Tír Na HiFi

Agree on the decoupling approach Nige and it was my first point of investigation.
I did feel the aluminium support plate was amplifying the vibration and I could reduce the hum by manipulating the plate by hand and once I took the transformers off the plate the hum dropped a little.

The improvements were small but stil worth it as an easy win for getting a reduction in hum.

I still think the quality of mains supply has an impact on the degree of hum/vibration as from my little knowledge on AC harmonics there could be a component of harmonics on some AC supplies depending on where you live which could be better or worse for some.

Its interesting listening to the large isolation transformer I have on the main Audio AC line some days with all kinds of pulsating and changing hum harmonics which i believe is worse during the day.

Back to the encapsulation, the epoxy has set nicely overnight and it has a solid glass like feel so it has mixed and set well.
Will get the unit temporarily back in the rack later and see where we are at with hum.
I will need to make a little adjustment to the support plate position which I should get through over the weekend.

Nigel did we get the tx type in the link?

https://sklep.toroidy.pl/en_US/p/TTSA00 ... to-50V/303

tony wrote: ↑Fri Mar 30, 2018 10:42 am Nigel did we get the tx type in the link?

https://sklep.toroidy.pl/en_US/p/TTSA00 ... to-50V/303

no they are standard
TS240 VA PRI:230V SEC: 10x6V (10x4A)

what they call audio grade has an epoxy filled centre with hole drilled in the centre of that for mounting also it looks like some 3m emi barrier wrapped around the edge
neither of which i think would help this tiny hum much

the one they do in the stainless dome looks cool though

Ok but Pearse is doing something similar he is not? The stainless steel one is the audiopc one I got. It does look great alright. Lampizator are using it now or a version of it in their Komputer builds. LZ pricing is scary.

Update on the amp with the potted transformers running.
Day one was great with reduced hum which i could not hear from my listening position and I had to get my ear within 2 feet away to begin to hear a little hum so a big improvement for mine.

Day 2 on Saturday in the early afternoon and I could hear a lot of pulsating hum louder than the previous day but by the evening it was gone and back to some magical listening for the evening.

This afternoon back again with pulsating hum so I took the amp out and changed the power source but it was still there so I began leaning on the amp panels and i could make a reduction by leaning on the top cover panel in different locations.
Removing the top cover was so much better and back to normal.
I have added some small metal washers at the 6 fastening locations between the top panel and the heat sinks which they are fastened to and now back to quite listening again.

Seems some of this aggressive hum may be coming from the top cover so maybe worth removing it to see if hum drops for some here.
If it does then maybe try some damping material or washers under the top panel and see if this gives a good improvement.

Other than that i had a magnificent evening yesterday enjoying some magic from the amp and was particularly blown away with an album called The Piano by Herbie Hancock, never heard piano sound more real and in the room.

I was thinking that I might talk with Cloneys to see if they would be interested in taking a loan of the amp for demo purposes for say a month to see what the feedback would be, would be interesting to see what the response might be.

We should probably work on a BOM and some diagrams this year in case others are interested in building a similar amp, what you say Nige?

sounds like its pure vibration resonance, id be inclined to try dissipation,
try some rubber o rings of various sizes on bolts and screws etc maybe some mouse mat material or similar under the tx secondaries (the 6v ac out)
mount the tx a bit looser with o rings etc
we might be pissing against the wind trying to kill the hum with rigidity, in fact the rigidity could make it louder

i doubt it would be in cloneys interest to take it, "if" it sounds better than what they stock
would be interesting if they did though

well the bom isnt an issue, if its requested we can do it, there'd be a bit of work in it
the idea of the gb was to have supervised building of what essentially is quite a large project so that mistakes weren't made

I'm with Nigel on the resonance thing - I think some decoupling would be worth trying, you could it very simply by just loosening the tx mounting bolts.

Definitely we need a booklet for this build, with good photos throughout, schematics and some text to explain it all. Sources and part numbers are all good too. Its not high priority but a service manual would be great.

Nigel had tried to nudge me gently in the manual direction. He has sent a variety of stuff to me. Will dig it out. Would agree it is very worthwhile doing up some kind of manual/list of parts/sources etc. Noted as well re TX noise. I wonder Nigel is that why you never heard any as the lid was generally off. Going to take a trip over to healy to see how much a copper lid would be (aka Lampi Golden gate!) Mind you Aidan my son was wondering about the new amp and immediately advised me the Jadis was much more impressive looking!

doesnt look more impressive from my angle




maybe toughened glass for a lid and some red led lights :) so theres still some glow

And dry ice, don't forget the dry ice:)