160VA 2x18V transformer enough for mono A3? - diyAudio
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Old 14th July 2004, 02:38 PM   #1
Stabist is offline Stabist  Slovenia
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Default 160VA 2x18V transformer enough for mono A3?

Hello!

I've got 2 superbly build transformers - 160VA/2x18V each - the thing is - they are build to operate "24h/day" supplying those 160VA - so I guess they won't have problems with A3's 100W draws for one channel?!?
Or am I wrong?

'Cause I've noticed that some people use 300VA transformers per channel etc for A3 ....

Thanks

Oh btw - I'be got 4pcs of second hand Sprague 24.000uF/30V caps - so 2 per channel - will that be enough or should I get another 4 caps (eg new Panasonics 22.000/35V) ...?
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Old 14th July 2004, 03:15 PM   #2
MikeW is offline MikeW  United States
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Default OK

They should be OK. You want more caps. Build a C-R-C or a C-L-C it will be quieter and have a little more bass.
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Old 14th July 2004, 03:34 PM   #3
Stabist is offline Stabist  Slovenia
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Hehe - so the C-L-C or C-R-C is the way to things
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Old 14th July 2004, 03:44 PM   #4
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I think you should give them a try. Just note
that the voltage will probably be lower than
the A3's +/-25V (no big deal).

I second Mike's suggestion on more caps and
pi-filtering. Less voltage loss with CLC but
then it's probably harder getting the inductors. Of
course, you may want to try it with just 2
caps and see if the noise level is acceptable.

Have fun,
Dennis
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Old 14th July 2004, 07:05 PM   #5
Stabist is offline Stabist  Slovenia
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How do I choose proper inductor? Because I've found a "local" shop whit quite a lot of inductors in their offer - and also prices are very aceptable ... I'll just have to check if they have the right value for me ...

Hmm - another project I intend to do - A5 - I have allready 4x25V/900VA transformer and 4 Sprague 69.000uF/50V - 2 per channel ... I didn't intend to use CRC or CLC PSU configuration in PSU - but now I'm not sure anymore - you all talk about hum - and that the way to avoid him is filtering in PSU ... I won't be able to experiment with adding additional caps and inductors or resistors after the chassis will once be done ... So I'll have to decide before ...

The fact is - right now I have an diy version of A5 here in my room - that uses two Spragues 69.000uF/50V in PSU - and the hum can actually be heard when there is no music ...
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Old 14th July 2004, 07:55 PM   #6
MikeW is offline MikeW  United States
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Try to do some simulations with http://www.duncanamps.com/software.html
You can try both. Start with C-R-C .33 ohms and C-L-C 1.0mH.
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Old 14th July 2004, 10:20 PM   #7
Stabist is offline Stabist  Slovenia
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Thanks MikeW! I'll try and see what kind of results I will get ...

BTW - today I borrowed A5 from my friend ... To make a comparison beetwen my Zenv4 and A5 ... And to see what will I gain if/when finishing my A5 (it's a project that had status quo for last 18months )

And?
With one word - incomparable!!! WOW ... What can A5 do with my "little" floorstand babies (Focal diy) ... Incredible - allready Zen seemed quite musical amp for me - but my speakers are nominated as 5ohms ones - so altough he has 2A bias - it was noticable he would need more power to better control them ... And that's where A5 comes out!

More detailes, better bass (not so much more bass - but indeed "better bass" - better defined, etc) Soundstage - bigger ... No doubt ... And most important - with Zen at quiet listening - there like throwing a towel on speakers - so detailes are gone - but not with A5 ...

Hehe - when I start it up, I said to myself - MAX 1h of listening - then you have to study ... Khhmmm - now it's like 5h later - and I'm still listening ... I just made a 10min break to report here

"Crazy" ...

Btw - A5 has 60W/8R - but what about 4R?
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Old 15th July 2004, 09:09 AM   #8
uli is offline uli  Austria
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Quote:
Originally posted by Stabist
The fact is - right now I have an diy version of A5 here in my room - that uses two Spragues 69.000uF/50V in PSU - and the hum can actually be heard when there is no music ...
Hi,

often this hum is caused by b-grade Xformers. Put your ear at the
enclosure of the amp. When you encounter a mechanical buzz,
this noise will be heard in the speakers too.
2x 69000 F should be enough if the Xformer is ok.

Uli

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Old 15th July 2004, 09:21 AM   #9
Stabist is offline Stabist  Slovenia
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Well, we might have problems with getting different exotic parts here - but fortunately the transformers with "made in Slovenia" mark are one of the best in the world - the transformer was custom made and is completely quiet ...
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Old 15th July 2004, 09:26 AM   #10
uli is offline uli  Austria
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Quote:
Originally posted by Stabist
Well, we might have problems with getting different exotic parts here - but fortunately the transformers with "made in Slovenia" mark are one of the best in the world - the transformer was custom made and is completely quiet ...

could you provide a source for the Xformers?

TX

Uli

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