Buzzy problem - DAC64 + TVC + SPM1200 + Tukans.

I was unhappy about my high street systems lack of involvement musically so about ten years ago I got my first hifi = naim gear + tukans.
Got inexpensive CD player as I felt they should all be the same.
It didn't solve the problem but I kept telling myself it was lack of concentration on my part.
Finally I had to do something about it - ended up unwillingly auditioning DAC64 and realised it solved the problem for me. I now believe that the various problems with CD playback (jitter and sampling rate) were the problem all along.
I've never auditioned another DAC and I don't intend to - I've got my music back which is all I ever wanted.
However I then found the Naim gear was too forward and too bright.
Didn't want to change it but finally felt I had to.
Web research and success of DAC64 led me to Chord and finally I auditioned and bought a SPM1200 secondhand - fantastic.
I should probably have left it there (no doubt very famous last words) but I felt that the NAC72 was probably letting it down and maybe I should replace that while I was about it. Ended up getting a TVC as I liked the idea of them - as little interference with the signal as possible.
Received it (a Django) about a month ago - also fantastic.
Except....
I listen to classical and with some music I get a buzzing in the tweeter with piano at certain pitches (the C above middle C and the E and G above that) and also some strings (viols, for some reason - not a major problem as I don't like viols too much - they were on the radio).
However this really annoys me as I feel it should now be pretty much blemish free (not perfect, but without any obvious defects).
The speakers are still the Tukans, which I understand were designed to go with the Naim amps, but I still fell this shouldn't be happening - it doesn't when I replace the 1200 with the NAP140.
I rang a Chord dealer who rang Chord for me who said this was a known problem and that I had to reduce the gain.
The Django has a gain switch which gives you the option to increase the gain, but not to reduce it. Neither position solved the problem - and I don't know what 'gain' is in the first place.
Is this problem known to you guys? I'd just like to know what the solution is likely to be. If it means selling the Django then so be it, but could it be that harder to drive speakers are the answer?
Also while we're on the topic - I got hold of XLR cabling for my new toy - DAC to Django to 1200. So I was disappointed to find that it rendered all but three of the volume settings on the Django unusable.
I realise that XLR removes noise by sending the signal twice, once inverted, and then subtracts the two eliminating noise and doubling the signal strength, but I didn't realise it would have such a drastic effect on the volume - I think I'd assumed that the signal was then halved back to the original level. Does double the strength equal twice the volume or does it vary proportionately in some way? It's very annoying - I don't mind going back to single-ended, but it's that raised, then dashed, expectation thing.
Anyway that's got a load off my chest. I await your comments with interest.

JaFo.

 

Does it occur on both channels and at various levels of attenuation on the TVC?

Does the effect decrease as the attenuation is less (ie playing louder)?

 

Maybe the Chord dealer meant that the gain in the power amp has to be reduced.... worth asking them for specific details? If that is the case it might have to go back to Chord for adjustment. Gain is, in effect, added volume.

Using balanced (XLR) connections usually results in adding 6db of volume over the RCA connections. That's common with all equipment.

The buzzing you are hearing.... there has ben some discussion on forums about 'ringing' problems with TVC pre-amps, but not sure if that could be your problem.

 

Murray,

I've just listened to it again, and I'd say that the problem seems to go decrease a bit as volume goes up, but also as it goes down.
It also seems to be the same on both channels. (Though I didn't do volume check on second channel).

Alan,

I'm 99% certain he said something (tho' I don't remember what) that specifically related it to the pre-amp.
I didn't know that you could alter the gain in a power amp.
Thanks for the info re balanced.
I did see the mention in another thread with (I think) results of tests using TVC's on square waves. This is the sort of info I'm after - if this can cause the buzzing then I know where the problem is, unfortunately my technical knowledge is very limited and I don't really know what the conclusions about TVC's really were, and whether 'ringing' is what I'm hearing. I suppose I should have posed that question, but I was still trying to make up my mind where I was I think.

Thanks to both of you for your replies.

Cheers,

JaFo.

 

JaFo, this could be an impedance problem with the Django and Chord. TVCs are far from a universal solution to the search for the perfect passive pre. As you change the volume setting on the Django you also change both the input and output impedance.

What is the input impedance of the Chord? (I'm guessing its low)
High capacitasnce cables are also a big no-no here, so what asre you using?

<edit> Hmm the spec says 112K balanced which should be fine - that has me stumped.

 

Hi Jafo,

I had the use of an MFA Silver TVC for a few weeks and had problems with the way it produced string tone, piano and brass particularly at lower levels. I mentioned it here complete with pics of the square wave ringing I found on my scope. There are quite a few enthusiastic tvc users on this forum who disagreed, and the individual who 'developed' these with S&B told me I must have an early sample as all such ringing issues were now resolved and were irrelevant anyway. I returned it to the dealer who afaik is still quite happy that it is representative of the breed and still uses it as a demo model.

I have since heard another 'new' copper one but to my ears the character I heard and didn't get on with was still evident.

All I can say is that it wasn't for me. I find good active pre-amps sound more convincing. Whether it's what you are hearing or whether there is a duff connection or power amp overload problem (unlikely I'd have thought) I don't know.

I'll be interested to read what conclusion you come to though.

rgs,

Murray


re-reading your original post you say that the problem doesn't seem to be evident with the Naim power amp which would rather indicate that what you are hearing maybe related to the Chord rather than the tvc.

 

Rob,

The input impedance is 20k Ohms. I got that from the documentation accompanying. I've no idea whether that's low or not.

The cabling is some bits of wire I found on a skip - well works for me.
Only kidding. I imagine that the name of Mr. Les Wolstenholme is well-known to you guys round here. Well while wondering whether to get some of his gear, I came across a site he recommended called Flashbacksales.co.uk.
I got their standard OFC cabling which I think they describe as 'EHG' which I presume means Extra High Grade. I don't know whether this is high capacitance or not. Sorry if this doesn't answer your question.
Incidentally I don't expect a recommendation from someone with my lack of technical knowhow to carry much weight, but I think flashbacksales are very good and their prices extremely reasonable.

When you say 'high capacitance' is a big no-no do you mean big no-no as in 'unplug right away', 'serious deterioration in sound quality' or 'causes hard-core audiophiles to weep'?

Cheers,

JaFo.

 

If you like the chord64 dac, you will like the benchmark media DAC1. Half a dozen of us did an A/B with the two dac's and no one could tell any difference (on revealing active ATC 50 studio monitors). You could swap them as it's half the price for the same sound. Only difference is simple black case, or bling machined case with glass bits Both operate on the same principle. Might give you more budget to help out swapping other gear, if req.

P.S unlikely as it's both channels, but it could be your speakers. I had a pair of large PMC soft dome midranges changed under warranty last year, with your symptoms. (Mind you, they were a particuarly odd mid range design, not found in many applications).

 

Rob,

"JaFo, this could be an impedance problem with the Django and Chord. TVCs are far from a universal solution to the search for the perfect passive pre. As you change the volume setting on the Django you also change both the input and output impedance."

In my last post I should also have said 'thank you' for this information("far from a universal solution"). Not being funny, I don't know what it means exactly (is 'impedance' that same as 'resistance'?), but it does make me realise that I may have jumped too soon with the Django. I felt that being so simple there wasn't anything that could go wrong. Ha Ha! I should have known better! Well if I do end up selling it at least I may get something that has that remote volume control I'd love.

Murray,

("rereading your original post")
I'm sure that when I did the test replacing the 1200 with the 140 I separately tried replacing the Django with the 72 + Hicap. At least I know I put them in at one point, and I'm sure it would have been to listen for the buzzing, not just to appreciate the difference. But it's a good point - I suppose I'll end up getting them out of their boxes again just to make sure!

Cheers,

JaFo.

 

Kub3,

Thanks for the advice re the DAC64 but I think I'm very unlikely to change it. I expect that, as is the way with computer chips and software, whatever you can get to do a certain job for a certain amount of money today, you'll get to a better job for half the money tomorrow. But I have a sentimental attachment to something which solved the fundamental problem of my so-called 'hifi' system - single-handedly it brought more pleasure into my music listening than any other thing. On top of that there is the build quality which is a constant source of satisfaction. (And which makes it sound better - does, does, does a million times does - there that proves it).
And it's got pretty LEDs. What more could anybody possibly want?
Cheers,
JaFo.