 switching two sets of parallel TIP35's. One output per set into one transformer, one rectifier, two filter caps. A single + and - rail supply both amplifiers.

I'll fire it up one of these days and see if it still works...

[jol50]

Thanks for posting the test Tsmith. I wonder what kind of output the old coustic amp300 had, I should have kept those they worked nice supposedly 2x75.

[tsmith1315]

You're certainly welcome, jol. I'll look for any tests concerning Coustic's products.

I worked with Coustic stuff around '87-'88 or so. Amp190, Amp380, seems like there was one in between... HEXFET proudly displayed on the cover, I felt like it was to capatalize on RF's success with the MOSEFT Power 300, 650, and 1000.

We sold a lot of Amp190's as an entry-level amp to folks that couldn't come off the big money, but still wanted an amplifier. Something like $129, and better than an EQ booster, but they were harsh and unsatisfying to install. In the same price range the Alphasonik MA2025, Proton222, and others were much more pleasant to listen to, more potent (not a lot more potent, maybe just better dynamic power), and thus were more satisfying when the install was done. But the dealer I worked with then had nothing else in that price range.

The 380's were the same, only bigger. Everytime I installed one, I had hopes that it would really rock. After all, it was a good sized amp. But I can't remember a single time I was pleased with the results. Just set it up as good as I could get it, and send it on it's way. I always felt like the saleperson could have sold something else that would have done a better job.

But I have to admit, I kinda liked their heatsinks.


In the years after, Coustic gained momentum and went with those big "Plain Vanilla" ads in the magazines, sometimes several pages. I never dealt with their products after '88 or so, and have no input on them. It looks like they made changes for the better, and enjoyed good success during the 90's.

[jol50]

The amp150/300/500 were earlier and had partially TO3 in them. I got them used in the late 80s. They were square much like LP amps in appearance and all black with the 'C' emblem on top center. Spider nest inside worse but similar to LP, I think the 150 is on ampguts. I ran some of the newer ones in other people's cars and agree; they worked but Actually back then any amp that was not a top name and didn't use TO3 seemed to be lackluster. I don't think these early coustic were as good as LP, but at the price they were much cheaper and not far off. One of my favorite heat sinks, and anodized black not paint. I posted photos of 150 and 300s on this thread someplace.

I ran a proton once back then that worked well, plenty of alpines that didn't seem that powerful but sounded nice, some kenwoods that worked ok, even some early pyramid that worked ok not as powerful as the coustic. Ran the blaupunkt STK based amps I still have, they were not the best sound but great on IB subs and cheap because nobody wanted them. Full range they lacked, but ok with EQ. Had a STK sanyo that was weaker and sounded worse. I beat all those pretty hard with no problems, finally blew one of the STK running it 2 ohms on four 10s IB for a few years. That blaupunkt went louder and clearer on IB subs than any other amp I tried (150-300w), mind you the subs I used were not huge HD things. They might have a HP in them at 20Hz or something.

Seems like if you used a so-so brand they just didn't put out, but if you ran say a kenwood quality/etc amp larger than you needed it was fine. Those old square k-woods worked ok, ran hot though, we sold a pile of those and anything else kenwood. The LP had the most power and highest cost, RF and SS were also good amps that place sold. Those little punch45/75/150 put out. I installed a 45 on a set of 8" kenwood subs we sold all the time and it didn't work bad I was surprised. Those subs had a flat honeycomb cone, sold a ton of them and I never see any around. Of course a pair of 8s IB was not much but better than nothing, and all many people could afford in that time frame. Man that stuff was pricey. Amps then really had different sounds, I always tuned my systems with different ones.

I got a coustic 380 for like $35 for a friend's collection, I don't think he has used it yet I'll ask him. It looked like a typical 2x75 old school or 2x100+ new ratings, to be real general. They got bought at some time IIRC. I've never used newer ones either. In fact this kicker zx700.5 I have now is one of the few newer amps I've run for some time and I don't really like it. It distorts in a way I don't like on highs. I had an old mrv alpine 5ch in there that was smaller but worked better for sound, I put the kicker back in and my slight alternator whine came back. I need to get my new subs and go to separate amps. The kicker works and the class D subsection is great, but I think I can easily find better sounding old stuff for highs at least for my uses. I like the alpine mrv for a reasonable old amp, I have some 2 and 7 (mosfet outputs) series to try. The kicker would be ideal to run subs and midbass bridged, but I have too many other amps to try.

[damage]

Actually, I ran SoundStream D60s on my highs and Coustic 190s bridged on my two JBL subs. They lasted about 3 years before toasting the subs.

Other than blowing the outputs at the touch of a hat when shorted against the chassis, I have zero complaints about Coustic. Certainly better than any Pyramid I ever used. Like you said, a very solid entry level amp. Hard to buy much better at $3.45/hour flipping burgers.

I actually just bought a DR514. I hear they are a very nice sounding amp. We'll see when it gets here.

[tsmith1315]

Originally Posted by damage

Other than blowing the outputs at the touch of a hat when shorted against the chassis, I have zero complaints about Coustic. Certainly better than any Pyramid I ever used. Like you said, a very solid entry level amp. Hard to buy much better at $3.45/hour flipping burgers.

They were not even a little forgiving of shorted speaker wires. Otherwise, we found them to be very reliable. As for Pyramid back then, well... Yugo had a better reputation.

Many customers would spend two or three years building a system, one piece at a time, on $3.45/hr. And in general they were the best, most appreciative customers and a pleasure to have around the shop.

[damage]

Originally Posted by tsmith1315

Many customers would spend two or three years building a system, one piece at a time, on $3.45/hr. And in general they were the best, most appreciative customers and a pleasure to have around the shop.

Yea, that was me. Took me a while to build my system. Always bought stuff from the clearance/used section.

Used to be two guys at Custom Sounds here in Austin, Steve and Mike. Those poor guys humored me beyond belief. I can't even imagined what they thought when I came into the shop. Great guys then and in hindsight even more so!

[tsmith1315]

Here's a schematic for that M&M PA250.

Drawn by hand, I won't listen to any gripes about that!