I am also very curious about C21. I have it soldered on the bottom of my board but haven't soldered C9 yet, so it could come out easily.
If bypassing a BG electrolytic produces resonances as reported, then would that be easily measured with a scope? It seems a resonance would be visible. Is this a known fact or subjectively determined observation? I am guessing someone made a subjective choice, maybe even Mauro, that C21 was a good thing. Do any of you My_ref historians know the origin of C21?
I also haven't mounted D1-3 yet as I want to use a quieter diode. What are the recommended replacements? I am really curious about C5 as well. Some capacitance seems in order but I am guessing.
Regarding R3, I was prepared to buy some Mills 12 watt at 0.47 ohms because they are quality resistors and I wouldn't need a heat sink. Dario, could you augment your comments about the mills? Most refined sound good, but the other comments, not so much.
The more I work with this amp, the more I want it to be the best it can be. Many thanks for posting on upgrades. And Uriah, I hope you understand the magnitude of all of our appreciation for your efforts. Well done.
TIA,
rick
Originally, there was a regular high-quality electrolytic at C9 - Panasonic FM and Elna Silmic were among the popular choices. It made sense to bypass the electrolytic with a small film cap, and that's what ended up on the Twister Pear board as C21. After C9 was upgraded to a Black Gate in the Ultimate BoM, C21 still hung around, although bypassing a Black Gate is not recommended. So there's some question now on whether it is better to drop it, as Dario and others suggest.
My 2c: if C9 is a Black Gate or a Polymer or maybe an OSCON, omit C21. If it's an electrolytic, retain it.
D1 to D3 are not in the audio supply path, so it doesn't really matter how quiet they are. Plain old 1N4004 will do fine. If you want a fast soft-recovery equivalent, Philips BYV26E (1000V, 1A) or similar is a good starting point.
C5 is just a snubber/suppressor, and anything from 10 nF to a few 100 nF should be fine.
You're welcome, Rick
C9 was specified in Mauro's original BOM as 'Audio Grade' or 'Low-ESR 105°'
Was Mauro that suggested that a film bypass of C9 could be benefic.
And for regular elcos so it is.
It seems that BGs sounds better without, that's all.
Regarding D1, D3 I'm using SBYV27-100 and recomend them too.
The Mills isn't bad, only at the moment I prefer both the original Xicon and the Caddock.
In the next week or two I hope to make my recomendations final.
Sure, they're not in the audio path but they pollute the AC section with spikes, until the 1N4001 are there C5 is absolutely needed.
My choice is to use soft recovery diodes and leave C5 void or with a little cap like a 10nF MKP10.
You may be a Linux guru, but you're no MyRef guru. Congratulations on building one working amp from parts you found in your junk drawer. Don't start telling us, who have spent a lot of money on quality parts and a lot of time building several versions of this amplifier, what sounds good and what is not important. I think anyone who selects parts based on whether they fit inside a case or not has very little to offer about quality of sound.
If you want to start peddling kits like a street vendor, you had better get permission from the original designer and the original kit seller first.
Before everyone freaks out about C21: if you have already mounted it, leave it alone. The amp sounds WONDERFUL with C21 in the circuit. If Dario reports that there is an improvement without it (I don't have any motivation to remove mine to find out for myself), you can remove it by snipping the leads later. I would like to know exactly who recommends that no bypass, especially one of such a small value, be used with a BG? The larger value bypass originally used did cause resonances. I hear no such artifacts using the current C21.
Peace,
Tom E
If you want to start peddling kits like a street vendor, you had better get permission from the original designer and the original kit seller first.
Before everyone freaks out about C21: if you have already mounted it, leave it alone. The amp sounds WONDERFUL with C21 in the circuit. If Dario reports that there is an improvement without it (I don't have any motivation to remove mine to find out for myself), you can remove it by snipping the leads later. I would like to know exactly who recommends that no bypass, especially one of such a small value, be used with a BG? The larger value bypass originally used did cause resonances. I hear no such artifacts using the current C21.
Peace,
Tom E
At no time did I offer to sell a complete kit based on others' work. I merely offered to (possibly in the future) put together a group buy for an alternate, value-oriented BoM for the existing Twisted Pear board sourced directly from Uriah. Uriah *does* have permission to sell bare boards, and AFAIK, he has run out of the component kits and does not wish to offer the component kits again. Any potential builder who legitimately acquires a bare board from Uriah or elsewhere is at liberty to source his components from anywhere, and is not bound to use the specific BoM that was originally developed for that PCB.
That alternate, value-oriented BoM is my own original work. I sourced the parts, prototyped and auditioned the resulting circuit and found it to be of good quality, even if it is not to the same exalted standards that you claim to be guided by. In any event, that BoM will be offered merely as a convenience to builders in India who do not have access to the full range of components available internationally, and will find it difficult to import them individually. It will not be offered here at diyaudio, or to anybody outside of India.
To summarize, I am not offering anything that I don't have the right to sell.
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Hmmm.
Taking something from DIYAudio, not offering it to the members @ DIYAudio and only distributing to market that can't be "observed" buy DIYAudio...
It may not be illegal but it IS CERTAINLY unethical.
Twisted Pair got direct permission from Mauro to develop the PCBs. Uriah got permission to reorder the SAME PCBs for another round of GB's HERE @ DIYAudio.
It would be unethical to take Mauro's IP away from DIYAudio without direct permission.
Developing another BOM for a DIYAudio project is perfectly fine AND encouraged. But if it is to be sold it should be offered here @ DIYAudio FIRST and FOREMOST. All other markets should be considered secondary.
Report from the field...
Hello everyone,
among the caps that I've tried some are going to be definitive.
The Silver Micas in C10 and C34, after burn-in, are nice improvements:
more air, soundstage, refined high range and tighter bass
For 1,5$ each they're not cheap but...
Russ White was right... for its own MyRef he used SMs in place of ceramics...
The 4.7uF MKS2XL in place of the 100uF Silmics are a big improvement, tighter bass, more air and refined high range when you put Silmics back you ear an immediate sense of confusion...
I'm waiting some 10uF MKS2XL to try in C1-C2..
The metal can version of the LM318 is also an improvement, more subtle, is somewhat more 'natural' and less harsh. Not so important but if you can buy two at a good price...buy them!
And remember:
C12 Wima FKP2 220pF
Hello everyone,
among the caps that I've tried some are going to be definitive.
The Silver Micas in C10 and C34, after burn-in, are nice improvements:
more air, soundstage, refined high range and tighter bass
For 1,5$ each they're not cheap but...
Russ White was right... for its own MyRef he used SMs in place of ceramics...
The 4.7uF MKS2XL in place of the 100uF Silmics are a big improvement, tighter bass, more air and refined high range when you put Silmics back you ear an immediate sense of confusion...
I'm waiting some 10uF MKS2XL to try in C1-C2..
The metal can version of the LM318 is also an improvement, more subtle, is somewhat more 'natural' and less harsh. Not so important but if you can buy two at a good price...buy them!
And remember:
C12 Wima FKP2 220pF
Attachments
Troy,
I was going to answer about the thickness definitively but lemme go check....
Okay, same thickness.
Also, after I ordered them I freaked out because I thought I ordered the wrong copper but after checking and comparing my order from the last GB and Twisted Pear's recommendation and this order... all were the same.
Uriah
I was going to answer about the thickness definitively but lemme go check....
Okay, same thickness.
Also, after I ordered them I freaked out because I thought I ordered the wrong copper but after checking and comparing my order from the last GB and Twisted Pear's recommendation and this order... all were the same.
Uriah
Dario, you are making some pretty radical changes to values, and that makes me wary of adopting some of your recommendations. How can a 4.7uf part be as effective as one originally spec'd at 100uf? I guess I don't understand enough about bypassing, but you would expect that those original values were chosen by Mauro for a reason. I'm all in favor of selecting better parts, but I'm not sure I want to start changing values so drastically.
Regarding Silmics, I'm not sure they were the right choice for any part of this amp, but you and I have disgareed about that all along. I recommend people try more Panny FM's if they want to experiment. They're really an excellent cap for being so cheap, especially compared to some of the other stuff we're doing here.
Silver mica's for C10 and C34 will be in my next build.
Has anyone considered these for C12, C30 or C32? I wonder if they're any better than the WIMA FKP's, which are the same basic configuration.
Amtrans AMCH Series Film & Foil Capacitors
Dario, have you experimented with C30 or C32 at all? I'm not sure they're important to signal quality.
Peace,
Tom E
Regarding Silmics, I'm not sure they were the right choice for any part of this amp, but you and I have disgareed about that all along. I recommend people try more Panny FM's if they want to experiment. They're really an excellent cap for being so cheap, especially compared to some of the other stuff we're doing here.
Silver mica's for C10 and C34 will be in my next build.
Has anyone considered these for C12, C30 or C32? I wonder if they're any better than the WIMA FKP's, which are the same basic configuration.
Amtrans AMCH Series Film & Foil Capacitors
Dario, have you experimented with C30 or C32 at all? I'm not sure they're important to signal quality.
Peace,
Tom E
Hi Tom,
With C6-C11 I'm only doing some experiments.
No recommendation... yet
But usually what is important here is ESR and Ripple and a film cap, even much smaller as in this case, is much better in these parameters.
Tom, please don't do it again.
Don't suggest people to try again caps that were part of the previous BOM...
No way FMs are better than Silmics in this application.
I do agree that difference is not night and day but Silmics do an excellent (and better) work.
Obviously a film cap is way better than ANY electrolythic, even Black Gates (btw I've buyed also them for this position).
I'll wait you comments, after some hours of burn-in, of course...
I don't now, never tried them but they resembles the black drops that I've ripped off from my Sony SACD Player (see the attached photo)... FKP2s were MUCH better...
Tom, take a look at the datasheet... DF 0.1%
A good electrolythic is better...
Not with C30, here I've used directly an FKP2 because I think this position needs one.
But with C32, sure I did!
I've tried both a Silver Mica and an FKP2 and preferred the latter by a slight margin... and the improvement versus a ceramic is BIG.
It was one of the most rewarding mods...
Attachments
Hi Uriah,
I don't know, never used tantalums, their failure mode...scares me a bit.
Hi Sandbasser,
obviously they're the same values, these caps are critical for the compensation...
Is anybody interested in a stereo kit? I have a partial. It has 2 boards, 2 LM3886, all resistors except 1R 1/4W Metal Film. No Caps No Actives. Luckily if you are after the ultimate BOM ... Tom and Dario are still changing the game on this amp and the capacitor shoot out is still very live. This gives you a good start on the kit with parts that wont change and the actives, which you need to source, will not change either. Well, its all thats left so if you are on the fence you already waited to long, dont wait this little bit longer and totally miss out. $35.. Not bad huh?
I'd gladly offer it here if there's sufficient interest and the practical logistic problems are solved. If it's going to cost $15 to ship a $20 kit from India to the US, it's probably not going to work out. I have already listed the preliminary BoM earlier, and anybody is free to pick and choose from it and source individual items from wherever they want.
That apart, I don't have PCBs to sell along with the components - anybody interested may please contact Uriah directly.
The Silver Micas in C10 and C34, after burn-in, are nice improvements:
more air, soundstage, refined high range and tighter bass
For 1,5$ each they're not cheap but...
Ah, I see you've taken a leaf out of my BoM
The 4.7uF MKS2XL in place of the 100uF Silmics are a big improvement, tighter bass, more air and refined high range when you put Silmics back you ear an immediate sense of confusion...
I'm waiting some 10uF MKS2XL to try in C1-C2..
So those square box-type WIMAs with silver lettering are MKS2XL? I've only seen 1 uF/63V locally, but let me see if I can get higher values.
BTW, I tried 33uF/35V Black Gate PK at C6/C11 and they're fine even without burn-in. My guess is that 4.7uF/35V Black Gate will work just as well - that LM318 is not driving any heavy loads. It's just 47K and some high-Z compensation networks that it has to drive.
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