Mod your Beresford 7520

[larry]

Hi,

Can I know what's the value of the MLC 8 / 9? I have remove it previously and have lost it. Is the code 101? More detail of the capacitor will be welcome.

[StanleyB]

100pF

[dave2010]

StanleyB

Good to see you here. I suppose I've not had my Caiman for a week yet, but it's still going OK, and really nice.

Ron over on another MB would like some info - http://www.bbc.co.uk/dna/mbradio3/F7...w=20#p93223093

bws

Dave

[StanleyB]

Spit out the question you want to ask Dave. I am not a member on that forum.

[dave2010]

Stanley

I answered Ron - see http://www.bbc.co.uk/dna/mbradio3/F7...=yes#p93260408

Basically he's looking for a way to get a 24 bit/88.2 or 96kHz input via USB. Looking at the manual the Caiman doesn't do this right now.

Thanks for quick prompting anyway.

Dave

[leo]

Majority of dacs can't yet accept 24/96 from USB , tbh the quality of the Caimans USB input is actually very good and its nice to have the option of USB as standard with it even if it is limited to 24/44.1.

[larry]

Hi AOS ppl,

I have some problem with my 7520. Hope you people can help me in it. Yesterday I was using this DAC connected to my hifi. Everything was ok. Until when I decided to listen through headphone. The right channel give out cracking sound occasionally and it is very obvious. I have the MLC 5 6 8 9 remove. Using two LME49720. So I change the hp opamp to the stock. The problem is still there. Till today I decided to give it one more try. With lme49720 in line and stock in hp amp. the cracking sound was gone. So I though was unstable due to high BW. So I try with ths4032 on line and lme49720 on hp and result the cracking sound did not appear. Anything wrong with my dac?

[leo]

May have been a dodgy connection on the op-amp socket, I've had this happen before (not with the Beresford dac) if its ok now you may have improved connection after removing and inserting the chips

See how it goes, if you don't notice it again I wouldn't worry

[dave2010]

leo

The usb does also do 32 and 48 kHz. The word size is limited to 16 bits, which arguably gives a slight dip in quality - depending on material. I don't know enough about USB to be sure, but I have a hunch that the error handling on usb links may be problematic for streaming audio. Either there'll be errors, but they won't be corrected, or there'll be errors which will require a retransmit, and that'll mess up the timing. Maybe there's sufficient buffering in the DAC to render this only a minor problem, but otherwise, and if I'm right about this, then it'd make sense to use really good cables. The only experience I've had with errors on usb cables is trying to retrieve data from a Humax Freeview box (9200?). It really did make a difference using short, better cables, and also routing them away from other kit - and, oddly enough, the floor. I understand that part of the problem was due to the
poor driver for the Humax, but even so, the fact that the box was driven into an error resend mode thus triggering calamity suggests that the bits on a usb wire are not reliably error free, particularly if there is a potential interference source nearby. For most computer purposes some errors are not normallly a problem, as everything will be sorted eventually, but for audio streaming applications problems should be avoided and minimised, otherwise the sound really will suffer. I don't know the details of any cables which are good enough to reduce this problem reliably.

Until recently I didn't know the benefits and limitations of SPDIF. For quality audio right now it does seem to be good, but in the longer term I think we're going to have to either have something completely new or migrate to HDMI in order to handle sound with multple channels in high quality.

[StanleyB]

Neither TOSLINK nor Digital Coax have error correction, so it is a bit difficult to single out USB on that front. In any case, in all the years of copying data from PC to harddisk I can't remember a single file that was incorrectly copied. The same goes for anything I printed via the USB port.

As for the suggestion that 16 bit gives a slight dip in quality: I guess we'll all have to throw out our 16 bit/44.1KHz discs then since their quality is suspect . Let's face it, higher bit files are not yet mainstream, and not cheap to buy either. So catering for the minority need of 96KHz USB audio would involve a price hike since higher bit rate USB components don't come cheap. There are a couple of DACs on the market that support 96KHz, but I can't ever remember reading a review or test on any of those DACs where USB audio files of different bit rates and frequencies were tested. I'll be interested to know if anyone has.