Collection of mods for Beresford TC-7520

[leo]

Ok, thought I'd try and gather various mods etc for Stans TC-7520 dac and add them on here, if we could keep this as a mod thread only and keep the discussions on the other threads just so it makes things easier to find

We'll start with the basics first, if I've done anything wrong or if its not clear just let us know, the idea here is to make things easy
Other mods will be added later but for now

Heres a pic of the riser board containing the op-amps



Below with the THS4032 fitted for the fixed output and AD826 for the HA/variable
For the THS4032 I used this browndog adaptor I converted to allow room with the 100nf ceramic fitted http://theartofsound.net/forum/showthread.php?t=2507



Below with the LM4562 fitted for the fixed output, Stan recommded removing MLC5 / MLC6 ceramics if using this particular op-amp, I compared with and without and must agree I preferred it without those caps, you can easily compare ,either by cutting one side of the caps leg or carefully taking out the riser board and desoldering the caps altogether (watch out for the hot melt glue and double sided sticky pad )
I've also not yet tested other op-amps with the caps removed, be careful with high bandwidth types



Below with the metal can LM4562HA for the fixed output



Op-amps I've tried so far in the fixed out which seem to behave

OPA2132
OPA2107
AD826
LM4562
LM4562HA metal can
Various NE5532
THS4032 + 100nf bypass, I got best results soldering this cap directly onto the THS4032 pins rather than the socket pins, so far its behaving

Only types I've tried so far for the variable out are OPA2107,AD826 and LM4562, all these worked, I personally like AD826 so far but its only early days

Most op-amps can be found here http://uk.farnell.com/ and also Ebay

Latest update 04/07/09

Swapping PCM1716 to WM8716

Warning, this is a fiddly job, not recommended if your not comfortable working with SMD, a mistake can result in a Knackered dac!
My advice is wait for Stans SE version

I used precision side cutters to cut the legs, I then removed each remaining leg on the pads with desolder wick
As can be seen I managed to lift pad for pin12, luckily it wasn't connected to anything
The board was cleaned with pcb cleaning fluid to remove caked on flux etc







This mod made quite a noticeable difference to the sound, straight away I found it was smoother yet crisp in the highs
Left to warm up dynamics increase nicely

Added 05/09/99
Results may vary with this mod depending on op-amp, system used etc
Stans mod to the Caiman, details here http://theartofsound.net/forum/showthread.php?t=3740 also added a few pics and notes here for easy finding

If original 100pf ceramics are still inplace these need to be removed and replaced with resistor (Stan found 36k to be best so far, I'd have to agree) and 100nf ceramic cap soldered in series
Mod seems to work best with NA version of LM4562



Fit as below



Update 23/12/09

Onboard 5v reg for dac and receiver changed to a diy discrete (this particular one in below pic is designed by John Swenson) I built it on vero/matrix
Other possible replacements are what Stan uses, Mouser Part No: 580-7805SR-C Manufacturer Part No: 7805SR-C, theres also a 12v version which can be used for supplying the Caimans audioboard , you need to swap the main external psu though to one of Stans 15v Caiman upgrades to give the needed voltage drop for the regulator

Alternative type regs are avaialble from Paul Hynes, Audiocom, Hi-fi upgrades etc, I hope to try a few of these others and do a mini shoot out, I'll add updates

Signal capacitors on audioboard replaced with a set from Stan, some details here post 72 http://theartofsound.net/forum/showt...?t=4580&page=8

I was quite pleased with these mods, both go well togther and help squeeze some more out of this unit




Limks to useful posts updated 24/06/2010


Stans mod to change the default input selection http://theartofsound.net/forum/showthread.php?p=131177
Stans mod to increase gain http://theartofsound.net/forum/showp...&postcount=449
Stans mod to shorten track from audioboard http://theartofsound.net/forum/showt...t=4580&page=49

Values and locations for those wanting to cap roll on the main pcb around regulation, dac and receiver IC , Elna SilmicII seems to be the favourite choice from those who's tried them http://theartofsound.net/forum/showp...&postcount=457 http://theartofsound.net/forum/showp...postcount=1586

List of part numbers for the caps , Thanks Fran (fmzip)

Nichicon Muse Caps
UES1C470MPM

Elna Caps
RFS-25v221 2pcs
RFS-16V101 1pc
RFS-16V100 8pcs

Wima Cap
MKS20-.068/63/10

MartinT's diy external psu http://theartofsound.net/forum/showthread.php?t=6110
Stans idea using a linear CB radio psu http://theartofsound.net/forum/showt...&highlight=psu

Murata regs tried and recommended by Stan, thanks to fmzip for link
http://parts.digikey.com/1/parts/159...-7805sr-c.html

http://search.digikey.com/scripts/Dk...words=7812sr-c

Dexa regulators tried and recommended by MartinT, thanks to Martin for link
http://www.newclassd.com/index.php?page=34

Updates 04/07/2010

Stans mod for bypassing output stage op-amps
http://theartofsound.net/forum/showt...411#post134411