agedhorse

Sure hope they don't go spraying things down with "magic cure-all spray", I see plenty of gear damaged from such treatment. ESPECIALLY switch contact cleaners.

Why does your amp need servicing?

The foot switch is no longer available? Didn't it get introduced just last year?

Ok, that's a GB 410 standard, had to go back deep into the archives but it was a model from the mid to late 1990's and was shipped 8 ohm as standard with a 4 ohm optional version as well. I do still have a limited number of recone kits available for this model in both 8 ohms (standard cabinet, series-parallel wiring) and 4 ohms (optional cabinet, 16 ohm driver parallel wiring).

Can’t open the pictures

Can you post a picture?

Yes, this is correct.

IME, most 300 watt RMS speaker that will handle this kind of power may be quite colored due to the heavier suspension and long wound voice coil (compared with gap depth) required for mechanical robustness. This results in significant high frequency rolloff compared with a full range or extended range design.

Some but certainly not all manufacturers provide these specifications. Depending on the circuit topology, the input impedance may be different or the same between passive and active inputs. On the Subway amps, the input impedance is ~1M in both passive and active positions. The specifications for the Subway amps are located in the back of the respective owner’s manuals.

Yeah, I did kind of get that switched around

In general, where the OUTPUT impedance of the SOURCE is less than 1/10th the INPUT impedance of the LOAD, the effects of loading can be ignored. If this is not true, it's possible for issues to occur. This is independent of level, a different parameter entirely. [edit for garbled response, clearly reversed]

Are you aware that SWR as a company has been shut down for almost 7 years and that there is no support available (including parts)?

Running an iPod into the instrument input of an amp shouldn't damage it. I do it all the time as a test signal source.

The ASX-2 models are long in the tooth, but they are actually still quite a ways better or more appropriate (all things considered) that much of the competition. That's why they are still being used in a variety of current products. With regard to rated power, there are different applications that exploit different aspects from all of these modules. That's one of the confusing things, where somebody looks at a data sheet or a marketing sheet and comes to a conclusion that simply does not apply for a particular application. I ran into this head-on when I designed an application around the 250ASX2 module that allowed the amp to operate BTL into 4 ohms even though the specifications stated 8 ohm minimum load in BTL mode. Initially, it was claimed that I was a fake, and that it was impossible, couldn't be done, would blow up, and couldn't deliver 900 watts RMS into such a load. This was from other amp manufacturers, as well as end users who hadn't even the slightest clue about amplifier engineering but were high and vocal on the bully pulpit. In the end, with ICEPower's support and approval, we received a patent for our approach and delivered many thousands of highly reliable amps based on this "impossible" platform. We were the first to use this part like this, and obviously others followed what we did with their own interpretations (some successful and some not). Some of the concepts behind the newer AS1 platform came out of the research and data that resulted from our off-sheet application of the ASX2 parts. I can't go into anymore on this. The short story is that there is more going on in many of these products than the average or even technically inclined person might ever imagine.

ICEPower only sells OEM, that represents 99.9% of their business. That’s likely why it’s not worth the effort or the cost on an older product. Those who buy a product like this on eBay from China, outside of the authorized distribution network, are getting what they pay for in the sense that eBay is well known as a marketplace for counterfeit goods. Profusion is an authorized distributor for some ICEPower models, but yes they are more expensive.

It’s class AB.

The genuine parts are more expensive to build, the test process is very comprehensive, the factory’s are more expensive to operate because they are under NRTL (nationally recognized test lab) inspections, and the products include international safety and EMC compliance which is also costly to maintain. All OEM’s who currently use this part are aware of the situation now, but the damage is done. Most quality OEMs buy directly from ICEPower so there is no issue with us receiving counterfeit parts as the tracking is quite thorough and serial numbered.

It is unfortunate. As a long time (as in almost the beginning of IcePower when they were financed and partially owned by B&O) designer of products using IcePower parts, I have access to much more information than most do. The backstory is complicated and confidential, but it was basically outright theft of their IP. Unfortunately it's hard (read as virtually impossible) to enforce anything in China, and there were some amp manufacturers that used of IcePower product that were tempted by the lower price of the counterfeits (most didn't realize they were counterfeits as they were marketed as surplus from a large Chinese contract manufacturer who got stick with thousands of these parts) only to learn that they were counterfeits and the reliability was nowhere near the same. Counterfeiting is a very real problem. I got burned once (about 20 years ago) when I ordered a National Semiconductor part from a reputable authorized National Semiconductor distributor. The parts didn't work the same, but they looked identical in every way. Sent them to the manufacturer for x-ray analysis and it turned out to be a different die inside the package with different characteristics. It turned out that a customer ordered many thousands of these parts and then returned counterfeit parts in counterfeit sealed packaging to the distributor (common practice) several thousand of the parts for credit. They were an expensive enough part that it was worth the hassle apparently.

Virtually all ICEPower 125ASX modules available on ebay that are shipped out of China and Hong Kong are counterfeit.

True until you have an accident, or a momentary lapse of good judgement.

Impedance looks good I will be able to sleep well tonight!

The "gain factor" of a tube does not necessarily translate into circuit gain. It depends very much on the circuit itself. There are circuits where a tube with "higher gain" will result in a circuit performing with LOWER gain. It really does depend on the circuit the tube is used in. Forgive my use of the word tube in place of valve...

Hopefully, being asked to turn down and your divorce don't have anything in common...

From my experience designing amps, this is generally the most accurate description of what's really going on. And to add... conformation bias is very much a real thing that can be a frustrating source of "non-difference".