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may even be possible to add switches so you can compare against the standard voltage or against an external one, I've not looked into it all properly yet tbh, I just did a few easy simple mods, this thread never really took off so I just left it as is:)
Brilliant Leo, I thought I did a search on all VMID refs within the datasheet, doh! I knew it wouldn't work as it stands! I guess RTFM applies here :)
Well mate I've not tried it yet so can't be 100%
Problem with a lot of dacs is that they don't give enough details, the internal diagram for the wm8501 is only basic, it doesn't show us all the details
BTW, I'm well into modding this unit now. Here's what I've done so far:
- removed 3.3V switching reg & replaced with external supply
- removed 5V reg & replaced with external supply
- tapped I2S to a socket that I can plug my I2S ESS DAC into (ES9022 at the moment - ES9018 eventually)
- although I wasn't particularly interested in the WM8051 on-board DAC I decided to experiment with it as it will drive headphone loads without problem.
- Removed output coupling caps & wired directly - sounds good through external caps
- played around with VMID & tried a transformer output between VMID & Vout (cancelling the 2.5V bias) - sounded distorted
- supplied external 2.5V on one leg of trafo primary instead of VMID - sounds wonderful
So with your suggestion I'll now try to disable VMID & supply it with external 2.5V
Things left to do:
- remove 1.2V switching reg & supply from external
- remove wifi board (I'm only interested in wired connection) - this can be done with the 1.2V & 3.3V external supply in place & unit doesn't report a hardware error
- remove 11.289MHz clock & provide external clock to Xilinx pin 42
- disable SPDIF on 74HC chip
- further de-couple all sensitive chips.
- would love to provide a clean 3.3V directly to Xilinx chip as I think it would benefit from a clean supply but the PS is provided through a power plane & no traces showing that can be cut. This has to share the 3.3V PS with Realtek & 74HC & WM8501. I could remove the 74HC & WM off the 3.3V bus but not the Realtek.
Anyway, the device has good potential & I've order a low jitter clock to complete my mods. Sound from the WM DAC via transformers is very good.
You've tried a lot more than me with the Receiver, anyway It will be interesting to see how you find the modded receiver compares as a transport against the modded Hi-face and Musiland:)
Hi,Quote:
Originally Posted by jkeny
My first post here. Found just what I was looking for. Wow thats an impressive list you have there.:stalks: ATM I am at the PSU upgrade stage and decoupling of the critical stages, not swapped the regulators yet.
Care to share any pictures ?
Peter.
Hi Peter,Quote:
Originally Posted by UKPD
I'm not getting notifications from this forum so apologies.
I have to report the sad news of the demise of my SBR - a minutes silence, please :). My latest mod - removed the 1.2V reg & connected a wire - while connecting my 3.3V battery the gnd wire of the 1.2V supply touched the + end of 3.3V battery. It did n't die immediately, seemed to be OK for a while & then died a short time later :( Now the front led just slowly flashes through different colours & the ethernet port does not seem to be working or the led on the optical out. Any ideas? Kapput? I was hoping it might have been a diode blown but I fear the worst - these batteries can put out 120Amp instantaneous current!! Beware of loose wires & late nights - I usually have all my connectors in place before connecting anything. just when it was getting interesting too!
Anyway, sob, sob, I don't have any pics of my set-up yet but here's a site with pics & info -
http://www.lampizator.eu/LAMPIZATOR/...queezebox.html
And another that I have posted on http://forums.slimdevices.com/showpo...&postcount=133
BTW, Leo, I contacted Wolfson about ENABLE/VMID so I wouldn't kill the WM8501 (how ironic is that). The support engineer has been just quoting the datasheet for 2 days now - can't get a straight answer from him. I might escalate it?
Anybody know of a cheap WORKING SBR - I have a good case so damaged case would be fine?
Sorry for the late reply(back from work). I feel your pain,:(
ARe you shure it's all dead? Maybe you can use Wi-Fi node instead of LAN.
I do have a spare squeezebox but I'ts V-1 (if thats any good for you).
Peter
Yes, I'll look into the wifi side but I suspect the worstQuote:
Originally Posted by UKPD
Thanks for your generous offer but I wanted to stick with the SB receiver as I believe that it has the best potential for sound & I've already put some research into it (as you can see)
Anyway, I'll help here, if I can, while I wait for a cheap SBR to become available.
What do you think of this reply from Wolfson about how to supply an external 2.5V - I think it's piffleQuote:
I appreciate the datasheet is a little confusing but I do not believe it to be incorrect.
Internally the VMID is generated using a simple resistor divider circuit and therefore you should be able to change it using an external source without turning the internal supply off. You should also be able to AC couple a signal onto the internally generated VMID supply.
There is no way of turning the internal VMID supply off without disabling the whole device through the use of the ENABLE pin.
I hope this helps.