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Old 15th January 2013, 03:20 AM   #1
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Default My SIT - First Impressions and.........

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Finally got my SIT plugged in and had time for a brief listening test. First impressions. Very liquid, less analytical that my F5 and the sound stage is much more forward. Not sure yet on what effects changing the bias does but I have notice already that that running it too high causes a little edge to vocals.

Very interesting, I now have the SIT bug and I'm wondering how far it can be taken and what a real Pass Labs SIT sounds like.

Although it sounds and works perfectly some odd stuff going on with my biasing.

Regards,
Dan
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Old 15th January 2013, 08:02 AM   #2
generg is offline generg  Germany
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It is time to look if your sound card does 48kHz and 24bit and to look at the distortion spectra with a free program....

Nice to see you complete HiFi!
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Old 15th January 2013, 10:44 AM   #3
protos is offline protos  Greece
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It is driving those speakers?
How efficient are they?
Perhaps it is worth looking at only driving the main speakers until 100hz with the SIT since you have a sub. Then you can put some nice film caps on the SIT output (I use 200uF) for a nice improvement in transparency.
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Last edited by protos; 15th January 2013 at 10:47 AM.
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Old 15th January 2013, 11:43 AM   #4
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Originally Posted by generg View Post
It is time to look if your sound card does 48kHz and 24bit and to look at the distortion spectra with a free program....

Nice to see you complete HiFi!
The silver case in the picture is a TDA1541A NOS DAC. Above that is a Shigaclone Transport. No sound card.

Regards,
Dan
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Old 15th January 2013, 11:59 AM   #5
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Originally Posted by protos View Post
It is driving those speakers?
How efficient are they?
Perhaps it is worth looking at only driving the main speakers until 100hz with the SIT since you have a sub. Then you can put some nice film caps on the SIT output (I use 200uF) for a nice improvement in transparency.
The SIT pictured above is driving my line arrays that are 10 ohms and 94db. I am sub(less) for the moment because the 'magic smoke' came out of my sub amp.

I'll post detailed pictures under "Pictures of your DIY Pass Amplifier" thread later but I kind of boxed myself in here if you'll excuse the pun. My goal here was to build my SIT compact enough that it would fit neatly into a regular AV rack space. It was a major PITA doing so but I succeeded. The downside to that approach is I have very little room for mods or extra components. This version of the SIT fascinates me and I'll going to re-read the entire thread. After that I'm going to consider another SIT in a Pass-like enclosure that will have room for 'fine tuning'.

Regards,
Dan

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Old 15th January 2013, 02:15 PM   #6
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That's really exquisite.

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Old 15th January 2013, 02:17 PM   #7
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Nice build...
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Old 15th January 2013, 02:53 PM   #8
generg is offline generg  Germany
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Quote:
Originally Posted by dantwomey View Post
The silver case in the picture is a TDA1541A NOS DAC. Above that is a Shigaclone Transport. No sound card.

Regards,
Dan
Hi Dan,

I did not express myself clearly, I wanted to suggest you to measure the SIT amp with a PC and a sound card and a free program for distortion.
As Mike said, changing the bias also changes with the SIT the distortion not in the same way like in the FET amps, (more bias, less distortion) as far as I understood, the ratio k2 /k3 may change and the absolute THD value.

But I am sure you saw Mikes values that higher Ampere give in this case not always less distortion.

So what do I want to say.....

Really nice speakers!
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Old 15th January 2013, 03:29 PM   #9
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Quote:
Originally Posted by generg View Post
Hi Dan,

I did not express myself clearly, I wanted to suggest you to measure the SIT amp with a PC and a sound card and a free program for distortion.
As Mike said, changing the bias also changes with the SIT the distortion not in the same way like in the FET amps, (more bias, less distortion) as far as I understood, the ratio k2 /k3 may change and the absolute THD value.

But I am sure you saw Mikes values that higher Ampere give in this case not always less distortion.

So what do I want to say.....

Really nice speakers!
Of all the stuff that goes into building an amplifier, drilling and cutting, soldering, wiring, etc. The theory end of things is my weak point. I'll have to re-read the entire thread again to 'come up to speed' on bias tuning.

Thanks for your input.

Regards,
Dan
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Old 15th January 2013, 03:31 PM   #10
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Originally Posted by Nelson Pass View Post
That's really exquisite.

As posted elsewhere......

My sincere thanks goes out to Father Nelson who generously tends to his flock of DIY followers.
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