AMPEG QC

Have other Ampeg owners had as many problems as I with Ampeg products? I will list the products and their problems/outcome.


Bought SVT Pro3...top rattled when fan came on...took top off and put foam tape on top to prevent rattling. Sold it.
Bought BXT410hl4...was the "boomiest" bottom I ever owned. Sold it.
BA115 Combo Amp....overheated and "farting" sound. Returned for BA210.
BA210, arrived with one speakers voice coil rubbing against the gap. Had to repair this myself.Also had 20 guage!! wiring for two 10" speakers with 220 watts rms. Sold it.
SVT350 head. Fan was replaced and it still sounded like a jet engine. Finally rubber mounted it to get rid of the noise.Used it with 210 bottom on a 410he bottom.Traded head in on SVT1000.
Sold both bottoms, 210 was rear ported "boom box"
Bought the 810e.
Svt1000...good loud clean amp...but wanted a Classic. Sold the SVT1000 and bought the SVT CL. Defective, right out of the box. Sent it back to store, got a replacement which works great!!
810e cabinet...very poor insulation. Ordered various insulation and installed foam insulation on the bare wood spots, and there were a lot of these spots. Sounds slightly deeper and warmer now.

As you can see, I have had more than my fair share of problems, but finally I am happy. I have stuck with Ampeg for 20 years, off and on. I do notice a decline in quality control. These problems should have been caught before they left the plant.

I have spent a lot of time with home audio, and have never recieved a defective product. One company I dealt with, ran their power amps at full power for 48 hours before they released it.

When I pay 1000.00 for a bass bottom, I expect it to have ample insulation in it. I expect a 1600.00 head to arrive working. There was NO damage to the box. I figure a 600.00 bass head should not sound like a jet or rattle trap.

Any other stories out there, like the overheatring amp problems so many have had?

 

Actualy, I am qualified...two degrees in electronics.. This was a discussion on another site...amp that got hot and made "farting" sounds started to smell, so I turned it of. I did not overdrive the amp. Both bottoms I sent back had very little insulation in them. Ported bottoms MUST be well insulated, or they boom. Fan noise was cheap noisy fans. My svt cl for instance, has the fan in front...it is very quiet.

As for the 20 guage wiring...current needs copper....look it up on the web...these bottoms should be using at least 14 guage wire in my opinion, but heavy guage wire costs more...so does insulation. Remember, there is the ability to throw 10-15 amps of current with some amp heads...into 18-20 guage wire?? You do the math.

Insulation replaced with comparable insulation, matted/foam kind. Insulation in one of the 810 chambers was hanging down. Was not stapled correctly.

Could be worse, I have pics of not one but two different Hartke cabs with the internal bracing broken. Hartke said it was because it was their "first run".???!!!

 

"Increasing the amount of fill will (correct me if I'm wrong someone) increase volume (loudness) but decrease low-end response"

Actually, depending on what you use, you could experience both. I belive the percentage is 10-15 that added damping "fools" a speaker into thinking it's in a bigger enclosure.

 

That is in part true, and probably the main use for the damping, however it can alter the highs/mids, lows and volume by the amount and TYPE used.

 

Originally Posted by etnops
great question.

here's what's happening, technically.

by adding the acoustic stuffing (polyfill, fiberglass, foam, etc) to the degree of 24-30oz per cubic ft (in sealed cabinet), you effectively lower the resonance of the system by about 15%. theoretical gain is to the tune of 30%, but it's never really attainable.

a resonance, is the point where the system (driver, cabinet) is at it's most efficient. technically, a resonance is described as a transfer of two energies - kinetic and potential. it's where the forces from the acoustic suspension of the mechanical parts of the speaker (spider, surround, and volume of air in cabint) are in perfect harmony with the electrical part of the system (motor [ permanent magnet] and voice coil).

the way the polyfill lowers the system resonance, can be expressed with thermal dynamics. simply, the compression of the volume of air in the cabinet requires energy (from driver). when the air compresses there is obvious friction of the air molecules, and this friction generates heat (energy in itself). by replacing part of the volume of air in the cabinet with a better thermal conductor (polyfill, fiberglass, foam, etc) you essential "trick" the system into "thinking" it's in a larger enclosure. because the air/polyfill combo can store energy (heat) more efficiently. now, as with actually increasing the physical box size to achieve the same effect (lowering of the resonance), you gain overall system efficiency. by adding polyfill, you do not increase efficiency, only benefit from the acoustic response as if you were to have a more efficient system.

obviously, when you lower the resonance, it plays deeper. but also some other things happen.
the type of resonance makes an impact on acoustic/sonic signature.
how much energy the system stores at resonance, will dictate the amount of "ringing" the driver will exhibit when playing at resonance. imagine an inflatable rubber ball with 0.040" thick material, and if you hit it, how it goes "boooooooing". now imagine the same ball, but with 0.100" thick material, and how it would sound if you hit it -> "bong". this analogy describes the amount of "damping" the system has. how fast it is to return to it's rest state, after the signal isn't present. or how much the driver keeps moving after the signal is gone.

 

An EXCELLENT point!! Some stereo speaker designers use little or no internal bracing in their speakers. They claim the "resonance" of the cabinet adds to the warmth of the speaker. Then you have designers who brace the @#$% out of their cabs.

Thats why there's vanilla and chocolate.....different tastes

 

Yes, was rather rude, but we all have opinions.

 

You are probably right on both points.