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Courtiestown - Naim Amplifier (Avondale) Upgrade Project

All 3 of those schematics show EF output stages (not Sziklai).
The Rotel 820 I had had a much simpler schematic than the one above - same for the poweramp stage of my RA840BX and my RB850.

If you want a Sziklai o/p stage you could always go for a Nait5i.
 
In an amp with a Sziklai output stage the emitters of the final power transistors will connect to the rails, not the load - Audiolab 8000 for instance.
 
Good evening all,

It's been a while since I posted in this thread, having to work for a living is a pain at times.

Having ordered transformers from ETC I've finally been able to run a side by side comparison between a 2 x Canterbury toroid powered SE amplifier against the 2 x ETC EI powered SE amplifier.

I was slightly sceptical that a transformer could affect the 'sound' of an amplifier but as the experiment was only going to cost £500 I thought it was worth a punt.

I started off listening to a pair of KanII's through a pair of NCC300 monoblocks (still for sale by the way) driven by Tidal through my MacBook - still waiting on a new ethernet adaptor for the Starlink system so the KSH is out of action.

Next up was the ETC powered SE amplifier, then the toroid powered SE amplifier and then back to the ETC powered SE amplifier again.

I'm not going to attempt to get bogged down in to too many details here but there was a considerable difference between the two SE amplifiers.

The ETC powered SE amplifier was simply 'better'. There was a deeper soundstage, a greater sense of involvement, foot tapping and wanting to 'sing along'.

I really don't understand why a transformer should make such a difference.

Regards

Richard
 
Ouch! I'm going to have re-do several projects with ETCs! Thanks for your efforts, experiments, and reporting.

Flash
 
Good morning all,

I should report everything here of course which I didn't in the above post.

There is a very low level mechanical 'hum' from the ETC transformers but it is very low level - I can't hear it from the listening position - it becomes inaudible at 2ft away.

The electrically induced hum is a different issue. There is some but again it is very low level. I have positioned the transformers as close to the back of the case as possible and located the boards as far away as possible.

I need to look some more at the wiring but I strongly suspect that I am going to need to look at additional screening.

Regards

Richard
 
sq225917 said:
What's the difference in voltage out, winding resistance and VA?
Click to expand...
As you ask! All three transformers have a 240V primary and with 35V secondaries.

The ETC windings appear to be circa 1R5 both primary and secondary. I have no idea viz a viz the toroid windings.

VA - the toroid is a Canterbury HN5 at 818VA and the ETC are 2 x 500VA in a larger VA frame.

Regards

Richard
 
What experiments have you undertaken with snubbing? A little carefully crafted filtering calculated/measured with a quasimodo board might provide interesting results. I can lend you a quasimodo board if you have a scope. Its the easiest way to eliminate ringing from the secondary/diodes.

See diyaudio.com thread for details, it's basically a square wave generator with an adjustable filter section to make an ideal c-rc filter, way better than trial and error.
 
Good afternoon all,

Well things are still progressing on the upgrade front. I have just fitted the first pair of ETC transformers I bought to another SE amplifier.

Having had no significant noise issues with the other pair I had high hopes for this pair. I'm aware that both Graham and James have both had issues on this front.

Unfortunately I will have to join the band wagon insofar as this pair are noticeably noisier than the other pair.

Using the iPhone NIOSH app I'm showing circa 29dB some 30cm away with the power off and 32dB with the power on. You can definitely hear them - I could hear them whilst running the amplifier 'on test' driving them from 0 to 240V on the variac.

I had hoped to avoid this............

Both transformers are mounted to the inner baseplate - is this acting as a sounding board???

rXTc2sz.jpg


Ignoring the hum (which you can't hear with the volume at 70 on the Linn KSH anyway) I tried the title track from Tool's 'Fear Inoculum' and Keenan's vocals 'stand out' which they never did before (at least on my system) so something has changed.

Today's question relates to Carey's drumming - there are a fair number of video's out there analysing what this guy does sat behind a drum kit but, strangely, they don't attempt to copy it..........I wonder why?

Regards

Richard
 
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Good morning all,

While I try and suppress my irritation at the 'buzzing' transformers I spent some time yesterday listening to a variety of bits of music with which I was familiar.

As I have transitioned from the Naim amplification across to the current SE set-up and now converted four of the 10 channels to EI transformers the musical 'presentation' continues to improve.

It does also highlight what can only be called wide differences in the recordings themselves however.

At the risk of repeating myself (and I do realise there are a great many other speakers out there) but the Isobariks continue to 'rise to the occasion'. Lots of soundstage in evidence (on the right recordings) both wall to wall and front to back - very 'immersive' I guess you would describe it as.

Regards

Richard
 
Ive moved back to Tiger Toroids to suppress my frustration of the ETC hum/buzz, the Tiger Toroids are totally silent electrically and mechanically. There is a slight loss in low level detail but I'll have to live with that for now.
 
laverda said:
Ive moved back to Tiger Toroids to suppress my frustration of the ETC hum/buzz, the Tiger Toroids are totally silent electrically and mechanically. There is a slight loss in low level detail but I'll have to live with that for now.
Click to expand...
Sad to read this. I use EI cores with preamp, DAC and phono but these are relative small. The only big EI core transformer I have is in my isolation unit and yes there is a buzz.

Anyone made a comparison between R-cores and EI-cores with a poweramp ? The problem with R-cores is that it's very hard to get them custom made.
C-cores are also an option, though kind of costly, rarely seen as main transformer so haven't yet read a real comparison with them.
 
ramona said:
Sad to read this. I use EI cores with preamp, DAC and phono but these are relative small. The only big EI core transformer I have is in my isolation unit and yes there is a buzz.

Anyone made a comparison between R-cores and EI-cores with a poweramp ? The problem with R-cores is that it's very hard to get them custom made.
C-cores are also an option, though kind of costly, rarely seen as main transformer so haven't yet read a real comparison with them.
Click to expand...
I have other EI transformers from other manufacturers in use or have used inc larger for power amps and none exhibit the level of noise I'm hearing with these. Ive never gone down the C- core route but it's a thought. :)
 
Good evening all,

I'll be taking the buzzing transformer 'issue' off line.

I am convinced that EI pattern transformers do have a positive impact on the sound so this is an avenue I intend to pursue.

Regards

Richard
 
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Good afternoon all,

Decided to come in and carry out some sound pressure level readings of the system viz a viz another thread on the forum and was instantly hit by the hum coming from the most recently fitted ETC's.

Having the NIOSH app. open on the iPhone this is the reading some 15cm directly in front the amplifier microphone pointing towards said amplifier with the power off (much the same as the other day):-

irl2Y9C.png


This is the reading with the power on:-

BzYDvEa.png


I've just checked and at this time power to the house is coming from the Tesla PW2 as it was at the time of the last readings (the Sunsynk inverter power runs out about 15:00 or thereabouts).

Regards

Richard
 
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