John Curl's Blowtorch preamplifier part II

[kgrlee]

Originally Posted by kgrlee

I'll get my lawyers to see Yamaha et al for infringing my Powered Integrated Super Sub patents.

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.

[kgrlee]

Originally Posted by Chris Hornbeck

Those who have bothered to read through the thread know that this has been answered several times already.

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.

[bcarso]

Originally Posted by kgrlee

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.

[RNMarsh]

Originally Posted by kgrlee

______________
Mr. Marsh, I tried this in the 70's and it was old then. There was a very old Wharfedale Engineering Memo with test results too. As you say, 1 resistor.

Anyone got a copy of TAA article?

It's the great grandfather of the supa dupa ACE stuff.

I'm not sure you get bass extension though you get other good stuff.

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

[john curl]

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.

[kgrlee]

Originally Posted by RNMarsh

I somehow missed that Wharedale Engineering Memo of thiers. Maybe others did too. Send me a copy, pls.

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.

... I've never read anywhere about using a single resistor.

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.

[RNMarsh]

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 .... ?

[hitsware]

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 ............

[morinix]

John,
When you take your last breath humanity looses what you have mastered.

[Trevor White]

Originally Posted by bcarso

IIRC:
Essentially, two issues: unavailable parts; likely need for a lot of hand-holding.

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 !!