maf_au said:Just a note about the heat performance of my case and some responses of visitors regarding my Mauro amp.
I've had a LOT of visitors recently, and about 55 people over for my 50th birthday party. It wasn't a dance party, so I have no tale of woe about the amp catching fire or anything like that
We left the test system running on the dining room table from about 9am until the following morning around 2am. This is the Mauro, Russ's FreeBird, Rotel 965BX CDP and my Tannoy 603 small bookshelf speakers. People swapped CD's as they felt, there was probably something on about 2/3 the time. Volume was louder than normal because of the extra background noise.
By about 10PM the rear of the case adjacent to where the 3886's are located, was hot to touch, but not so hot you had to remove your finger, It got no hotter than that. I have thought about adding a small heatsink to the back of the case, but I'm not sure it is required, I may wait until summer to see how it goes in warmer weather.
During the party there was a lot of talking going on, but I still had many comments about the sound and look of the amps. When things got quieter, and at other times, a few people have had a more serious listen. All have been delighted at the sound quality, some are genuinely stunned. My sister 'wants one'
Have to say that's a pretty positive endorsement of the amp.. Well done Mauro, Russ and everyone else involved. Can't wait to have a go at RevC!
Michael
Michael, your experience is the same as mine. The Rev A seems to run a little warm when driving a moderate load (your Tannoys are very similar in load to my Cryolites) for a while. But nothing to worry about.
Adding a heatsink can't hurt.
Happy birthday. And thanks for you kind remarks. I wish I could have made the party.
You did a great job building your pre and power amps.
Cheers!
Russ
Too many amps...
Sorry to bomb the list, but I think someone here may want this...
I have an extra REV A stereo amp board complete and tested if anyone would like to buy it from me contact me off the list. I would keep it, but I already have 4 versions of the amp. This is the original Rev A stereo PCB completely populated and tested. I just don't want it to sit around collecting dust when It is such a great amp. All of the parts are the ones from Brian Donegan, except the power resistors for the LM318 which I have upgraded with beefier (3W) parts.
All you will need is a case/HS, connectors, and a trafo.
Cheers!
Russ
Sorry to bomb the list, but I think someone here may want this...
I have an extra REV A stereo amp board complete and tested if anyone would like to buy it from me contact me off the list. I would keep it, but I already have 4 versions of the amp. This is the original Rev A stereo PCB completely populated and tested.
I just don't want it to sit around collecting dust when It is such a great amp. All of the parts are the ones from Brian Donegan, except the power resistors for the LM318 which I have upgraded with beefier (3W) parts. All you will need is a case/HS, connectors, and a trafo.
Cheers!
Russ
I start to make this amp too. I hope will sound well. Now I use an Atoll PR100+ AM100 and EposM22 and the source is a Creek CD50MK2. Cables are from Neotech, pure silver and it sound very atisfactory. In the past I've made a lot of power amplifiers but I did not like how they sound. Please , someone tell me how does this amp sound! Thanks!
Progress report
Ok Beta Testers, great news. the amp is alive and well, sounds excellent as the other prototype did.
No adverse effects from the new layout glad to say.
A couple of notes on things which have already been addressed for production but you beta testers will notice.
1) The fastons will fit tight. using a pair of pliers you should be able to work them in as the holes are, if it feels too tight just use a small drill bit (around 1/16") to bore it out a little.
2) The input pin header is close to the back end of the PCB, just make sure you put it on straight so it does not extend over the edge. It is easy to get it right. Probably won't even be an issue.
3) For some reason the drill size for the NC pins on the LM3886 were a little too small, you will need to bore those out just a bit with a small drill.
Other than those things, nothing special required.
Cheers!
Russ
Ok Beta Testers, great news. the amp is alive and well, sounds excellent as the other prototype did.
No adverse effects from the new layout glad to say.
A couple of notes on things which have already been addressed for production but you beta testers will notice.
1) The fastons will fit tight. using a pair of pliers you should be able to work them in as the holes are, if it feels too tight just use a small drill bit (around 1/16") to bore it out a little.
2) The input pin header is close to the back end of the PCB, just make sure you put it on straight so it does not extend over the edge. It is easy to get it right. Probably won't even be an issue.
3) For some reason the drill size for the NC pins on the LM3886 were a little too small, you will need to bore those out just a bit with a small drill.
Other than those things, nothing special required.
Cheers!
Russ
Re: Progress report
Hi Russ
Excellent - But I would be very interested to hear if you can hear any improvement over the single sided board over the next few days.
If the two sound exactly the same ( hope you're using identical components ) how will you decide what version to go with ?
I'm wondering how price / size compare.
mike
Russ White said:Ok Beta Testers, great news. the amp is alive and well, sounds excellent as the other prototype did.
No adverse effects from the new layout glad to say.
Hi Russ
Excellent - But I would be very interested to hear if you can hear any improvement over the single sided board over the next few days.
If the two sound exactly the same ( hope you're using identical components ) how will you decide what version to go with ?
I'm wondering how price / size compare.
mike
Re: Re: Progress report
Hi Mike,
Good post. Here is the short of it.
The 2 sided board is the one slated for production for these reasons, some of which are not necessarily virtues of 2 sided boards, they just happen to have occured in that revision.
1) The 2 sided board eliminates all jumpers.
2) It has better laid out power tracks that have less RCL interaction at different points in the circuit (the power take off for the LM318 as an example).
3) Cost is not much different compared to the single sided PCB.
4) It should be less prone to mistakes by less experienced builders(forgetting to run the jumper would be very bad).
Those reasons observed. Any sonic improvement when both PCBs are configured the same is so slight I cannot detect it. That is until I did something last night (but now the test is not equal). I added the film cap (100nf) between the pins of the 220uf cap in the NFB. Wow
, that really makes the amp sound different. I think better. Slightly less forward, but excellent presence and soundstage. The amp just started sounding warmer... fuller, but possibly less bright.
The beta board was created before Mauro made that suggestion so, to test it with the beta boards you simply solder the cap between the pins on the NFB cap, but the production board has a spot for the film bypass cap, which of course can be omitted should one choose.
To close, the sinlge sided layout is perfectly good, but the 2 sided board is more mature, and more practical to be sure.
I can't wait until a few more have built the beta boards. I am anxious for their reports.
Cheers!
Russ
mikelm said:
Hi Mike,
Good post. Here is the short of it.
The 2 sided board is the one slated for production for these reasons, some of which are not necessarily virtues of 2 sided boards, they just happen to have occured in that revision.
1) The 2 sided board eliminates all jumpers.
2) It has better laid out power tracks that have less RCL interaction at different points in the circuit (the power take off for the LM318 as an example).
3) Cost is not much different compared to the single sided PCB.
4) It should be less prone to mistakes by less experienced builders(forgetting to run the jumper would be very bad).
Those reasons observed. Any sonic improvement when both PCBs are configured the same is so slight I cannot detect it. That is until I did something last night (but now the test is not equal).
I added the film cap (100nf) between the pins of the 220uf cap in the NFB. Wow , that really makes the amp sound different. I think better. Slightly less forward, but excellent presence and soundstage. The amp just started sounding warmer... fuller, but possibly less bright.The beta board was created before Mauro made that suggestion so, to test it with the beta boards you simply solder the cap between the pins on the NFB cap, but the production board has a spot for the film bypass cap, which of course can be omitted should one choose.
To close, the sinlge sided layout is perfectly good, but the 2 sided board is more mature, and more practical to be sure.
I can't wait until a few more have built the beta boards. I am anxious for their reports.
Cheers!
Russ