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Old 8th October 2005, 09:47 AM   #21
soongsc is offline soongsc  Taiwan
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What pre was used during the review? Or was there no pre at all?
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Old 8th October 2005, 10:17 AM   #22
Nuuk is offline Nuuk  United Kingdom
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Quote:
What pre was used during the review? Or was there no pre at all?
From the review:

Quote:
As an experiment, I tried the T-AMP with an active pre-amp (unity gain class A discrete transistor). I found that this made the T-AMP less fatiguing but at a cost of adding back one of the veils that it had removed. In other words, I was trading transparency for a 'gentler' presentation. I'm not sure which way I would go with the T-AMP if I was using it permanently but fortunately, there are alternatives that don't require the active stage. But if you have a T-AMP, and find it fatiguing, it may be worth trying an active pre-amp.
The active pre-amp used was the one described here.

To clarify, I felt that the class-T amps (unlike the GC's) are generally better without an active pre-amp.
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Old 8th October 2005, 01:23 PM   #23
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Hi Nuuk,

Thanks for the great review !

I had the Autocostruire 2020 in my system for about a month and got Charlize 4 days ago. I was planning to write my comment on a new tread, but I feel that it would be better to write here about my experience. First, the Autocostruire is a good amp for sure. The only mod I made is to use some Solen film & foil cap (0.1uf) in // with the input cap. This had a good impact on the sound. The amp soud more natural and the bass is more present. Still, the amp was not in the same league as my Rogue Tempest Magnum (KT-90, 12AX7, 12AU7).

After 48 of continuous playing (2 days ago), I decided to listen to some music using Charlize. I started with Bill Evans Ė You must beleive in spring. Like you I think that piano (as well as vocal) is a very challenging test. This is where the autocostruire donít succeed to sound as good as my tubes amp. With Charlize, only after a few notes, I knew that things would be different. Charlize capacity to deliver the piano is breath taking. Very natural and the 3-D representation is just like it is with my tube amp. Instrument are not only sources located in different plans, they are there with their full 3-d shape.

Yesterday, after 72 hours off continuous playing, I listened to different music style : Pink Floyd, Camel, Diana Krall, Folk, Plitch & Davis and the amp succeeded to deliver all this music style with brio. The only problem I have with Charlize is the big Pop I get when I open the amp. I have the mute switch, but it donít make much difference in my system. I will probably try some 4uf input cap and see if the bass is still good to my taste. I would think so as I have no problem with the Autocostruire bass (with the // cap).

Charlize will stay in my main system with the Rogue and the Autocostruire will be used in a second system. Well, maybe I'll have to sell my tubes amp.

The evaluation of the amp was made with the following system :

CDP : Arcam alpha 9
Pre : Stepped attenuator (25K)
IC : DIY made with silver plated 22 AWG wire
Speaker cables : DIY made with cat-5 (Chrss V.)
Speakers : DIY 3 ways (85 dB, 4 ohm) http://cf.pg.photos.yahoo.com/ph/dan...bum?.dir=/7382
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Old 8th October 2005, 02:53 PM   #24
Ropie is offline Ropie  United Kingdom
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Speakers : DIY 3 ways (85 dB, 4 ohm) http://cf.pg.photos.yahoo.com/ph/dan...bum?.dir=/7382
Nice speakers!!
Art Deco inspiration?
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Old 8th October 2005, 02:55 PM   #25
Nuuk is offline Nuuk  United Kingdom
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That's very interesting Daniel. If you have time, try removing the input caps from the Autocostruire and replace them with some 4.7 uF polyprops. I have found this to make a big improvement. I f I ahve some 0.1's here, I'll try bypassing the 4.7's.

Unfortunately, with the 4.7 uFs, the turn on noise is nearly as bad as with Chralize. But when amps sound this good, I am prepared to make a small sacrifice (at least temporarily).

Oh, and nice looking speakers!
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Old 8th October 2005, 03:29 PM   #26
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Originally posted by Ropie


Nice speakers!!
Art Deco inspiration?
Thanks !

Well, this is just a personnal taste with no real inspiration source. The original desing was simply regular monitors on bass boxes. For me it was just to plain (little square boxes over big square boxes). So, I decided to use sone 2 inches quater round. Before making the real thing, I made some drawing on a MDF board (full size) to see how they would look. I was please with the look of the drawing and decided to with this design. I was not sure that peoples would like it as much as me, but so far the comments are very positive. And you know what, they sound better then they look

Back to the main subject now

Thanks again,
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Old 8th October 2005, 03:36 PM   #27
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Originally posted by Nuuk
That's very interesting Daniel. If you have time, try removing the input caps from the Autocostruire and replace them with some 4.7 uF polyprops. I have found this to make a big improvement. I f I ahve some 0.1's here, I'll try bypassing the 4.7's.

Unfortunately, with the 4.7 uFs, the turn on noise is nearly as bad as with Chralize. But when amps sound this good, I am prepared to make a small sacrifice (at least temporarily).

Oh, and nice looking speakers!
This is what I plan to do. I'll order some 4.7uF Sonicap and will try them on both the autocostruire and Charlize amp. I don't think that I'll do it into the near future as I'll soon be out of the DIY arena for a few moths (hip surgery). Anyway, the amp. sound so good, I'll be able to live with it as it is for a few months.

Thanks for the positive comments about my speakers .

Regards,
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Old 8th October 2005, 03:40 PM   #28
Will is offline Will  Malaysia
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Nuuk,

Was there an off the hook comparison between these digital babies with a VBIGC instead ? I'd be interested to know cos many amp can't come close.


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Old 8th October 2005, 03:55 PM   #29
Nuuk is offline Nuuk  United Kingdom
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Was there an off the hook comparison between these digital babies with a VBIGC instead ? I'd be interested to know cos many amp can't come close.
I love my VBIGC and you can see how much work went into building it. But it doesn't sound as good as a GC with one of the discrete SS buffers! As Isaid, when I have some more time and I have had a rest from all this hi-fi lark, I will do some closer comparsions between the GC's and class-T amps.
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Old 8th October 2005, 06:42 PM   #30
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Nuuk:

I have all four of the amps you reviewed and had reached the same conclusions you did. Thanks for the great work.

Regards,
Larry Welsh
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