NVA amplifier info sought

[markzb]

Hi everyone.

I would like to ask any of you if you have a circuit diagram of a NVA amplifier that I could have a look at. I am thinking of building one and would appreciate any info or positive views you may have on these amplifiers.

I found it to be a very transparent and satisfying amplifier many years ago and am now drawn to its simplicity and low component count ( from memory at least!)

Many many thanks

mark

[martinab2]

Had a few of these amps in for repair over the years. Nothing magical about the design - just very straightforward class AB push pull bipolar transistor stuff with short signal path, no protection circuitry, and oversized power supplies. Quite similar to the smaller Naim and Exposure designs as i remember. No schematics left unfortunately, and probably not that many of the old amps around either. Although they sounded excellent when new, some of the smaller integrated amps were badly affected by changes in component tolerances due to ageing resulting in spontaneous oscillation / meltdown.

If you are interested in taking the minimalist design idea to its ultimate conclusion, it might be worth having a look at the Nelson Pass Zen series www.passdiy.com. For more conventional designs, the Elliot Sound Products pages at http://sound.westhost.com/ are worth a look

[diy4fun]

Originally posted by martinab2
Had a few of these amps in for repair over the years.

Hi martinab2
I have an old Nva ap30 amp with a broken soldier near speaker terminals.
I would try to repair it.
How is possible to open this amp whithout breaking the case?
The case is glued very strong.

Thank for your answer.
Regards
Sentenza

[Paul Ranson]

Why not get in touch with NVA and see what Richard can do?

Probably simplest to go via his EBay shop,

http://stores.ebay.co.uk/nene-valley-audio

Paul

[diy4fun]

Hi Paul
Thank for you answer
Before to "say" with Dunn, I like to try repair the amp.

I know the site of Richard Dunn, but I prefer don't send the amp to uk for maybe only a broken welding.
Is expensive and in the past I have a bad experiences with Royal Mail and DHL...I pair of tdl studio 2 arrived to me with cabinet broken.

I bought this "second hand" amp from a friend, and this model was check and upgrade one year ago from Richard Dunn.
The amp worked fine (amazing sound!) for a lot of time, but two days ago the sound was change, a little distorsion appear... like when you have a cold welding or the connections is not perfect.
I check the speaker cables and the signal but when move the amp the sound appear or disappear.
I thinked: maybe a welding inside the amp was broken...

I tryed to open the amp, and a part of welding in the cable (solid core) from pcb to speaker terminals was broken.
But is impossible (for me..) to open for repair the case is glued
My amp is an older version.
Only the part down the case have a screws, but if you move this part the solid core cables inside the amp breacking, is very interesting amp but i whona @#"$$%!!

In the past only NVA have a service in this amp?
I think is possible to open the case without breacking it.
I don't know how, any idea?
How is possible to breack the glue?
I try with cutter and phone but I fail.

Thanks for the answers
Regards
Sentenza

[quickie]

Use a wood chisel to remove the top plate.

Paul.