Duda! Good to see you again. I thought this thread would bring back a lot of people I had not seen in quite some time!
New thread is here
http://www.diyaudio.com/forums/group-buys/160768-myref_c-ultimate-bom.html#post2076120
New thread is here
http://www.diyaudio.com/forums/group-buys/160768-myref_c-ultimate-bom.html#post2076120
Let's go again
Silmics are not the culprits for the murder of highs, the 220nF MKS2 were instead...
Silmics are quite as open as FMs.
NOO!
First the value was found using both Silmics and FMs and the most important thing is that a different value moves the soundstage back or forth, bigger the value more recessed are voices.
The tonal balance doesn't change with value.
Regarding C21 I've first used FKP2 to determine the value using first 10nF (that simplified music), after 33nF (that added something) and last 22nF (that seemed right)
I had too the suspect that this value could be related to FKP2s so Ive repeated the test with MKS2s starting with 100nF going down to 10nF with the very same results.
In both cases the 22nF bypass sounded 'right', highs are better, bass too and voices are correctly placed and focused (better than Silmics alone)
Uh, yeah, FKP2s are much better than MKS2s
If Uriah wants to make premium kits I think he should use resistors known to be good for audio, like CMF/RN55 or Takmans or PRP.
Talking about resistors the BOM should be fixed replacing R2 with 10 KOhm (as suggested by Mr. Pass) and R42 with 47 Ohm (as suggested by Mauro and as the original TP kit)
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Keep it coming guys if you have more to say about it. We certainly have time on our side.
I would like to use something like PRP or Takmans or Shinkohs. Have either of you tried Holco? They are premium and not terribly pricey. PRP are a little large. Holco are a nice size, about the same as the Dale's. Not that this is a big deal but I forget how much room I had on the board. My boards got destroyed in our move and I really need a good amp. I didnt want to pay the price for new boards without the benefit of group buy pricing and I didnt want the same amp I previously had, plus I have had several requests for more boards. I wanted the same amp I had.. but even better. This is a tweakers amp it seems and you two have shown beyond a shadow of a doubt that premium parts matter in this one.
Its going to be hard to come up with an input cap as the two of you disagree on that but on most other things you are of the same mind.. even if you nit pick a few details But then again the nitpicking is what has you both extremely happy with your amps.
I noted your resistor remarks Dario. Looks like Tom also agrees with your R42 recommendation. He has 33k in R2. Are you using 10k there? Did you note the difference when you made the change, assuming you did?
Uriah
I would like to use something like PRP or Takmans or Shinkohs. Have either of you tried Holco? They are premium and not terribly pricey. PRP are a little large. Holco are a nice size, about the same as the Dale's. Not that this is a big deal but I forget how much room I had on the board. My boards got destroyed in our move and I really need a good amp. I didnt want to pay the price for new boards without the benefit of group buy pricing and I didnt want the same amp I previously had, plus I have had several requests for more boards. I wanted the same amp I had.. but even better. This is a tweakers amp it seems and you two have shown beyond a shadow of a doubt that premium parts matter in this one.
Its going to be hard to come up with an input cap as the two of you disagree on that but on most other things you are of the same mind.. even if you nit pick a few details
But then again the nitpicking is what has you both extremely happy with your amps.I noted your resistor remarks Dario. Looks like Tom also agrees with your R42 recommendation. He has 33k in R2. Are you using 10k there? Did you note the difference when you made the change, assuming you did?
Uriah
Hi Uriah,
Holco changed their end caps with magnetic ones some years ago because they were fragile but now they sound awful, at least some say so.
I've tried Holco NOS with my gainglone and they were good but Takmans (carbon type) were better, Holcos sounds somewhat confused.
I would go for Takmans or Dales, both are the right size for the boards (1/4 Watt).
Not exactly, we reccomend different caps because we tried different caps but we both agree that film/foil caps are the way to go.
If I remember correctly also Allen Wright of Vacuum State likes the Mundorf Zn stating that they're one the most transparent/neutral caps he tried. (here a comment)
Also IT Audyn Cap Kp Sn are highly regarded as coupling caps (here a comment)
Both are tin/film caps.
I've mounted directly 10K in R2 trusting Mr. Pass...
If you've read the thread I've linked Nelson found the problem directly in the datasheet and suggested to trim the current, the modified value for the resistor is only a consequence.
Regarding R42 I think that it isn't important that Tom and I do agree, the important thing is that Mauro Penasa suggested that change.
Holco changed their end caps with magnetic ones some years ago because they were fragile but now they sound awful, at least some say so.
I've tried Holco NOS with my gainglone and they were good but Takmans (carbon type) were better, Holcos sounds somewhat confused.
I would go for Takmans or Dales, both are the right size for the boards (1/4 Watt).
Not exactly, we reccomend different caps because we tried different caps but we both agree that film/foil caps are the way to go.
If I remember correctly also Allen Wright of Vacuum State likes the Mundorf Zn stating that they're one the most transparent/neutral caps he tried. (here a comment)
Also IT Audyn Cap Kp Sn are highly regarded as coupling caps (here a comment)
Both are tin/film caps.
I've mounted directly 10K in R2 trusting Mr. Pass...
If you've read the thread I've linked Nelson found the problem directly in the datasheet and suggested to trim the current, the modified value for the resistor is only a consequence.
Regarding R42 I think that it isn't important that Tom and I do agree, the important thing is that Mauro Penasa suggested that change.
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Uriah and all,
One more important point about construction of the "ultimate" My Ref: do NOT use those crappy connectors to attach signal wires, input or output, to the board. Direct soldering is superior sonically to any connector. On the power side I soldered direct as well, but I don't know if it makes an audible difference. Uriah, leave those out of the kit!
The only aspect of this amp that I didn't play with is the power supply. I did not try the separate diodes instead of the single rectifier, and I did not experiment with any other aspect. My kit came with 12k uF supply caps, and those give really good bass; perhaps 10k is equally good. Maybe some power supply experts could contribute here. In the original thread, all kinds of weird schemes were discussed and tried in an attempt to "improve" the PS, but none were universally adopted as better than the simple, cost effective scheme Mauro presented.
My enclosures are the cheapest, thinnest aluminum project boxes, so I did some work to damp vibration. I lined a lot of the inside with Soundcoat from Parts Connexion, and I used a Deflex toroid pad under the transformer. I also wrapped the input cap, which is off board, in neoprene foam rubber and attached it to the enclosure with a cable tie. The tops are made from 1/2" thick plywood with metal cooling grates. The entire enclosure is very "dead" and everything within is snug and secure, immune to vibration.
The only point that Dario and I will never agree on is the Silmic/Blackgate cap. There might be a couple aspects of this kit that we may have to leave up to individual builders unless we can get a consensus some other way. I wish Dario and I could trade amps for a while!
Peace,
Tom E
One more important point about construction of the "ultimate" My Ref: do NOT use those crappy connectors to attach signal wires, input or output, to the board. Direct soldering is superior sonically to any connector. On the power side I soldered direct as well, but I don't know if it makes an audible difference. Uriah, leave those out of the kit!
The only aspect of this amp that I didn't play with is the power supply. I did not try the separate diodes instead of the single rectifier, and I did not experiment with any other aspect. My kit came with 12k uF supply caps, and those give really good bass; perhaps 10k is equally good. Maybe some power supply experts could contribute here. In the original thread, all kinds of weird schemes were discussed and tried in an attempt to "improve" the PS, but none were universally adopted as better than the simple, cost effective scheme Mauro presented.
My enclosures are the cheapest, thinnest aluminum project boxes, so I did some work to damp vibration. I lined a lot of the inside with Soundcoat from Parts Connexion, and I used a Deflex toroid pad under the transformer. I also wrapped the input cap, which is off board, in neoprene foam rubber and attached it to the enclosure with a cable tie. The tops are made from 1/2" thick plywood with metal cooling grates. The entire enclosure is very "dead" and everything within is snug and secure, immune to vibration.
The only point that Dario and I will never agree on is the Silmic/Blackgate cap. There might be a couple aspects of this kit that we may have to leave up to individual builders unless we can get a consensus some other way. I wish Dario and I could trade amps for a while!
Peace,
Tom E
No reason we cant get one of each for that cap. I dont think it would cost much more.
I agree about direct soldering. I ended up doing the same thing.
I think I will go with Darios suggestion of MUR820's. Need to find a good solution for power supply cap. Nichicon's Audio Power caps might be my first investigation.
Uriah
I agree about direct soldering. I ended up doing the same thing.
I think I will go with Darios suggestion of MUR820's. Need to find a good solution for power supply cap. Nichicon's Audio Power caps might be my first investigation.
Uriah
Regarding value of R2, 33k or 10k: I have read the comment by Pass and realize that he is promoting higher current from the mute pin, which requires smaller value resistor. That was pure speculation on his part. He has never designed a chip amp, and he doesn't care too much about them, as far as I know. I never saw that anyone confirmed that this change provides better sonics in the My Ref. I used 33k because it was in the original BOM and Mauro's design. I don't know if it really makes any difference, and I don't care which value you pick, so no controversy there.
One aspect of this design that I wanted to play with but never got the time to try is using a better relay. I think the current one was chosen by Russ White of Twisted Pair. I'm not sure Mauro ever designated one. Knowing that TP was sometimes more interested in economy than best quality, I suspect that there might be better relays available. Has anyone experimented with that? Dario, which one do you use?
Peace,
Tom E
One aspect of this design that I wanted to play with but never got the time to try is using a better relay. I think the current one was chosen by Russ White of Twisted Pair. I'm not sure Mauro ever designated one. Knowing that TP was sometimes more interested in economy than best quality, I suspect that there might be better relays available. Has anyone experimented with that? Dario, which one do you use?
Peace,
Tom E
This post sounds reasonable for me and a member some posts over says it sounds better with the reccomended current.
The LM3886 is still a power opamp also in the MyRef and if biasing differently the mute current could correct that glitch in distorsion I'm happy with it...
The same one in kit.
Omron is a leader in the relay market and the G5LE is audio-rated in the datasheet and has silver alloy contacts, I don't think there's much better.
Uriah and all,
A couple more observations, as long as things are starting to get active again.
The My Ref's I have built are the quietest amplifiers I've ever had. There is no noise whatsoever at any volume level. I think builders who encounter problems with hum have added something to the basic amp circuit or just plain built them improperly. There is no need to take any unusual measures to ensure silent operation.
Having said that, I am experiencing a unique problem with these amps. They are very sensitive to spikes on the mains such as motor starts. When my furnace motor turns on, I get anything from a low level thump to a startling pop over one or both speakers. I have installed small caps across the line inside each amp, but that seems to have had very little effect. In a search here, I found that other users of the 3886 chip have the same problem. Do any other users of the My Ref experience this type of noise? If so, can anyone propose a solution? Uriah, is it possible for you to ask Mauro if he can think of a solution?
One point regarding the group buy: it is not necessary to include transformers or enclosures because I don't think there is much to be saved there from a large order, and everyone has their own preference. Besides, shipping and reshipping would eat up any potential economy. People should be encouraged to spend a few more dollars to get a quality transformer of adequate capacity. There is no point in trying to save a couple bucks on cheap or small trannies and compromising performance right from the start.
Peace,
Tom E
A couple more observations, as long as things are starting to get active again.
The My Ref's I have built are the quietest amplifiers I've ever had. There is no noise whatsoever at any volume level. I think builders who encounter problems with hum have added something to the basic amp circuit or just plain built them improperly. There is no need to take any unusual measures to ensure silent operation.
Having said that, I am experiencing a unique problem with these amps. They are very sensitive to spikes on the mains such as motor starts. When my furnace motor turns on, I get anything from a low level thump to a startling pop over one or both speakers. I have installed small caps across the line inside each amp, but that seems to have had very little effect. In a search here, I found that other users of the 3886 chip have the same problem. Do any other users of the My Ref experience this type of noise? If so, can anyone propose a solution? Uriah, is it possible for you to ask Mauro if he can think of a solution?
One point regarding the group buy: it is not necessary to include transformers or enclosures because I don't think there is much to be saved there from a large order, and everyone has their own preference. Besides, shipping and reshipping would eat up any potential economy. People should be encouraged to spend a few more dollars to get a quality transformer of adequate capacity. There is no point in trying to save a couple bucks on cheap or small trannies and compromising performance right from the start.
Peace,
Tom E
I can ask Mauro. Thats a good idea. I had the same problem and found the solution in replacing the old lightswitch. When in the room with lights out, turn the light on, and in that split second before light I saw sparks. Replaced the switch. No more problem. Now the old wiring in the house was my main problem though. I got fridge noise to when the fridge relay clicked on/off. They had removed the grounding. Literally. Ground was tied to neutral in the wall sockets all through the house. I rewired my listening room and voila. I talked to my electrician friend and he said it was common for some crazy reason back then to wire that way. So yeah its the houses problem but the amp is sensitive to it.
I've the same problem, for now I'm simply ignoring it.
Here a possible solution (untested)
But pay attention to an error in the post: they suggest using X Rated caps between line and neutral AND live and safety ground!!
X rated caps are designed to be used between live and neutral, Y rated caps between live/neutral and safety ground.
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How about a kit with options? Not options to buy but one kit with several build options. Builder can test them and pick the one that sounds best with there system.
Just a thought
I've been having trouble filtering noise generated from a switching power. Do you know how large capacitance values these caps go up to.
I have taken some filter caps from a computer PSU, and nother their positions.
They placed one 0.47uF 250v metallized polyprop X2 rated soldered at the input socket, between line and neutral. One 0.1uF of te same characteristics near the pins of the first transfoermer, a little one. And two Y2 rated 250v caps with the inscription "SEM AA 222M 600" between both line and neutral, to ground.
I may put them in my MyRef_C I am going to build, and then pray for being able to discern any minimal subtle difference
They placed one 0.47uF 250v metallized polyprop X2 rated soldered at the input socket, between line and neutral. One 0.1uF of te same characteristics near the pins of the first transfoermer, a little one. And two Y2 rated 250v caps with the inscription "SEM AA 222M 600" between both line and neutral, to ground.
I may put them in my MyRef_C I am going to build, and then pray for being able to discern any minimal subtle difference
