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Old 8th December 2012, 02:01 PM   #351
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Does anyone uses the SMPS from hifimediy to power their DDX? Or is it better to use the linear power supply?
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Old 13th December 2012, 06:56 AM   #352
raschaa is offline raschaa  Germany
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I have the DDX hooked up to SMPS 300R, 38v turned down to 36v. No real listening yet, just hooked up "on the fly" for a quick test. Am working on the case right now.

Have noticed some "irregularities":

-dip switch on/off positions do not correlate with user manual table
- light hiss on free input channels, hooked up toslink input was dead quiet with source turned all the way down
- led-segments have different brightness
- no "." (dot) lighting on display during stand-by (completely dark)

only cosmetic issues, hoping the audio quality lets me accept them...

p.s. my first post^^ as a long time passive reader. Hi and thanks!
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Old 19th December 2012, 09:20 AM   #353
raschaa is offline raschaa  Germany
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All righty, got it up and running. First SQ impression is good, nice sound stage.

I do have one issue that I don't understand. I have a SBTouch connected via toslink to the DDX and it plays much quieter than my previously used Sure TA2024 via analog cinch. I have to set DDX at 0db and am still lacking quite a bit in subjective SPL in comparison. This strikes me as strange seeing that the DDX has a bit more power than a TA2024.

Ideas?
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Old 20th December 2012, 04:22 PM   #354
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The voltage gain differs from amp to amp.

Usually you find values in the range of 20-30db. That can make up your difference.

A difference you could measure at the amp outputs or even with a simple SPL meter (see iPhone/Android apps). Best with a single tone.



But. There are more factors.

The more precise your chain gets the less grunge you'll experience. That grunge can make you think your system plays louder. A lot of people report
a rather "thin" listening experience with better equipment and turn their volume control further up.


But. It could aslo be the case that if you havn't done much tweaking to the DDX, your old amp could deliver a better "punch" (better dynamics) . This might sound louder on the first glance. Note: I'd give the DDX needs at least two weeks to settle.


A lot of of options. No clear answer. I know.


I think your question is not that easy to answer. Try the simple measurements first. Then read the datasheets. Usually you'll
find the base voltage gain listed.

Cheers

Last edited by soundcheck; 20th December 2012 at 04:24 PM.
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Old 20th December 2012, 04:30 PM   #355
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Quote:
Originally Posted by raschaa View Post
- light hiss on free input channels, hooked up toslink input was dead quiet with
That what happens on rather poorly isolated SPDIF coaxes.

That's why I recommended to supply at least one SPDIF input with pulsetransformer.


However, even with a pulsetransformer in place you wouldn't wipe out all the junk.


Cheers

Last edited by soundcheck; 20th December 2012 at 04:35 PM.
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Old 20th December 2012, 06:25 PM   #356
raschaa is offline raschaa  Germany
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Hey Klaus!

was kind of waiting for you to answer^^ Yes, my question is kind of "diffuse"...

I really should just let the amp "settle" as you commented. SQ wise I'm very impressed and it is already a good step beyond what I was listening to before. Miles Davis - Kind of Blue remaster was excellent as is J. McLaughlin - Live at Royal Albert Hall just rigt now. Alas I do listen to a lot of electronic stuff as well and that you can never hear to loud

Subjectively I could turn up the old amp until I started to hear the "grunge" and would then back off a bit. That was quite loud for 15cm single driver tqwt speakers. Now I can turn the SBT and DDX both to max and there is no Grunge and the speakers handle it fine except for maybe extreme electronic bass attacks. This leaves me thinking that there could/should be more SPL to be had??? But then again the 75w@8ohms of the DDX are not going to be so much more than the 10w the 2024 supposedly cranks out.... Sure-Elctronics website lists 27.6dB power gain for my old amp...

Wouldn't know how to measure at the outputs (Multimeter?), may just try a SPL app for grins.

Does your amp display have different brightnesses on the led segments?
Do you plan on documenting your DDX mods on your blog?

Danke schon mal
Ragnar
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Old 21st December 2012, 08:50 AM   #357
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* I havn't really looked at the display brightness. I run it in auto-off mode
anyhow.
What I figured is that the timer seems to be much lower then 5s.

* I might consider to write something about the DDX320 V2 on my blog.


Cheers
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Old 21st December 2012, 07:32 PM   #358
raschaa is offline raschaa  Germany
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Nick gave me the heads up on the undocumented +10db feature of dip 4.... and yes those must be chinese seconds

By the way, have you done any "serious" attempts of using the sub feature?

Would really like to see one of your excellent write ups with the DDX as topic!
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Old 24th December 2012, 02:25 AM   #359
i2k92 is offline i2k92  Indonesia
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Anyone here compared the DDX with other HifimeDIY T1 & T2 amps ? I know that's not apple to apple comparison as they're all different beast. I just try to justify to buy the DDX or not as I have both T1 & T2.
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Old 24th December 2012, 08:58 AM   #360
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Quote:
Originally Posted by i2k92 View Post
Anyone here compared the DDX with other HifimeDIY T1 & T2 amps ? I know that's not apple to apple comparison as they're all different beast. I just try to justify to buy the DDX or not as I have both T1 & T2.
Hi.

As a matter of fact, you need to compare your DAC+T1+cable/connectors+volumecontrol/preamp vs. DDX320.

It'll be not that easy to compare. However.


The class-d powerstages should have a pretty similar sound signature at least.
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