Sorry ZM. I can post circuit today when I get home if you are still interested.
The attached and simplified schematic was shown by Mr. Pass at BAF 2015 using IXN....Mosfet; except a VFET is used instead. It "Schades" a solid state triode. Is there added value to this approach [though redundant!], and/or can too much of 'triode'ing" be detrimental to sonics?
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Papa's amp is setup for push pull up to 2 x bias. The top device acts as a source follower it's not your regular ccs.
Edit: I think I misunderstood what you are trying to discuss. I'll think about it.
http://www.diyaudio.com/forums/atta...s-your-diy-pass-amplifier-20150323_202744.jpg
This type of heatsink and I will use 4 of them in this amp.
Hi Tord,
Thanks for the picture! They look incredible and LARGE! Where do you buy them - only in Sweden?
The guys from Linear Systems did a very thorough walk-thru towards the end of the day, including interviews.
I was kind-of clamped to my chair most of the day and didn't get out and about until it was over.
60+V SMPS's are commonly available for industrial electronics. A trusted brand is Lambda which was founded in San Diego, is still there, and currently owned by TDK. Attached is an image of their Vega line which outputs up to 62V. Another option is the Ametek/Sorensen XG and XFR Programmable rackmount PSU's. Used mostly in process and robotic control. Attached is the front page from their XG brochure.
While the Lambda can be purchased used for around $200-$250, the Sorensen's are not cheap. A XG or XFR with 60+VDC output is normally $700+. Then there is the noise, both ambient fan noise and ripple noise.
The most important question with SMPS is "but will it sound good"? I owned a Yamaha "tour amp" with "750W x 2 into 8 Ohms" in a 2U package, but it never sounded right - no coherence, flat dynamics, very little cadence. Dumped it and bought a Nakamichi PA-7, restored it, and am 100 times happier. The flip side of the coin is a Studer 961 mixer, the goto location mixer for the classical recording engineer, and it uses a SMPS with 15V rails. Seems to do pretty well to my ears.
So if the consensus is that a SMPS could and would work in this minimalist topology, I'd be all over it. So what's the word?
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Here's a much lower cost alternative to a 60V SMPS, and may well be worth doing an A/B with a linear supply.
Siemens SITOP 24V 20A industrial power supplies on eBay can be had for around $100 each. These are very well built units for use with robots. I use them to drive my DC motors and they run 24/7. The best thing about them is that they are fanless. No noise, just heat. The not so good thing is that its ripple spec is at <200mVpp. To step it up to 60V rail voltage, just use a DC to DC converter. I found one for $21.66 on Amazon, with a purported 600W rating. It looks like it may even work as advertised: here's a YouTube review: https://www.youtube.com/watch?v=cUpJs6Z41YM.
So for $250 plus PS caps, this may be a good SMPS solution. The unanswered question still is: "but will it sound good"?
Siemens SITOP 24V 20A industrial power supplies on eBay can be had for around $100 each. These are very well built units for use with robots. I use them to drive my DC motors and they run 24/7. The best thing about them is that they are fanless. No noise, just heat. The not so good thing is that its ripple spec is at <200mVpp. To step it up to 60V rail voltage, just use a DC to DC converter. I found one for $21.66 on Amazon, with a purported 600W rating. It looks like it may even work as advertised: here's a YouTube review: https://www.youtube.com/watch?v=cUpJs6Z41YM.
So for $250 plus PS caps, this may be a good SMPS solution. The unanswered question still is: "but will it sound good"?
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This one could work. And it has aux voltage outputs that can be used by those who want to bias SITs.
Connexelectronic
Connexelectronic
Hello ci11. May consider a Li-ion or a sealed Pb-acid battery PSU to play your music, and then recharge it when the sound system is off. If several batteries are in series, one may do a stepped [vari-proportional comes to mind] PSU to manage heat. I'll look [n Google] for the battery, and its power capability which is currently used in hobby drones; soon to flood the marker in December.
Hi Antoinel,
Thanks for the suggestion.
SLA may well be a good option - one of the country's top mastering engineers told me years ago when I was in his studio that his main console and amps ran on batteries. I also have some "extreme" audiophile friends who claim they could even hear the difference between various chemistries.
Do you have something specific in mind?
Hello ci11. It is an interesting thought [or a reality] that different chemistries in batteries affect subjective performance of audio gear. I do not have anything specific except to think out loud as follows:
1. A suitable linear power supply is one like used in a commercial 200-500 W [a guess] Class A amp. One may build it given respectable and equivalent components and its schematic.
2. Hopefully Mr. Pass will grant diyers the details of the specific PSU for the SE units he already showed at BAF 2015. He excels at designs of linear PSUs which are practical and have respectable performance.
3. Why not consider a battery as a potential option to power this Class A brute? The overall technology of batteries is highly advanced. Among the PSU options of linear, switching, battery, one will choose the PSU with the optimal balance of cost, complexity, performance and long term reliability. I hope that your friends who practice battery PSUs can share with you the balance of these vectors in the event that you choose this path. They already have valuable data, and designs.
Hi Anotinel,
Yes, I do have Mr. Pass will share his wisdom on the PSU. For now, I am planning one half of his CSX1 PSU, and he already answered an earlier post of mine re sizes of caps needed.
Alas, the mastering engineer "friend" was actually a prospect (not yet customer) when I was in the business 20 years ago. We are quite far apart now - industry wise or physical vicinity. I seem to recall something a "subfloor full of car batteries". For this 200W dissipation amp, a battery solution may well be feasible. Let me check with the boss to see how she feels about it.
So I am waiting patiently to see how this unfolds - papa will finish his article in due course and I will study it deeply before proceeding.
Thanks again for the inspiration.
I am ready... ?
Hi all,
I have the attached case ready, with Noctua fan of right size and heat sinks to go inside the square pipe. I used this pipe for F6 for some days and it was more than enough.
I have two power supplys that have two adjustable 30V 3A and in series can make two 60V 30A, just short of 3.2A. FETs are cominig soon from Mouser I am open to the suggestion of power supply.
I also have two 48V 16A SMPS which can be used with DC-DC converter that ci11 suggested? These can even go inside the pipe(120mmx120mm internal).
So help me try this amplifier cicruit with power supply idea.
BTW, I have limited experience with battery for audio and I felt the differences from SLA, Li-ion, and Li-Fe in FET preamp. I liked the SLA and got this feeling that 'why inefficient things normaly sound better?' One thing about the SLA is that the voltage drops over a time unlike modern LI-ion or Li-Fe, and this high current from battery kind of scares me. But I would like to listen if I have a chance.
One link about battery for tube audio. Warning!
Chul
Hi all,
I have the attached case ready, with Noctua fan of right size and heat sinks to go inside the square pipe. I used this pipe for F6 for some days and it was more than enough.
I have two power supplys that have two adjustable 30V 3A and in series can make two 60V 30A, just short of 3.2A. FETs are cominig soon from Mouser I am open to the suggestion of power supply.
I also have two 48V 16A SMPS which can be used with DC-DC converter that ci11 suggested? These can even go inside the pipe(120mmx120mm internal).
So help me try this amplifier cicruit with power supply idea.
BTW, I have limited experience with battery for audio and I felt the differences from SLA, Li-ion, and Li-Fe in FET preamp. I liked the SLA and got this feeling that 'why inefficient things normaly sound better?' One thing about the SLA is that the voltage drops over a time unlike modern LI-ion or Li-Fe, and this high current from battery kind of scares me.
But I would like to listen if I have a chance. One link about battery for tube audio. Warning!
Chul
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