Nuuks T-amp article on TNT out now

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#22
What pre was used during the review? Or was there no pre at all?
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From the review:

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.
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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. 😉
 
#23
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 – 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 don’t 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 don’t 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/daniel_bouchard2/album?.dir=/7382
 
#25
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! :up:
 
#26
Ropie said:


Nice speakers!!
Art Deco inspiration?
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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 :angel:

Thanks again,
 
#27
Nuuk said:
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! :up:
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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,
 
#29
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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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. 😉
 
#31
Just got one of Nuuks basic IGCs running, after frying the first...
Point to point 1 - veroboard 0
What rateing heatink should I ask for? Seems like it gets hot very quickly without a sink...
Used old 4ohm car speakers rigged in series for quick test... pluged into my wifes walkman radio thingy... Expected some hum or something, thought I had no power.. then turned up the volume... nice surprise... all the sound there.. none of the expected noise...
 
#34
Nuuk,

Great review! Thanks for putting your thoughts out there for the rest of us :up: Just out of curiosity, what input coupling caps were used with each of the amps (excluding the SI which you already said used 2.2uF polypropylenes). I only ask because I know the AMP3 gives you a choice of 3.3uF electrolytic or 2.2uF ceramic and I don't know what the others come with.

Brian
 
#35
Just noticed that the AMP 6 uses the Tripath 2020 chip used by the Charlize and the Autocostruire... Do you think that it would share the characteristic 2020 sound you observed?
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Yes, that is interesting. I thought that the same as AMP-6 was the AMP-3 but without the surface mount components:wrench: I didn't realise that it used the 2020 chip too!

I would guess that the sound would have some similarity to the Audiodigit and Charlize 2020 amplifiers. I wonder if 41Hz would like to supply a sample for comaprison! 😉
 
#36
Just out of curiosity, what input coupling caps were used with each of the amps (excluding the SI which you already said used 2.2uF polypropylenes).
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I use the 2.2 uF film caps with the AMP-3. The Audiodigit (Autocostruire) 2020 has similar 2.2 uF film (polyester I guess) caps and the Charlize uses 10 uF electrolytics. My preference is to use 4.7 uF polypropylenes (which I have now done with the Audiodigit to good effect)! :att'n:
 
#37
Nuuk said:


I use the 2.2 uF film caps with the AMP-3. The Audiodigit (Autocostruire) 2020 has similar 2.2 uF film (polyester I guess) caps and the Charlize uses 10 uF electrolytics. My preference is to use 4.7 uF polypropylenes (which I have now done with the Audiodigit to good effect)! :att'n:
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I kind of wonder how film caps perform with a DC bias on it. I am about finished with an AMP3, and noticed the DC offset required on the input. Older circuit designs always used electrolytics like the Charlize. Would the Charlize sound even better with film caps?
 
#39
I wonder if 41Hz would like to supply a sample for comaprison!
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I just had a look at the AMP-6 and it's not quite so simple to comapre it with theother class-T amplifiers!

It has it's own on-board power supply requiring a 15 VAC transformer that I don't have. So it's not just a question of building one and comparing it with the same SMPS etc! :att'n:
 
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