Hi All,
As I wrote in an earlier post, I am hoping to end up with a set of amps that give the capability to Bi_Amp a set of speakers. Well during my struggle with my two naughty amps, I have had great success with the base system.
These are Linuxguru's V1.3 Premium MyRef-Cs combined with Uriah's Lighter Note Attenuator. I have a very good Oppo to play CDs with but in sticking with the DIY format, I hooked up the modified PS1. Playing through Paul Carmody's "The Sunflowers" open baffle design speakers I'm pretty sure Nancy Wilson's entire road troupe snuck into my house and she's singing just to me from the other room.
A great tip of the hat to Siva!
Besides developing a "Kick-A.." version of this amp, his support during a week-long hunt for my noobee screw-ups was absolutely outstanding. Thanks to all for being there and sharing.
Now on to designing a case and the two misbehaving siblings.
BTW: I got six of the Sonicaps in the mail today but won't try them for a week or so as per Madisonears. Everything is so sweet and clear as is, it's hard to believe they will get better, but I will report as the burn-in proceeds.
Regards, Bob M.
As I wrote in an earlier post, I am hoping to end up with a set of amps that give the capability to Bi_Amp a set of speakers. Well during my struggle with my two naughty amps, I have had great success with the base system.
These are Linuxguru's V1.3 Premium MyRef-Cs combined with Uriah's Lighter Note Attenuator. I have a very good Oppo to play CDs with but in sticking with the DIY format, I hooked up the modified PS1. Playing through Paul Carmody's "The Sunflowers" open baffle design speakers I'm pretty sure Nancy Wilson's entire road troupe snuck into my house and she's singing just to me from the other room.
A great tip of the hat to Siva!
Besides developing a "Kick-A.." version of this amp, his support during a week-long hunt for my noobee screw-ups was absolutely outstanding. Thanks to all for being there and sharing.
Now on to designing a case and the two misbehaving siblings.
BTW: I got six of the Sonicaps in the mail today but won't try them for a week or so as per Madisonears. Everything is so sweet and clear as is, it's hard to believe they will get better, but I will report as the burn-in proceeds.
Regards, Bob M.
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Bob, thanks for the compliments. You're very quick at prototyping and reworking stuff yourself!
I hope you get the other two TPA V1.2 boards debugged soon - if you wish, you can safely replicate or mix-and-match my BoM with the Ultimate BoM on the Twisted Pear boards for most of the components, except for a handful of components that are too large to fit.
I hope you get the other two TPA V1.2 boards debugged soon - if you wish, you can safely replicate or mix-and-match my BoM with the Ultimate BoM on the Twisted Pear boards for most of the components, except for a handful of components that are too large to fit.
R3 Alternative
Dario,
I actually reordered that part from Mouser from your BOM thinking I would get the smaller heat sink but received the same monster. I modded it to make it fit and ensure no contact.
Do you think this one from Siva's V1.3 would be compatible with your BOM? It seems to eliminate both the size and HS problems.
Fataba metal-plate non-inductive non-magnetic resistor.
Dario,
I actually reordered that part from Mouser from your BOM thinking I would get the smaller heat sink but received the same monster. I modded it to make it fit and ensure no contact.
Do you think this one from Siva's V1.3 would be compatible with your BOM? It seems to eliminate both the size and HS problems.
Fataba metal-plate non-inductive non-magnetic resistor.
In "normal" domestic use, that resistor should never get as high as warm.
If it gets warm then you are driving your chipamp to very high average output levels, eg sinewave testing.
The only important consideration is that the resistor and the traces feeding it keep the same resistance for all music listening operation. Keeping the resistances the same implies low tempco and low Delta T. The heatsink just helps with Delta T and only for the resistor, not the traces.
If you want/need good current control in the Howland circuit then you must ensure that everything remains as cool as possible, not just the resistor.
If it gets warm then you are driving your chipamp to very high average output levels, eg sinewave testing.
The only important consideration is that the resistor and the traces feeding it keep the same resistance for all music listening operation. Keeping the resistances the same implies low tempco and low Delta T. The heatsink just helps with Delta T and only for the resistor, not the traces.
If you want/need good current control in the Howland circuit then you must ensure that everything remains as cool as possible, not just the resistor.
Hi Bob,
mine heatsinks (as seen in the tutorial) are from Banzai Music, in my BOM you can find this alternate code: 532-577202B00 which is much smaller and similar to the one in the tutorial.
The main (and bigger) code is there since most people thought a bigger heatsink was safer.
But if you're sure that the heatsink make no contact you can use the one you already have.
I've tried also those and didn't found any significative difference from the original Xicon cement/ceramic ones (Mouser 280-PRM5-0.47-RC).
They would be a downgrade from the Caddocks.
Don't bother, my question about the small heatsink was to be sure you've checked it for no contact, go further in troubleshooting.
Dario, Andrew - Thanks for clearing that up. I will cut down what I have and mount the Caddocs lower in the board.
Bob M.
Bob M.
Another Myref finished
Hey guys here is mine Myref Twisted Pear kit with Mundorf input caps,500VA 4x22V trafo mounted in Diy chassis.
So far very solid deep bass but i feel the mid's need more time to open up. Maybe it's the Mundorf cap that needs break in?
Thank you Dario and all others for the suggestions! [ /B]
Hey guys here is mine Myref Twisted Pear kit with Mundorf input caps,500VA 4x22V trafo mounted in Diy chassis.
So far very solid deep bass but i feel the mid's need more time to open up. Maybe it's the Mundorf cap that needs break in?
Thank you Dario and all others for the suggestions! [ /B]
Attachments
My bet goes for refurbished gear. have a look at the non-used holes in the back.
Whatever, a great looking chassis
Regards,
Thanks guys! Too bad there's no more place for the Lightspeed attenuator....
Well i would have to make another bigger case
Attachments
1) If it's a NatSemi LM318N, try rolling with TI LM318P.
2) Remove all the rail-to-ground bypass caps around the chipamp and LM318. From memory, I think they're C17, C18, C19, C20.
3) Try a Black Gate or Nichicon Muse KZ at C9.
4) Try a 10 or 22nF Wima FKP2 at C7.
Very nice chassis - nearly perfect, simple and uncluttered layout.
Thanks but where can i find the Black Gate for c9?
Would the black Gate sound superior compared to Nichicon Muse?
Would the black Gate sound superior compared to Nichicon Muse?
They're already removed
I agree for the BG but a Silmic II is better than a KZ
Also remove Wima MKS2 from C21 in case of the BG or swap it with a 22nF FKP2 if you use a Silmic or a Panny FM
It's not easy...
Yes, definitively.
Also consider swapping all Panny FCs with Panny FM for C1, C2 and Silmic II for C6, C11.
BTW It's a very nice build! 🙂
As of 03/02/11 the Black Gates were in stock at:
Michael Percy Audio
11731 Stillwater Creek Road
Nevada City, CA 95959
<mpercy@pacbell.net>
www.percyaudio.com
(530) 470-8650
(530) 470-8651 fax
I spoke to him on the phone and ask how many he had. His response was “some”.
Bob M.
Michael Percy Audio
11731 Stillwater Creek Road
Nevada City, CA 95959
<mpercy@pacbell.net>
www.percyaudio.com
(530) 470-8650
(530) 470-8651 fax
I spoke to him on the phone and ask how many he had. His response was “some”.
Bob M.
AS I have mentioned, one of goals is to come up with a one-box setup to do bi-amping on a variety of speakers.
I have assumed that four identical amps would be the way to go. I’m now considering the idea that the low end might not need all the refinement the MyRefs provide. In fact, there might be a benefit using an amp more targeted to driving woofers.
Are there any suggestions of any DIY designs (chipamp or non-chipamp) that would fit this scenario and still be of the quality of the MyRefs? There is no problem for me to use four of these great amps, but I thought I would just run the Idea up the flagpole.
Bob M.
I have assumed that four identical amps would be the way to go. I’m now considering the idea that the low end might not need all the refinement the MyRefs provide. In fact, there might be a benefit using an amp more targeted to driving woofers.
Are there any suggestions of any DIY designs (chipamp or non-chipamp) that would fit this scenario and still be of the quality of the MyRefs? There is no problem for me to use four of these great amps, but I thought I would just run the Idea up the flagpole.
Bob M.
Yup, good idea - MyRef for the mid + tweeters of the Sunflower (or similar speakers), an EBay BPA-300 or similar for the woofer.
Just IMHO: however, at normal indoor listening volumes, a MyRef driving everything will still trump this combo on coherence/imaging/soundstage.
Just IMHO: however, at normal indoor listening volumes, a MyRef driving everything will still trump this combo on coherence/imaging/soundstage.
BPA 300 may be more than required. It would certainly work, and sound good but a properly designed pa 100 or ba 150 may do the trick, depending on the driver, for less money and complexity.
And you avoid the nuisance of needing a balance signal (and an unbalanced one for the top end.
Myref-C Problem
Making some progress!
Well my little saga continues. I ordered new LM318s and Dale resistors for the non-performing Twisted Pear V1.2 MyRefs but they won’t arrive till next week. In the meanwhile I found a spare LM318 so I reassembled one of the units. I also put in one of the new Sonicaps in C13 and replaced the Nichicon 220uF 50V in C9 with a 35V cap.
SUCCESS 😀 - kind of …….
No more constant clicks at power up and the sound is clear with no distortion for a good period of time. It starts to reappear and accelerate as the amp heats up. So naturally I positioned a small PC fan on the heat sink and determined it is all heat related. I can drive the amp at full volume (up to 1.5 hours so far) with no problems, distortion or clicks. Remove the fan and the clicks return. The amp does not turn off, it just cycles momentarily –almost instantaneously.
So here is my quandary. My toroids might be too strong as they produce 26.1V from a direct read on the leads. Madisonears recommends staying with 22V and I see a lot of people having success with 24V. What surprises me is these toroids work perfectly well with my two BrianGTs and the two Linuxguru V1.3 builds. The heat sinks on the naughty TP V1.2 amps are the same as those on the BrianGTs. The LM3886s are firmly mounted with good heat transfer paste applied. The raise in temperature is so fast and so dramatic (you can't touch the heat sink) that I would think a larger heat sink would only mask what I think is an over-voltage or other component problem.
I am considering submerging these two in a pool of liquid nitrogen but hope someone can suggest a simpler solution.
Regards (with open ears) Bob M.
Making some progress!
Well my little saga continues. I ordered new LM318s and Dale resistors for the non-performing Twisted Pear V1.2 MyRefs but they won’t arrive till next week. In the meanwhile I found a spare LM318 so I reassembled one of the units. I also put in one of the new Sonicaps in C13 and replaced the Nichicon 220uF 50V in C9 with a 35V cap.
SUCCESS 😀 - kind of …….
No more constant clicks at power up and the sound is clear with no distortion for a good period of time. It starts to reappear and accelerate as the amp heats up. So naturally I positioned a small PC fan on the heat sink and determined it is all heat related. I can drive the amp at full volume (up to 1.5 hours so far) with no problems, distortion or clicks. Remove the fan and the clicks return. The amp does not turn off, it just cycles momentarily –almost instantaneously.
So here is my quandary. My toroids might be too strong as they produce 26.1V from a direct read on the leads. Madisonears recommends staying with 22V and I see a lot of people having success with 24V. What surprises me is these toroids work perfectly well with my two BrianGTs and the two Linuxguru V1.3 builds. The heat sinks on the naughty TP V1.2 amps are the same as those on the BrianGTs. The LM3886s are firmly mounted with good heat transfer paste applied. The raise in temperature is so fast and so dramatic (you can't touch the heat sink) that I would think a larger heat sink would only mask what I think is an over-voltage or other component problem.
I am considering submerging these two in a pool of liquid nitrogen but hope someone can suggest a simpler solution.
Regards (with open ears) Bob M.
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