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Old 23rd November 2012, 06:14 PM   #331
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Folks.

After a couple of more hours of break-in, I have to tell you that
- to me - the sound got even better. It was kind of expected.

The untweaked device sounds awesome.

I'm really wondering if I should touch it for tweaking at all.



HifiMeDiy. Thx a lot. Already at this early stage I think I can say
that you've done a great job with the V2 device.


Wish:
You might post the key-codes for the remote control. This way I can program my programmable remote and use it until you send out
your remotes.
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Old 24th November 2012, 08:26 AM   #332
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Hi there.


HifiMe has sent me the remote control codes via mail. Thx a lot.

BTW:

I just learned that there was a change with the latest firmware.

There's been a +10dB function (DIP switch 4#) introduced.

The manual says that Dip4 is not used.

What it does: The amp starts at -10 instead of -20.


What I havn't figured out yet is how to store the actual volume setting!?!?
After powering up the device defaults to -20/-10.
DDX V1 recalled the latest settings.
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Old 28th November 2012, 07:57 AM   #333
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One more update.

I learned that the remotes are on its way since a couple of days.
Great.

Unfortunately I didn't make lirc work on my PC with the remote codes they send over.

######

The amp got broken in a little further. It still gets better.

Me and a friend of mine do pinned the rather first critical point (in audiophile terms) .

The coils that are used by HifiMe does not seem to be the first choice.
But that was mentioned earlier. They used the same type of coils
on the DDX V1.

Unfortunately they didn't consider my earlier made upgrade proposal.
I even mentioned measuremets of different coil types (done by different manufacturers).
These have shown that it can be done better.

The coils cause some kind of "bloat". They impact the air between instruments. The attack gets softened.

If you've heard your tracks without it before, you won't be able to accept this more then obvious weakness ( in audiohile terms ).

These parts have to go.

There are alternatives.

Very often you'll find ( also over here at DIY-Audio) Wuerth PD Typ XXL mentioned. These cost a little above a $ each.
I do have them myself. They definately sound better and linear - without bloat - then the stock coils.

I also run (on the DDX V1) aircoils from Mundorf, which are still my favourites,
though more expensive.
The reason behind running air-coils are mainly my 98db/w speakers.
At the low power levels that I'm running, magnetic emissions from aircoils are managable. Air Core coils are known for best linarity and complete lack
of signal distortion due to core saturation effects.

Vibration effects do play another role here. I guess the type of coils and the way HifiMe mounts (using the wire as stands) their coils can cause some further negative sideffects due to vibrations.


As I said. HifiMe is aware of this point. Keep the fingers crossed that they do something about it.
We hopefully see a better solution with the next release. The cost factor for a reasonable solution is pretty low. But that won't help the V2 owners now.

Until then we've to heat up the soldering irons.

Next I'll have a look at the Lelon power caps. The datasheet doesn't look that bad at all though.

Perhaps these caps are better then their reputation (over here at DIY-Audio).
I mean -- the amp sounds damned good after break-in and coil swap.
And I'd guess that HifiMe compared those Lelons to Panas FC or similar. ( Would be nice if HifiMe would comment this one!?!?)

Cheers

Last edited by soundcheck; 28th November 2012 at 08:10 AM.
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Old 28th November 2012, 09:17 AM   #334
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One more:

Some layout comments.

1. I do have the impression that either a decoupling cap for the TCXO
is missing or it is much too far away from the TCXO.
Workaround: It might be a good idea to solder a very low esr cap (22uf or similar ) right to the TCXO pins. I don't think the Elnas are the best choice for that job.

2. Decoupling cap was removed from Toslink.
At least on the V1 decoupling the Toslink made a big difference.

3. The entire outputstage parts (R/L/C) are IMO much too close to each other. This might cause unwanted interferences.
My workaround. I'll place my swapped coils underneath the board.

Cheers
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Old 28th November 2012, 06:37 PM   #335
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@Soundcheck

Does the new board have an I2S header ?. I think you made a very good point about that earlier in this thread.

thanks
Pepe
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Old 29th November 2012, 06:44 AM   #336
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Quote:
Originally Posted by lindamar View Post
@Soundcheck

Does the new board have an I2S header ?. I think you made a very good point about that earlier in this thread.

thanks
Pepe

I have to check if they still use the master clock mode - synchronous clocking of WM8805 and STA320 as they did with CS8416 and STA320.

They do have introduced an easy way to access the I2S lines right in
front of the STA320 chip. You might recognize the 4 big white arrows right beside it on the board image .

However. Meanwhile I got away from I2S. Running SPDIF or Toslink can have advantages. The WM8805 sorts many of the incoming distortions out and ends up with 50ps jitter according to spec. With Toslink I achieve the galvanic isolation. Any distortions you'll feed through I2S end up right at the heart of the machine.
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Old 29th November 2012, 08:15 AM   #337
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Thank you very much for such a detailed explanation, I can appreciate in the picture where to plug the I2S signals.

Given that I have Ian´s reclocking unit (provides a clean I2S output as you may already know), I was wondering whether this amplifier could benefit from a clean and pure I2S input. What is your feeling about that ?

Cheers and thanks again
Pepe
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Old 29th November 2012, 12:42 PM   #338
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Quote:
Originally Posted by lindamar View Post
Thank you very much for such a detailed explanation, I can appreciate in the picture where to plug the I2S signals.

Given that I have Ian´s reclocking unit (provides a clean I2S output as you may already know), I was wondering whether this amplifier could benefit from a clean and pure I2S input. What is your feeling about that ?

Cheers and thanks again
Pepe
I followed IANs thread for quite some time. For sure he's trying to push the
limits with his work. His boards look impressive. The feedback is quite positive.
(Though nobody ever responded to my question, if all sources feeding the reclocker were sounding equal with that device in the chain. )

He also runs the Sabre in sync mode. You might be able to get the DDX hooked up to the reclocker.

In any case I'd expect the reclocker to have some impact.

Though I'd say the coil issues I mentioned before, potentially have more impact than a couple of picoseconds of jitter.
I'd address this bottleneck first.


I'm personally not a big fan of making chains more complex then needed anymore. ( I rather give feedback to HifiMe to improve their devices )
The more stuff you loop in, the higher the risk that you catch other/new issues through the backdoor.


Let us know, if you manage to get it work.

Last edited by soundcheck; 29th November 2012 at 01:03 PM.
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Old 2nd December 2012, 10:54 AM   #339
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Hi folks.


Short update.

I replaced the Techcode DC1507 DC/DC converter with A123 based 3.3V
battery supply (just 3 cells in parallel) . Those DC/DC converters
don't have the best reputation.


My battery supply I've been also using with the DDX V1. I could easily reuse it.

Desoldering the DC1507 is a little tricky. The brave ones might cut off the legs and clean the pads after that.

But obviously that's the way of no return.

I soldered the supply line right at the inductor (filter for DC1507) output, in front of the blue Panasonic cap. That's a nice fad pad and trace.
Ground went to that 9 hole ground pad close by.

It was done in ten minutes.

As usual adrenalin raises to extreme levels, when you switch on your device the first time.

First the high voltage. Next the LiPoFes. I use two switches.

Yeah. The red LED went on. Great.

Now press the play button. Sound!!!. Cool.

It then took 10s seconds to realize what's going on.

Another serious step up!!!

This modification is highly recommended.

Enjoy.
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Old 3rd December 2012, 02:50 PM   #340
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Hi Soundcheck,

Where can I buy the Wuerth PD Typ XXL you mentioned? Any model number?

Ackcheng
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