Ok so I've got it all connected up on a test board and noticed my layout is less than ideal for easy wiring ( I can't test yet as I can't cut my heatsink yet).
So another question. Im sure it's ideal if all wiring is short as possible but is it ok if wires from rectifier to amps is a little longer as shown on Peter's integrated amp here
I can see it's an advantage to have a layout where all your boards are connected without top or bottom covers attached so wiring from both sides is easier but I cant find a layout that achieves that with the aluminium I have to build the case.(3mm and 5 mm sheet)
My test layout is similar to the diagram I previously posted but a bit tighter.
Also can I mount the amp boards vertically?. My transformer needs 65mm and the boards are 72mm so the case wouldn't get much taller.
So another question. Im sure it's ideal if all wiring is short as possible but is it ok if wires from rectifier to amps is a little longer as shown on Peter's integrated amp here
I can see it's an advantage to have a layout where all your boards are connected without top or bottom covers attached so wiring from both sides is easier but I cant find a layout that achieves that with the aluminium I have to build the case.(3mm and 5 mm sheet)
My test layout is similar to the diagram I previously posted but a bit tighter.
Also can I mount the amp boards vertically?. My transformer needs 65mm and the boards are 72mm so the case wouldn't get much taller.
I don’t think 5mm heatsinks are sufficient for a stereo pair, unless you are bonding in a way to have the sides also conduct the heat away, which would be difficult for efficient heat transfer.
If the side are thicker aluminum - why not move one to each side and move the rectifier board elsewhere?
Looks nice to be so compact, but you will find is massively more difficult to actually install. I would suggest a 200x300 or even better a 300x300 IMO.
If the side are thicker aluminum - why not move one to each side and move the rectifier board elsewhere?
Looks nice to be so compact, but you will find is massively more difficult to actually install. I would suggest a 200x300 or even better a 300x300 IMO.
So YAY. The AMP works. On my test board with some old heat sinks on the chips. cant crank it because it's wee small hours here. Barely gets warm. DC at the binding posts is reading -48mV and -51mV. (No volume pot)
I'll give this some extended play over the next few days to see how warm/hot it can get
I'll give this some extended play over the next few days to see how warm/hot it can get
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So I've been listening to this amp nearly all day everyday for the past week... in a largish art studio where I work 11m x 7m with a 3-4m sloped ceiling. Mostly at moderate volumes when the heat-sink gets just warm, and sometimes at loud-ish (talking not possible) volumes where the heat-sink gets hot, but not too hot to touch. Given that this is still on my test scenario with heatsink that wont fit inside my proposed case I will look at obtaining either a smaller finned heatsink or a larger aluminium or copper slab.
It sounds pretty nice also.
My only comparison here is mid 80's rotel (ra870bx) that I've used daily since then. My speakers are klipsch rp400m with a klipsch sub and another small 2 way diy so I have no comment on bass with the gainclone yet. A,B ing both amps the gainclone reminds me of a tube amp but thankfully not as warm. It seems to be better than the rotel at mid range transients. The soundstage is also bigger, I'm hearing things I never heard before in places I never herd them.
It's super quiet. My source is a diy streamer and dac playing flac files from a local server.
Thank you Peter Daniel for answering my dumb noob questions. I'll get this into hopefully a beautiful case over the holidays and share pics.
Next project is to replace the amazing diy towers I had that a past girlfriend made me get rid of cause they were too big. Finding driver supply in NZ difficult though.
It sounds pretty nice also.
My only comparison here is mid 80's rotel (ra870bx) that I've used daily since then. My speakers are klipsch rp400m with a klipsch sub and another small 2 way diy so I have no comment on bass with the gainclone yet. A,B ing both amps the gainclone reminds me of a tube amp but thankfully not as warm. It seems to be better than the rotel at mid range transients. The soundstage is also bigger, I'm hearing things I never heard before in places I never herd them.
It's super quiet. My source is a diy streamer and dac playing flac files from a local server.
Thank you Peter Daniel for answering my dumb noob questions. I'll get this into hopefully a beautiful case over the holidays and share pics.
Next project is to replace the amazing diy towers I had that a past girlfriend made me get rid of cause they were too big. Finding driver supply in NZ difficult though.
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Hi! After several iterations it's done. Works and sounds fine. I didn't found the reason of a small offset difference, because the chips were matched, and to be honest it's impossible to hear, only to see with voltmeter.
Peter, thank you a lot for this amp idea and for your help, advises and involvement! It was a pleasure! Next will be a matched monoblocks I think )
https://video.wixstatic.com/video/7232dc_ce1ac0fb01e24cf1a03f33e23250b202/1080p/mp4/file.mp4
Peter, thank you a lot for this amp idea and for your help, advises and involvement! It was a pleasure! Next will be a matched monoblocks I think )
https://video.wixstatic.com/video/7232dc_ce1ac0fb01e24cf1a03f33e23250b202/1080p/mp4/file.mp4
I put together one of Peter’s premium kits few years ago and I was thinking of upgrading by replacing the 680 and 22k kiwame resistors with Vishay 102 resistors, and I was wondering whether anyone has made this substitution and if so how it changed the sound. Thank you for sharing your experience.
Just finished LM3875 Audiosector monoblocks.
Attachments
These are stunning! I noticed that you used Mundorf caps. What value did you use? Also, I am interested in your use of wood boxes, because I am thinking of upgrading my power supply by placing my transformers on a spruce board on the theory that vibrations will have a more pleasing resonance. Has anyone done such an experiment?
Thanks
Had my wife's boss over for a meal the other night - he wants to commission a pair "exactly like them"
The Mundorf caps are 1500uf 100v. 22k Resistors both MK132s and 680R is Kiwame as per PD's preference.
I've not done any component swapping.
The front badges are antique Chinese coins with a faux jade bead cut in half and led mounted behind. On account of these being finished around Chinese New Year I'm calling them Metal Ox (even though they are largely constructed from wood).
At the moment they are naked on the underside - so no putting the fingers in there please!
Noticing details in the mid range that I don't think I'm hearing when my ancient Chord SPM900 is in use.
I can't comment on resonance properties of wood etc. It's just what I have available to me and I'm happy with how they worked out. The 50mm teak + the 300VA R-core transformers add up to a satisfying weight.
Had my wife's boss over for a meal the other night - he wants to commission a pair "exactly like them"
The Mundorf caps are 1500uf 100v. 22k Resistors both MK132s and 680R is Kiwame as per PD's preference.
I've not done any component swapping.
The front badges are antique Chinese coins with a faux jade bead cut in half and led mounted behind. On account of these being finished around Chinese New Year I'm calling them Metal Ox (even though they are largely constructed from wood).
At the moment they are naked on the underside - so no putting the fingers in there please!
Noticing details in the mid range that I don't think I'm hearing when my ancient Chord SPM900 is in use.
I can't comment on resonance properties of wood etc. It's just what I have available to me and I'm happy with how they worked out. The 50mm teak + the 300VA R-core transformers add up to a satisfying weight.
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So I have a little niggle with the new mono blocks. Doesn't effect their operation but it bugs me.
Monoblocks are meant to be the same right? But when I turn them off, the led on one turns off immediately, the other fades over time.
Before I go back inside to see what/anything is physically different, which one is exhibiting the correct behaviour? Off immediately or fade?
Monoblocks are meant to be the same right? But when I turn them off, the led on one turns off immediately, the other fades over time.
Before I go back inside to see what/anything is physically different, which one is exhibiting the correct behaviour? Off immediately or fade?
I have two questions about the snubber implementation that I hope that one of you can address. Currently on my rectifier board I have a 6800 mf caps which are bypassed by 10 mf blackgates. I was thinking of adding a snubber. Two questions:
1. Peter mentioned that for the snubber the cap must be at least 10000. Is 6800 close enough? And why is it important to have a really big cap?
2. Do I need to remove the 10 mf cap if I want to put the snubber? The placement of the resistor is not a problem as it can go over the cap without touching it.
1. Peter mentioned that for the snubber the cap must be at least 10000. Is 6800 close enough? And why is it important to have a really big cap?
2. Do I need to remove the 10 mf cap if I want to put the snubber? The placement of the resistor is not a problem as it can go over the cap without touching it.
The snubber was actually a solution to a really big cap. The gainclone amps were usually using rather small caps in a range of 1000-2000uf because that created good sound with well defined and controlled bass.
Some people started complaining that with hard to drive speakers they couldn’t get enough bass so they started adding more capacitance, but that didn’t sound good. And then, one guy figured out that by adding snubber, he can make large caps to sound good as well.
So, 10000 or 6800uf doesn’t make any difference here. Try the snubber and see for yourself if you like it or not. You don’t need to remove 10mf cap neither, listen with and without cap and see what you like better.
Some people started complaining that with hard to drive speakers they couldn’t get enough bass so they started adding more capacitance, but that didn’t sound good. And then, one guy figured out that by adding snubber, he can make large caps to sound good as well.
So, 10000 or 6800uf doesn’t make any difference here. Try the snubber and see for yourself if you like it or not. You don’t need to remove 10mf cap neither, listen with and without cap and see what you like better.
Used Gainclone LM3875 cutting out periodically and coming back
Hello all
Recently I picked up an used Gainclone based on LM3875 using audiosector kits. I have connected it to an Elac FS127 4ohm floor stander with 85db @1Watt/1 meter speaker. The speaker is rated 80/120watts. The dac used is allo boss2. The problem I am facing is that even when no music is playing the amp/speaker cuts out in a pattern and makes a soft noise... Like it's losing power and coming back. Only observation being it's not a clean drop and come back. It sounds like a kadak-dak-boom... Like 2 or 3 syllable sound. Soft sound.
I picked it up locally in bangalore India and I am not aware of its exact build and usage history.
Let me also emphasise that when the gainclone is playing well it sounds amazing... Really transparent, slightly warmer and loud. I did not observe any other issue l, just this. Any way to fix this problem?
I have attached a few pictures. Looking for your comments and support.
Thanks,
Bhooshan
Hello all
Recently I picked up an used Gainclone based on LM3875 using audiosector kits. I have connected it to an Elac FS127 4ohm floor stander with 85db @1Watt/1 meter speaker. The speaker is rated 80/120watts. The dac used is allo boss2. The problem I am facing is that even when no music is playing the amp/speaker cuts out in a pattern and makes a soft noise... Like it's losing power and coming back. Only observation being it's not a clean drop and come back. It sounds like a kadak-dak-boom... Like 2 or 3 syllable sound. Soft sound.
I picked it up locally in bangalore India and I am not aware of its exact build and usage history.
Let me also emphasise that when the gainclone is playing well it sounds amazing... Really transparent, slightly warmer and loud. I did not observe any other issue l, just this. Any way to fix this problem?
I have attached a few pictures. Looking for your comments and support.
Thanks,
Bhooshan
