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In Reply to: RE: In other words, signal quality matters greatly posted by cics on June 17, 2010 at 10:08:41
Hi,I need to take a new trace when I get to test another unit. But the traces shown above are not that good at all.
I previously posted on my modifications for the Musiland Monitor 01 USD, which includes the traces from my mods without the tube section.
http://www.audioasylum.com/forums/pcaudio/messages/6/66884.html
The tubed output stage does better. The figure comes from the NEC Digiscope. I did a doubletake too, but the numbers came up like this.
I think it calculates the rise time from 30% to 70% around the zero crossing. Still, the output is very square, a lot better than the above.
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Edits: 06/17/10Follow Ups:
I used a cheap Creative soundcard (which outputs TTL and yes its crap) for that measurement (using ELAB-080 DSO). Your Musiland trace looks good and even better after mods.
A tube output stage makes a lot of sense. Given that BMC encoding is used for both S/PDIF & AES/EBU and they can be readily converted to/from, can the tube design be extended to AES/EBU?
Hi,
> can the tube design be extended to AES/EBU?
Sure, it just needs a different wiring up. This will all go into the Manual.
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
hey Bro, remember dr. fikusz had tried on using AES/EBU however the result is NEGATIVE..
What he said:
I am sure that a single ended connection is best for S/PDIF signal. I do not like toslink and I don't like AES/EBU either.
The "pro" looking AES/EBU connection is using XLR and it looks OH SO PROFESSIONAL WOWIE ZOWIE. We buy by the eyes. But the AES/EBU is not invented to be better. It is invented to be LONG DISTANCE.
The RS422 industrial data transmission from which AES/EBU derives can travel as long as 1,8 km (over one mile) on the twisted pair balanced cable. The S/PDIF in coax cable can travel up to few single meters. THAT IS THE DIFFERENCE. But the S/PDIF signal on both ends exists ONLY as simple single ended asymetrical signal. We must make it balanced artificially by means of adding a balancing transformer which badly distorts the signal. Then we use in our systems one metre cable (not one mile !) and we must use de-symmertization transformer on other end again. That's two unnecessary transformers, two too many for me.
In analog systems, the ballanced XLR has more meaning - as described HERE, but in digital - the signal itself is never trully ballanced, it is the sending media that is ballanced to make long distance possible.
so why is the AES/EBU sounding better on many transport/dac combos ?
Answer is easy. Because the S/PDIF on all transports that I have seen, and I have analyzed about 40 different ones - is made wrongly and it uses an ugly separation transformer as well. So in that scenario - S/PDIF can not beat AES/EBU because they both have the biggest limiting factor - the transformer."
Like my previous post, removing the pulse trans will help in sound revealing transparency.
Hi,
> hey Bro, remember dr. fikusz had tried on using AES/EBU
> however the result is NEGATIVE..
Yes. But that this mean it is universally applicable?
Generally when done to equal levels of implementation, AES/EBU usually sounds better.
> But the S/PDIF signal on both ends exists ONLY as simple
> single ended asymetrical signal.
Actually, wrong. Almost all receivers out there have balanced inputs.
> We must make it balanced artificially by means of adding a
> balancing transformer which badly distorts the signal.
Wrong again. AES/EBU can be made "transformerless", secondly, the traces shown from the Musiland (as well as the Tube Stages I designed) use transformers. Transformers only distort the signal if used wrongly.
The key to understanding is that all these interfaces are radio-frequency designs. We can make wireless routers that work reliable at 2.4GHz. The 25MHz needed for SPDIF and/or AES/EBU are actually quite easy, this merely Shortwave radio frequencies.
> Then we use in our systems one metre cable
Ouch. A 1 meter coax cable is precisely the worst length or an SPDIF cable.
> Like my previous post, removing the pulse trans will help
> in sound revealing transparency.
Actually, you may wish to read the blog posts over at www.diyhifisupply.com. You are right insofar - removing the original tranformers (which are basically inappropriate) improved sound quality.
HOWEVER, correctly implementing some higher quality transformers improved the sound quality even further.
Then getting rid of the two daisy chained inverters that drive the digital outputs on the Musiland and using instead a linear tube stage while retaining the transformer produced further improvements.
The bottom line - as I often say, it is not what you do (e.g. use transformers in SPDIF or AES/EBU interfaces) but how you do it that makes the difference.
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Hi Thorsten
> HOWEVER, correctly implementing some higher quality transformers
improved the sound quality even further.
What output transformer would you recommend for the Juli@ to replace the Hanrun?
Regards
Hi,> What output transformer would you recommend for the Juli@
> to replace the Hanrun?First, I do not know the Juli@ first hand, I have no idea of circuit implementation etc. So it is impossible to make an informed suggestion.
Second, simple transformer swapping gets you nowhere fast.
You need to be able to find a transformer that is sufficiently consistent in production (harder than you think) and characterise it's parasitic (unwanted) behaviours and then design a circuit that gets the best out of this transformer.
For example people ask me "Which transformer do you use for your musiland mod's, I want to try them."
My answer is always:
"Knowing Brand and type will not help you, unless you know my exact application circuit, which is not for public dissemination. And to avoid negativity from people using the transformers wrong and then complaining they are not good and this reflecting back badly on my designs I'm not telling the first part either."
I hope you understand.
Ciao T
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Edits: 06/18/10
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