Some time ago I had the first auditions with the Dado GW MK3 preamp which I was very surprised at, how well it sounded.
Last night I did an audition with amp Dado 200 MOSFET amp and GW MK3 preamp.
What can I say ... It's so good that I stayed until late at night to listen.
It impresses you all - crystalline voices, very beautiful and articulated bass (even at low volume), very silent. Having a lower voltage (+ _45V) and a generous heatsinks, I set a 300mA bias on the MOSFET. The sound was special. I will come back with pictures later, this amp deserves to be put in the beautiful case.
A question
Would it be a win if I put 2SJ201 / 2SK1530 (instead of IRFP240 / 9240)?
If so, what changes should I make?
Thank you.
I am glad you like the amp. If you intend to run this amp on +-45V you need to change the resistors R3 and R8 from 3k3 2W to 2k2 2W to keep zener shunt regulation, with 3k3 it's shunt current is to low.
I don't have experience with 2SJ201 / 2SK1530 and can't say that amp will sound better
. You could have problem with the space as 2SJ201 / 2SK1530 are in bigger case. I don't think you have to change anything just be careful with the bias (put the P1 on max value before power on and than readjust the bias)Damir
Some time ago I had the first auditions with the Dado GW MK3 preamp which I was very surprised at, how well it sounded.
Last night I did an audition with amp Dado 200 MOSFET amp and GW MK3 preamp.
A question
Would it be a win if I put 2SJ201 / 2SK1530 (instead of IRFP240 / 9240)?
If so, what changes should I make?
Thank you.
Hi,
also keep in mind that the 2SJ201 / 2SK1530 are low Ugs voltage Vertical Fets, so you also have to change the Vbe Multiplier. This can't be done only by simulation, maybe their temp. coefficient (temp. drift) is also different.
But also a nice idea, since i have 4 pairs of the Toshiba still in my store
BR
Günni
Hi,
also keep in mind that the 2SJ201 / 2SK1530 are low Ugs voltage Vertical Fets, so you also have to change the Vbe Multiplier. This can't be done only by simulation, maybe their temp. coefficient (temp. drift) is also different.
But also a nice idea, since i have 4 pairs of the Toshiba still in my store
BR
Günni
Hi Gunni,
Yes, the Vgsoff is between 0.8 and 2.5 V, but I don't have spice models to sim it.
As I don't have those transistors and not easy to find not fake ones, I will not simulate it.
BR Damir
especially for vitalica, the LT Spice models for the requested Toshiba vertical Mosfets 2SK1530/2SJ201 can be found at CordellAudio.com - SPICE Models, he has also the IRFP models there for comparing.
Due to business, i nearly find any time to continue with your 120W LatFet CFA. PCB is equipped and mounted on the heatsink, the first error is solved on the PCB. Maybe in 1 or 2 weeks i can turn on the power switch and start debugging
BR
Günni
Due to business, i nearly find any time to continue with your 120W LatFet CFA. PCB is equipped and mounted on the heatsink, the first error is solved on the PCB. Maybe in 1 or 2 weeks i can turn on the power switch and start debugging
BR
Günni
I did some quick simulation. The bias can be set if R64 is increased to 3k3, but the thermal compensation is a bit overcompensated. To get that part better it will need to change the Vbe multiplier more, and test that in real amp, not my intention to do that, maybe someone is willing to tray.
BR Damir
by the way simulation gives similar values for PM, GM and ULGF
Last edited:
Hello,
i built the amplifier. There's only one problem. Q6 and Q8 are getting quite warm. The current through R14 (100 ohms) is 10mA. The current through R4 (820 ohms) is 1.5mA. The voltage at the diodes D11 D12 is 1.85V. I suspect that the voltage on the LED D11 and D12 is too high. Do you have comparison values? Maybe I have to increase the resistance of R4 and R7.
Thank you
Gerd
i built the amplifier. There's only one problem. Q6 and Q8 are getting quite warm. The current through R14 (100 ohms) is 10mA. The current through R4 (820 ohms) is 1.5mA. The voltage at the diodes D11 D12 is 1.85V. I suspect that the voltage on the LED D11 and D12 is too high. Do you have comparison values? Maybe I have to increase the resistance of R4 and R7.
Thank you
Gerd
Some time ago I had the first auditions with the Dado GW MK3 preamp which I was very surprised at, how well it sounded.
Last night I did an audition with amp Dado 200 MOSFET amp and GW MK3 preamp.
What can I say ... It's so good that I stayed until late at night to listen.
It impresses you all - crystalline voices, very beautiful and articulated bass (even at low volume), very silent. Having a lower voltage (+ _45V) and a generous heatsinks, I set a 300mA bias on the MOSFET. The sound was special. I will come back with pictures later, this amp deserves to be put in the beautiful case.
A question
Would it be a win if I put 2SJ201 / 2SK1530 (instead of IRFP240 / 9240)?
If so, what changes should I make?
Thank you.
What are you using as music source?
Hi Gerd,
The optimal current trough R4 could varies between 6 and 8 mA. Even 10 mA is OK but you have to use small heat sinks for Q6 and Q8.
To decrease that current you can increase resistors R4 and R7, try 910R.
Best regards
Damir
Hello Damir,
I am not ready yet. A few parts are still missing. I have just adjusted the bias current and made a few measurements. The amplifier is very broadband. With my 2 MHz frequency generator I could not determine the upper limit frequency. Attached some pictures.
Best regards
Gerd
I am not ready yet. A few parts are still missing. I have just adjusted the bias current and made a few measurements. The amplifier is very broadband. With my 2 MHz frequency generator I could not determine the upper limit frequency. Attached some pictures.
Best regards
Gerd
Attachments
Hi Gerd,
It looks good. I'll wait for your listening impression and measurement.
Best regards
Damir
DSD 256- HQPlayer- Amanero -Sygnalist DCS1V2.6-Preamplifier GW mk3 (Dadod)
24/96 - Renderer - DAC AK4990 (Discrete outputstage-balanced)- Preamplifier GW mk3 (Dadod)
Renderer NMR media renderer interface - electronic, engineering and consulting
DCS1 V2.6 PureDSD
DAC AK4990 -http://www.diyaudio.com/forums/vendor-s-bazaar/274456-ak4490-usb-dac-dsd-support.html
Build finally done, first impressions
Used a F5 turbo recently as my main amp. I wanted to try something with a totally opposite design philosophy to hear and compare for myself, so build the 200W CFA amp.
I consider myself as experienced builder, but this was for sure not an easy build.
I build the front end first, left VAS, drivers & output empty to test to avoid fireworks. Then completed the amp and tested with small SMPS so a mistake would not directly be fatal. After all test, build in case with bigger classic power supply.
Measured distortion is very low, actually lower than my test setup for amps currently can measure reliable.
Wanted to listen quickly, so my build is quick & dirty. Will clean up and make it a little more safe later.
For listening, I have pro-audio background. So first thing to do with a new amp? Turn it up until clip
The amp sounds very good, most interesting is it also sounds very good when pushed very loud, close to clipping. Many amps loose precision at loud volume, especially in the high side of the audio range. This amp keeps sounding controlled, even at ear bleeding volumes.
Need to do some serious listening later but so far very promising.
Used a F5 turbo recently as my main amp. I wanted to try something with a totally opposite design philosophy to hear and compare for myself, so build the 200W CFA amp.
I consider myself as experienced builder, but this was for sure not an easy build.
I build the front end first, left VAS, drivers & output empty to test to avoid fireworks. Then completed the amp and tested with small SMPS so a mistake would not directly be fatal. After all test, build in case with bigger classic power supply.
Measured distortion is very low, actually lower than my test setup for amps currently can measure reliable.
Wanted to listen quickly, so my build is quick & dirty. Will clean up and make it a little more safe later.
For listening, I have pro-audio background. So first thing to do with a new amp? Turn it up until clip
The amp sounds very good, most interesting is it also sounds very good when pushed very loud, close to clipping. Many amps loose precision at loud volume, especially in the high side of the audio range. This amp keeps sounding controlled, even at ear bleeding volumes.
Need to do some serious listening later but so far very promising.
Attachments
Used a F5 turbo recently as my main amp. I wanted to try something with a totally opposite design philosophy to hear and compare for myself, so build the 200W CFA amp.
I consider myself as experienced builder, but this was for sure not an easy build.
I build the front end first, left VAS, drivers & output empty to test to avoid fireworks. Then completed the amp and tested with small SMPS so a mistake would not directly be fatal. After all test, build in case with bigger classic power supply.
Measured distortion is very low, actually lower than my test setup for amps currently can measure reliable.
Wanted to listen quickly, so my build is quick & dirty. Will clean up and make it a little more safe later.
For listening, I have pro-audio background. So first thing to do with a new amp? Turn it up until clip
The amp sounds very good, most interesting is it also sounds very good when pushed very loud, close to clipping. Many amps loose precision at loud volume, especially in the high side of the audio range. This amp keeps sounding controlled, even at ear bleeding volumes.
Need to do some serious listening later but so far very promising.
I'll wait for more serious listening and your evolution about.
