The High-End, how Hi-End is this amplifier board? (Ebay)

Ian Finch

Member
Paid Member
2010-04-11 4:22 am
Coffs Harbour, NSW
Bad, yes - *ss, yes - cheap, yes also.

The label on the PCB claiming "500W+500W" has been laughed about earlier this year so maybe you weren't watching then.
What have you really got? 2 channels with 2 pairs of 150W max. transistor output.
In class AB you may get 135W/8R if the cooling you supply is good and the power you supply is based on around 57V rails that don't sag too much. Perhaps you can squeeze 200W into a resistive 4R load, but not for too long.

You pay $32 + postage and I'm sure you'll get your money's worth - it's certainly a good price even if the parts are way underspecified for reliability. It's the risk and the sure knowledge that it will be a long way from "high end" anything except perhaps hopes.

The fact that it has sold just 70 units to an international market from that seller doesn't say anything other than some guys can't resist cheap - cheap anything.
 
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redjr

Member
2011-05-05 4:29 am
CT
Bad, yes - *ss, yes - cheap, yes also.

The label on the PCB claiming "500W+500W" has been laughed about earlier this year so maybe you weren't watching then.
What have you really got? 2 channels with 2 pairs of 150W max. transistor output.
In class AB you may get 135W/8R if the cooling you supply is good and the power you supply is based on around 57V rails that don't sag too much. Perhaps you can squeeze 200W into a resistive 4R load, but not for too long.

You pay $32 + postage and I'm sure you'll get your money's worth - it's certainly a good price even if the parts are way underspecified for reliability. It's the risk and the sure knowledge that it will be a long way from "high end" anything except perhaps hopes.

The fact that it has sold just 70 units to an international market from that seller doesn't say anything other than some guys can't resist cheap - cheap anything.
Yes, but is the design sound? I understand those Toshiba output devices to be very good. Yes? I've been using those devices in another amp board (LM4702 based) with linear PSU @ +-60v rails. I'm very pleased with the overall sound for about a year now. Not sure how many watts it's capable of but it gets plenty loud when I occasionally crank it and sounds very clean.

Rick
 

Ian Finch

Member
Paid Member
2010-04-11 4:22 am
Coffs Harbour, NSW
Yes, but is the design sound? I understand those Toshiba output devices to be very good. Yes?......
I haven't seen a schematic but I have heard a pair of these used with B&W CM9s at a friend's workshop. They arrived preassembled without schematic and given a rudimentary audition, I can say that they sound OK, if a bit synthetic. They are clean and relatively quiet but these days it is unusual to hear distinctly bad audio coming from any commercial amplifier. Genuine 2SC5200/A1943 transistors are indeed very good for low-cost audio types. Some would prefer On-semi's parts on manufacturing reputation but these aren't as cheap for the kit producers to source.

From what I could see, the PCB layout is unusual but seemingly a standard design, and could just as easily have come from the forum. The transistors I saw were not usual laser-marked Toshibas but they are now manufacturing a different TT prefix series of these in China so it's harder to say whether genuine or not. Even if these are just low grade copies, they will likely satisfy many buyers who have no clue how small their real power needs are.

IIRC, you built D. Self's latest preamp, Redjr, so by now you'd know quite a bit about those different ways of looking at sound quality, I'd think. So what were you looking for - the sort of high-end, as in low distortion muscle or perhaps sweet, deep imaging audiophile quality? I can say it's neither of these but is still good value and looks as if you could modify it without difficulty. For maybe $50, you could find a use even if it started out awful in your view. One obstacle is finding a piece of metal to slip between PCB and output transistors to couple to a heatsink. It's set up for thin sections which is not really good. :(
 

redjr

Member
2011-05-05 4:29 am
CT
I haven't seen a schematic but I have heard a pair of these used with B&W CM9s at a friend's workshop. They arrived preassembled without schematic and given a rudimentary audition, I can say that they sound OK, if a bit synthetic. They are clean and relatively quiet but these days it is unusual to hear distinctly bad audio coming from any commercial amplifier. Genuine 2SC5200/A1943 transistors are indeed very good for low-cost audio types. Some would prefer On-semi's parts on manufacturing reputation but these aren't as cheap for the kit producers to source.

From what I could see, the PCB layout is unusual but seemingly a standard design, and could just as easily have come from the forum. The transistors I saw were not usual laser-marked Toshibas but they are now manufacturing a different TT prefix series of these in China so it's harder to say whether genuine or not. Even if these are just low grade copies, they will likely satisfy many buyers who have no clue how small their real power needs are.

IIRC, you built D. Self's latest preamp, Redjr, so by now you'd know quite a bit about those different ways of looking at sound quality, I'd think. So what were you looking for - the sort of high-end, as in low distortion muscle or perhaps sweet, deep imaging audiophile quality? I can say it's neither of these but is still good value and looks as if you could modify it without difficulty. For maybe $50, you could find a use even if it started out awful in your view. One obstacle is finding a piece of metal to slip between PCB and output transistors to couple to a heatsink. It's set up for thin sections which is not really good. :(
I have no skin in this game since I'm not going to build the amp in question. But from your comments, I got the sense you were dis'ng it out-right which seemed a bit unfair. My exception was with the output devices. For the 4702 amp module I built, I paid extra for genuine Toshiba parts since I had read and heard nothing but good things about them and noticed them being used in more and more designs. The China vendor offered both, so I opted for the Toshiba parts for a bit more money. In all honesty though, I'm not sure I could hear a difference between the genuine article or fakes. :) It was the first class AB amp I've built from the module level up.

In fairness, I have been bitten by the class D bug lately, so that's pretty much what I've been building recently. So, my class AB amp has seen some idle time of late. My next project will be either based on ICEamp modules, or NCore technology. Maybe I'll be able to tell a difference between them and your typical run-of-the-mill class D variety amp. Dunno. I'll reply later about the DS pre I built when I have more time.

Rick