Just realised I know all about Yamaha AST. 😱
Wharfedale did an OEM AST for Yamaha. They were surprised that we knew at least as much as they did about it.
Most OEM projects are cost-cutting exercises by both parties but this was very satisfying cos their priority was to get best sound & performance.
They sent Tanaka-san, who designed the NS1000 as head of their Tech team. He was semi-retired and didn't really understand dis evil electronic stuff but all the young engineers deferred to him in everything.
I was honoured to meet the designer of probably the best Japanese speaker every made. Wharfedale bought a lot of competitor's speakers over the years. Most were unpacked, listened to, re-packed & returned the same day.
The NS1000 was one of only 2 competitor's speakers we kept and might appear in our Blind Listening Tests over nearly 2 decades.
Chris, I have read through several 100 pages of this thread(s) and know JC has refused several times to release the schematic. But I don't see where he says why.
Please excuse me for not reading all 2000+ pages but its hard for a beach bum hu kunt reed en rite. 😱
IIRC:
Essentially, two issues: unavailable parts; likely need for a lot of hand-holding.
Gorey details
I somehow missed that Wharedale Engineering Memo of thiers. Maybe others did too. Send me a copy, pls. But, if it was the same well goody for them. I have no idea now when I did it... but it was done on a Hafler amp, first. I've never read anywhere about using a single resistor.
My article with it was a different amp but nothing special other than low feedback which at the time was thought must have high distortion. So, I wanted to show that wasnt necessarily so. I was aware of the ACE Bass of the era. It never worked for me when I tried it. But my idea was more inspired by Giles Hibbert from Blackfriars, Oxford.... if one needs the gorey details. From a small 1/3 page circuit idea quicky in the back of W.World which showed no data... just an idea. Well, as ideas go, one thing leads to another. I published my version's results more publicly for all... rather than an engineering memo. I am sure of what I did and showed the measured results. Thus, perhaps, contributing to its acceptance over here on this side of the pond. Thx-RNMarsh (Today, I went and bought some Motional Feedback resistors to do it to the amps I have now) All should try it - just need to be sure of the value for your amp and the grounding has to be beefed up for the high current and the like. None of which i intend to get into... there are enough talents here to figure it out themselves for thier own amps.
Today, I would do it only for dedicated bass amps, though. -Thx RNMarsh
I somehow missed that Wharedale Engineering Memo of thiers. Maybe others did too. Send me a copy, pls. But, if it was the same well goody for them. I have no idea now when I did it... but it was done on a Hafler amp, first. I've never read anywhere about using a single resistor.
My article with it was a different amp but nothing special other than low feedback which at the time was thought must have high distortion. So, I wanted to show that wasnt necessarily so. I was aware of the ACE Bass of the era. It never worked for me when I tried it. But my idea was more inspired by Giles Hibbert from Blackfriars, Oxford.... if one needs the gorey details. From a small 1/3 page circuit idea quicky in the back of W.World which showed no data... just an idea. Well, as ideas go, one thing leads to another. I published my version's results more publicly for all... rather than an engineering memo. I am sure of what I did and showed the measured results. Thus, perhaps, contributing to its acceptance over here on this side of the pond. Thx-RNMarsh (Today, I went and bought some Motional Feedback resistors to do it to the amps I have now) All should try it - just need to be sure of the value for your amp and the grounding has to be beefed up for the high current and the like. None of which i intend to get into... there are enough talents here to figure it out themselves for thier own amps.
Today, I would do it only for dedicated bass amps, though. -Thx RNMarsh
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Thanks Chris and Bcarso for explaining why I don't publish the schematic. I think that much of the input to me is not for the reason usually offered.
Sadly, the whole stash of Wharfedale Eng. Memos has gone to the bonfire in the sky. 😡
I wish I still had some. Loadsa stuff including the LEAK Truspeed (suspended chassis turntable) which is around the time of the AR turntable. Not quite clear which came first but Tony Emerson certainly modified Truspeed cos he found the AR had better isolation.
Mr. Marsh, for what it's worth, the Yamaha patent, once you get past the fancy EQ, doesn't really do more than your single resistor.
So all credit to you for making this simple technique more widely known and pointing out the THD reduction benefit. In my book, elegance & KISS has a very high standing.
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I have a system in the garage -- Tv and cd/dvd player and Tv and now shared with a pool table et al.... There, I have a Yamaha bass/sub with some sort of built in electronics which they claim as some form of servo. But its only a couple years old... do you think.... ? could it be...... ? Is it .... ?
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Amazon.com: Yamaha YAS-101BL Front Surround System, Piano Black: Electronics
Yamaha always was inovative ........
The easiest way to servo a woofer is to use a DVC woofer.
Output of amp to 1 coil and feedback from the other.
Makes the 'speaker as a microphone' a new and insightfull
phrase ............
Yamaha always was inovative ........
The easiest way to servo a woofer is to use a DVC woofer.
Output of amp to 1 coil and feedback from the other.
Makes the 'speaker as a microphone' a new and insightfull
phrase ............
What about if someone needs to repair one ?? Where do they get the service information from ?
There are lots of schematics and SM's for amplifiers no longer made or with parts that are no longer available. Big fiz !!
Also how about the guru publish a design aimed at diyer's after all this is a diy forum 😉 Too much to ask I guess or maybe it just avoids scrutiny !!
Blowtorch is a legend.
You don't know the secret of the happy hours to sold the parts.
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As far i'm in concern, this preamplifier is a master piece that:
- I have never seen.
- I have never listened to.
- I am not rich enough to even dream to buy.
- Is no more on the market
- His author refuse to show the schematic.
- His author refuse blind tests of it.
- Was build with mysterious and/or now obsoletes parts.
- Is build with perfect wires sensible to the current flow witch need to be burned out during 30 days on the coil and 30 more days after assembly (assembly process being sensible to the hours of the day).
- Is claimed by his author as one of the best of the world (if not the best).
- Is the matter of a thread of >= 1470 pages.
Can-you imagine the idea i can have about the intellectual sanity of my neighbors. 😉
And mine, to keep posting on this thread, as well.
- I have never seen.
- I have never listened to.
- I am not rich enough to even dream to buy.
- Is no more on the market
- His author refuse to show the schematic.
- His author refuse blind tests of it.
- Was build with mysterious and/or now obsoletes parts.
- Is build with perfect wires sensible to the current flow witch need to be burned out during 30 days on the coil and 30 more days after assembly (assembly process being sensible to the hours of the day).
- Is claimed by his author as one of the best of the world (if not the best).
- Is the matter of a thread of >= 1470 pages.
Can-you imagine the idea i can have about the intellectual sanity of my neighbors. 😉
And mine, to keep posting on this thread, as well.
Du.uh! Not sure how JC translates this into good excuses for not posting a schematic .. 😕
I'm sure there are enough true gurus here who can help find replacements for Unobtainium and provide alternative hand-holding ..
JC can sit on the sidelines & yell out, "Hot!", "Not even warm!" or "Cold!" as appropriate and as it suits his fancy. Brad & Scott will ply him with $zillion glasses of vino.
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I have. It seemed fine.
The schematic isn't that mysterious and can be pieced together from knowing the topologies that John generally uses, looking at the hints given, and a bit of common sense. The special thing about it lies in the stories about the materials used; beyond that, what you have is a solid, well-engineered preamp.
thousands and thousands of posts by the so called guru and not one proposal for a diy project for the benefit of our less learned guests !! The excuses are totally absurd 🙁
Actually, there was. It's in a separate thread on discrete opamp design. Ended up with Scott Wurcer putting up some interesting designs.
If John doesn't want to post an explicit schematic, that's his right. He has said several times (and he's right) that if you can't puzzle out the schematic from what he's disclosed and the photos, you'd have little chance of getting the thing right even with an explicit schematic.
If John doesn't want to post an explicit schematic, that's his right. He has said several times (and he's right) that if you can't puzzle out the schematic from what he's disclosed and the photos, you'd have little chance of getting the thing right even with an explicit schematic.
The hardest would be the case. The controls and sw,s I am sure you could get better ones today, provided you have the money. The connectors and the PCB material was also discusted a while back, and most likely you could get better ones ,or least similar quality. The topology as Sy said, can be pieced together. What is left are those rare fets. So the whole thing would be like a semi interesting puzzel. If you need a pre amplifier. I don't. 🙂
OK, and thanks SY (for once) for coming to my defense on this. For some reason, I have to take a number of 'cheap shots' every week, and I have to 'lump' it.
The design is a 4 quadrant, all fet, folded cascode, first used by Charles Hansen, but WITHOUT an output buffer. The unit is double servoed, and has no global feedback.
It is essentially a terminated (1K) balanced-in, balanced-out transconductance amplifier operating in rich Class A, at about +/- 30V, which is highly regulated.
At the time of my first refusal to publish the exact schematic, I was still finishing the units started by my former business partner, Bob Crump, and I still had one or two for sale ultimately, so I decided not to release the schematic at that time.
Now, that time has passed, and the parts difficulty has recently been reduced by Linear Systems. Now all you have to do is buy a bunch of complementary J-fets, pick only the highest Idss units, then get a very good match (at least 1ma) or better.
Any qualified design engineer can built their own circuit from this description. Some already have.
For the record, the exact schematic is not really the point of this exercise. It is the WAY that we put everything that we could think of into the Blowtorch, to make it as close to a 'straight wire with gain', as possible, AND we were successful.
I have given a number of circuits here that people could take, AND build.
For example the schematics for Parasound JC-2, and Parasound JC-3 are on this website, and the Levinson JC-2 and JC-3 power amp are here as well. Build those with my blessing.
The design is a 4 quadrant, all fet, folded cascode, first used by Charles Hansen, but WITHOUT an output buffer. The unit is double servoed, and has no global feedback.
It is essentially a terminated (1K) balanced-in, balanced-out transconductance amplifier operating in rich Class A, at about +/- 30V, which is highly regulated.
At the time of my first refusal to publish the exact schematic, I was still finishing the units started by my former business partner, Bob Crump, and I still had one or two for sale ultimately, so I decided not to release the schematic at that time.
Now, that time has passed, and the parts difficulty has recently been reduced by Linear Systems. Now all you have to do is buy a bunch of complementary J-fets, pick only the highest Idss units, then get a very good match (at least 1ma) or better.
Any qualified design engineer can built their own circuit from this description. Some already have.
For the record, the exact schematic is not really the point of this exercise. It is the WAY that we put everything that we could think of into the Blowtorch, to make it as close to a 'straight wire with gain', as possible, AND we were successful.
I have given a number of circuits here that people could take, AND build.
For example the schematics for Parasound JC-2, and Parasound JC-3 are on this website, and the Levinson JC-2 and JC-3 power amp are here as well. Build those with my blessing.
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