Anyone finished burning in their TC-7520 yet?

[tizer2000uk]

I must admit I remain slightly sceptical myself, I'm a man of logical thinking and the burning in process does not make an awful lot of sense to me. Maybe alot of it has to do with one's hearing becoming more accustomed to the sound over time?

I would also be interested to know if anyone here has ever had two units side by side and heard a noticeable difference.

I had quite an interesting chat with one of the guys at work who has been designing electronic wizardry for space and defence companies for many years and who also has designed alot of his own audio kit for home and he remains very skeptical about such things as very expensive cabling, the burning in process, isolation platforms for amplifiers and valve amps.

He mentioned building an amplifier which essentially delivered every last ounce of information from an audio track, something he tested by hearing a recording made and then having it played back on his amp.

For him the music sounded exactly the same as it did when recorded in the studio, others however thought the sound was too 'clinical', especially when playing back modern mainstream cd's, on valve amps however people though the sound was 'warmer'.

He basicly said that valve amps colour the sound and tell some white lies to make recordings, especially bad ones sound more appealing, aparently being able to hear the pedals on a piano within the mix is not everyones cup of tea.

His views on why manufacturers charge megabucks for electronic gadgetry cannot however be printed in such polite company.

[Photochromatic]

Crossposted by request from http://theartofsound.net/forum/showt...5619#post35619
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So here is another review - somebody please check the nightly backups are working, I'm not going to do this again!

I received my TC-7520 the week before last, two days after it shipped, and about a week before I was expecting it. Good start!

First Impressions
The unit looks good in spite of lacking some of the flashy accoutrements of some of its competition. It feels solid, the finish is clean, the detail on the front has a minimalist, quality feel, and I like blue LEDs! Around back, the connectors are clearly labelled and the screws underneath all sit nicely. You get the feeling that you could happily drop this down the stairs and it would still work. I won't
The volume knob moves smoothly, with perhaps a little less resistance than I would like, but it does have a quality feel to the motion.
I don't like the wall-wart PSU but I won't complain at this price! At least it is small.

Setup
I listen mainly with headphones, so the headphone amp stage is of as much interest to me as the DAC itself.
The TC-7520 is connected via TOSLINK to a Mac Pro, set to 44k1, 24-bit output. I play mainly ALAC (lossless) files from iTunes, although there are some mp3 and AAC in there too, as well as a few higher resolution 96k-24bit WAV files. All of the ALAC is ripped by yours truly using MAX to get bit-perfect transfers. I'm mainly listening on Audio-Technica ATH-M50 headphones, which are very revealing and detailed (sometimes to a fault). I have others I sometimes use to see if what I am hearing is cans-related, but I know the M-50s really well.

Burn-In
My TC-7520 has about 200 hours of use on the clock now, and I think it has settled down quite a lot.
The DAC burned in over about 50 hours. Initially there was a sibilant character to the high's and an almost hyper-detailed character to the sound in general, but it has settled down and opened out to become much more musical than my initial impression of it.
The head amp is *mostly* burned in now. It managed to be both tight up high and sloppy down low to start with. The tightness at the high end was quite quick to disappear (30-40 hours) and the bass has firmed up a lot, and is still improving. It is still challenged a little by some of my most difficult tracks that are very bassy and busy, especially if there is a lot of gain in the recording. However the improvement so far has been substantial *and* is continuing *and* I am nit-picking over some dozen particularly challenging tracks. Give it another 100 hours, and I am sure it will be fine.

Warmup
I find that the amp in particular needs about 30 minutes from cold to sound at its best. I rarely turn stuff off anyway.

Impressions
The first thing I notice when listening via the 7520 is actually the spaciousness of the sound stage, even when listening with closed headphones. I can place individual violins of the LSO when listening to Elgar. I could almost reach out and smack the guy with the cough in the bar where Miles Davis is playing. The imaging is very precise, and live music in particular just, well, comes to life.
The detail and clarity are also excellent. Fret movements, picks, snares, spit(!) - its all there. I like to hear detail in my music, even to a fault. I am loving the detail that the 7520 reveals, especially in live and/or largely acoustic music. Some of my stuff is originally ripped from vinyl and even in that I am hearing detail that I had forgotten (or never knew) was there.
Vocals are lovely - especially female vocals (although that may just be my preference anyway). I'm finding it hard to multi-task when listening via the TC-7520 because I keep having to stop and listen!
When playing "loud" music, I am impressed by the ability of the 7520 to clearly show detail in the midst of distortion (note comments about the amp and busy bass though).
Overall, the character of the DAC + Head Amp is slightly warm (but without adding colour), not at all clinical, and remarkably versatile. I can go from Punk to Jazz to Metal to Classical without noticing any real shortcomings.
I should also mention the noise floor of the amp - there isn't one! Turned up all the way, I can't hear any hiss at all through 38-ohm headphones. None at all. Nice.

USB
I have A/B'd the USB and the TOSLINK connectors and can't discern any difference at all. That's a good USB stage!

Low Bit-rate Files
As I have posted earlier, the TC-7520 seems to do something to enhance the sound (or at least mask the errors) in low bit-rate files. It is almost like some kind of up-sampling is at work (although I doubt it, given Stan's opinion of up-sampling). 64 and 128-bit .mp3 files don't sound like lossless by any means, but they don't offend as much as normal. Almost as though something has smoothed out the spiky bits of the waveform where the errors are, and left the rest alone. It is not that they sound better, as much as that they don't sound as bad! Given the detail that the 7520 otherwise imparts, I would expect it to emphasise the difference between the LQ and HQ files, and it does, just not offensively.

My Verdict
I paid USD200 for this device. I am very happy.
I think the DAC is excellent value for money. I'm not an expert on high-end DACs, but I have heard a few, and to my mind the TC-7520 is proof of the law of diminishing returns. I think you'd need to spend a pile of money on the rest of your rig before you needed something better then this.
If you are going to use headphones a lot, then the news is even better. This isn't the very best head amp I have heard, but it is at least 80% of amps which cost five times the money of the 7520, and then you'd still need a DAC.

[StanleyB]

The new external PSU has been cleared and received all the relevant approvals for use on mains anywhere in the world. A spy pic of it without a figure of 8 lead attached:


And a spy pic of the final production version of the power cap that is the key to the Virtual DC power supply inside the TC-7520. Its a beefed up version of the PSU in the TC-7510. Instantaneous current dumping ability is reckoned to be around 6Amps.

[Spectral Morn]

Very interesting Stan... This should help sound out quite a lot or at least that is what happens with psu upgrades on other products.


Regards D S D L---Neil

[Covenant]

Right Stanley a few questions if you dont mind....
Firstly, I think you said its a switched mode power supply-any reason why you havent gone down the linear route as this is supposed to give a cleaner supply?
Secondly, the power cap-I must have missed this one. Is it already in the 7520 or is it going to be a mod?
All good stuff though.

[StanleyB]

1. That particular switched mode PSU has been designed for ultra low noise and heat dissipation. It's main purpose is to top up the power cap, rather than drive the DAC electronic circuits. It's running at a modest 1.2A. The 'current dumping' is done by the power cap. The latter feeds parallel wired power supply rails that use separately regulated 5V for the digital section and 10V for the analogue feed. Each regulator is on its own PCB section as well in order to cut down on any noise bleeding between the digital and analogue section.

2. The power cap is already fitted to the existing TC-7520. But the printed top cap was not yet ready. As you can imagine, getting your own caps made ain't for the faint hearted.

Stan

[leo]

A SMPS goes nicely with these new green regulations

Correct me if I'm wrong Stan but I'd imagine supplying the dac with a linear supply would add a huge increase in price? its also hard getting the things to comply with the regs today unfortunately, its something which is causing a lot of companys some grief.
It seems like Stans done the clever thing and optimized the dac to be used with a smps, I can say this is no straightforward thing, wise choice on the big input cap too

A SMPS usually has a much stiffer supply than an average sized linear, its physically much smaller and lighter, input AC voltage is also less hassle than linears
Supplying these with a commercial unit like a dac makes total sense IMO

[Covenant]

I am sure you are right Leo but when I looked into this for my SB3 everyone said linear was the way to go and I coughed up £100 to have one made (silly me, I know).
Is it just that a dac is more suited to switched mode-no radio frequency issues?

[leo]

I am sure you are right Leo but when I looked into this for my SB3 everyone said linear was the way to go and I coughed up £100 to have one made (silly me, I know).
Is it just that a dac is more suited to switched mode-no radio frequency issues?

When I say regulations I mean these new environmental green friendly regulations which apply to electronic manufacturing, things like using ROHS compliant parts (lead free) and using SMPS which are more efficient than linears

SMPS's can cause problems with some hifi components, mainly things like the switching noise, the better SMPS's have switching noise at higher frequencies, these can still cause problems.
If a piece of equipment is designed to be used with a smps there is the small possibility a linear may actually sound worse with that particular equipment if its been designed to be used with SMPS's

This may not be the case at all with Stans dac but is something thats known to happen with some other gear.

You buy the dac with the SMPS and try a linear posting your thoughts if you think it sounds better or worse, the beauty with having an external supply, its easy to swap and compare

Theres no such thing as a perfect SMPS, they are getting better though, as long as the equipments been designed to deal with the switching noises etc it shouldn't be a problem

[StanleyB]

Correct me if I'm wrong Stan but I'd imagine supplying the dac with a linear supply would add a huge increase in price?

It's cheaper to make, but more expensive to ship. Also, linear has a couple of drawbacks. The 1st one is that I would need to develop 4 versions of 110V, 127V, 220V, 240V. The other thing is that the type of regulations circuits used in linear power supplies have not seen much progress in R&D for some decades. Then there is the EU plan to ban linear power supplies very soon.

Stan