Thanks Terry.
I'm on my way out to pick up some small drill bits and then to work on the boards.
I'm on my way out to pick up some small drill bits and then to work on the boards.
Hi smartx21
The SD1047 is Elvees one of Favorite Transistors build in his "Little cheap Circlophone"
Could this be a good place to use them?
The SD1047 is Elvees one of Favorite Transistors build in his "Little cheap Circlophone"
Could this be a good place to use them?
Well, I would like to share here that I was that one fortunate guy who got to rejig Hugh's Quasi PCB and my god, he is a master, who knows where to place each every component and trace. A meticulous attention to detail, that my layouts can never match, even the one's I have spent 100's of hours.
I took it as a challenge and I am glad Hugh liked my work. He s a true gentleman ..
Thanks Hugh!
Regards
Prasi
Well, we'll check it out!
Boards are coming from user @farjon.
Parts are being scavanged in bins and junks....
I just put my Quasi's back on and listening to them now. Forgot how nice they sound. 🙂
I just got a 5 pair pack of Onsemi NJW0281G/NJW0231G. The NJW0281G might be a good substitute for the 2SC5200.
http://www.onsemi.com/pub_link/Collateral/NJW0281-D.PDF
I might use these in the next pair of Quasi's that I make - maybe Dacz layout...
I just got a 5 pair pack of Onsemi NJW0281G/NJW0231G. The NJW0281G might be a good substitute for the 2SC5200.
http://www.onsemi.com/pub_link/Collateral/NJW0281-D.PDF
I might use these in the next pair of Quasi's that I make - maybe Dacz layout...
Attachments
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Hi I wanted generate the pdf's and post here for you, but unfortunately my virus scan has deleted my sprint
. Sorry.So I request Dacz or someone to post the pdf's here for convenience.
reg
Prasi
Hi I wanted generate the pdf's and post here for you, but unfortunately my virus scan has deleted my sprint
So I request Dacz or someone to post the pdf's here for convenience.
reg
Prasi
Here you go.
Thank you Prasi!
You polished my raw pcb and turned it into a Renaissance masterpieced......
Terry,
Thank you for your work, this is a wonderful backup for all of us!
As most realise now it's very easy to find high power nmos with 300+ W ratings, but it's more difficult to get them in npn devices.
The one that comes to mind is the 2SC3264 Sanken, there is an ON Semi 2N3668 (200W, 25A, 150V, but TO204AA, and finally a (Toshiba?)MT200 but in six pages of trawling through Google I find very little of them and the 175W+ devices are expensive. It rather looks like you have to use a matched pair of npn to move up to a 100W plus quasi, but then, it would be an interesting amp with a large nmos and two matched npns for a single output stage, so the novelty might attract some to build it out!
Cheers,
Hugh
You polished my raw pcb and turned it into a Renaissance masterpieced......
Terry,
Thank you for your work, this is a wonderful backup for all of us!
As most realise now it's very easy to find high power nmos with 300+ W ratings, but it's more difficult to get them in npn devices.
The one that comes to mind is the 2SC3264 Sanken, there is an ON Semi 2N3668 (200W, 25A, 150V, but TO204AA, and finally a (Toshiba?)MT200 but in six pages of trawling through Google I find very little of them and the 175W+ devices are expensive. It rather looks like you have to use a matched pair of npn to move up to a 100W plus quasi, but then, it would be an interesting amp with a large nmos and two matched npns for a single output stage, so the novelty might attract some to build it out!
Cheers,
Hugh
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Hugh could you provide a shematic with this configuation (high power nmos and matched npn......i have some good matched MJL3281)...
Marc
Thank you still4given
Do you have an explanation why Sprint Layout print files like this one?
http://www.diyaudio.com/forums/soli...mentary-mosfet-amplifier-133.html#post4838093
In the meantime a member of the forum offered me a set of stereo pcb (Thiagomogi or Prasi board).
🙂
Do you have an explanation why Sprint Layout print files like this one?
http://www.diyaudio.com/forums/soli...mentary-mosfet-amplifier-133.html#post4838093
In the meantime a member of the forum offered me a set of stereo pcb (Thiagomogi or Prasi board).
🙂
A BIG QUASI
Hi Marc,
This is a quick and dirty Spice schematic, so this is not built. (Some of the dissipations and currents/voltages on this schematic are not correct as they relate to the 42V rails, which I analysed very carefully but NOT this version). But I have no reason to think it would not work well as I did something like this five years ago! I have used an IRF90N20D here; the profile of the harmonic is very much driven by the choice of the mosfet. I would use a FQA69N25 Fairchild here, but don't have the model. Results are very good, and if you use C5200 (not fakes!) I would expect you could increase the rails to around 56V, no higher.
I have some concerns about stability at the clip on the negative waveform. This would come back to the B/C cap on the inverter, which should be a 4A device like the 2SA1837.
By using a 0.33R emitter resistor matched npns is not too critical, but it does help. This is a schemat, Marc, and would need some proto work, but it would be practical.
Harmonic Profile is excellent, better than the single npn version. Moreover, the mosfet NEVER turns off; at clip it's still passing more than 7mA.
Cheers,
Hugh
Hi Marc,
This is a quick and dirty Spice schematic, so this is not built. (Some of the dissipations and currents/voltages on this schematic are not correct as they relate to the 42V rails, which I analysed very carefully but NOT this version). But I have no reason to think it would not work well as I did something like this five years ago! I have used an IRF90N20D here; the profile of the harmonic is very much driven by the choice of the mosfet. I would use a FQA69N25 Fairchild here, but don't have the model. Results are very good, and if you use C5200 (not fakes!) I would expect you could increase the rails to around 56V, no higher.
I have some concerns about stability at the clip on the negative waveform. This would come back to the B/C cap on the inverter, which should be a 4A device like the 2SA1837.
By using a 0.33R emitter resistor matched npns is not too critical, but it does help. This is a schemat, Marc, and would need some proto work, but it would be practical.
Harmonic Profile is excellent, better than the single npn version. Moreover, the mosfet NEVER turns off; at clip it's still passing more than 7mA.
Cheers,
Hugh
Attachments
Nice schematic Hugh.
I noticed the addition of 2 small capacitors ; C8 (1nF) across D1 and C10 (12pF) across R5. These do not appear so far on any of the current PCB Layouts. (Prasi, Thiago and Dacz)
Should these 2 caps be added now before someone send these beautiful PCB to a PCB manuf ;-)
Thanks,
Eric
I noticed the addition of 2 small capacitors ; C8 (1nF) across D1 and C10 (12pF) across R5. These do not appear so far on any of the current PCB Layouts. (Prasi, Thiago and Dacz)
Should these 2 caps be added now before someone send these beautiful PCB to a PCB manuf ;-)
Thanks,
Eric
i had such an experience once when i imported a layout pdf in corel and pressed view/wireframe. pressing view/normal made everything ok. I dont sincerely have any solution to your specific issue.
reg
Prasi
Eric,
I would not change either of them on Prasi's layout. It is fine as it stands. I include them on this higher power amp because I found issues with stability at negative waveform near clip (46Vpeak). You often find that more powerful amps need additional stability because their slew rate has to be higher.
Cheers,
Hugh
I would not change either of them on Prasi's layout. It is fine as it stands. I include them on this higher power amp because I found issues with stability at negative waveform near clip (46Vpeak). You often find that more powerful amps need additional stability because their slew rate has to be higher.
Cheers,
Hugh
Hi Quasi builder.;-)
Is there a good samaritan working on upgrading their PCB layout to create this BIG QUASI version ? So far I think the PCB from Dacz is the only one that has all the latest mods suggested by Hugh. Note that C8 and C10 should be added on this more powerful Quasi.
If nobody will update their PCB I will simply use my present one and add the few required components, it would just be nice to know if someone intend to work on this.
Maybe we should create another thread if there is any interest.
Is the physical size of the suggested FQA69N25 similar to IRFP240..I didn't find much info about that FQA.. on the web. Where do we buy these.. ?
I just found in my junk a power transformer from an old Technics SU-V10X (rated 2 x 120W@8 ohm) which has a choice of 2 secondary based on the speaker's impedance..one is +/-37Vac and the other is +/-48Vac, filtering cap were rated 71Vdc. I believe the +/-37Vac would be appropriate for this big Quasi, any thought ?
Thanks in advance.
Eric
Is there a good samaritan working on upgrading their PCB layout to create this BIG QUASI version ? So far I think the PCB from Dacz is the only one that has all the latest mods suggested by Hugh. Note that C8 and C10 should be added on this more powerful Quasi.
If nobody will update their PCB I will simply use my present one and add the few required components, it would just be nice to know if someone intend to work on this.
Maybe we should create another thread if there is any interest.
Is the physical size of the suggested FQA69N25 similar to IRFP240..I didn't find much info about that FQA.. on the web. Where do we buy these.. ?
I just found in my junk a power transformer from an old Technics SU-V10X (rated 2 x 120W@8 ohm) which has a choice of 2 secondary based on the speaker's impedance..one is +/-37Vac and the other is +/-48Vac, filtering cap were rated 71Vdc. I believe the +/-37Vac would be appropriate for this big Quasi, any thought ?
Thanks in advance.
Eric
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