It looks familiar
You are just listening to the junctions of the MPSA92/42 through the laterals , that is the original's "signature".
OS
Interesting conclution ostripper.
The current GM models seems to use FZT857/957 instead of the MPSAs according to an other tread in this forum. Is this correct? The FZT857/957 have a COB of 20-25 pF!
What are the standing PCB sticks attached to those TO-92s? Heatsink/miller compensation combined?
- keantoken
Really , try the real Ksa/c 1381/3503's , I am listening to them now as my VAS.
NOTHING can compare to the 125V/us slew and how this equates to the final sonic signature. fairchild/mouser is the source , most of my pairs are 143- 150 Hfe ... all of them (E gain group).Very pleased with the semi's
.OS
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Hi KT,
The standing PCB stick are just heatsink as superglue sticks very well to polished copper & FR4 is much easier to work with. I imagine that a Miller capacitor can be added if one is needed. There is a flaw with this heatsink - the pins on the TO92 can break quite easily.
The VAS on the GM clone is running quite hot, I used a 60mm (W) x 50mm (H) x 3mm alu heatsink and it is running at 20C above the ambient.
Cheers, Stanley
Attachments
Hi tommy1000,
I also read the other thread, the VAS stage of the Telos 2500 is surprisingly similar to Mimesis 9. The FZT857/957 are SMT devices so that they can be potted together with the IPS to form a single thermal block - that would help to solve the drifting offset problem.
BTW, I found some internal pictures of the Telos 2500.
Cheers, Stanley
Attachments
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VAS choice
Hi OS,
I have tried BF469/470 & 2SB1109/D1609 & 2SA1538/3953 and they all sound a bit different, although the difference is quite subtle.
Philips BF469/470 - better bass & loss a bit in details
Hitachi 2SB1109/D1609 - very close to MPSA, slightly warmer bass
Sanyo 2SA1538/3953 - very clear treble, less bass.
I like the MPSA more than the others, I may have to make another board for the MPSA VAS.
Cheers, Stanley
Really , try the real Ksa/c 1381/3503's , I am listening to them now as my VAS.
NOTHING can compare to the 125V/us slew and how this equates to the final sonic signature. fairchild/mouser is the source , most of my pairs are 143- 150 Hfe ... all of them (E gain group).Very pleased with the semi's
OS
Hi OS,
I have tried BF469/470 & 2SB1109/D1609 & 2SA1538/3953 and they all sound a bit different, although the difference is quite subtle.
Philips BF469/470 - better bass & loss a bit in details
Hitachi 2SB1109/D1609 - very close to MPSA, slightly warmer bass
Sanyo 2SA1538/3953 - very clear treble, less bass.
I like the MPSA more than the others, I may have to make another board for the MPSA VAS.
Cheers, Stanley
Hi Sng,
swapping device/s at the same current setting is not a fair comparison.
Each device should have it's operating condition optimised to suit the characteristics of the device.
eg. the MPSA may perform well with Ic~300uA. Some of the alternatives may work better at 100uA or 800uA or some other value that should be determined.
swapping device/s at the same current setting is not a fair comparison.
Each device should have it's operating condition optimised to suit the characteristics of the device.
eg. the MPSA may perform well with Ic~300uA. Some of the alternatives may work better at 100uA or 800uA or some other value that should be determined.
Second channel populated
Hi all ,
I managed to finish, and the second channel, I started one channel, and I can easily adjust the offset to 1 mV. There is a difference between voltages 2 -3 V at rail drivers . I'll stick it into the case then do all the tests with audio generator and oscilloscope. I like the sound, but I had no real speakers when testing from a friend of mine
Alex .
Hi all ,
I managed to finish, and the second channel, I started one channel, and I can easily adjust the offset to 1 mV. There is a difference between voltages 2 -3 V at rail drivers . I'll stick it into the case then do all the tests with audio generator and oscilloscope. I like the sound, but I had no real speakers when testing from a friend of mine
Alex .
Attachments
Goldmund builders,
You guys now so well advanced with the Goldmund amplifier.
We will greatly appreciate if you all have finished the Goldmund clone, to create a new parts list to cover other builders to have also there benefit.
Because some of the parts are that difficult to get, would you all together create for us a new parts list with the components “that you have used”.
And mention where you get the difficult to get parts ordered.
What also is useful to create a simple up to date "PDF" file with the things to lookout for if there are errors in the schema.
Thanks, and keep us informed,
Rudy
Note, sorry that I wrote this for the second time
You guys now so well advanced with the Goldmund amplifier.
We will greatly appreciate if you all have finished the Goldmund clone, to create a new parts list to cover other builders to have also there benefit.
Because some of the parts are that difficult to get, would you all together create for us a new parts list with the components “that you have used”.
And mention where you get the difficult to get parts ordered.
What also is useful to create a simple up to date "PDF" file with the things to lookout for if there are errors in the schema.
Thanks, and keep us informed,
Rudy
Note, sorry that I wrote this for the second time
For those who might want to help in updating BOM list, I have upload an excel (windows) file, hopefully making work easier.
FileFactory Folder view - gm-work
bom-GM-up.xls
FileFactory Folder view - gm-work
bom-GM-up.xls
GM Mimesis 3 clone part list
Hi all,
I have built the Mimesis 3 using the AlexMM board, the amp sounds very good. I want to share the parts list that I used.
Please note that I am building the Mimesis 3 clone using 40V AC transformer & I only ordered 63V capacitors, so substitute them with 100V capacitors if you are building Mimesis 9.2 clone.
The most difficult bits is to find the right high-wattage ressistors - I chose Metal-Oxide type if that is available. I used carbon composite type for R20, R23 & the 100-ohm gate stoppers.
For the output MOSFETs, I used Renesis 2SJ162/K1058.
For T3 & T5 on the Protection circuit, I used 2N5551 instead of the BC449.
The attached file is not the complete parts list as I got some parts in my parts bin. I included the Mouser part number in the MS Excel spreadsheet, which can be used as a starting point to compile the complete part list.
Cheers, Stanley
Hi all,
I have built the Mimesis 3 using the AlexMM board, the amp sounds very good. I want to share the parts list that I used.
Please note that I am building the Mimesis 3 clone using 40V AC transformer & I only ordered 63V capacitors, so substitute them with 100V capacitors if you are building Mimesis 9.2 clone.
The most difficult bits is to find the right high-wattage ressistors - I chose Metal-Oxide type if that is available. I used carbon composite type for R20, R23 & the 100-ohm gate stoppers.
For the output MOSFETs, I used Renesis 2SJ162/K1058.
For T3 & T5 on the Protection circuit, I used 2N5551 instead of the BC449.
The attached file is not the complete parts list as I got some parts in my parts bin. I included the Mouser part number in the MS Excel spreadsheet, which can be used as a starting point to compile the complete part list.
Cheers, Stanley
Attachments
alex mm, I think those schematics are of mimesis9.2 (monoblock amp).
But i want the schematics of mimesis 9 only (the stereo amp)......
because i want to have stereo amp.... I wonder if it is available or not.........because i haven't found one....
Of course, no doubt that mimesis 9.2 x2 can be made for stereo. but i don't need that plenty of power. mimesis 9 will be great for me.
BTW, thanks for post alex mm....
Kindly post if you find or have mimesis 9(stereo amp version) schematics......
Thank you......
But i want the schematics of mimesis 9 only (the stereo amp)......
because i want to have stereo amp.... I wonder if it is available or not.........because i haven't found one....
Of course, no doubt that mimesis 9.2 x2 can be made for stereo. but i don't need that plenty of power. mimesis 9 will be great for me.
BTW, thanks for post alex mm....
Kindly post if you find or have mimesis 9(stereo amp version) schematics......
Thank you......
