Most of the components in place. 2N5564 is expected in the postbox one of the first few days. Now I just have to find a supplier of BUZ 900/905 that can deliver at a reasonable price. Anybody have good tips?
As far as possible, I want now in the first instance, to take advantage of the components I have lying already.
This means, among other things: T21/22: MJE 15029/15030.
D6/7/8/10 and D4/6 (Protection): 1N5393.
These changes I mean will be safe and without any impact on sound quality.
When it comes to T5/6, I have done changes which I'm more uncertain about.
I do have BC182L . They have placed the emitter and collector reversed compared to BC 182B. This is easily resolved by turning BC182L. But "my" BC 182L measures a HFE as high 1200, so I went skeptical to use them.
My data book says that the BC 546 B is equivalent to BC 182 B. But I mean to remember that in a previous post it has been mentioned anything that the T5/6 must be BC182B
Do not remember any more the reason for this conclusion, but believe that this emerged as a result of someones simutation work. I am grateful for any comments on this change in particular.
C1/2 in the protection circuit is two 220uF mounted back to back. My two 220 uF are 100V types.
Are these "safe" enough with respect to voltage (my transformer will provide 55V AC)?
I notice, for example, C4 is a 160V type (I have no wish that a condenser explode because the voltage tolerance of them is too low).
By the way: It has been a pleasure to work on the PCB from Bigpanda. Other comments on the PCB is beyond my expertise.
Eivind Stillingen
As far as possible, I want now in the first instance, to take advantage of the components I have lying already.
This means, among other things: T21/22: MJE 15029/15030.
D6/7/8/10 and D4/6 (Protection): 1N5393.
These changes I mean will be safe and without any impact on sound quality.
When it comes to T5/6, I have done changes which I'm more uncertain about.
I do have BC182L . They have placed the emitter and collector reversed compared to BC 182B. This is easily resolved by turning BC182L. But "my" BC 182L measures a HFE as high 1200, so I went skeptical to use them.
My data book says that the BC 546 B is equivalent to BC 182 B. But I mean to remember that in a previous post it has been mentioned anything that the T5/6 must be BC182B
Do not remember any more the reason for this conclusion, but believe that this emerged as a result of someones simutation work. I am grateful for any comments on this change in particular.
C1/2 in the protection circuit is two 220uF mounted back to back. My two 220 uF are 100V types.
Are these "safe" enough with respect to voltage (my transformer will provide 55V AC)?
I notice, for example, C4 is a 160V type (I have no wish that a condenser explode because the voltage tolerance of them is too low).
By the way: It has been a pleasure to work on the PCB from Bigpanda. Other comments on the PCB is beyond my expertise.
Eivind Stillingen
Attachments
Hello Eivind,
Good to see that you are working to build this Amplifier.
Am very curious about the end result how this amplifier is sound.
If you have this Goldmund clone stable, I also order the components and dare to build mine.
Here you find a supplier of BUZ 900 parts: Magnatec | Semiconductors | Discretes | MOSFET | MOSFETs & JFETs - N-Channel |BUZ900
I hope there will be also a group buy for the boards of The MONGREL OS Amplifier.
Keep us informed of your progress,
Regards,
Rudy
Good to see that you are working to build this Amplifier.
Am very curious about the end result how this amplifier is sound.
If you have this Goldmund clone stable, I also order the components and dare to build mine.
Here you find a supplier of BUZ 900 parts: Magnatec | Semiconductors | Discretes | MOSFET | MOSFETs & JFETs - N-Channel |BUZ900
I hope there will be also a group buy for the boards of The MONGREL OS Amplifier.
Keep us informed of your progress,
Regards,
Rudy
Rudy or Eivind, do you fellas have a BOM put together for this PCB? I got this PCB also and would make it easier for me to bank order parts.
Do please keep us posted on your progress... I will not be able to start this till the new year. The holidays deleted my piggy bank and expecting a newborn in February.
Thanks
Do please keep us posted on your progress... I will not be able to start this till the new year. The holidays deleted my piggy bank and expecting a newborn in February.
Thanks
Other link for information :
FileFactory Folder view - goldmund
If you find any error, please inform me and let me amend it to spare the next victim.
FileFactory Folder view - goldmund
If you find any error, please inform me and let me amend it to spare the next victim.
Alex,
Send me your mailing address and I will mail you a pair of the boards (if you like to have them).
tony_chan_cf@email.com
I will always keep my promise as far as I can go.
Send me your mailing address and I will mail you a pair of the boards (if you like to have them).
tony_chan_cf@email.com
I will always keep my promise as far as I can go.
Hello Alex and Bigpanda,
I want to thank you both for all the work and time for these wonderful Circuit boards.
It will be some time before I working on the Amplifier, but I certainly build these Goldmund clone.
Very nice Bigpanda that you sent Alex a circuit board for free
Regards,
Rudy
I want to thank you both for all the work and time for these wonderful Circuit boards.
It will be some time before I working on the Amplifier, but I certainly build these Goldmund clone.
Very nice Bigpanda that you sent Alex a circuit board for free
Regards,
Rudy
Last edited:
We should say: YOUR GREAT WORK!
This is a real Christmas gift for us all.
Thank you.
Max.
Hi Liliya,
what's your ultimate choice for the outputs, BUZ or ECN or something else ?
I guess there isn't much being done during this week, right? Everyone is having holiday and I think most of the guys received my boards just before (or probably after) Xmas.
BTW I am thinking of getting someone to do the heatsink bracket for me because I do not have a nice drill press for metal work - just good for pcb or thin metal, not 4mm thick aluminium. Anyone want to have the brackets drilled for them? Please let me know. I will try to see how much they cost me. I had some bracket 4.3mm thick at 38mm wide which should do the job. I might be able to get something thicker, just wonder if it is really necessary. Someone told me that he can get me 6mm but I haven't yet see it.
I have tried that years before but I almost got my fingers drilled or burnt. This time I might really get myself hurt doing it.
what's your ultimate choice for the outputs, BUZ or ECN or something else ?
I guess there isn't much being done during this week, right? Everyone is having holiday and I think most of the guys received my boards just before (or probably after) Xmas.
BTW I am thinking of getting someone to do the heatsink bracket for me because I do not have a nice drill press for metal work - just good for pcb or thin metal, not 4mm thick aluminium. Anyone want to have the brackets drilled for them? Please let me know. I will try to see how much they cost me. I had some bracket 4.3mm thick at 38mm wide which should do the job. I might be able to get something thicker, just wonder if it is really necessary. Someone told me that he can get me 6mm but I haven't yet see it.
I have tried that years before but I almost got my fingers drilled or burnt. This time I might really get myself hurt doing it.
Bigpanda
I have ordered this one, and the sellers says:
"EXICON ECF10N16 AND ECF10P16 LATERAL MOSFETS. TO-3 PACKAGE. THESE MOSFETS ARE RATED FOR 8 AMPS 160 VOLTS. I USE THESE TO REPLACE DISCONTINUED HITACHI 2SK134/2SJ49 OR 2SK135/2SJ50 MOSFETS.YOU WILL RECEIVE 1 N CHANNEL AND 1 P CHANNEL DEVICE . IF YOU PURCHASE MORE THAN ONE SET, GATE THRESHOLD VOLTAGE WILL BE MATCHED AT 100MA FOR NORMAL AUDIO BIASING."
Ultimate would perhaps be 2SK134/2SJ49, but they are very difficult to find, and if you find it, the prices are ......oih!!!
Heatsink bracket: I already have both 3mm and 4 mmm aluminium that will suits well for the the purpose.
I have also done this changes from the original schema: (From #934.We all remember that discussion?????)
BV - I cannot argue with you, because you're correct. That's how it usually is supposed to be connected. The very latest unpotted Goldmund modules (essentially A2 modules) use the new MPSA42 transistors, where they short C-B and bypass the Zener diode with a 1u capacitor.
However, the old Mimesis series of amps (with A1 modules), used BC182B transistors and shorted E-B. They also had no bypass capacitor for the Zener diode. The old Mimesis amplifiers had a very magical sound and that is what this entire thread is about. Cloning the old Goldmund Mimesis 9.2, Mimesis 3, and Mimesis 6 amplifiers. The PCB should follow the old design/schematic. As it stands, T6 is connected correctly. If any potential builders want to use an A2 module's configuration, it's up to them to make the necessary modifications on the PCB. If anyone wants to use the A2 module, here are the changes you'll need to make, READ CAREFULLY!!:
1.) Replace T3, T4, T5, and T6 with MPSA42 transistors.
2.) On T6, short C-B instead of E-B.
3.) Bypass the 6V Zener diode with a 1u film capacitor.
4.) Replace R11 (20K) resistor with a 10K resistor.
5.) Change the BIAS resistor R23 (330R) by soldering in parallel a 1K to 1K5 resistor. Goldmund's service manual gives a range here, so if the MOSFETS are still overheating, you'll have to go with the lower 1K resistor value.
This info is directly from Goldmund's service manual. After the changes, the amplifier should perform 100% correctly.
Now everyone can stop crying about the T6 transistor and use an A2 module where C-B is shorted.
Eivind Stillingen
I have ordered this one, and the sellers says:
"EXICON ECF10N16 AND ECF10P16 LATERAL MOSFETS. TO-3 PACKAGE. THESE MOSFETS ARE RATED FOR 8 AMPS 160 VOLTS. I USE THESE TO REPLACE DISCONTINUED HITACHI 2SK134/2SJ49 OR 2SK135/2SJ50 MOSFETS.YOU WILL RECEIVE 1 N CHANNEL AND 1 P CHANNEL DEVICE . IF YOU PURCHASE MORE THAN ONE SET, GATE THRESHOLD VOLTAGE WILL BE MATCHED AT 100MA FOR NORMAL AUDIO BIASING."
Ultimate would perhaps be 2SK134/2SJ49, but they are very difficult to find, and if you find it, the prices are ......oih!!!
Heatsink bracket: I already have both 3mm and 4 mmm aluminium that will suits well for the the purpose.
I have also done this changes from the original schema: (From #934.We all remember that discussion?????)
BV - I cannot argue with you, because you're correct. That's how it usually is supposed to be connected. The very latest unpotted Goldmund modules (essentially A2 modules) use the new MPSA42 transistors, where they short C-B and bypass the Zener diode with a 1u capacitor.
However, the old Mimesis series of amps (with A1 modules), used BC182B transistors and shorted E-B. They also had no bypass capacitor for the Zener diode. The old Mimesis amplifiers had a very magical sound and that is what this entire thread is about. Cloning the old Goldmund Mimesis 9.2, Mimesis 3, and Mimesis 6 amplifiers. The PCB should follow the old design/schematic. As it stands, T6 is connected correctly. If any potential builders want to use an A2 module's configuration, it's up to them to make the necessary modifications on the PCB. If anyone wants to use the A2 module, here are the changes you'll need to make, READ CAREFULLY!!:
1.) Replace T3, T4, T5, and T6 with MPSA42 transistors.
2.) On T6, short C-B instead of E-B.
3.) Bypass the 6V Zener diode with a 1u film capacitor.
4.) Replace R11 (20K) resistor with a 10K resistor.
5.) Change the BIAS resistor R23 (330R) by soldering in parallel a 1K to 1K5 resistor. Goldmund's service manual gives a range here, so if the MOSFETS are still overheating, you'll have to go with the lower 1K resistor value.
This info is directly from Goldmund's service manual. After the changes, the amplifier should perform 100% correctly.
Now everyone can stop crying about the T6 transistor and use an A2 module where C-B is shorted.
Eivind Stillingen