I have just found this threat today and could not stop reading - I know I want to build one!
If the group buy goes ahead, I would be interested in at least 4 boards.
Thanks Mihai for sharing this design (and your knowledge + support) with us.
Cheers!
If the group buy goes ahead, I would be interested in at least 4 boards.
Thanks Mihai for sharing this design (and your knowledge + support) with us.
Cheers!
DRZ1 said:
Hello DRZ1
I would be interested in your Altium files if you do not mind.
I am just trying to have a "plan B" in case the group buy doesn't go ahead in the next month or so.
Thanks for your help.
x-former
Hi Mihai,
I just got an transformer with 2x30 + 2x6VAC so it's possible to get 2x36VAC for the frontend and 2x30VAC for the output stage, my question is would the amp handle 40V DC on the rails ??
Greetings,
Pawel
Hi Mihai,
I just got an transformer with 2x30 + 2x6VAC so it's possible to get 2x36VAC for the frontend and 2x30VAC for the output stage, my question is would the amp handle 40V DC on the rails ??
Greetings,
Pawel
Re: x-former
Use separate pair of rectifiers for the 36,0 & 36,0Vac supplies. Then combine the zero volts lines.
36Vac will give around 51 to 52Vdc on nominal mains supply.
30Vac will give about 42 to 43Vdc on nominal mains supply.
What is the tolerance on your mains supply? +-6%, +-10%?
use a pair of power rectifiers for the 30,0 & 30,0Vac supplies.pzogal said:
Use separate pair of rectifiers for the 36,0 & 36,0Vac supplies. Then combine the zero volts lines.
36Vac will give around 51 to 52Vdc on nominal mains supply.
30Vac will give about 42 to 43Vdc on nominal mains supply.
What is the tolerance on your mains supply? +-6%, +-10%?
Hi Andrew,
30VAC will give little less DC, there is rectifier, too 🙂
I don't know the mains tolerance. I am just wondering what's the tolerance in Mihai's design.
Greetings,
Pawel
30VAC will give little less DC, there is rectifier, too 🙂
I don't know the mains tolerance. I am just wondering what's the tolerance in Mihai's design.
Greetings,
Pawel
30Vac * transformer regulation of about 5% gives 31.5Vac=44.5Vpk
subtract 1.4V for the rectifier and you have around 43Vdc from 30Vac.
Now add 6% mains tolerance and you potentially have almost 46Vdc at a few times during the year.
At very low currents the rectifier will drop less than 1.4V, could be as little as 1V.
subtract 1.4V for the rectifier and you have around 43Vdc from 30Vac.
Now add 6% mains tolerance and you potentially have almost 46Vdc at a few times during the year.
At very low currents the rectifier will drop less than 1.4V, could be as little as 1V.
OK, I agree with you
anyway there are 2 possible combinations with my transformer:
24VAC for the output stage
30VAC for the frontend
OR
30VAC for the output
36VAC for the frontend
in the 1st case one would have 30VAC would be not enough to get regulated 39DC (assuming tolerances of cource 🙂). So the question is either the amp would work with 34V DC FE (1st case) or how it's with max 45-46DC on the output stage.
Greetings,
Pawel
anyway there are 2 possible combinations with my transformer:
24VAC for the output stage
30VAC for the frontend
OR
30VAC for the output
36VAC for the frontend
in the 1st case one would have 30VAC would be not enough to get regulated 39DC (assuming tolerances of cource 🙂). So the question is either the amp would work with 34V DC FE (1st case) or how it's with max 45-46DC on the output stage.
Greetings,
Pawel
I already asked this question to Mihai, and the answer is yes if my memory is ok.
The main problem is not really the voltage but the power the final stage will dissipate. This amp goes pretty high in the class A region, about 180mA per output pair. At 45V on the rail the Power will be about 0.18A X 45 X 6 = 65W per side at iddle.... The transistor can handle it but you have to make really big heatsink.
The main problem is not really the voltage but the power the final stage will dissipate. This amp goes pretty high in the class A region, about 180mA per output pair. At 45V on the rail the Power will be about 0.18A X 45 X 6 = 65W per side at iddle.... The transistor can handle it but you have to make really big heatsink.
But, that 45 to 46Vdc will only be present when the mains is at maximum tolerance (+6%). These occasions should be infrequent and possibly short lasting.
Design the heatsink for 42 to 43Vdc which is likely to be delivered for considerable periods of time.
Check that none of the components get overloaded/overheated if a short term 46Vdc did occur.
Design the heatsink for 42 to 43Vdc which is likely to be delivered for considerable periods of time.
Check that none of the components get overloaded/overheated if a short term 46Vdc did occur.
and what about running lower voltage version of the frontend 34-35DC and 32 for the output stage ?
would it work ?
would it work ?
Ok, many thanks for the answer!
so the xformer is not a prob anymore right now 🙂
but there are others, for example transistors, some of them are hard to get in Germany, but I seem to have found alternatives:
2sc3423 - alt: 2sc3953 (rs components + local electronic shop), 2sc2911 (farnell)
2sc3423 is available at reichelt but after reading some posts on different forums, I have doubts about genuinity
MJE13035 - alt: ..33 ...31 (farnell)
same aplies for complementary pieces.
What are the sources for NJL... besides digikey and samples ? Anyone has experience and could comment on that ?
Greetings and thanks in advance,
Pawel
so the xformer is not a prob anymore right now 🙂
but there are others, for example transistors, some of them are hard to get in Germany, but I seem to have found alternatives:
2sc3423 - alt: 2sc3953 (rs components + local electronic shop), 2sc2911 (farnell)
2sc3423 is available at reichelt but after reading some posts on different forums, I have doubts about genuinity
MJE13035 - alt: ..33 ...31 (farnell)
same aplies for complementary pieces.
What are the sources for NJL... besides digikey and samples ? Anyone has experience and could comment on that ?
Greetings and thanks in advance,
Pawel
After some inquiries
Possible replacements of
2SC3423/2SA1360(difficult to get) is 2SC5171/2SA1930(ft =200Mhz and Cob=16pf, 20W dissipation, similar to T220 package)
or
2N5551/2N5401 at lower power.
and
Qmje15035/Qmje15034 replaced with
MJE15030/MJE15031
Possible replacements of
2SC3423/2SA1360(difficult to get) is 2SC5171/2SA1930(ft =200Mhz and Cob=16pf, 20W dissipation, similar to T220 package)
or
2N5551/2N5401 at lower power.
and
Qmje15035/Qmje15034 replaced with
MJE15030/MJE15031
Hello guys
Be honest with me, how it sound for your ears? It is so awfully bad?
I can not belive no one has finished yet!
Mihai
Be honest with me, how it sound for your ears? It is so awfully bad?
I can not belive no one has finished yet!
Mihai
Hi Mihai,
I am going definitely to make it, but right now, it's the stage of collecting parts and at the time being spare time is scarce 🙂 Btw, what do you use as preamp ?
Greetings,
Pawel
I am going definitely to make it, but right now, it's the stage of collecting parts and at the time being spare time is scarce 🙂 Btw, what do you use as preamp ?
Greetings,
Pawel
Hi Pawel,
I don't need a preamp. The Zout of the internal DAC is around 10ohm.
I use a 5k log pot for volume control.
BRg,
Mihai
I don't need a preamp. The Zout of the internal DAC is around 10ohm.
I use a 5k log pot for volume control.
BRg,
Mihai
Hi Mihai,
1st I am going to connect it to modded marantz CD53 which right now has output impedance about 100 ohm (assuming ideal opamps 🙂). But how do you deal with DC on input, do you have a cap on DAC output ? Right now, there are no output caps in my CDP and I don't care about DC, since there are input caps in my receiver which serves as an amp.
Greetings,
Pawel
1st I am going to connect it to modded marantz CD53 which right now has output impedance about 100 ohm (assuming ideal opamps 🙂). But how do you deal with DC on input, do you have a cap on DAC output ? Right now, there are no output caps in my CDP and I don't care about DC, since there are input caps in my receiver which serves as an amp.
Greetings,
Pawel
Hi Roender,
I saw you use a pot...
Sorry for this unrequested info but I thought you could be interested. I definitely am.
http://www.enjoythemusic.com/diy/0708/first_watt_b1_preamplifier.htm
Cheers,
M
I saw you use a pot...
Sorry for this unrequested info but I thought you could be interested. I definitely am.
http://www.enjoythemusic.com/diy/0708/first_watt_b1_preamplifier.htm
Cheers,
M