Loud isn't always better - listen to the music
I built this amp from a kit when I was into lots of power. Bigger is better? – not always I found out many, many years later. The kit was easy to build and was very powerful. High-end/high audio quality MOSFet amps these days would not be built the same way. The reason is most audiophiles are looking for very high quality, musicality and the passion of the performance. I build 1 watt MOSFet Class A SE amps or very modified 8 watt valve amps.
If you have a nice pair of speakers and want to experience the passion of well crafted music you may have to use a different amp. If you love your hard rock and want it so loud it will cause bone fractures – you are on the right path. So though the 5000 is a good amp it is a good amp for a particular style and taste.
I have moved from rock(after 40 years) to more Jazz. I’m looking for recording with an up-front female or male voice with minimal instrument backing. Or a three piece club jazz group of piano, slap bass and drums. I want it to hear the singer so clearly I can smell what they had fro breakfast three days ago. No for everyone and that’s what makes the world go round.
I’m always amazed at how cheap some of these high powered amps can be. If you do build it make sure your power supply is up to scratch. If you can fit bigger caps than suggested do so. If you can shield off PS from other circuitry – do it – this will help keep down hum and noise through the whole unit. If you play it loud these hums and things can be distracting. Looking into snubbing rectifier bridges, caps and t’former – this simple steps can make a good amp better.
happy listening.
I built this amp from a kit when I was into lots of power. Bigger is better? – not always I found out many, many years later. The kit was easy to build and was very powerful. High-end/high audio quality MOSFet amps these days would not be built the same way. The reason is most audiophiles are looking for very high quality, musicality and the passion of the performance. I build 1 watt MOSFet Class A SE amps or very modified 8 watt valve amps.
If you have a nice pair of speakers and want to experience the passion of well crafted music you may have to use a different amp. If you love your hard rock and want it so loud it will cause bone fractures – you are on the right path. So though the 5000 is a good amp it is a good amp for a particular style and taste.
I have moved from rock(after 40 years) to more Jazz. I’m looking for recording with an up-front female or male voice with minimal instrument backing. Or a three piece club jazz group of piano, slap bass and drums. I want it to hear the singer so clearly I can smell what they had fro breakfast three days ago. No for everyone and that’s what makes the world go round.
I’m always amazed at how cheap some of these high powered amps can be. If you do build it make sure your power supply is up to scratch. If you can fit bigger caps than suggested do so. If you can shield off PS from other circuitry – do it – this will help keep down hum and noise through the whole unit. If you play it loud these hums and things can be distracting. Looking into snubbing rectifier bridges, caps and t’former – this simple steps can make a good amp better.
happy listening.
suzyj said:
The higher THD+N is actually noise component at lower levels.
The distortion is sinking beneath noise floor. However your
approach is worth trying because the PGA's distortion is so
low at any level, especially at easy OP loads which you will
probably have.
2SK389 are very good however they are very hard to find.
Their device/device offset match is better than 404 from memory.
You should be able to do the whole thing DC coupled with
them at IP and some hand trimming.
OP of SKA is not a follower it is common source and driven by
a small sig bjt that is bootstrapped. You will find the basic
circuit here. If I only had a choice between SKA and 6000 I
would take the SKA. This is a VERY smart design that would
probably measure as good as 6000 with MUCH simpler signal
path. But I am sure the 6000 will be fun too.
http://members.dodo.com.au/~gregball/guru_001.htm
Unfortunately ampguru got banned from the forum. Bit of
a shame, very bright guy!
FWIW, I would just get the 6000 running. Maybe compare it to
SKA modules using same supply. The SKA modules are dirt cheap.
This might be quite fun and interesting. Compare the complex
beast to total simplicity. See what they each do.
Then try the AKSA and sell both of them 😀 (sorry)
No worries. I hope you enjoy the journey, it can be a lot of fun
and i am sure the RS5's will make everything very apparent.
Cheers
Terry
suzyj said:
The guys are right. Don't get too bound up in specs. You'll miss the forest hidden by the trees. Valves, MOSFets, Transistors or Magnetic Amplifiers - they can all sound good if design and construction is about the sound - not the specs. In the end you want to listen to this thing not file it's excreted data in some dark cabnet.
A good amp is alive, and breaths life into tiny magnetic dimples on a fabricated base or a wobble in vinyl . How well it does that is what reproduction is about not specs. Valve amps would have died with the first BC108 if they were to survive on specs - but guess what - they didn't die - they are still breathing.
Follow your hart not your head, this is an emotional descision.
happy listening
ETI 5000 / AEM 6000
Hello,
Suzy, why AEM 6000?
I said goodbye to modified Tilbrook amps almost 15 years ago. Since those times there has been some progress. Maybe not huge but some. In parts as well. for example you might try to use KSA1220A/KSC2690A instead of MJE340/350s or BFs in a number of applications.
Currently, I'm building four channel Stochino amp with minor changes - the main being using IRFP240/SHF9240 instead of IRFP640/9640 and low noise/high beta input transistors. The use of more robust power devices was partly based on Alex Suton bad experience with the 640/9640 devices. We discussed alternative power and input devices and Alex, after having the 640/9640s burned, decided to go for IRFP240/9240 plus low noise/high beta input matched pairs. The change resulted in a notable improvement. Anyway, ask Alex about that as his amps are running while mine are still being worked upon. The last time I heard from him he got rid of caps in the NFB and consequently was trying to reduce offset.
Stochino's amp attracted me by its specs - especially its high slew rate and related low IMs and TIMs. Of course I also listened to opinions of those who built these amps. Nevertheless, I was originally attracted to this design by its "philosphy". And that was similar to Otala's design philosphy which was implemented into Electrocompaniet amps. I heard one of these first time over 25 years ago and still remember the impression.
Sonically, in those times, Electrocompaniet seemed to me to be the most faithful of all the amps I listened to. So there is something in design philosophy and specs. Our ears/brain systems confirm that to some extent. Some amps had lower THDs but Electrocompaniet was much faster than any other known to me in those times, had much wider bandwidth and much lower IMs and TIMs. Anyway, sonically it stood out of the crowd. I hope that Stochino will also be a similar experience to me.
cheers,
PS from my experience most of the noticable progress in reproduction quality comes from switching to active systems plus the use of the best/most faithfull (and more rather than less efficient) speakers one can get within ones bufget.
Hello,
Suzy, why AEM 6000?
I said goodbye to modified Tilbrook amps almost 15 years ago. Since those times there has been some progress. Maybe not huge but some. In parts as well. for example you might try to use KSA1220A/KSC2690A instead of MJE340/350s or BFs in a number of applications.
Currently, I'm building four channel Stochino amp with minor changes - the main being using IRFP240/SHF9240 instead of IRFP640/9640 and low noise/high beta input transistors. The use of more robust power devices was partly based on Alex Suton bad experience with the 640/9640 devices. We discussed alternative power and input devices and Alex, after having the 640/9640s burned, decided to go for IRFP240/9240 plus low noise/high beta input matched pairs. The change resulted in a notable improvement. Anyway, ask Alex about that as his amps are running while mine are still being worked upon. The last time I heard from him he got rid of caps in the NFB and consequently was trying to reduce offset.
Stochino's amp attracted me by its specs - especially its high slew rate and related low IMs and TIMs. Of course I also listened to opinions of those who built these amps. Nevertheless, I was originally attracted to this design by its "philosphy". And that was similar to Otala's design philosphy which was implemented into Electrocompaniet amps. I heard one of these first time over 25 years ago and still remember the impression.
Sonically, in those times, Electrocompaniet seemed to me to be the most faithful of all the amps I listened to. So there is something in design philosophy and specs. Our ears/brain systems confirm that to some extent. Some amps had lower THDs but Electrocompaniet was much faster than any other known to me in those times, had much wider bandwidth and much lower IMs and TIMs. Anyway, sonically it stood out of the crowd. I hope that Stochino will also be a similar experience to me.
cheers,
PS from my experience most of the noticable progress in reproduction quality comes from switching to active systems plus the use of the best/most faithfull (and more rather than less efficient) speakers one can get within ones bufget.
Janusz,
Good to hear that you are working on the Stochino amp. I have several channels of Stochino amps, none have given me any trouble except for my own mistakes, twice.
I had suggested this amp a few days ago, but Suzyj didn't seem to take note.
I have also thought of IRFP240/9240 pair in place of IRF640/9640. Although the former can handle more heat, given Pd and a bigger die size, the transconductance is lower. If only we could get better P channel devices, the Stochino amp can get even better than what it is in stock condition.
By the way, what were the input transistors that Alex used which improved its also great performance? I'd like to try them out immediately.
Thanks,
Good to hear that you are working on the Stochino amp. I have several channels of Stochino amps, none have given me any trouble except for my own mistakes, twice.
I had suggested this amp a few days ago, but Suzyj didn't seem to take note.
I have also thought of IRFP240/9240 pair in place of IRF640/9640. Although the former can handle more heat, given Pd and a bigger die size, the transconductance is lower. If only we could get better P channel devices, the Stochino amp can get even better than what it is in stock condition.
By the way, what were the input transistors that Alex used which improved its also great performance? I'd like to try them out immediately.
Thanks,
Why ever would I want to try another design when I'm having so much fun with this one?
Thus far (in LTspice) I've doubled he value of the emitter/source degeneration resistors in each stage, which lowers the gain for each stage (and improving the stability), plus decreasing the feedback divider to 1/11th.
With no input filter, its 3dB cutoff point is around 3MHz, and I measure (very slowly, as I've gotta set the time step way low to get anything meaningful) -98dB H2, -104dB H3, ?? H4, -112dB H5 (driven by a 1V pk 1KHz sinewave), and a 4 Ohm resistive load.
I'm playing with intermods at the moment - putting a 10KHz and 11KHz sine wave in and having a look for the 1KHz output, but can't sind it thus far (at -100dB).
Of course that begs the question of how to measure these things on the real thing... We're not really set up for audio measurement. We have got a reasonable spec-an though - a R&S FSU, which goes down to 20Hz, though I'm not sure what its dynamic range is at audio...
Cheers,
Suzy
Thus far (in LTspice) I've doubled he value of the emitter/source degeneration resistors in each stage, which lowers the gain for each stage (and improving the stability), plus decreasing the feedback divider to 1/11th.
With no input filter, its 3dB cutoff point is around 3MHz, and I measure (very slowly, as I've gotta set the time step way low to get anything meaningful) -98dB H2, -104dB H3, ?? H4, -112dB H5 (driven by a 1V pk 1KHz sinewave), and a 4 Ohm resistive load.
I'm playing with intermods at the moment - putting a 10KHz and 11KHz sine wave in and having a look for the 1KHz output, but can't sind it thus far (at -100dB).
Of course that begs the question of how to measure these things on the real thing... We're not really set up for audio measurement. We have got a reasonable spec-an though - a R&S FSU, which goes down to 20Hz, though I'm not sure what its dynamic range is at audio...
Cheers,
Suzy
Stochino
Hi Sam,
When I saw the Stochino schematic for the first time I got puzzled by some of his component choices. Input pairs were one of these. The main problem is that with 1Ns it's practically impossible to match N and P pairs. So from what was available I decided to go for 2SA970/2SC2240 - BL versions. One of the reasons was that I was already thinking on getting rid of the NFB cap.
I suggested these Toshibas to Alex and he got them and used together with IRFP240/9240s and a few other component changes such as 100ohm gate resistors. All the "technical" problems he experienced dissapeared. When it comes to the input pairs he was able to match these within 1%. I got 100 of each type but have not been so successful. I have to live with somewhat worse input pair matching.
Anyway, he is now trying to minimize offset to aceptable levels with the NFB cap removed. You can visit his site: www.soton.ac.uk and write to him. I'm sorry I distorted his name to Suton in my previous mail. I think my first two Stochino modules will become operational after Easter. I have my transformer station in a separate box so some advantage here except for the economy of course.
IRFP640s have a couple of advantages, however in this design practical problems may arise from overheating. I opted for the bigger devices straight away because I wanted to use large transformers which I had laying around for a few years and these were 2x45V. No way I could use 640s with these. In the end, having heard about Alex's problems, I bought 2x40V trafos. Maybe I'll use 2x45v ones in sub-amps.
cheers,
Hi Sam,
When I saw the Stochino schematic for the first time I got puzzled by some of his component choices. Input pairs were one of these. The main problem is that with 1Ns it's practically impossible to match N and P pairs. So from what was available I decided to go for 2SA970/2SC2240 - BL versions. One of the reasons was that I was already thinking on getting rid of the NFB cap.
I suggested these Toshibas to Alex and he got them and used together with IRFP240/9240s and a few other component changes such as 100ohm gate resistors. All the "technical" problems he experienced dissapeared. When it comes to the input pairs he was able to match these within 1%. I got 100 of each type but have not been so successful. I have to live with somewhat worse input pair matching.
Anyway, he is now trying to minimize offset to aceptable levels with the NFB cap removed. You can visit his site: www.soton.ac.uk and write to him. I'm sorry I distorted his name to Suton in my previous mail. I think my first two Stochino modules will become operational after Easter. I have my transformer station in a separate box so some advantage here except for the economy of course.
IRFP640s have a couple of advantages, however in this design practical problems may arise from overheating. I opted for the bigger devices straight away because I wanted to use large transformers which I had laying around for a few years and these were 2x45V. No way I could use 640s with these. In the end, having heard about Alex's problems, I bought 2x40V trafos. Maybe I'll use 2x45v ones in sub-amps.
cheers,
suzyj said:
Hi Suzy,
Since you have done a fair bit already, keep going and finish
the project. Lots of stuff gets discussed here but never finished
so I would rather an AEM in the hand than lots of great ideas
half finished.
I'll bet any money you get the bug and build another one anyway.
Probably need to pump the power up and the frequency to really
stress the circuit and get meaningful results.
We have a completely open loop design (no feedback) that
measures (not simulates) better than that at those power levels.
Probably the cheapest isa high quality sound card and some
software. There are some very good soundcards available now
with super low distortion. Currently the best is Lynx model 2
or L22 but they are quite expensive. There are others that
are very good for much cheaper. Goto
www.pcavtech.com for some tests.
I used to have access to Audio Precision system one which was
very good (residual = 0.0005 on a good day) and can still get
access to a very good analog HP spectrum analyser which goes
about -100dB if you do the FFT sweep very slow and keep sweep
BW small. But I can definately see a Lynx in my future 🙂
WRT syms, they will tell some things but don't be surprised
when real measurements don't come close, especially at
higher frequencies due to modulated capacitance and beta
anomolies not accurately modelled in software.
Cheers,
Terry
suzyj said:
I didn't suggest that. 🙁
As you have expressed for an amplifier with very low distortion I just presented one, use it for your brain workout or whatever! 🙂
Cheers Michael
Ultima Thule said:Hi Suzy,
here's another exciting amplifier with impressing figures from a talented Serbian designer called boraomega here on diyAudio. 🙂
Cheers Michael
Michael,
Very interesting design, very linear but quite simple = smart
designer. Also note, really the whole design has gone back to
basics and just adressed each stage.
Of note is the cross coupled IP pair, which I first saw on the
data sheet of MAT04 in a instrumentation pre schematic.
Have a think about how this works (x coupled IP pair).
Cheers,
Terry
Hi Terry,
Are you kidding?
yeah I know, that diff IP is a bit "special", one should think twice here! 😎
Do you have that MAT 04 app.note?
Cheers Michael
Are you kidding?
yeah I know, that diff IP is a bit "special", one should think twice here! 😎
Do you have that MAT 04 app.note?
Cheers Michael
Ultima Thule said:
Michael,
Am I kidding.... about what?
MAT04 -data sheet- analog devices website.
Cheers,
Terry
Terry,
I think Michael is saying that the Bora design is not exactly simple.
It's certainly understandable, but it ain't simple, all things are relative...... it's no-holds-barred zero distortion school. For myself, I think it's a bit verbose, but then, as you know, I regard some distortion as inevitable and seek only to keep it very low order.
Am I right, Michael?
cheers,
Hugh
I think Michael is saying that the Bora design is not exactly simple.
It's certainly understandable, but it ain't simple, all things are relative...... it's no-holds-barred zero distortion school. For myself, I think it's a bit verbose, but then, as you know, I regard some distortion as inevitable and seek only to keep it very low order.
Am I right, Michael?
cheers,
Hugh
Hi Terry, Hugh,
yes, I wouldn't expect even from an analog pro to say it's simple! 🙂
Thanks Terry for pointing to Anlog, in their drawing is an additional diff pair on top of the cross quad diff.
The cross quad diff is really seldom seen in audio circuits, at least I have only seen Dr. Bora's Delta using it.
Have any of you, or anybody else for that matter played around with the cross quad diff?
BTW, I just started a new thread about the Cross Quad here if you guys would like to discuss it further.
Cheers Michael
yes, I wouldn't expect even from an analog pro to say it's simple! 🙂
Thanks Terry for pointing to Anlog, in their drawing is an additional diff pair on top of the cross quad diff.
The cross quad diff is really seldom seen in audio circuits, at least I have only seen Dr. Bora's Delta using it.
Have any of you, or anybody else for that matter played around with the cross quad diff?
BTW, I just started a new thread about the Cross Quad here if you guys would like to discuss it further.
Cheers Michael
Hi Suzy,
any development reports? 🙂
Just in case, (as mentioned in my other thread) about the cross quad diff input stage in Bora's schematic I attached to my earlier post #66, it's output is on the wrong pin of the output pair as the XQ does invert the output compared to an ordinary LTP.
Cheers Michael
any development reports? 🙂
Just in case, (as mentioned in my other thread) about the cross quad diff input stage in Bora's schematic I attached to my earlier post #66, it's output is on the wrong pin of the output pair as the XQ does invert the output compared to an ordinary LTP.
Cheers Michael
Ultima Thule said:
So far I've layed out the power amp PCBs (I think I posted details earlier), plus a preamp board (based on the PGA2310, and shamelessly derived from Mark Hennesy's work.
I've also done a control/front panel board, with PIC micro, IR receiver for remote, and a fluorescent display, as well as a video switch board, using a pair of MAX4314 video switches to select between four S-video sources.
Finally, I've done a power supply board, which provides 5V for the control board, plus switched +/- 8V for the video board, and +/- 18V for the preamp board, as well as a soft-start for the power amp transformer.
That's it 🙂 five PCBs. It will all go into a box using Conrad MF25-100 heatsinks as sides, with the rest being made from sheet aluminium.
Hi susyj
can you email me pic-control electronics,display,pic source-code once you have it ready
and free of bugs
thanks in advance
kind regards
mastertech
can you email me pic-control electronics,display,pic source-code once you have it ready
and free of bugs
thanks in advance
kind regards
mastertech
Hi Suzy,
I'm curious to know how you are heatsinking the driver transistors. Also the mechanics for your output transistor heatsinks.
I am happy to offer other comments on your published PCB design if you're interested.
Cheers,
Ralph
I'm curious to know how you are heatsinking the driver transistors. Also the mechanics for your output transistor heatsinks.
I am happy to offer other comments on your published PCB design if you're interested.
Cheers,
Ralph
ralphs99 said:
The driver transistors and output transistors are both mounted underneath the PCB, and are in contact with the main heatsink. A bolt passes through the PCB, then a spacer (different thickness for driver and output transistors to account for their different thicknesses), then the transistors themselves, and finally tapped into the heatsink.
I figured having everything on the one heatsink would make it more compact and a little less fussy to build than having little heatsinks for the driver transistors, but it does mean I have to machine some spacers to go under the PCB.
It would be good to hear any comments you have on the PCB.
Cheers,
Suzy
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