Up and playing
Built a new board yesterday. Got the amp playing this morning. It is the Rev A.
Like the sound, it seems rich and full. Gets the tonallity right, along with timbre. Lots of punch.
My speakers may not be optimal, 15 ohm, 100 dB efficient. The amp is pllaying at mW levels. The noise level is very low, measured 0.0 mv ac hum on initial check out. This required a little lead dressing, the speakers cables and input cable run right over the SIP bridge rectifiers.
I tried dowloading the image software, but only got down to 470K from the original 2.5 meg sizes. If someone more savy is willing I can send the pics. It is fairly nice, two boxes and very compact. The amp box is the heatsink.
Also get 13 and 10 mV dc offset. One channel in my first board wandered a little. Suspect the wiring on my part.
Enjoying a little Yoakam This Time,
George
Built a new board yesterday. Got the amp playing this morning. It is the Rev A.
Like the sound, it seems rich and full. Gets the tonallity right, along with timbre. Lots of punch.
My speakers may not be optimal, 15 ohm, 100 dB efficient. The amp is pllaying at mW levels. The noise level is very low, measured 0.0 mv ac hum on initial check out. This required a little lead dressing, the speakers cables and input cable run right over the SIP bridge rectifiers.
I tried dowloading the image software, but only got down to 470K from the original 2.5 meg sizes. If someone more savy is willing I can send the pics. It is fairly nice, two boxes and very compact. The amp box is the heatsink.
Also get 13 and 10 mV dc offset. One channel in my first board wandered a little. Suspect the wiring on my part.
Enjoying a little Yoakam This Time,
George
Panelhead,
How warm does the alu case get?
That's a nice tight and original implementation. My only critisism is that you did not line the amps/PS up with the preamp in the last photo. I thought about adjusting it with photoshop, but it was late
Are the wooden-fronted cases next to the preamp chipamps as well? How does the sound compare?
Michael
How warm does the alu case get?
That's a nice tight and original implementation. My only critisism is that you did not line the amps/PS up with the preamp in the last photo. I thought about adjusting it with photoshop, but it was late
Are the wooden-fronted cases next to the preamp chipamps as well? How does the sound compare?
Michael
Heat
Michael,
Thanks for posting the pics. I should have posed the equipment a little better.
In my system the case does not get very hot. Today I took it over to a fellow equipment lovers place. His speakers are mid 90's efficiency and normal impedance. We played the amp much louder than I do at home. I would guess the case was 130 degrees F. after 20 minutes or so.
There is some aluminum plate inbetween the LM3886 and the case. This is for spacing and to help make a heat "sink". The case itself is too thin for good heat transfer.
The cases next to the preamp are power supplies. One for the linestage and one for my Pearl phono. I have quit building nice cases. I spend a month building a nice chassis, and a week on the circuit. Look on the pass forum for pics of my pearl and on the solid state for pics of the Tao buffer linestage and Hirega Le Monstre.
This is my first amp using a chip. Always built discrete before.
George
maf_au said:Panelhead,
How warm does the alu case get?
That's a nice tight and original implementation. My only critisism is that you did not line the amps/PS up with the preamp in the last photo. I thought about adjusting it with photoshop, but it was late
Are the wooden-fronted cases next to the preamp chipamps as well? How does the sound compare?
Michael
Michael,
Thanks for posting the pics. I should have posed the equipment a little better.
In my system the case does not get very hot. Today I took it over to a fellow equipment lovers place. His speakers are mid 90's efficiency and normal impedance. We played the amp much louder than I do at home. I would guess the case was 130 degrees F. after 20 minutes or so.
There is some aluminum plate inbetween the LM3886 and the case. This is for spacing and to help make a heat "sink". The case itself is too thin for good heat transfer.
The cases next to the preamp are power supplies. One for the linestage and one for my Pearl phono. I have quit building nice cases. I spend a month building a nice chassis, and a week on the circuit. Look on the pass forum for pics of my pearl and on the solid state for pics of the Tao buffer linestage and Hirega Le Monstre.
This is my first amp using a chip. Always built discrete before.
George
Here it is...
This is the version of the board I will send to be manufactured, unless someone has something compelling for me to review...
I have been running these for two days now. I am quite sure it is going to work.
Here is how it looks now that I have fixed some things on the silkscreen and resized the 100V 100nf bypass cap on the LM3886...
This is the version of the board I will send to be manufactured, unless someone has something compelling for me to review...
I have been running these for two days now.
I am quite sure it is going to work. Here is how it looks now that I have fixed some things on the silkscreen and resized the 100V 100nf bypass cap on the LM3886...
Attachments
Russ,
Two items on your new board that are more musings than a need to change anything. On the Rev A that I built up with the earlier layout, I took Mauro seriously and used Elna Silmics for C1, C2, C17 and C18 to get the low ESR. The amp is very quiet, very fast, and does not get warm.
I have some Nichicon Muses for my next boards and they are 16 mm diameter. It is not clear they would fit on this board. (C1, C2 I believe.) How serious is the low ESR for those caps? And is there a way to make room for larger caps? Or is it needed?
Also, I was disappointed that the WIMA 1 uf's that I had would not fit for C13 and C29 (your C13) and had to go with the BC/Vishay to fit the board. Any idea if it would help to fit those in?
Either way, I would still want to purchase some boards and also look forward to the OP627 preamp boards becoming available.
Craig
Two items on your new board that are more musings than a need to change anything. On the Rev A that I built up with the earlier layout, I took Mauro seriously and used Elna Silmics for C1, C2, C17 and C18 to get the low ESR. The amp is very quiet, very fast, and does not get warm.
I have some Nichicon Muses for my next boards and they are 16 mm diameter. It is not clear they would fit on this board. (C1, C2 I believe.) How serious is the low ESR for those caps? And is there a way to make room for larger caps? Or is it needed?
Also, I was disappointed that the WIMA 1 uf's that I had would not fit for C13 and C29 (your C13) and had to go with the BC/Vishay to fit the board. Any idea if it would help to fit those in?
Either way, I would still want to purchase some boards and also look forward to the OP627 preamp boards becoming available.
Craig
hayenc said:
Hi Craig,
Great input.
My amps (both rev A and Rev C) run very cool now. I think my initial heat problem(on my RevA PCB) was due to one bad(high offset) lm318 on the REV A board. I swapped them both for new 318s and all is well.
Certainly using low ESR is critical for C1 and C2, and I am also using them for C6 and C11, it is not as important for C3 and C8, though I would feel free to experiment..
C17 and C18 do not exist on Mauro's initial REV A PCB.
That is one of my subtle changes (good suggestion Ed).I have tried wimas and panasonics for C17,18,19,20, I am sticking with the panasonics.
What lead spacing are you needing for C13? I may be able to adjust that, or add a third pad. For C13 I used Panasonic 2.2uf ECQ types, which fit fine.
I have some of the silmicII caps(220uf and 100uf), but honestly I don't think they perform significantly better than the Nichicon Low ESR types which I have a good stock of, I ended using Panasonic FCs for C1/C2 and Nichicon Low ESR for C6/C11. Those give excellent performance, and you can be sure they will fit.
The "freebird/yardbird" boards should be available soon.
Probably after I get back from vacation next week.Cheers!
Russ
Re: Comparing Rev A and C
Hi Dr. H,
I did not get as much time last night to compare as I wanted (about an hour), but some early notes:
1) Rev A, seems a little more upfront especially with vocals, and I really liked it with vocal artists like Dianna Krall, Edi Brickel, and such.
2) Rev C, is spacially superior in my opinion, maybe also a little better balanced between neutral, and forward.
3) Rev Cs soundstage is better than Rev A, with instruments staying firmly put. Example, in Nora Jones' "Cold Cold Heart" the upright bass tended to wander very slightly with Rev A, it is firmly planted with Rev C. It is not a large difference, but enough...
I will do more listening today, with a wider musical selection, but so far I would say that Rev C is really growing on me, and is worth the 4 or 5 extra components.
BTW DC offset was lower on my REV Cs than my REV As. About 2mv as opposed to 4mv. But those are both so low as not to be worried about.
Cheers!
Russ
Dr.H said:
Hi Dr. H,
I did not get as much time last night to compare as I wanted (about an hour), but some early notes:
1) Rev A, seems a little more upfront especially with vocals, and I really liked it with vocal artists like Dianna Krall, Edi Brickel, and such.
2) Rev C, is spacially superior in my opinion, maybe also a little better balanced between neutral, and forward.
3) Rev Cs soundstage is better than Rev A, with instruments staying firmly put. Example, in Nora Jones' "Cold Cold Heart" the upright bass tended to wander very slightly with Rev A, it is firmly planted with Rev C. It is not a large difference, but enough...
I will do more listening today, with a wider musical selection, but so far I would say that Rev C is really growing on me, and is worth the 4 or 5 extra components.
BTW DC offset was lower on my REV Cs than my REV As. About 2mv as opposed to 4mv. But those are both so low as not to be worried about.
Cheers!
Russ
Difference between Rev A / Rev C
Hi Russ, just in a few words: What exactly is the difference between Rev A and Rev C ? I know iI could find it somewhere here in the thread, but for me it´s a pain reading any posting and i´m not shure I understand it right ...
(I´m better in writing english than reading)
Thanks again !
Hi Russ, just in a few words: What exactly is the difference between Rev A and Rev C ? I know iI could find it somewhere here in the thread, but for me it´s a pain reading any posting and i´m not shure I understand it right ...
(I´m better in writing english than reading) Thanks again !
Re: Difference between Rev A / Rev C
Well... RevA is really the base revision, it is the version of the amp Mauro settled on on a good starting point for our experiments, and it is an excellent circuit.
RevB has some small chanes which improve the linearity of the input stage..
RevC is Mauro interpretation of Graham Maynard's ideas applied to the MyRef board.
The post to starting reading about that is here:
http://www.diyaudio.com/forums/showthread.php?postid=683346#post683346
Notice the graphs... RevC has excellent phase coherence through all of the audio range.
Cheers!
Russ
Hi SoP,SmellOfPoo said:
Well... RevA is really the base revision, it is the version of the amp Mauro settled on on a good starting point for our experiments, and it is an excellent circuit.
RevB has some small chanes which improve the linearity of the input stage..
RevC is Mauro interpretation of Graham Maynard's ideas applied to the MyRef board.
The post to starting reading about that is here:
http://www.diyaudio.com/forums/showthread.php?postid=683346#post683346
Notice the graphs... RevC has excellent phase coherence through all of the audio range.
Cheers!
Russ
Russ,
The Wima's I have are Mouser 505-m101.0/160/5 and it looks like it might be a bit difficult to fit them in. Lead spacing 22.5 mm with 10.5 mm width and 26.5 mm length. Looks a bit disruptive to try to fit that in, so would not worry about it. I will try the Panasonics
The Nichicon Muse KZ for C1 and C2 are 16 mm dia with 7.5 mm lead spacing. Might not be too hard to fit those in.
Have to run to my real job, so will comment more later.
Craig
The Wima's I have are Mouser 505-m101.0/160/5 and it looks like it might be a bit difficult to fit them in. Lead spacing 22.5 mm with 10.5 mm width and 26.5 mm length. Looks a bit disruptive to try to fit that in, so would not worry about it. I will try the Panasonics
The Nichicon Muse KZ for C1 and C2 are 16 mm dia with 7.5 mm lead spacing. Might not be too hard to fit those in.
Have to run to my real job, so will comment more later.
Craig