I have boards and kits available; have replied to your PM.
Here is my baseline premium BoM for the Version 1.3 PCB (some resistor improvements have been made- R5, R6, R7, R8, R9 are now Megitt/Holco H4. C6, C7, C11 are still experimental, since the Black Gates are no longer available).
To all new and future builders of MyRef, whatever version:
The part selection for this wonderful little device is not as critical as the preceding posts might lead you to believe. What Dario and I (with help from others) have done is REFINE the sound of this amp to our liking. The basic amp design is what produces the remarkable sonic characteristics. You do not need to have this or that resistor or cap to get this amp to sound good: the original group buy used the cheapest parts available, and it sounded good. Dario and I knew it could sound better, so off we went on our journey of discovery.
Don't obsess over having only the very best parts to arrive at the ultimate, because there is no such thing. Buy a kit (or just the boards for a true adventure) from linuxguru and start building and listening. When you want to improve on the excellent sound you initially get, you can buy some fancy parts for not very much money (compared to buying $3000 amplifiers!) and try them until you a find a combination that's best for you.
I've written it here so many times that careful readers might roll their eyes at the redundancy: the single most important element in the sound of these amps is C13. Buy a good cap (or three different good caps to experiment for yourself, and come back to tell us about it) for that spot, and all the other little details will fall into place or not even be important enough to worry about. If you do a lot of experimenting and wreck a board--so what! The xformers and chassis will cost more than the rest of the amp. Buy another board, desolder the good stuff, then put it in a new board with a few better parts. I wrecked boards twice and built a slightly better new amp each time.
But I must tell you that the new IC's I just built make a much bigger difference in my system than changing a few minor components of this amp ever did.
Peace,
Tom E
The part selection for this wonderful little device is not as critical as the preceding posts might lead you to believe. What Dario and I (with help from others) have done is REFINE the sound of this amp to our liking. The basic amp design is what produces the remarkable sonic characteristics. You do not need to have this or that resistor or cap to get this amp to sound good: the original group buy used the cheapest parts available, and it sounded good. Dario and I knew it could sound better, so off we went on our journey of discovery.
Don't obsess over having only the very best parts to arrive at the ultimate, because there is no such thing. Buy a kit (or just the boards for a true adventure) from linuxguru and start building and listening. When you want to improve on the excellent sound you initially get, you can buy some fancy parts for not very much money (compared to buying $3000 amplifiers!) and try them until you a find a combination that's best for you.
I've written it here so many times that careful readers might roll their eyes at the redundancy: the single most important element in the sound of these amps is C13. Buy a good cap (or three different good caps to experiment for yourself, and come back to tell us about it) for that spot, and all the other little details will fall into place or not even be important enough to worry about. If you do a lot of experimenting and wreck a board--so what! The xformers and chassis will cost more than the rest of the amp. Buy another board, desolder the good stuff, then put it in a new board with a few better parts. I wrecked boards twice and built a slightly better new amp each time.
But I must tell you that the new IC's I just built make a much bigger difference in my system than changing a few minor components of this amp ever did.
Peace,
Tom E
The attached BOM is the last one.
I've yet to decide the right value for the FKP2 in C7.
So far 10nF seems good.
When I'll try the Sonicaps in C13 they'll probably replace Obbligatos and/or possibly the Zns
I do agree with Tom but, IMHO, when the BOM suggests standard (but selected) parts (like KOAs in R1, R4 or the various FKP2) it's really a pity to miss the (not subtle) improvement.
So my suggestion is to stick to the BOM unless you want to experiment, possibly comparing with BOM's parts.
In such case don't miss to post your findings here on the thread...
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Sonicaps now ordered.
Will get then installed in the next couple of weeks as I'm out and about when they arrive from Italy.My MyRef sings!!
About seven months after receiving my kit, I finally finished my MyRef this evening. Quite a challenge to build from scratch, but 20 minutes in, no problems yet and sounds wonderful!! My thanks to all who have posted on this site, I found the advice provided really useful, to Uriah for putting together such a superb kit and Mauro for designing a fantastic amp.
About seven months after receiving my kit, I finally finished my MyRef this evening. Quite a challenge to build from scratch, but 20 minutes in, no problems yet and sounds wonderful!! My thanks to all who have posted on this site, I found the advice provided really useful, to Uriah for putting together such a superb kit and Mauro for designing a fantastic amp.
Hi all-
In the following post there is a picture of a partially stuffed Linuxguru PCB. I was hoping someone had a picture of a fully populated board. I generally like to do a visual comparison before I power up new boards.
http://www.diyaudio.com/forums/chip-amps/134726-new-my-ref-rev-c-thread-106.html#post2297595
In the following post there is a picture of a partially stuffed Linuxguru PCB. I was hoping someone had a picture of a fully populated board. I generally like to do a visual comparison before I power up new boards.
http://www.diyaudio.com/forums/chip-amps/134726-new-my-ref-rev-c-thread-106.html#post2297595
That posting shows an early Version 1.3 build with the standard, aka 'value' BoM, as it looked at that time.
Here's a posting with a pic of a more up-to-date Version 1.3 build, closer to the current premium BoM:
http://www.diyaudio.com/forums/chip-amps/167458-myrefc-build-guide-66.html#post2405885
Hi everyone,
I've just completed my first two My_ref RevC boards and they both passed good audio first try, however I have a couple of questions.
Firstly, I'm using kits supplied by Peter (aka schro20), which have the 1.2 revision layout and his 'standard' components. The attached photo is the same as mine, though this one wasn't constructed by me.
While my amps produced great results straight away, and even better since they broke in a little, there is a noticable amount of noise at the speakers, with or without a source connected. My speakers are Audioline AL-600, an 8ohm vented 3-way that claim 94dB @ 1 watt - 1 metre sensitivity (though I'm suspect of this). In a quiet room I can clearly hear them hissing from a metre or two away from the speakers.
As each channel is the same I don't think I have made a mistake during construction (unless I've made the same one twice of course). Is the My_Ref RevC known to be a little noisy? This really doesn't bother me too much, I just want to know if there could be something wrong. I should also note that the amps are not enclosed and the leads are not shielded yet, which surely wont help.
Secondly, is anyone able to tell me the input sensitivity of the RevC? I have searched somewhat with no result. This will help in deciding what to put in front of the amps.
Thanks to everyone who has contributed to this great project. I love the sound of this amp so far and am looking forward to improving my system in general.
Cheers
Tani.
I've just completed my first two My_ref RevC boards and they both passed good audio first try, however I have a couple of questions.
Firstly, I'm using kits supplied by Peter (aka schro20), which have the 1.2 revision layout and his 'standard' components. The attached photo is the same as mine, though this one wasn't constructed by me.
While my amps produced great results straight away, and even better since they broke in a little, there is a noticable amount of noise at the speakers, with or without a source connected. My speakers are Audioline AL-600, an 8ohm vented 3-way that claim 94dB @ 1 watt - 1 metre sensitivity (though I'm suspect of this). In a quiet room I can clearly hear them hissing from a metre or two away from the speakers.
As each channel is the same I don't think I have made a mistake during construction (unless I've made the same one twice of course). Is the My_Ref RevC known to be a little noisy? This really doesn't bother me too much, I just want to know if there could be something wrong. I should also note that the amps are not enclosed and the leads are not shielded yet, which surely wont help.
Secondly, is anyone able to tell me the input sensitivity of the RevC? I have searched somewhat with no result. This will help in deciding what to put in front of the amps.
Thanks to everyone who has contributed to this great project. I love the sound of this amp so far and am looking forward to improving my system in general.
Cheers
Tani.
Attachments
I assembled those units.
Your speakers are more sensitive than the norm of 87db.
Try shorting the inputs of the amp and see if the noise persists.
The MyRef is the most quiet amp I've ever had in my system, and that includes some very expensive SS amps. If you hear hiss, it's probably coming from somewhere else, but I can't tell you where. Hum would mean poor grounding or some other basic problem. I've never heard ANY hiss from this amp. Has anyone else? This amp is so quiet, it might be passing hiss from other components that you've never been able to hear before!
Enclosure and shielding might affect the noise, but it might not make any difference. I ran my very first build without any enclosure (the amps were attached to a piece of wood, transformers right next to them!) or shielding of cables, and it was still totally silent.
Peace,
Tom E
Enclosure and shielding might affect the noise, but it might not make any difference. I ran my very first build without any enclosure (the amps were attached to a piece of wood, transformers right next to them!) or shielding of cables, and it was still totally silent.
Peace,
Tom E
First short at the chassis input and if the noise continues short across the PCB's themselves.
Best of luck.
Hi Tom,
I thought that the MyRef was reputably quiet. I'll double check everything when I get home, but I'm sure that the amp was making noise without any input at all... though now I'm questioning my recollection of what I did. I clearly need a more concerted testing process to isolate possible sources... I guess listening to music distracted me from a proper troubleshooting process... damn those arts getting in the way of science.
Also good to know that unshielded bench testing shouldn't be causing adverse results... one less thing to test.
Thanks Tom.
I thought that the MyRef was reputably quiet. I'll double check everything when I get home, but I'm sure that the amp was making noise without any input at all... though now I'm questioning my recollection of what I did. I clearly need a more concerted testing process to isolate possible sources... I guess listening to music distracted me from a proper troubleshooting process... damn those arts getting in the way of science.
Also good to know that unshielded bench testing shouldn't be causing adverse results... one less thing to test.
Thanks Tom.
Just finished the interim wiring of mine in the alu chassis tonight. Just the trick AMB switchery to sort out. My dual mono amps are absolutely silent. No hiss, no hummmmm.
Using an AYA DAC and TX102 TVC if that's of any use. Also, my amps are not grounded together, if that makes any difference to the price of fish.
HTH
Jon
Using an AYA DAC and TX102 TVC if that's of any use. Also, my amps are not grounded together, if that makes any difference to the price of fish.
HTH
Jon
As others have already stated, this is one of the quietest amps ever. There should be no hiss at all, and any hum is likely to be as a result of grounding/shielding/pickup issues.
However, there are a few things that you can check/modify on your board:
1) Verify that the opamp is authentic NatSemi or TI.
2) Verify that the chipamp is authentic NatSemi.
3) If you're using an integrated bridge rectifier at BR1, replace it with discrete fast/soft rectifiers like the MUR8xx series at D1 to D4.
4) Use a high-quality snubber cap C7. Polyester film is OK, e.g. Wima MKS3.
5) Remove the polyester bypass caps at C17, C18, C19, C20. They aren't responsible for the hiss, but they certainly hurt the sonics and interfere with the 'floating rails' topology of the MyRef.
6) R1, R4 should preferably be CFRs, not metal-oxide as shown in the picture. Leads must be non-magnetic - the cheap metal-oxides are invariably magnetic.
7) Verify that all the resistors in the small-signal (ground-plane) area have non-magnetic leads to reduce EMI pickup. In particular, R10 and R13 shunt resistors should preferably be CFRs with non-magnetic leads. R7 should also be non-magnetic.
8) Use shielded wire from the source to the input connector - the input can easily pick up hiss from switching power supplies, PCs, CRTs, etc.
9) If ceramics are used at C10, C12, C32 and C34, they should be C0G with non-magnetic leads.
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