Zero Feedback Impedance Amplifiers

[zinsula]

Originally posted by zinsula
Doesn't this depend frome the driver too? Note that Susan seems to use line array speakers, each driver being 2".

Well, my post was too late...and not quite correct...VERY nice looking speakers. Did you get those from a sculptor?

I have a separate bass speaker for that - which amongst other reasons is to minimize the Doppler effects

And those bass speakers fired with another of your amps? Or a passive crossover?

Tino

[Susan-Parker]

Hi everyone,

For those that might be interested, this is a higher power output transformer.

http://www.susan-parker.co.uk/zeus-out-tx-75w.htm

However I have yet to characterise it.

N.B. It's primary purpose is to extend the bottom end bass.

Best wishes,
Susan.

[Susan-Parker]

Hi Tino,

Originally posted by zinsula


Well, my post was too late...and not quite correct...VERY nice looking speakers. Did you get those from a sculptor?

And those bass speakers fired with another of your amps? Or a passive crossover?

Tino

Thank you.

Not exactly, they were made at a marble place outside Lisbon in Portugal. I have another two white shells and a couple of pairs of the previous version with smaller 50mm drivers.

That's all that exist on this planet - the marble place closed some years ago.

I did get quoted from sculptors here in the UK, and they were wanting about a thousand pounds each shell! Not commercially viable.

I am working on a torroid version (they don't work for a full range amp) amp for the bass speaker (which is 4 ohms). I know that torroids have been used for valve amps, but that is different. These saturate at about 10 kHz and start turning sine waves into square ones.

However at the moment we live in a small apartment and low bass isn't a strong requirment as we don't want to be anti-social!

IMHO crossovers should be in the pre-amp part, not in the speakers.

I use wide range drivers, first order crossovers and non-ported enclosures.

===

Hi PMA,

how about all of that electronics before your impedance amplifier. Does not it destroy the sound?

Not really. Like any electroncs design there are better and less good ways of doing things.

Most good systems are okay until one:

A. Uses phono cables to interconnect pieces of equipment.
B. Uses negative feedback amplifiers to drive loudspeakers.
C. Pays $10,000 for a pair of cables.

I am still refining the drive circuit for my amplifiers, but what I have at the moment works okay for the time being.

==========

Best wishes,
Susan.

[EUVL]

Susan,

Good lord, 9 pages in 2 days. I think you're doing 10 times better than Nelson Pass at the moment.

And I still think that you could offer interested parties a kit. Why not make the output transformers yourself and offer the pair at a fair price. And don't start work until you have say 20 units sold. John Clancy is starting a group buy in another thread for S&B input transformers, and says price drops significantly after 20 units. So if Sowter does not want the business, I am sure someone else in the UK might be.

You complain of having no success promoting your equipment commercially. Now this may be a start -- even if it may not make total sense financially. At least you're a lot more well known than 3 days ago. : )

Keep it going. Time to start a DAC thread under the digital forum, and a speaker thread at the speaker forum. Full invasion of diyaudio from 3 directions. : )


Patrick

[Susan-Parker]

Hi Everyone,

This is the bass speaker that goes with the spheres.

It was designed to be driven by a high power version of my amplifier.



http://www.susan-parker.co.uk/susan-speaker-bass.htm

As before I have pulled off the text I was using in the hope of commercial sucess - but everyone seemed to have been sold on the idea of ported designs. "Never mind the quality, feel the hammer blows to the tummy". Shrug.

Best wishes,
Susan.

[Susan-Parker]

Hi Patrick,

Originally posted by EUVL
Susan,

Good lord, 9 pages in 2 days. I think you're doing 10 times better than Nelson Pass at the moment.

And I still think that you could offer interested parties a kit. Why not make the output transformers yourself and offer the pair at a fair price. And don't start work until you have say 20 units sold. John Clancy is starting a group buy in another thread for S&B input transformers, and says price drops significantly after 20 units. So if Sowter does not want the business, I am sure someone else in the UK might be.

You complain of having no success promoting your equipment commercially. Now this may be a start -- even if it may not make total sense financially. At least you're a lot more well known than 3 days ago. : )

Keep it going. Time to start a DAC thread under the digital forum, and a speaker thread at the speaker forum. Full invasion of diyaudio from 3 directions. : )

Patrick

I didn't realize I was doing well at this - being the first time on the forum an' all.

If there really are people interested in having a go then I would be happy to do something.

However I will have to put in something for my time, and regretfully charge VAT (where appropriate).

I am reluctant to take money from people just because I think I have the best thing since sliced bread. I know how easy it is to get enthralled in ones own creations and forget that the rest of the world isn't necessary of the same opinion or reasoning.

I would propose that I could put together some bits for a stereo pair and send them to some third party (perhaps Graham Maynard if he has the time and is willing) who could give an independent and informed opinion.

It may be disappointing to me if it is not liked, but at least I won't have my name in the mud and people after my blood.

If it gets the thumbs up then I would be more than happy to supply kits to others interested in the amplifier - I could also match up mosfet pairs (I reckon that I need at least twenty from a batch to find close matches).

Whilst I would love to get involved in speakers and DACs for the time being I will have to content myself with this one thread about amplifiers as I regretfully don't have the time to deal with more than this (boring things like earning a living and homemaking).

Plus I have a commitment to finish off the design for a model steam locomotive boiler (totally different from anyone elses of course) which I want to have built for display at the Sandown Park model engineering exhibition (end of December).

Many thanks once again for your interest, enthusiasm and positive comments.

Best wishes,
Susan.

[till]

I am reluctant to take money from people just because I think I have the best thing since sliced bread. I know how easy it is to get enthralled in ones own creations and forget that the rest of the world isn't necessary of the same opinion or reasoning.

hey, people on this board build amplifiers for interest. We had amps made from power regulators, digital logic chips, lighbulbs, and high output impedance amps (see www.firstwatt.com). Who thinks he is in need of Krell or Mark Levinson gear should go an buy some. Who thinks he needs an easy to build sucess guarantied amp will build a gainclone. Who will be interested in your amp will be aware of it is only suitable for special taste and special speakers.

[Susan-Parker]

Hi Till

Originally posted by till


hey, people on this board build amplifiers for interest. We had amps made from power regulators, digital logic chips, lighbulbs, and high output impedance amps (see www.firstwatt.com). Who thinks he is in need of Krell or Mark Levinson gear should go an buy some. Who thinks he needs an easy to build sucess guarantied amp will build a gainclone. Who will be interested in your amp will be aware of it is only suitable for special taste and special speakers.

Thank you for your post and the reference to the First Watt amplifier, which I had not seen before.

----

I will look into the costs of supplying a basic amp kit if that is what people would like.

I am assuming thta I needn't worry about normal parts like DC power supply componets, heatsinks etc.?

I have asked a US based lamination manufacturer if they will supply direct to individuals in the US as the cost of shipping gets prohibitive over 2 kgs (4.4 lbs). Europe isn't as bad.

What would you consider to be the essential components required in a kit?

Many thanks.

Best wishes,
Susan.

[kilowattski]

I would say that the kit would be comprised of the input and output transformers. The power supply is simple enough for most any DIYer to tackle on their own and the other parts are fairly easy to get. BTW, great job on a very innovative design.

[enochRoot]

i agree...transformers only, but maybe make matched fets an add-on option for those of us that don't want to bother (or can't) match fets