Bob, it's good to know that you tracked it down - at a casual glance, it's possible to confuse the gold tolerance band on a 47k 5% resistor with the gold exponent band on a 47R 1% resistor. Other problems are between red and brown, orange and red, gold and orange, etc. On 1% MFRs with 5 bands, it's possible to read the bands in the wrong direction, starting with the tolerance.
So everyone is up and happily running now? That's great. I'd like to know if PJN is using a socket for his 318 chip. Although they're very convenient, I don't like sockets because of the problems they can cause. Perhaps you just found one of those problems.
There probably aren't many amps where you can use a resistor one thousand times the specified value and get it to not blow up, or even more, to work.
Now it's time for Linuxguru to build a pair of his beautiful new layouts and let us know how good they sound.
I hope it's not so good that I have to build another pair. I've already got four of these amps, two of which I haven't even heard yet. Soon, though, with a full report after break-in.
Peace,
Tom E
There probably aren't many amps where you can use a resistor one thousand times the specified value and get it to not blow up, or even more, to work.
Now it's time for Linuxguru to build a pair of his beautiful new layouts and let us know how good they sound.
I hope it's not so good that I have to build another pair. I've already got four of these amps, two of which I haven't even heard yet. Soon, though, with a full report after break-in.
Peace,
Tom E
Almost done on the first two version 1.4 boards - checking everything, going slowly and carefully on the assembly. At the moment, I'll be happy as long as there is no regression from version 1.3.
Just a little note on mounting LM3886s on a heat sink. Depending on the material and the tools used it is possible to create a small compression ridge or raised area around the hole during drilling and tapping. I found this on the 1/16" copper plate that is laminated as the business side of an aluminum heat sink. It might not cause a problem but lightly scraping with a utility knife blade held perpendicular to the face of the HS will indicate the error, remove it and will insure a uniform surface. I polished mine with some sticky-back 600 & 1000 grit mounted on a small piece of super flat tile.
Probably overkill but it made me feel "professional"
Bob M.
Probably overkill but it made me feel "professional"
Bob M.
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Guys,
I've received 2 pairs of Linuxguru's v1.3 boards and most of the required electronic parts. I'm actually going to order the LMs, toroids and het sinks. There's one question regarding the LMs. Which model do you use, the T or TF version, and why? I understand that the T version offers a better heat dissipation compered to TF, doesn't it?
I've received 2 pairs of Linuxguru's v1.3 boards and most of the required electronic parts. I'm actually going to order the LMs, toroids and het sinks. There's one question regarding the LMs. Which model do you use, the T or TF version, and why? I understand that the T version offers a better heat dissipation compered to TF, doesn't it?
The T is different from the TF.
The TF is electrically insulated from the heatsink.
If you need electrical insulation from the heatsink you must add an electrical insulator to the T version.
You must then compare your electrical insulator's Thermal Characteristics to the TF's or to what your design requires.
A poor selection of insulator could easily make your "modified" T worse than a TF for heat transfer.
The TF is electrically insulated from the heatsink.
If you need electrical insulation from the heatsink you must add an electrical insulator to the T version.
You must then compare your electrical insulator's Thermal Characteristics to the TF's or to what your design requires.
A poor selection of insulator could easily make your "modified" T worse than a TF for heat transfer.
Hi Guys,
I think I am at or near "burn-in" of my linuxguru V1.3 amps. The impression is a general "mellowing" and increased cohesiveness with slightly reduced edginess in the mid-range (which I had interpreted as "presence") and a bit less "sparkle" at the very top.
I am interested in the subjective descriptions/impressions of the veterans on this forum of what is heard at full burn-in, if you care to share.
Haven't put the Sonicaps in these two yet as I'd like to be able to hear the full effect of the change.
Regards, Bob M.
I think I am at or near "burn-in" of my linuxguru V1.3 amps. The impression is a general "mellowing" and increased cohesiveness with slightly reduced edginess in the mid-range (which I had interpreted as "presence") and a bit less "sparkle" at the very top.
I am interested in the subjective descriptions/impressions of the veterans on this forum of what is heard at full burn-in, if you care to share.
Haven't put the Sonicaps in these two yet as I'd like to be able to hear the full effect of the change.
Regards, Bob M.
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It's consistent with burn-in of C1, C2 (Muse KZ). I must confess that I haven't actually auditioned the exact combination of caps that are on your boards (C1, C2:Muse KZ, C6, C11: Cerafine and C9: Black Gate PK), but in general the KZs have short burn-in periods (~10-25 hours) and the Black Gate has much longer burn-in (~100-300 hours). I don't know about the Cerafines.
If the "edge" is off, then you're part way there. The Blackgates do take the longest, other than a Mundorf SIO cap: maybe more than a hundred hours. The one thing that should continue to improve with additional break-in is the sense of space, three dimensionality of images. Things will open up, there should be more air, and bass might get a little more forceful as the Blackgate settles.
Good idea to hold off on the Sonicaps. They will change a lot in the span of a single CD, and continue to slightly improve for another few dozen hours.
Peace,
Tom E
Good idea to hold off on the Sonicaps. They will change a lot in the span of a single CD, and continue to slightly improve for another few dozen hours.
Peace,
Tom E
Yup, go with a Panny FM, Elna Silmic/Silmic II/Cerafine or a Nichicon Muse FG for C6/C11. They're less edgy out of the box, and either have short burn-in periods or don't require burn-in.
Jaw Dropping!
Hey Madisonears, et al.
Ok, Ok, I believe you.
I just couldn’t wait any longer so I put the Blackgates (220uf 16V) and the Sonicaps (Gen 1, 1.5uf 200V) in my V1.3 boards from Siva. I really had not expected what you described as “more space and a larger stage” The best way I can describe the difference after one hour is, with some source material, my listening room is now one giant set of headphones. I was very happy with the quality and amount of sound before I upgraded these two components. I am not exaggerating when I say I now feel I was listening through ear muffs and not ear phones. In my thirty years of speaker building and amp buying/building, I have often heard something like “removes a veil or opens a window”. This is the first time I have experienced that change with jaw dropping clarity.
I am so glad I took your advice to wait a good period of time before making the change. It is clearly dramatic. You made a home run call on the Sonicaps.
I also got some of the Vampire parts I need for the final in-case build in the mail yesterday. I went with the lugs this time for as solid a connection as I can get.
Some initial impressions:
1. The bass is slightly more robust, but more importantly has increased impact without any boom.
2. The midrange again has a balanced impact and tonal accuracy that when combined with the bottom end imparts a physical element to the whole experience.
3. The upper octaves can only be described as shimmering and precise.
4. That often overused phrase “the walls of the room seem to disappear” truly describes the impression I am hearing.
A note of caution – I have heard some folks say the Ref-Cs are good but not all that much better than some other LM3886 designs. I don’t think one can appreciate these amps without some very good and accurate (not necessarily expensive) speakers. I feel very fortunate to have chosen to build a pair of Paul Carmody’s “SunFlower” speakers a few months ago. Surely the open back concept therein contributes to the "spacial" delights of this combination. Paul has even developed a new crossover that brings some of the advantages of single point source designs to his already remarkable body of work. I am sure there a many, many other great speakers – my point is – try not to underestimate the need for speakers of the same quality as that of the MyRef-Cs.
My gratitude to all of you, especially the veterans, for leading me to and through this fantastic journey.
Regards, Bob M.
P.S. To you fellow NASCAR fans, another way to describe what I heard today is kind of what racing would be like without those silly restrictor plates.
Hey Madisonears, et al.
Ok, Ok, I believe you.
I just couldn’t wait any longer so I put the Blackgates (220uf 16V) and the Sonicaps (Gen 1, 1.5uf 200V) in my V1.3 boards from Siva. I really had not expected what you described as “more space and a larger stage” The best way I can describe the difference after one hour is, with some source material, my listening room is now one giant set of headphones. I was very happy with the quality and amount of sound before I upgraded these two components. I am not exaggerating when I say I now feel I was listening through ear muffs and not ear phones. In my thirty years of speaker building and amp buying/building, I have often heard something like “removes a veil or opens a window”. This is the first time I have experienced that change with jaw dropping clarity.
I am so glad I took your advice to wait a good period of time before making the change. It is clearly dramatic. You made a home run call on the Sonicaps.
I also got some of the Vampire parts I need for the final in-case build in the mail yesterday. I went with the lugs this time for as solid a connection as I can get.
Some initial impressions:
1. The bass is slightly more robust, but more importantly has increased impact without any boom.
2. The midrange again has a balanced impact and tonal accuracy that when combined with the bottom end imparts a physical element to the whole experience.
3. The upper octaves can only be described as shimmering and precise.
4. That often overused phrase “the walls of the room seem to disappear” truly describes the impression I am hearing.
A note of caution – I have heard some folks say the Ref-Cs are good but not all that much better than some other LM3886 designs. I don’t think one can appreciate these amps without some very good and accurate (not necessarily expensive) speakers. I feel very fortunate to have chosen to build a pair of Paul Carmody’s “SunFlower” speakers a few months ago. Surely the open back concept therein contributes to the "spacial" delights of this combination. Paul has even developed a new crossover that brings some of the advantages of single point source designs to his already remarkable body of work. I am sure there a many, many other great speakers – my point is – try not to underestimate the need for speakers of the same quality as that of the MyRef-Cs.
My gratitude to all of you, especially the veterans, for leading me to and through this fantastic journey.
Regards, Bob M.
P.S. To you fellow NASCAR fans, another way to describe what I heard today is kind of what racing would be like without those silly restrictor plates.