I like the look of these amps, plus they are dead cheap. im going to use them for monitoring in a small studio. If it doesnt cut the mustard, its not much of a gamble, but if it does, great deal.
Especially as i like the idea of building Amps, rather than the actual doing.
i do want to ask one thing, as i have the chance of an SMPS, from my friend with these ratings, (24V, 0~14.6A ±1% 150mV 81%) would it be compatible with the 2 way Sure electronics amp.
i see on the board it gives these requirements for power..
Power: DC 6 - 26V, 6 - 12A
Signal: 0 - 500mV 2V Maximum (RMS)
would it be too much, sorry to ask, but im new to Amp building.
thanks for any info🙂
Especially as i like the idea of building Amps, rather than the actual doing.
i do want to ask one thing, as i have the chance of an SMPS, from my friend with these ratings, (24V, 0~14.6A ±1% 150mV 81%) would it be compatible with the 2 way Sure electronics amp.
i see on the board it gives these requirements for power..
Power: DC 6 - 26V, 6 - 12A
Signal: 0 - 500mV 2V Maximum (RMS)
would it be too much, sorry to ask, but im new to Amp building.
thanks for any info🙂
I purchased this amp (the 100W x 2) 5 days ago and paid for it. No reply from these people in 5 days (emailed a few times: not even a word from them). Anybody experienced this kind of bad behaviour and bad customer care from this seller?
Kooka said:
same here....
I can imagine that they are very busy sending orders and stuff, but some confirmation of actually recieving my payment would be nice!!!
I paid 7 days ago now, and sent them an email about half an hour ago seeking confirmation...
TWOJZ said:
I had my reply 3 minutes ago, after telling them that if I did not get a reply within today with confirmation of shipment they would have got a very negative feedback.
It worked... they sent me the reply with tracking code: shipped today!
I've been playing with the 4 channel module for a few days - here's what I've discovered so far:
The zobel (?) filters on my amp are 10R and 1.3uF (I think, as I had to measure the cap in situ).
Power enters the chip at two corners. The bypass cap sitting closest to these pins is 1uF. This surprised me a bit as all the 41hz amps have 0.1uF bypasses...
There doesn't seem to be any rf filtering on the audio input (unless it's on-board the chip).
Mine produced a significant amount of hiss on all channels (when used with Rogers LS5/9 speakers - hardly super-efficient).
I made the following changes and the background hiss was lowered significantly (although not as much as I'd like!)
1. replace 1uF bypasses on power pins with 0.22uF ceramic (from an old 41hz kit)
2. add 300pF silver mica from each input to ground
3. add a thick earth cable from chassis ground to amp 0V connection (as well as 0V from smps) and also to both audio grounds
This made a significant difference to the hiss level, although I can't say what was most beneficial as I did all changes at once!
This amp was made for a friend who has Mission M73 loudspeakers. When I connected the amp to his speakers last night the background noise was barely audible and he was very happy with the sound 🙂
The zobel (?) filters on my amp are 10R and 1.3uF (I think, as I had to measure the cap in situ).
Power enters the chip at two corners. The bypass cap sitting closest to these pins is 1uF. This surprised me a bit as all the 41hz amps have 0.1uF bypasses...
There doesn't seem to be any rf filtering on the audio input (unless it's on-board the chip).
Mine produced a significant amount of hiss on all channels (when used with Rogers LS5/9 speakers - hardly super-efficient).
I made the following changes and the background hiss was lowered significantly (although not as much as I'd like!)
1. replace 1uF bypasses on power pins with 0.22uF ceramic (from an old 41hz kit)
2. add 300pF silver mica from each input to ground
3. add a thick earth cable from chassis ground to amp 0V connection (as well as 0V from smps) and also to both audio grounds
This made a significant difference to the hiss level, although I can't say what was most beneficial as I did all changes at once!
This amp was made for a friend who has Mission M73 loudspeakers. When I connected the amp to his speakers last night the background noise was barely audible and he was very happy with the sound 🙂
sharpi31 said:
That's interesting. I don't have the amp in my hands yes (just shipped today, it seems...), so which are the bypass caps to be switched to 0.22uF ones? Remember the caps location on the board?
I ordered a 2X 100 watt board but recieved a 4X100 instead.
I am competely ignorant as to the workings of D class amps as I have spent lifetime playing with valves. Just thought it would be fun to play with.
On first firing up the amp I was greeted by plume of smoke from CH 1 zobel network resistor. I rapidly switched off and checked all connections both input and output.
Found nothing amiss but measured the offending resistor which now reads around 4 ohms instead of 10.
The amp has since worked faultlessly but I think I should do something about the failed resistor.
No 10R's in the junk box but the nearest I can find are some nice little
6. 8R wirewounds. Would these be suitable replacements or is the existing value critical and if used do I need to replace the series caps with a different value.
I checked the DC offset on all 4 channels. Channel 1 with the failed resistor reads around 40 mv and the others around 24 mv
Does this seem about right.
STU
I am competely ignorant as to the workings of D class amps as I have spent lifetime playing with valves. Just thought it would be fun to play with.
On first firing up the amp I was greeted by plume of smoke from CH 1 zobel network resistor. I rapidly switched off and checked all connections both input and output.
Found nothing amiss but measured the offending resistor which now reads around 4 ohms instead of 10.
The amp has since worked faultlessly but I think I should do something about the failed resistor.
No 10R's in the junk box but the nearest I can find are some nice little
6. 8R wirewounds. Would these be suitable replacements or is the existing value critical and if used do I need to replace the series caps with a different value.
I checked the DC offset on all 4 channels. Channel 1 with the failed resistor reads around 40 mv and the others around 24 mv
Does this seem about right.
STU
Stuart Dean said:
according to them, the amplifiers are tested for 12 hours before shipping...
I hope you told them what happened.
TWOJZ said:
They claimed they tested it, not that it passed. Read the fine print.
javascript:smilie('😀')
Big Grin
Kooka,
You will need to remove the heatsink to see these caps (easily done). When you look at the chip you will see two corners where the third pin from the outside edge is cut short. The two pins at each of these corners are tied together on the pcb and connected to the V+ rail.
Beside these power pins is a small cap that looks identical to the caps on the zobel filter: a tiny yellow axial thing. I used snips to remove this cap but left a bit of the leg in the pcb hole to give me something to solder the new cap too. I soldered the other leg of the new cap directly onto the two power pins. You are doing exactly the same thing at each corner (mirror image).
I used 0.22uF ceramic caps as the 0.1uF caps I had were too large to fit under the heatsink (Wima FKP).
A better option may be to install a 10uF panasonic FM in parallel with a 0.1uF bypass... Just remember that the heatsink must end up flat with the top of the chip!
i've learned to be a bit easier on sellers that are not based in the US. As long as I get my items in a reasonable amount of time, I don't need the seller to update me on every step of the process. Tracking info is nice, but its not going to get me the parts any quicker. Their feedback rating seems pretty good compared to some of those out there, so I'll sit back patiently and wait for my toys to come. I've not seen a reason yet to think that we're getting the shaft in any manner.
on a separate note, these amps seem to be a bit messy with flux. what is everyone's recommendation on how to clean this stuff off? any prefered methods?
SQ Kid said:
yes, but would you not expect to be notified at least that they have received your payment?
who says they aren't still sitting there, waiting for my money, when as far as I know, they already have it...
i guess i also forgot to mention i also work for an internet-based company. i can say they know they've gotten their money, especially if you pay with PayPal. I spent half of today processing online orders, many of which were ebay/paypal orders. trust me, i'm just as cautious of ebay sellers, i've been burned before and its not fun. i'm also someone who likes to get their purchases ASAP. they have a 100% positive feedback rating with only 2 retracted ratings (a rating thats even more telling than the rest of their feedback), i'll sit back and wait a bit more.
SQ, not everywhere has the same culture as the US. Some countries are a little more laid back. 😉
oh yeah, there's also the fact that ebay calculated my postage incorrectly, so I quickly transfered the amount, $20 less than it was meant to be... lol
so!!!! I'd like some confirmation that they actually sent my item! lol
so!!!! I'd like some confirmation that they actually sent my item! lol
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