Uriah,
Oops, sorry. I see I forgot to include that on my ultimate BOM. My bad. You made a good catch there, and we all will appreciate it eventually.
Any part with a tighter tolerance should be suitable, not necessarily the Vishay/Dale part. I'm not sure whether Mauro ever said it made a difference, but it makes sense to me to have better control over the power supply. Initially, some people suggested active regulation, but I think that was never supported by sufficiently improved sonics for the level of complexity involved.
I didn't mean to be critical of your work so far. I know it takes a lot of time and effort.
Peace,
Tom E
Oops, sorry. I see I forgot to include that on my ultimate BOM. My bad. You made a good catch there, and we all will appreciate it eventually.
Any part with a tighter tolerance should be suitable, not necessarily the Vishay/Dale part. I'm not sure whether Mauro ever said it made a difference, but it makes sense to me to have better control over the power supply. Initially, some people suggested active regulation, but I think that was never supported by sufficiently improved sonics for the level of complexity involved.
I didn't mean to be critical of your work so far. I know it takes a lot of time and effort.
Peace,
Tom E
-please sign me up for a stereo pair- my e-mail is vglaso@basicisp.net. - just moved-have (new-to-me) computer and need new projects. Wish I had more to offer, but am constantly learning- - thanks-
HI guys
Tom, no, I just dont want you to think I am trying to scrimp on this project. Even if we throw one dollar needlessly at a resistor that doesnt matter that is okay with me as long as we dont spend a dollar less and ruin the whole thing.
Guy with pot question: You can use a regular pot. I have done so with this amp. I used a 25k and it was fine. Probably there is a 'better' value and I would guess its more down around 10k depending on the output of your source.
Vglaso I am putting you on the list.
Making progress with the BOM. Nearly there but screwed up and got quotes for 200 per PRP rather than 100. So I have to backtrack with that guy and see if I can still get good pricing. NOW I think that we could sell 200 of them but it might take a hefty investment on my part, so we will see how the final numbers go on 100 and maybe I will spring for the extra 100. Dunno. Might be a dumb idea.
Uriah
Tom, no, I just dont want you to think I am trying to scrimp on this project. Even if we throw one dollar needlessly at a resistor that doesnt matter that is okay with me as long as we dont spend a dollar less and ruin the whole thing.
Guy with pot question: You can use a regular pot. I have done so with this amp. I used a 25k and it was fine. Probably there is a 'better' value and I would guess its more down around 10k depending on the output of your source.
Vglaso I am putting you on the list.
Making progress with the BOM. Nearly there but screwed up and got quotes for 200 per PRP rather than 100. So I have to backtrack with that guy and see if I can still get good pricing. NOW I think that we could sell 200 of them but it might take a hefty investment on my part, so we will see how the final numbers go on 100 and maybe I will spring for the extra 100. Dunno. Might be a dumb idea.
Uriah
Yeah, it's a good idea to ask price for 100 of them rather than 200. Later, if we are more than 200, it will always be cheaper than the original thought.
I just stumbled on this thread but I am familiar with the amp design and have wanted it for a while. More people will jump on board with the group buy once prices are available. If numbers get critical, delay a bit and others will come. I am not necessarily a believer in 'boutique' components, nor a disbeliever as I haven't heard such an amp, but definitely believe that there is some price point up the ladder that must be achieved to get good performance. You can't populate the board with only cost in mind. So, Here's my question. Any thoughts as to the price difference between these kits and simply populating a board with quality, yet average, components?
Thanks to all who are working to get this buy together and I might have to jump on board,
rick
Thanks to all who are working to get this buy together and I might have to jump on board,
rick
K,
TOM AND DARIO did you guys prefer to use the spades to connect to the board or do you prefer to go straight in with soldered wire to the board for any/all connections?
I just double checked BOM against Silk.
We need to add an LED. I am going for MUR820's rather than the mono GBJ for diodes. I think this was Dario's suggestion. MUR820 are soft switching.
R42 is changed from 270R to 47R. Its in a little filter circuit and apparently sounds better. Cool 🙂
Dario Or Tom you had suggested replacing R2 with 10K. Makes sense. This is the mute resistor and its value in all other LM3886 circuits I have seen is closer to 10k than 33k.
Had anyone noticed this thing is a Howland Current Pump? I knew it was a current pump but wasnt aware it was a Howland. Now the MyRefC flavor of Howland Current Pump is the IMPROVED Howland Current Pump on Page 4 of AN-1515. R3 in our circuit is R13 from AN-1515. I can see why we went so low in value with R3 since we have a huge amount of current vs what they are talking about in the app note.
The reason we want close matching on R5, R8 and R6, R9 is that the Howland Current Pump is very good at rejecting noise... as long as those resistors match in pairs. We want R8/R9 to equal (R5/R6)+R3 as close as we can. With the Original HCP it was desperately important to have .1 to .01% matching but with the improved we have a lot more leeway. Dont worry, I am still buying a few hundred more of them than necessary to match the heck out of them since 'just getting there' is not the point. There is always room for improvement and the tighter the matching the better the noise rejection. 🙂 Well, I was happy I figured that out. Some of you already knew and some of you dont care. Maybe one or two are in the same boat with me going 'huh, cool.'
Should have the numbers tomorrow guys.
TOM AND DARIO did you guys prefer to use the spades to connect to the board or do you prefer to go straight in with soldered wire to the board for any/all connections?
URIAH
TOM AND DARIO did you guys prefer to use the spades to connect to the board or do you prefer to go straight in with soldered wire to the board for any/all connections?
I just double checked BOM against Silk.
We need to add an LED. I am going for MUR820's rather than the mono GBJ for diodes. I think this was Dario's suggestion. MUR820 are soft switching.
R42 is changed from 270R to 47R. Its in a little filter circuit and apparently sounds better. Cool 🙂
Dario Or Tom you had suggested replacing R2 with 10K. Makes sense. This is the mute resistor and its value in all other LM3886 circuits I have seen is closer to 10k than 33k.
Had anyone noticed this thing is a Howland Current Pump? I knew it was a current pump but wasnt aware it was a Howland. Now the MyRefC flavor of Howland Current Pump is the IMPROVED Howland Current Pump on Page 4 of AN-1515. R3 in our circuit is R13 from AN-1515. I can see why we went so low in value with R3 since we have a huge amount of current vs what they are talking about in the app note.
The reason we want close matching on R5, R8 and R6, R9 is that the Howland Current Pump is very good at rejecting noise... as long as those resistors match in pairs. We want R8/R9 to equal (R5/R6)+R3 as close as we can. With the Original HCP it was desperately important to have .1 to .01% matching but with the improved we have a lot more leeway. Dont worry, I am still buying a few hundred more of them than necessary to match the heck out of them since 'just getting there' is not the point. There is always room for improvement and the tighter the matching the better the noise rejection. 🙂 Well, I was happy I figured that out. Some of you already knew and some of you dont care. Maybe one or two are in the same boat with me going 'huh, cool.'
Should have the numbers tomorrow guys.
TOM AND DARIO did you guys prefer to use the spades to connect to the board or do you prefer to go straight in with soldered wire to the board for any/all connections?
URIAH
IMHO, I would try to put both options for the connection to the board.They don't take up to much space. If not, I would go with the soldering option, it is a better connection.
Because we are aiming to get a high end amp, I think we should go in a precision matched series of resistors, I don't think about extremely fancy brands, just ones with good drift and precision like 0,1%, or better 0.01% if possible.
Just my 2ç
Because we are aiming to get a high end amp, I think we should go in a precision matched series of resistors, I don't think about extremely fancy brands, just ones with good drift and precision like 0,1%, or better 0.01% if possible.
Just my 2ç
Definitely I am still matching .1 or better. That means a difference of 2-22Ohms. Since we are just doing division here such as R9/R8 should equal R6/R5 then a 22k resistor does not need to be .1-.01% close to 22k it needs to be .1-.01% of 22k close to its pair. So a set that was not close to 22k, like 21,700 would still be perfect if they were both at 21,700. See what I mean? So the matching for these will not be hard to do. I am buying a few hundred more of each one to make sure it comes out well, but I have every confidence that it will be near perfect with that many resistors.
If you look at AN-1515 page 4 and on you will see what I mean as to why we want to match the resistors to each other more than we want to match them to a certain number.
Uriah
If you look at AN-1515 page 4 and on you will see what I mean as to why we want to match the resistors to each other more than we want to match them to a certain number.
Uriah
BTW, looking at the MUR820 datasheet you can see that they are rated for 200v. Will it be enough for our purposes?
Sorry for the late answer but it seems DIYAudio no longer send me emails... 😕
In my MyRef I'm using spades, smaller than the original ones (Mouser 534-1287) and even for line level inputs... IMHO it's better when you have to assemble/disassemble modules from casing.
I think that is better to include them so everyone can have the choice to use them or not.
Yes, it was me
Mauro said that with 47R the amp is more stable, nothing about sound.
Yes, mine suggestion. This resistor mod is the one that should improve sound. (I'm using 10K)
Sure, it was indcated in the original MyRef thread 😉
I'm going to try Varistors to try to stop spikes (Mouser 94-2381-592-52516 <220V> or 594-2381-592-51316 <110V>), I will report in the next days.
In my MyRef I'm using spades, smaller than the original ones (Mouser 534-1287) and even for line level inputs... IMHO it's better when you have to assemble/disassemble modules from casing.
I think that is better to include them so everyone can have the choice to use them or not.
Yes, it was me
Mauro said that with 47R the amp is more stable, nothing about sound.
Yes, mine suggestion. This resistor mod is the one that should improve sound. (I'm using 10K)
Sure, it was indcated in the original MyRef thread 😉
I'm going to try Varistors to try to stop spikes (Mouser 94-2381-592-52516 <220V> or 594-2381-592-51316 <110V>), I will report in the next days.
I soldered ALL of the connections to my boards because I don't like using connectors. Almost all of them are tin-plated. Ugh! I think the signal input and speaker outputs should definitley be soldered. For power input, connectors would be okay. The board already has provisons for both. I say let people buy connectors if they want to use them, but I doubt including them will change the cost by much. Again, it's your call.
It has been stated many times by Mauro and Russ that absolute value of those matched pair resistors is not important, but matching them as closely as possible to each other is critical to efficient operation. Uriah, do you realize that a standard ohmmeter will not offer enough resolution to accurately match to the level of precison required? When I bought my PRP's from Parts Connexion, they matched them for me for a fee. Since we don't want to pay that fee for so many parts, perhaps you could ask Parts Connexion how they do their matching. They seem to have done an excellent job of it, as my chips run very cool.
If you want to avoid matching, just buy a resistor that has tolerances close enough to match within 0.1%. I bet they'll be expensive, though.
Have you ever heard of a Wheatstone Bridge?
As for the other changes, they were all promoted by Dario, and I'm completely okay with them as he seems to have good analytical skills. I'm eager to hear the amps with MUR diodes to learn if it's better than the bridge.
Dario, what's that last bit in your post about Varistors to stop spikes? You mean audible clicks from mains spikes? That would be way cool. In Wisconsin in the winter, my furnace comes on every 30 minutes, and half the time the pop over the speakers makes me jump in my chair! I wonder if summer thunderstorms will have any effect? Is that your own idea? Can anyone find out from Mauro or even National Semi if there is a solution? This is the only weakness of this amp design.
Peace,
Tom E
It has been stated many times by Mauro and Russ that absolute value of those matched pair resistors is not important, but matching them as closely as possible to each other is critical to efficient operation. Uriah, do you realize that a standard ohmmeter will not offer enough resolution to accurately match to the level of precison required? When I bought my PRP's from Parts Connexion, they matched them for me for a fee. Since we don't want to pay that fee for so many parts, perhaps you could ask Parts Connexion how they do their matching. They seem to have done an excellent job of it, as my chips run very cool.
If you want to avoid matching, just buy a resistor that has tolerances close enough to match within 0.1%. I bet they'll be expensive, though.
Have you ever heard of a Wheatstone Bridge?
As for the other changes, they were all promoted by Dario, and I'm completely okay with them as he seems to have good analytical skills. I'm eager to hear the amps with MUR diodes to learn if it's better than the bridge.
Dario, what's that last bit in your post about Varistors to stop spikes? You mean audible clicks from mains spikes? That would be way cool. In Wisconsin in the winter, my furnace comes on every 30 minutes, and half the time the pop over the speakers makes me jump in my chair! I wonder if summer thunderstorms will have any effect? Is that your own idea? Can anyone find out from Mauro or even National Semi if there is a solution? This is the only weakness of this amp design.
Peace,
Tom E
I agree, Tom, that 0.1% resistors would be an easier and safer buy.
Yes, the varistor between Live and Neutral is to tame voltage spikes generated from on/off switching of refrigerators, furnaces and so on but the idea it's not mine, I've taken it here.
I've soldered 20 minutes ago the varistor and so far not a single spike was heard... can't say nothing for sure about the possible sonic impact but it seems that nothing changed.
Note:
Pay attention to an error in the linked 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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My multimeters give me incredible resolution. I had to get something wonderful to test LDRs with. They are HP3478A. I bet my matching would be better than PartsConnexion 🙂 I have purchased a few .01% resistors from Mouser to test it and it is dead on.
Guys I really appreciate the in depth answers. Thanks so much.
Dario I had problems with getting emails for quite some time to. Now I am back up to speed. Actually in this thread I didnt get emails for several days at one time.
Well Parts Connexion is trying to firm up their quote with me. I think I am going to go with 220uf Silmic rather than Black Gate for C9. I really want to try Black Gate but I believe that the Silmics are giving excellent performance and the 6.95 per Black Gate price tag, even once they discount for quantity, is going to be really high, versus what I would consider a hell of a deal on the Silmics.
The Shinkoh at 3.50 each before discounts is bothering me a bit to. These three parts alone increase the cost by about 14 dollars before whatever discount they are going give me. So thats nearly 30 bucks per stereo kit. They want 25% of the cash right away to even hold the parts til I start collecting money from you guys. So its a little hard to consider coming up with 25% of $1400 just for those 3 parts.
I know its ground we have covered but lets talk about it again. First, I have my mind pretty made up on the Black Gate unless you guys have decided that its just an absolute must versus a Silmic. But, what about Shinkoh? Is PRP something that is good enough to replace the Shinkoh in positions R10 and R12?
I will take Dario's suggestions on resistor values for R2 and R42.
Uriah
Guys I really appreciate the in depth answers. Thanks so much.
Dario I had problems with getting emails for quite some time to. Now I am back up to speed. Actually in this thread I didnt get emails for several days at one time.
Well Parts Connexion is trying to firm up their quote with me. I think I am going to go with 220uf Silmic rather than Black Gate for C9. I really want to try Black Gate but I believe that the Silmics are giving excellent performance and the 6.95 per Black Gate price tag, even once they discount for quantity, is going to be really high, versus what I would consider a hell of a deal on the Silmics.
The Shinkoh at 3.50 each before discounts is bothering me a bit to. These three parts alone increase the cost by about 14 dollars before whatever discount they are going give me. So thats nearly 30 bucks per stereo kit. They want 25% of the cash right away to even hold the parts til I start collecting money from you guys. So its a little hard to consider coming up with 25% of $1400 just for those 3 parts.
I know its ground we have covered but lets talk about it again. First, I have my mind pretty made up on the Black Gate unless you guys have decided that its just an absolute must versus a Silmic. But, what about Shinkoh? Is PRP something that is good enough to replace the Shinkoh in positions R10 and R12?
I will take Dario's suggestions on resistor values for R2 and R42.
Uriah
As you know I've used Takmans metal film in all signal path position except in R10 and R12 where I've used Takmans carbon film and I'm fine with them.
To me the real important thing is that all signal path resistors are designed/tested for audio, or at least non magnetic with copper wires so PRPs, IMHO, are perfectly suitable.
Tom could say us if Shinkos made a SO big difference when replacing PRPs to justify the cost difference.
I agree that, for the price difference, the PRP's will probably be suitable in all positions. I went nuts and bought the Shinkohs and my amps sound SOOO good, but I honestly can't say that any single resistor will make a huge difference. I have read that Shinkohs are the best, but that doesn't mean PRP's will not be okay. For the price difference, get the PRP's, which are designed specifically for audio circuits and have a very good reputation, and we'll all be happy. It sounds like you are well equipped to perform accurate matching.
I tried Silmic's at C9 and didn't like them at all, but Dario likes them a lot and I respect his opinion. I don't think he has tried Blackgates, although he did try some other types. I gave my Silmic's to another builder to try and he also didn't care for them. I settled on the Blackgates because they really did make a huge difference, perhaps moreso than any part other than C13. Just look at the position of this part in the signal path.
If we build these amps with Silmic at C9 and they sound muffled or otherwise distorted, people can decide whether to go back to Panny FM's or invest in the superlative though expensive Blackgates. Many people like Silmic's. I wanted to like them, but I actually preferred the original Panny FM's. I'm willing to give Silmic's another try, just to go along with the crowd, but I honestly believe the ULTIMATE My Ref will have a Blackgate at C9.
How big a discount will PC give you? Is the difference between just another SS amp and something that sounds like a $3000 tube amp worth the cost of that part?
Peace,
Tom E
I tried Silmic's at C9 and didn't like them at all, but Dario likes them a lot and I respect his opinion. I don't think he has tried Blackgates, although he did try some other types. I gave my Silmic's to another builder to try and he also didn't care for them. I settled on the Blackgates because they really did make a huge difference, perhaps moreso than any part other than C13. Just look at the position of this part in the signal path.
If we build these amps with Silmic at C9 and they sound muffled or otherwise distorted, people can decide whether to go back to Panny FM's or invest in the superlative though expensive Blackgates. Many people like Silmic's. I wanted to like them, but I actually preferred the original Panny FM's. I'm willing to give Silmic's another try, just to go along with the crowd, but I honestly believe the ULTIMATE My Ref will have a Blackgate at C9.
How big a discount will PC give you? Is the difference between just another SS amp and something that sounds like a $3000 tube amp worth the cost of that part?
Peace,
Tom E
They are only offering me a 15% discount on the Black Gates. Of course I have tried to get a quote from Michael Percy but we all know how successful that usually ends up being. Seriously, I ask for a quote for thousands of dollars of stuff and he doesnt respond? I dont get it. Spoke to him on the phone to. I will try him again today. By phone. If you say BG is that big then lets try to do it.
Uriah
Uriah
Forget Percy. I have tried to deal with him in the past and he is unresponsive, a waste of time. Others have made similar complaints, while some seem pleased with his service (or lack of it). The guy does not know the first thing about running a business; it must be merely a hobby for him. Reward Parts Connexion, a professional organization, with your patronage. I think they are a class act, and their prices are competitive. The reason they won't drop price further on Blackgates is because of limited supply. ANY discount is a sign of cooperation. If they sell a bunch to you (us), they have fewer to sell elsewhere.
Peace,
Tom E
Peace,
Tom E
From my point of view, I would give a go to the PRP's and the Blackgates. Maybe some Takmans could be good too, I used them in my DCB1 preamplifier and sound quite good. I used the carbon ones as shown in PC.
Have a look at the Holcos too, they are already getting a discount of 60% at PC.
Have a look at the Holcos too, they are already getting a discount of 60% at PC.
K. Tried Percy to no avail again. Going with Parts Connexion. They are revising quote and sending it to me today for 25% downpayment.
Will bug my pcb guy for pricing again.
Uriah
Will bug my pcb guy for pricing again.
Uriah
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