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05-22-2005 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,345
Joined on 05-28-2004

Post #: 1
Post ID: 1017
Reply to: 1017
“A” sound from “B” system?

Me! Me! Me! Me! Me! Me!

Me and sub-90dB sensitive speakers and not SET amplifiers! I would rather raise money for Bush/Chaney campaign or to merry a Fidelity Investment business annalist.! However, it is what I am currently listening.

A couple weeks ago I put my paws on Dima Kireev’s amplifier. This is kind of one-stage hybrid that utilized Dima’s proprietary class “FAGB” operation. The amp is somewhere above 150W and can drive anything: from 2uF capacitor to an extra cheese pizza. I did submerge the output cables into the pizza souse and can testify that pepperonis were jumping in the pizza’s cheese well according the amplitude of the input signal… :-)

The amp now is under evaluation. It has no name but operationally I call it “The Breathe of Apocalypses”. This amp is a SS brother of Melquiades and it behaves accordingly so far. I kind of have those beautiful signs of the Melquiades’ dynamic anomalies. It is too early to make any further of final conclusion about it’s sound but even now there are few interesting things in that this amp does.

DimaAmp.jpg

The loudspeakers are 88dB wonderful Scan-Speak 21W/8555-00 drivers in acoustic suspended sealed-inclosure and ribbon tweeters.

Rgs,
The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
05-22-2005 Post does not mapped to Knowledge Tree
Chirag
New York
Posts 32
Joined on 06-13-2004

Post #: 2
Post ID: 1018
Reply to: 1017
SS + SS!

Hi Kitty,

This combo is quite interesting and amazingly coincidental....I had scan speak 18W's sitting around from my old speakers and just recently had them put in sealed boxes.  I was using a Seas silk dome on top (in free air) but found out an old discontinued pair of, believe it or not, radio shack ribbons had a much more tonal respect.  I'm still struggling with finding a good baffle step for the crossover and ribbon xover points (no time!), but it still does several things correctly.

Keep us updated on this FAGB DimAmp...it would be interesting to see how much musical sauce this SS amp offers the pizza baking stone compared to the Melquiades.

Best,
Chirag

05-22-2005 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,345
Joined on 05-28-2004

Post #: 3
Post ID: 1019
Reply to: 1018
“DimAmp” is very slick name for this amplifier ...

....and particularly for us - the software freaks, for whom the word “Dim” has an "added value"….  Sure I will keep informing how it goes…

The Scan-Speak’s SD-1 “smartly overhang” motors are very interesting and if your 18W is made around the SD-1 then it is it certainly the thing to try.

The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
05-22-2005 Post does not mapped to Knowledge Tree
Chirag
New York
Posts 32
Joined on 06-13-2004

Post #: 4
Post ID: 1020
Reply to: 1019
SD-1
I have no idea what the SD-1 motor is, but i know my woofers have it and they give me decent results.  if only SS would make a high efficiency woofer with softer paper cones and double the SD magnet....

Hey, what kind of crossovering is the DimAmp seeing?  Are you sticking to 1st order slopes even with the nasty breakups higher up in the 21W carbon woofer?

best,
c

btw, I have some midrange and midbass horns sitting next to me that I'll get a chance to utilize after an exam in a few weeks...i won't have anything below 80hz or over 10k (or an amplifier!), but it will be a very interesting start....
05-23-2005 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,345
Joined on 05-28-2004

Post #: 5
Post ID: 1021
Reply to: 1020
Chirag about to step into the muddy water of hornoswamp...

 Chirag wrote:
Hey, what kind of crossovering is the DimAmp seeing?  Are you sticking to 1st order slopes even with the nasty breakups higher up in the 21W carbon woofer?

Sure, my 21W has no “nasty breakups higher up”, well it perhaps has after 5-7K but I do not go this far. The speaker all-together are very much not perfect but it does what need from it - namely to get a rough picture of the DimAmp amplifier. The more demanding and conclusive listening will not be via those speakers. I do not what to put any time in those speakers (they are without the tweeters are my delay channels) but to my surprise the speakers perform way better then it would be expected from 5-minutes-made loudspeaker. Well, they sound better then 90% of the CES presented loudspeakers… :-)
 Chirag wrote:
btw, I have some midrange and midbass horns sitting next to me that I'll get a chance to utilize after an exam in a few weeks...i won't have anything below 80hz or over 10k (or an amplifier!), but it will be a very interesting start....

Hey, this is nice; keep posted, probably in a new thread, something like “Chiragy horno-ride”

:-)
The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
05-23-2005 Post does not mapped to Knowledge Tree
Alex Yakovlev
NJ, US
Posts 45
Joined on 10-06-2004

Post #: 6
Post ID: 1023
Reply to: 1017
Re: “A” sound from “B” system?
What is the volume of those SS enclosures?
Dima's amp looks weird, I like it. Don't enclose it...
05-23-2005 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,345
Joined on 05-28-2004

Post #: 7
Post ID: 1024
Reply to: 1023
Dima’s Amp: the first blood.

Alex, I do not remember already the volume of those boxes, what is the deference? Thos drivers have an average sealed Qs and Fs I believe 19Hz, you might easy to circulate any volume you want. I slightly overdamped them, as usually, form where they should be…

Anyhow, I took the DimAmp today for a first time to walk out of my home. I stoped at a local friend of mine and let the amp to drive Kharma Ceramique 3.2 loudspeakers. The speakers have sub 90dB sensitively and power handling slightly less then 5W. This Kharma are king of solid-state sounding with typically aggressive Focal tweeter that was specially designed to whistle the brains out of the reviewers heads. With all imperfections the Kharma 3.2 are the best Kharma loudspeakers and I was interested how the DimAmp would be able to deal with them. Certainly those loudspeakers are very much from faultlessness but what do you want form a high-end product that cost juts $25.000?

To my surprise it was not bad. I mean I am looking at the time I spent listening all of it and I can’t recall the negative effect that I would typically attributed to amplifiers. Certainly the Kharma 3.2 is not a real loudspeaker in obsolete trims and they, while were driven by DimAmp, were the weakest element of that installation… However the one step at time. The DimAmp had swallowed the Kharma 3.2 easy and without even chewing. Now I need a serious contestant to drive… the prospective candidates are shaping up already… 

Meanwhile the amp is driving my woofer towers…

BTW, I think Dima has a Real name for his amp. I hope he would show up in here and would let us know it… The good thing should be referred by own name… It really deserves it.

Rgs,
The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
05-23-2005 Post does not mapped to Knowledge Tree
Chirag
New York
Posts 32
Joined on 06-13-2004

Post #: 8
Post ID: 1025
Reply to: 1023
Size of Box
Alex,

I tend to aim for Q's around 0.5-0.6 for my sealed boxes, but thats only because I prefer my listening in smaller nearfield rooms.  If you have a much larger room, you *might* be able to get away with something closer to 1.

the 18W works fine in 0.5cu ft...I bet the 21W will work the same with a bit more extension in 0.75-1cu ft.  But like Romy said, these aren't exactly end all speakers.  I just needed something not attached to my skull while I study for an exam coming up since I don't have the time just yet to figure out what the hell amplifier I need for Tantrics...

Best,
Chirag
05-24-2005 Post does not mapped to Knowledge Tree
deemon
Posts 23
Joined on 05-25-2004

Post #: 9
Post ID: 1026
Reply to: 1024
Re: Dima’s Amp: the first blood.
 Romy the Cat wrote:

BTW, I think Dima has a Real name for his amp. I hope he would show up in here and would let us know it… The good thing should be referred by own name… It really deserves it.


OK , being inspired by Romy's Melquiades :-) I do propose another exotic name to this beast - Zarathustra ! I think the name is good , isn't it ? ;-)

Best regards
Dima
05-24-2005 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,345
Joined on 05-28-2004

Post #: 10
Post ID: 1027
Reply to: 1026
Also Sprach Zarathustra...

Interestingly that I did not know what Zarathustra was. I heard this word somewhere as Richard Strauss’s composition but I never knew what was behind it. I would encourage whoever does not know to families themselves with what “Zarathustra” is all about.

http://www.livius.org/za-zn/zarathustra/zarathustra.htm

http://etext.library.adelaide.edu.au/n/n67a/

Rgs,
The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
05-24-2005 Post does not mapped to Knowledge Tree
Alex Yakovlev
NJ, US
Posts 45
Joined on 10-06-2004

Post #: 11
Post ID: 1028
Reply to: 1027
Speakers...
The reason why I asked about speaker enclosures is that I played with few SS drivers and the only one that I was able to make sound reasonably good in small box was 18 cm Revelator.
08-03-2005 Post does not mapped to Knowledge Tree
morricab
Posts 51
Joined on 07-13-2005

Post #: 12
Post ID: 1259
Reply to: 1017
Re: “A” sound from “B” system?

Hi Romy,

Could you explain a little more about the amp?  If I understand you correctly it is a 1 tube stage with solid state (Mosfet or Bipolar??) output.  If it is Mosfet then it is likely to be running without negative feedack, is that right?  I am quite interested in this kind of amplifier because I have heard a couple that can compete very well with the better tube amps I have heard.  My own amp is a Sphinx Project 14 that is using 2 tube stages and MOSFET output with no negative feedback.  I have also an amp on loan that is using only 1 tube stage and MoSFET output with no feedback.  Both can drive just about anything and both sound quite correct tonally and dynamically.  The sphinx is also biased about 30 watts Class A and the smaller amp is about 15 watts Class A, so under normal conditions they never leave Class A.  I don't know how many other hybrid amps you are familiar with, Romy, but another one to check out that I heard good sound from was the Pathos InPower. 

08-03-2005 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,345
Joined on 05-28-2004

Post #: 13
Post ID: 1262
Reply to: 1259
Dima's Zarathustra amp.

 morricab wrote:
Could you explain a little more about the amp?  If I understand you correctly it is a 1 tube stage with solid state (Mosfet or Bipolar??) output.  If it is Mosfet then it is likely to be running without negative feedack, is that right?  I am quite interested in this kind of amplifier because I have heard a couple that can compete very well with the better tube amps I have heard.  My own amp is a Sphinx Project 14 that is using 2 tube stages and MOSFET output with no negative feedback.  I have also an amp on loan that is using only 1 tube stage and MoSFET output with no feedback.  Both can drive just about anything and both sound quite correct tonally and dynamically.  The sphinx is also biased about 30 watts Class A and the smaller amp is about 15 watts Class A, so under normal conditions they never leave Class A.  I don't know how many other hybrid amps you are familiar with, Romy, but another one to check out that I heard good sound from was the Pathos InPower. 
Morricab,

I am not in position to comment about the Zarathustra amp. There is Dima, who is hanging around this forum, the actual godfather of the Zarathustra and he should and could be the person with whom you might collaborate on it. Ironically, Dima designed this amp in order to let a windy friend of mine (who was at that time was about to mass manufacture electrostatic loudspeakers) be able to drive with Zarathustra a have capacitive load…

Rgs,
Romy


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
08-04-2005 Post does not mapped to Knowledge Tree
deemon
Posts 23
Joined on 05-25-2004

Post #: 14
Post ID: 1264
Reply to: 1259
Re: “A” sound from “B” system?
Hi all !

 morricab wrote:

Hi Romy,

Could you explain a little more about the amp?  If I understand you correctly it is a 1 tube stage with solid state (Mosfet or Bipolar??) output.  If it is Mosfet then it is likely to be running without negative feedack, is that right?  I am quite interested in this kind of amplifier because I have heard a couple that can compete very well with the better tube amps I have heard.  My own amp is a Sphinx Project 14 that is using 2 tube stages and MOSFET output with no negative feedback.  I have also an amp on loan that is using only 1 tube stage and MoSFET output with no feedback.  Both can drive just about anything and both sound quite correct tonally and dynamically.  The sphinx is also biased about 30 watts Class A and the smaller amp is about 15 watts Class A, so under normal conditions they never leave Class A.  I don't know how many other hybrid amps you are familiar with, Romy, but another one to check out that I heard good sound from was the Pathos InPower. 




Yes , it's one tube stage ( SRPP ) input with bipolar follower output . I used a very special output circuit , it works without feedback in AB class . And what is interesting - the bias is relatively small , not more than 1 W in Class A , so we have "pure" AB .....  

Best regards
Dima
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   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  A quest for a better monitor...  Dome tweeters and brightness in SL600...  Audio Discussions  Forum     97  591376  06-08-2006
  »  New  Rightsizing from extreme systems......  It is Hot! The summer playback...  Audio Discussions  Forum     7  42131  06-17-2006
  »  New  Cool running AB amplifier.. with good sound...  How about more current integrateds?...  Audio Discussions  Forum     11  62917  07-25-2006
  »  New  Macondo’s MiniMe or about Pilot Acoustic Systems..  Injection Pilot?...  Audio Discussions  Forum     213  1129861  09-03-2008
  »  New  Yamaha B-2 V-FET amplifier...  I do like my B-2...  Audio Discussions  Forum     19  111298  07-20-2009
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