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Old 16th May 2006, 09:02 PM   #161
Mad_K is offline Mad_K  Norway
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Nice! I think SEWA will rock pretty good on those Forte models
I have the RB75 and I am very satisfied with the combination..
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Old 17th May 2006, 03:11 PM   #162
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Mads:

Do you have any gerbers available for this board? I would like to get boards built. I realize I can do it the "other way", but gerbers would be great. Thanks!

Chris
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Old 17th May 2006, 05:34 PM   #163
Tyimo is offline Tyimo  Hungary
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Default The listening test

Hi Mad!

I report you about my listening test.
I told you already that it was not realy 100% A-B test, but even more to collecting the listening first impressions.
I don't want (and can't ) to explain which amps how was sounding, just to say shortly the most important impressions.
We tryed each amp with each preamp and loudspeakers and offcourse with different cabels.

The sources:
Yamaha CDX-993
Yamaha DVD S-830 for DVDAudio
Marantz CDP 5000

The cabels:
VDH-Clearwater
Cardas
Monitor-Symetric
Oelbach-Rattlesnake Silver
DIY CAT5

The loudspeakers:
Impulse H6 /90dB
Shahinian Compass clone /89dB
My own design: BR-TML speaker /90dB

The preamps:
2 BOZ (with different pots and parts)
2 BOSOZ (with different pots and parts)
REMUS Tube Line Stage
MF X-10D tube buffer

The amps:
Hiraga Le Monster-with original transistors!
JLH1969-with MJ15003 transistors
ZEN "classic"
ZEN ZV4
ZEN BALANCED 25Watt
Zen Lite
Aleph5
Gaincard with LM 1875
ION Obelisk clone
Quad II. tube amp
and the SEWA V1 with 30VDC/2A= 10Watt

The musics:
Patricia Barber -ModernCool
Patricia Barber-Verse
Renaud Garcia-FonsTrio-Arcoluz
Diana Krall DVD Audios
Massive Attack, BEP

And here comes the result:

First: every amps are very good amps, each are better than any commerse HI-FI (SONY,DENON, ETC.)

The weaklings:
-ION Obelisk clone Class AB amp: nice sound, good for office or kitchen :-)
-Gaincard with LM 1875: nice clear, but a kind of solid state sound
-Quad II. tube amp: nice, but a bit boring and lifeless tube sound

The serious amps:
-Hiraga Le Monster: very nice and strong sound, but nothing special, if not that: You can't believe how can this 8 Watt amp to be so strong!!
-JLH1969: this is realy a very good sounding amp! A refference amp for ever. Very musical sound, one of the best.
-ZEN "classic": nice and very pleasant sound for the ears, but the bass, dynamic, details, soundstage imagineing not so perfect than the ....... see later
-ZEN ZV4: nice and very strong and dynamic sound, but also not perfect like the......
-ZEN BALANCED 25Watt: nice and brutal strong dynamic and bass etc. sound! A bit "dark" or gloomy sound. I am afraid I prefer the 2nd harmonic distorsions more....
-Zen Lite: It is a realy nice sounding amp, almost perfect, but the details and the sound stage imagineing and the bass control are not so fine than the....... see later
-Aleph5: very nice tube like sound with brutal power and dynamic.
-SEWA V1: O.K. here comes the winner! Nice, soft, warm etc. sound, but the most important what makes this amp unambiguous better than the others are the very strong and realy(!) detailed, controled bass, mega-brutal dynamic, incredible fine micro details and excellent 3D sound stage. The music simply alive in the listening room!!!
I have never listened or felt such a good presence feeling!

One more thing: maybe I am a sick perverse, but I like my BOZ very much. It has not so relaxed sound than the BOSOZ but the BOZ's "excited" sound make the details sharper.
Interesting: The ZEN "classic" and the ZEN ZV4 liked very much the MF X-10D tube buffer between the preamp and the amps. The improvement was realy big with the tube buffer, but my SEWA V1 worked excellent even without the buffer and gave the same nice warm sound!!

So, I tryed to explain my feelings and experiences. Sorry for my bad english, but I think, if I could speak even perfect it would also very hard to write down what I heard.
And for last: offcourse the most important: the whole HI-FI is standing on matter of taste!
But, the SEWA V1 is realy better!!!!


Thanks and Greets for Mr. Pass and Mad!!!!

Tyimo
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Old 17th May 2006, 07:23 PM   #164
lohk is offline lohk  Europe
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Thanks for that test, Tyimo, and do not worry about your english - it was clear in all details. This is definitely mouthwatering and makes at least me looking forward to the boards too. Very much indeed.

Klaus
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Old 18th May 2006, 05:33 AM   #165
Mad_K is offline Mad_K  Norway
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Default Listening test

WOW! What an interesting comparison! I have much the same impression as you have, so I found your results to be very accurate! Your english is more than good enough Maybe the most interesting finding (to me) was the discovery that BOZ was the best preamp for SEWAr1. I've just tried BZLS (BOSOZ), PASS X2r1 (also DIY) and some opamp designs (OPA2134, OPA627 and OPA2227). From these the X2r1 was the best, but now I'm very curious about the BOZ..


Chris; as soon as this proto-batch is verified, I'll order a new batch of boards Anyone interested should send me a email so I know how many that are needed.
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Old 18th May 2006, 08:23 AM   #166
Vix is offline Vix  Yugoslavia
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Hi Tyimo!

Nice to hear good things about SEWA; I was never really intersted to build this one, but after I read your amplifier comparison test, I am

Since I obtained Jfets, I recently finnished ZEN V8. It sounds much better than my ZEN V3, which is now sitting on a floor, awaiting mutation

I thought it will get transformed into ZEN V9. On the other hand, I'd like t try to convert it to SEWA Rev1 and compare it to ZEN V8.

One question for you Tyimo: You could try to convert your ZEN lite to SEWA with a lightbulb instead of CCS. It should be fairly easy.

I feel a bit perplexed about the phenomena of current sources vs. the subjective sound quality.CCS gives more power and bass, but lamps (or resistors), despite lower power, sound more "musical".....I still can't say which one is "better". It seems to be a matter of taste....

Regards,

Vix
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Old 18th May 2006, 09:30 AM   #167
Mad_K is offline Mad_K  Norway
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I found SEWArA (with power resistor), now renamed OTA, to be too "musical" But as Vix, says; it's a matter of taste...
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Old 18th May 2006, 05:14 PM   #168
Tyimo is offline Tyimo  Hungary
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Hi!
First of all: everybody are welcome!!

Quote:
Maybe the most interesting finding (to me) was the discovery that BOZ was the best preamp for SEWAr1.
Mad, I didn't say that the BOZ is the best, I just say that in some way it is better than the BOSOZ: Sharper details, but not so "relaxed". But the difference is not so big and important.


Quote:
One question for you Tyimo: You could try to convert your ZEN lite to SEWA with a lightbulb instead of CCS. It should be fairly easy.
Vix: Yes, I think I will try with bulbs or even more with a 100mH inductor!!!

Quote:
I feel a bit perplexed about the phenomena of current sources vs. the subjective sound quality.CCS gives more power and bass, but lamps (or resistors), despite lower power, sound more "musical".....I still can't say which one is "better". It seems to be a matter of taste.
When I bulit my Zen Lite I felt the same in comparison with the Zen "Classic". But now, I am not realy sure, because the SEWA V1 with the CCS has very musical sound too. Offcourse, I have to try because "the probe of the pudding is the taste"

One is sure:I think I will not go back to any Common Source Mode amps, because I like so much the advantages of the Mosfet Followers (source followers ).
I would like to know how is sounding Andrea Ciuffoli 's Power Follower amp?
Has somebody any info?

Greets:

Tyimo
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Old 18th May 2006, 07:10 PM   #169
Mad_K is offline Mad_K  Norway
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The main difference from SEWA to "Power Follower 99" is in the PSU. If you use only a 3300uF cap and add a zener regulated follwer for PSU you'll be pretty close. Also, he uses a negative rail, which was discussed earlier in this thread (or was it in the OTA thread?) and was abandoned beacause of poor PSRR.
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Old 18th May 2006, 07:18 PM   #170
Tyimo is offline Tyimo  Hungary
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Thanks Mad!

I will forget it.

What do you think about to use an inductor instead of the light bulbs?
I could use the same low voltage PSU from the SEWA V1.

Greets:

Tyimo

P.S.: With VII Audio I am in seventh heaven
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