I know that..My point is that you can take any already great sounding BJT voltage stage like luxman's hawksford cascode or your Goldmund , drive Laterals with it and it will sound all that much better.
OS
I like that ..Wahib, fullcomp to hawksford... driving laterals, Sweeeet! gotta have it!!
Hi, OS
That s a 30 years old design..
You had noticed the input cascoded jfets also...
It will surely be Goldmund s "next design" in a 10 years or so !!
Gentleman, please start a thread with your improvements. There's nothing to gain this way.
/Hugo
Some culture in matter of technical improvements and evolution
will not hurt , quite the contrary...
I'm never sure where to start when I consider designing an FET amp. Only special amps can drive hundreds of nF's of capacitance gracefully (the amplifier sees hundreds of nF if the capacitance is moved up to the driver stage as in an FET amp), plus there's a bunch of self-resonance and oscillation gotchas to watch out for. It must be hard for a simulator to accurately predict the behavior of a real FET amp.
The high degeneration on the differentials means very low phase distortion, which really helps stability when there is minimal compensation. That is, if you can account for the FETs' nonlinear capacitance. But I have no experience in this realm.
- keantoken
The high degeneration on the differentials means very low phase distortion, which really helps stability when there is minimal compensation. That is, if you can account for the FETs' nonlinear capacitance. But I have no experience in this realm.
- keantoken
Oh yeah , I also have a voltage tripler similar to the goldmund that runs off of a small 24-0-24 trafo , the only difference is that it feeds a high gain capacitance multiplier before feeding the 20mA rails of the modular voltage stage, WAY superior to the goldmund. Separate grounds , adjustable current sources , all those things a mega thousand dollar amp (should) have .
I looked at the Arcam DiVA A75 schematic, and sure enough they have a similar arrangement. I first saw this used on Steve Dunlap's Krill amp though.
Is your improved design available for my perusal?
You should listen to me and apex ,we are "hands on" .. instead of debating abstract opinions , we hear all these amps , see them fail , see which ones stand the test of time , and build a LOT of them (below). maybe I should pot whole voltage stages ... he he..
OS
Yeah I need to get more hands on - especially now I finally bought a 'scope! I never seem to have the time though
Some culture in matter of technical improvements and evolution
will not hurt , quite the contrary...
Then do so in a constructive way. Preventing people to build a design because it doesn't suit you is not in the spirit of diy. Present your own, in a separate thread. That will be far more productive than running in circles.
Final word.
will not hurt , quite the contrary...
Then do so in a constructive way. Preventing people to build a design because it doesn't suit you is not in the spirit of diy. Present your own, in a separate thread. That will be far more productive than running in circles.
Final word.
'Goldmund' is HITACHI HMA-7500 from 1978 with 'improvements', my F100 (with HITACHI MOSFETs) also, you can use old HITACHI design
Thanks Apex. I think what you mean with the improvement is the "driver" for the MOSFET. I haven't built the HMA-7500 but I think I will not "like" the sound. I have built many of similar circuit arrangement, the last one is boraomega's Sigma.
This F100 of yours, have you posted it here in diyaudio? I think I haven't seen one.
" Preventing people to build a design because it doesn't suit you is not in the spirit of diy. Present your own, in a separate thread. That will be far more productive than running in circles."Final word
Agree and seconded .... we have to move on....i'm sure many of us are waiting for the group buy of this project....
Agree and seconded .... we have to move on....i'm sure many of us are waiting for the group buy of this project....
Last edited:
. Preventing people to build a design because it doesn't suit you is not in the spirit of diy. Final word.
Netlist, being a moderator doesn t make utterly wrong statements
more credible...
http://www.diyaudio.com/forums/soli...plifier-i-have-ever-heard-17.html#post2322631
I know that..
We all know that the perceived sound of a amplifier is subjective at best but those laterals are made JUST for audio. My old Hitachi lateral amp had a 4 transistor circuit similar to the goldmund running at 20ma HOT class A ,it was the ONLY amp besides the mighty 8000$ genesis stealth (200w class A)that sounded "magical" to me. I was listening to that "hot" class A voltage stage moderated by the Hitachi lateral class AB stage with it's unique switching distortion (BTW , different then that of your typical BJT). APEX audio builds lots of amps , you should listen to him ... that Japanese Lateral amp with the non-switching circuit would be what I would shoot for in a new amp creation , I feel it would easily put the overpriced Goldmund to shame .. BIGTIME.
OS
Hi Os, I like your CX input and VAS stage but I'm not sure that it will be that simple to modify it for a lateral MOSFET. I'm having that "plan" to start designing my own (by first modifying existing amps such as the Stochino) but I'm afraid of burning my laterals... Or at least, I believe that it will not be that easy to get what I want to get, somebody with outstanding qualification should do it for me... Somebody with good ears, or at least similar preference...
Why 100V/us you asked? Well, tube amps don't have such slew rate but they are musical. Many modern designs are "better" (according to your criteria I believe) but not as musical. I want a musical yet "quick" amplifier... Why that much of a slew rate you will ask? Well, I know what explanantion the theorists will say but I still want it that way...
You say you have that good sounding class-A MOSFET amp? Can you make similar sounding amp in class-B? Is it not possible?
This is why the schematic posted by Nagysaudio is interesting to me (and can sound good). If you know what I mean...
HITACHI HMA-7500mkII is 'HITACHI HMA-7500 with improvements'. Do you have ever heard 'Goldmund' amp and compare sound with HITACHI? F100 with HITACHI MOSFETs you can see in thread: http://www.diyaudio.com/forums/solid-state/162081-dc-servo-mosfet-amplifier-13.html post #123.
Regards
Attachments
Last edited:
Yes, I like the driver for the MOSFET in the HMA-7500mkII compared to the previous version. The front end, tho many will prefer such front end, are not important for me.
Thanks for your F100, I think I will build it. But I don't understand what kind of "improvement" you have done with the circuit. The DC servo, that's "standard". The Q7-Q8, that's interesting (I don't know why they are there), I want to know how it will affect the sound...
Add:
Actually I have tried to "clean up" the schematic for the HMA-7500mkII after somebody posted it here before (was it you?). I haven't finished and I'm not sure whether I can "clean it up" to have a "clear" schematic that I can build.
Last edited:
i dont know, this line of discussion turns me off, its ok to have a technical discussion based on the notion of sharing of knowledge and experience, however what i am seeing in the more critical posts is posturing and ego.
im sure there are other ways to build this circuit. im sure there are more advanced techniques. i still find this thread enjoyable and frankly i havent seen many designs with separate power supplies which i find interesting. Ii for one would not mind if someone cloned this schematic and set out to make it better, creating a thread called "the best amp ive heard -reborn". that would be contributing.
but to come here and essentially post messages that says "dont partake in this thread and design because its old -my design in thread xyz is superior" smacks of ego when the person posting is the guy who created the alternate thread.
there may be more than meets the eye of which i am not aware of, but i am interested in the sharing of knowledge and experiences and i for one dont think that its right to dismiss another members ideas or contribution in this way. it smacks of elitism and will make less confident members think twice about posting.
so can we go back to being gentlemen please?
par
Last edited:
Final work PCB ....
....I think I will stop now to prepare others PCB's, because I have not much support from you , only one detailed picture would be great to have it , to make an
better layout . Until now are 3 boards , main board amplifier one , second an smal protection board and the last one PSU combined with protection board .
I doo my best , learn a lot from posted messages and means a lot for me like a
diy-er . Please dont laff about my poor english . Here is the PCB's . I have all time good intention ....
Regards Alex.
....I think I will stop now
to prepare others PCB's, because I have not much support from you , only one detailed picture would be great to have it , to make anbetter layout . Until now are 3 boards , main board amplifier one , second an smal protection board and the last one PSU combined with protection board .
I doo my best , learn a lot from posted messages and means a lot for me like a
diy-er . Please dont laff about my poor english .
Here is the PCB's . I have all time good intention ....Regards Alex.
Attachments
If Q7-Q8 works like a VI limiter then it is optional, and then I have built many of similar designs in the past.
Sometimes (actually often
) I wonder, do those designers know what I know, or they just don't want to share what they know.......I think I will stop now
Why in a hurry. This thread will not be dead. And I think I will like this amplifier... Surely will build one, unless somebody would point me to better 100v/us 60W lateral mosfet design.
If Q7-Q8 works like a VI limiter then it is optional, and then I have built many of similar designs in the past.
Sometimes (actually often
Do you know this?
