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Another project, all digital DDX amplifier
Another project, all digital DDX amplifier
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Old 14th February 2013, 05:35 AM   #421
hochopeper is online now hochopeper  Australia
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Join Date: Feb 2009
Location: Brisbane, Australia
Originally Posted by soundcheck View Post
You didn't get the point. ian is also changing/evolving rather continously his "ultimate" (that was the thread announcement of day one) reclocker. That's why I brought his project up.

My thread appearance over there:
I was just questioning the "ultimate" subject about that project. There was no misunderstanding.
I never received an answer if the source wouldn't matter with this device anymore as long as bitperfect data are received. That's IMO the key question of todays digital audio. It wasn't answered, and that's why I left that thread.

I've been fooled much too often to run after the next "ultimate" thing.

Please stop spreading nonsense.

Sorry for the intrusion and off topic post but I have seen a few people now criticise Ian's FIFO outside of his thread with baseless claims.

EDIT: moved my post to the FIFO thread where it is more on-topic - Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter

Last edited by hochopeper; 14th February 2013 at 05:40 AM.
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Old 14th February 2013, 05:40 AM   #422
Forane12 is offline Forane12  Bulgaria
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Join Date: Apr 2008
I bought the DDX320 to try to do what soundcheck proposed, it was supposed to be sacrificed... That is why I was kind of unhappy-as I said it died before I did anything to it, that was my disappointment I wasn't trying to bash the efforts of the guys who made it, I was simply wondering why some who can create a product like that and has the ability to program and design does not spend a little more time to make it right... I hope I did show respect by buying it and using two nice magnesium-alloy boxes to house the batteries and the designed recharger, I was hoping that if it is going to die it will be from something I have done to it... Apologies for the spam, next post from me will be on sound quality
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Old 14th February 2013, 06:41 AM   #423
raschaa is offline raschaa  Germany
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Join Date: Oct 2012

Cross-post offtopic bashing.... I as a "noob" in this forum can only get the impression that there must be something fishy with aforementioned FIFO if other forumites deem it necessary to hijack other threads and flame a poster for voicing his opinion. If said FIFO is soooo good then in my opinion it would speak for itself and not need active defending in a thread where (most likely) nobody would really care if product x has been questioned..... at the moment the whole fuss is down to 2 posters, if not alter-ego accounts

People, get a life, relax and listen to whatever floats your boat...
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Old 14th February 2013, 08:04 AM   #424
soundcheck is offline soundcheck  Germany
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Join Date: Mar 2005
Location: DUS
I didn't even critizise that project itself. How could I. I don't even own that product. I just received vague answers in the past.

Both of the guys that posted here are close followers and main posters over there and try to put my comments out of context.

I'm obviously writing too much. People can pick and choose what fits best.

I left a comment over there. I don't have problems to start up a discussion.

Sorry HifiMeDiy and folks over here to cause that trouble. It hasn't been my intention.
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Old 14th February 2013, 10:09 AM   #425
soundcheck is offline soundcheck  Germany
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Join Date: Mar 2005
Location: DUS
DDX V2 - outputstage part II.

The missing Zobels for channel 1 and 2 I mentioned some posts earlier are actually missing snubbers. These are meant for protecting the STM508 mosfets from the reactance (nasty spikes) of the output coils.

Why did they take them out on channel 1 and 2? Hmmh.

BUUUT. Surprise Surprise.

I just figured - after concentrating mainly on channel 1 and 2 all the time - that the bass channel 3 seems to be built according to datasheet!?!?
including snubber, decoupling and identical cap values where expected and also bridges both channels of the 2nd STA508.
Channel 1 and 2 seems to be done completely different when it comes to filters. I'm a bit confused.

I wrote them a mail - to take it offline. I'd like to hear what they say about it. Perhaps I missed something.


Last edited by soundcheck; 14th February 2013 at 10:29 AM.
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Old 14th February 2013, 03:23 PM   #426
raschaa is offline raschaa  Germany
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yes that would be interesting to know why they did not implement them.

My Remote problems are now reduced to one, the subwoofer volume control only works in the "vol-" direction, "vol+" does absolutely nothing... unless.... I default all settings and go directly to the subwoofer volume feature, then I can go up and down as I please. As soon as I use the vol control for, well, the "normal" volume, I can only turn the sub down not up...
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Old 14th February 2013, 05:36 PM   #427
soundcheck is offline soundcheck  Germany
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Join Date: Mar 2005
Location: DUS
I did some filter calculations ( at least I tried to )

What happens if they reduce the butterworth filter cap from 0.47uf to 0.1uf?

1. They'll increase the cutoff frequency from e.g. 22 to 47khz at L=44uH and
That's perhaps not that critical.
2. They also lower the Q of the filter. That's probably pretty positive in this case.
In the case of C=0.47 the filter was underdamped, which caused peaking in
the highs. Getting the Q lower lowered the peaking. Still not perfect, but better.
3. On the woofer amp all that shouldn't matter. That's why they left it the way it

That could be an explanation. Or complete nonsense.

In my case I lowered the stock coil values to 10uH each. That means I end up at an even lower Q and higher cutoff frequency.


Last edited by soundcheck; 14th February 2013 at 05:42 PM.
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Old 22nd February 2013, 08:40 PM   #428
jrling is offline jrling  United Kingdom
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Location: London England
Would it be possible to output PWM from a suitably equipped PC mobo with suitably configured player software direct to the DDX320 and bypass the PCM stage altogether?
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Old 4th March 2013, 07:54 AM   #429
kevkwak is offline kevkwak
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Join Date: Mar 2013
I recently bought one of the Hifimediy amps (version 2.1) and was very happy with it driving 2-way tannoys (@ 8 ohms). Very detailed, precise amp.

However, I dug my old set of B&W Concept 90's (CM1 & CM2) out and felt that the amp was a little underpowered for those speakers.

I checked out the ST chips and found the STA517B was pretty much a direct drop-in "upgrade" - This gives 175w @ 8-ohms rather than the 75w @ 8-ohms from the STA510A chips. It does require more voltage ~57v max but I'm running it at 36v as I was on the original chip and seems to be approx. 10-15db louder from my tests (with the B&W's and amp at -17db volume) - Quick, easy upgrade.

This is great as the amp feels more than capable of driving the speakers now. Since the amp is only working at ~65% now (36v) it's in its sweet spot rather than driving it to 95-98%. More headroom and the whole "balance" of the frequency range sounds more linear, more appealing - I know technically it should sound the same but there's definitely a more "natural" and perhaps "weighty" output from it.

If you have re-flow capabilities I'd highly recommend this simple mod! Obviously the chip isn't being used to its full potential at this voltage but it's running at a nice level. Increasing the voltage means changing out a good few components on the board but I haven't really looked into that yet (and perhaps changing the sub output chip although that's just the same process).
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Old 23rd May 2013, 09:13 PM   #430
Dhika08 is offline Dhika08
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Join Date: Feb 2012
Did you ever had i2c bus problem with your DDX??
I can't read and write using sta308a ddx processor??
do you have any idea??
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