Zen v4 and bass distorsions ...

[Stabist]

Hi!

Kirc and I have made Penultimate Zen (and a BoZ as a preamp to match with v4) - the sound and the soundstage are very "good" - but - there is something that bothers me - in some songs there is somekind of a distrosion in bass "region" - the loudspeaker just begins to "bzzzz" during the play - like some kind of a resonance.
It can be partly eliminated with lovering the CD out volume control (and consequently raising the level at preamp pot to remain in same volume level) - btw the CD player is marantz 63 - so my guess is that it might be conected with too high CD player's output??
The other thing that comes to my mind is - the toroid transformer has only 300W - but as far as I understood - that's really the MIN! that can be used for Zen v4.
Bias is set on 1.35A.
Also another guess - the capacitors in power supply are two 10 years old Sprague powerlytics - 50V/69.000uF each ... They are still OK nevertheless their age - but - can it be that there is a beter solution to use more smaller ones??

Another hint that also occured to me - maybe the v4 is just so much better than my previous amp - and it just amplifies also all distorsions that are allready recorded on a CD ...

I surely have to listen more musical material to find out the right reason- These are just first 2 days impresions ...

Thanks for any advices and thoughts in advance!

[stefanobilliani]

I would suggest to let flow 2amps on ZV4 and use 300w transformer for only one channel


stefano

[PMA]

Stabist,
is not there a grounding problem?
Pavel

[Stabist]

Hi Stefano - I know that it is better to flow 2amps - BUT in this moment there is a limit - not enough heatsinks available - but we're "working" on solving that problem There is only one limit in this case - money ...
Also - I am avare about transformer- but than again - same reason as above ...
Another thing is - Zv4 was made just out of pure curiosity to find out some things about mr. Nelson's briliant designs! And after it was clearly seen the amp preforms very vell - there was another decision to make also matching Bride ...

But both of them are just a prediction for our plans for the future - Aleph5 and one of the preamps.

SO that's why we wouldn't like to spend any more $$ for this amp as really necesary - it is a bit unfair, I admit - 'cause A5 is our main goal ...

PMA - I admit - it ain't yet in a housing - so if that's the ground you're refering to here's the answer; but otherwise ground conenctions looks OK to me - Ok concerning the circumstances ofcourse.

[Stabist]

Hi - me again ...

Hmm - must explain some facts about myself .. Kirc is quite experienced in DiY; I myself am not. So - the v4/BoZ project was "sponzoured" by me and made by him ...
Now he's on 12 days vacation and I have time to discover things ..

So - today I've read some literature on the Net written by mr. Nelson - it explained a lot of things I didn't know before ... So - now I'm quite aware of quite few "mistakes" that were made during "building" my combination up ...
So - next "modification" will be done:
- "bigger" transformer - or another 300W one to make dual mono topology
- bias set to 2amps - now I see this is something we shouldn't change too much - especially while my loudspeakers are 5ohms one ...
- chassis with enough big heatsinks and no more improvisation in this section and therefore smaller bias settings - hmm - I'have a question related with them! If v4 has around 100W/ch dissipation - will heatsinks with 0,3K/W koeficient be enough or not??? And also - if the rest of the chasis is made out of 5mm thick aluminium - will it also bring something to cooling the amp down - or is there no significant change??

Thanks in replays!