Ants Beresford TC-7520 mods & guide
Hi all,
I've been playing with the TC-7520 for a while now so I thought I'd share my mods with everyone as a guide. I'll include the layman's terms key at the bottom so everyone whether novice or DIY guru can follow, I'll also include various instructions together with costs and links to the parts used - all being well it will help someone along the way.
No.01: “plug and play”
I recommend purchasing a 'better' PSU from the off, I chose the “Maplins High Power Multi-Voltage Desktop Power Supply” as it has a greater current delivery than the standard Beresford wall plug, it is still however a SMPS so not ideal for audio but the HF noise is dealt with further down the list.
This power supply will not automatically make your 7520 significantly 'better' but it's a start and every little tweak adds up to a bigger picture.
It's the most expensive of my 'mods' coming in at £37
Link: http://www.maplin.co.uk/ac-dc-multi-...r-supply-48517
No.02: “op-amps”
I swapped the 5532's out for LME49720HA tin hat in the fixed position and LM4562NA in the headphone/variable position with superb effect, much more dynamic and musical with a more apparent spacial presentation, a highly impressive mod.
It's an absolute doddle to do too, insert a small flat head screwdriver between the old 5532 op-amps and their sockets, lightly 'turn' the screwdriver to push the op-amps out of their sockets, take care not to use any other components on the board as leverage, once they're lifted slightly – pull out by hand.
Looking from the front of the TC-7520 Insert the LM4562NA op-amp (Headphone/variable) so that the small semi-circular recess is facing towards the right of the socket, lightly align the op-amps legs and press in firmly.
The insertion of the LME49720HA is slightly different as this op-amp needs the circular orientated pins forming/bending slightly with a pair of thin nosed pliers to fit the square socket. Make sure the 'PIN' (photo below) is pointing towards the front right hole in the socket and press in firmly taking care that all the legs are situated correctly.
Job done – Told you it was easy!
I highly recommend purchasing the LME49720HA from “yp53” on ebay, his service is truly excellent and at £12 delivered – rather cheap.
Link: http://www.ebay.co.uk/itm/LME49720HA...ht_1633wt_1396
Piccy:
No.03: “op-amp de-coupling/coupling”
For this mod you have to remove the op-amp PCB – To do this you need to carefully remove the glue that bonds the PCB to the headphone socket, there is also a double sided sticky pad underneath the board which with a thin screwdriver carefully prize the board away from the headphone socket and gently lift the whole PCB.
I use Nichicon MUSE ES 47uF 50V (UES1H470MPM) here with great effect, they're quite a large cap so need the legs bending 90 degrees, don't worry – they leave 1-2mm gap between the front panel and lid. They're Bi-Polarised so more suited to the application.
I found the mod to widen the sound-stage and produce a more revealing listen.
They're incredibly good value at only 32p each
Link: http://www.hificollective.co.uk/comp...chicon_es.html
Piccy:
* At this point I'll add I purchase all my capacitors from http://www.hificollective.co.uk/ , Nick (the owner) is a superb guy and in my experience his service is second to none.
No.04 “MLC5/6”
Here's a simple one that only involves removing 2 components (yellow capacitors) from the PCB, like myself by de-soldering and removing or by simply snipping the legs, either way the mod compliments the LME49720HA quite nicely – Strings seems to be more pronounced and accurate, a good old 'free' mod.
Piccy:
No.05 “Swapping the DAC chip”
NOTE: This is definitely one for the experienced DIYer so please don't even consider it if you feel unsure, it is extremely fiddly and if done wrong can render your TC-7520 useless.
I replaced the Burr-Brown PCM1716 with the Wolfson WM8716 and here's my method – I used a couple of wooden cocktail sticks and inserted them under each run of legs and simply flooded all of the pins with solder whilst gently sliding the 'sticks' further under the legs, swapping from side to side the chip soon rises and releases, there were no lifted seats and enough solder was left to simply place the WM8716 in situ and gently heat the pins flowing the solder underneath, I did not add any 'extra' solder as I knew if I bridged any pins I would have a hard time removing it.
It was well worth the £6 outlay, there is more control over the whole spectrum, the mids are more 'punchy' and the bass is lower, again a wider sound stage. Overall – very happy with this mod.
Link: http://eshop.tirnaelectronics.co.uk/...roducts_id=181
No.06 “10v regulator RC Filter”
Again – one for the more experienced DIYer as the whole PCB needs to be removed and soldering is required. I'm not particularly keen on the idea of SMPS for audio due to the HF switching noise so to combat this I used a simple RC filter for the 10v 3pin regulator.
Here's how – There is a jumper (J15) just in front and which feeds the 10v regulator, I removed this jumper and replaced it with a 1ohm resistor in the right hole feeding the positive pin of a Nichicon MUSE KZ 1000uF 25v (UKZ1E102MHM ) capacitor and back down into the left hole. The negative pin of the cap is linked to GND at MLC12. Vuala – simple HF filter.
The cap is big so needs seating at 90 degrees and it fits perfectly in the space given.
The cap is only 95p and the result is well worth it.
Link: http://www.hificollective.co.uk/comp...chicon_kz.html
Piccy:
No.07 “bulk DAC caps”
Again – one for the experienced.
I see quite a few folk have replaced the bulk caps around the DAC with Elna Silmics – I'm not really a fan of Silmics as I find them a little boomy and soft. My favourite electrolytics bar none are the Nichicon MUSE KZ's, they're very cheap, well damped and I find them dynamic and rhythmic. Here's what I replaced with the KZ's:
EC2 – 220uF 25v (39p) UKZ1E221MHM
TC2 – 100uf 25v (33p) UKZ1E101MPM
TC1/3/4/5/6/7/8 & EC3 – 10uF 100v (50p) UKZ2A100MPM
All at a cost of under £6, a vast improvement over the OEM's (IMO) - More outright scale to the output.
Quick tip – I found the best way to fit the caps was to remove the 'bunged' solder from the pad holes by holding a solder sucker on one side of the PCB whilst heating the other, click/suck/gone.
Link: http://www.hificollective.co.uk/comp...chicon_kz.html
Piccy:
No.08 “post 10v reg de-coupling”
Again – an easy one whilst the board's out.
Another KZ here (EC19) in the form of 220uF 25v (UKZ1E221MHM), no apparent improvement here but a 'better' cap can't hurt after a reg and at 39p, you may as well.
Link: http://www.hificollective.co.uk/comp...chicon_kz.html
Piccy:
No.09 “the ribbon”
This was not a planned mod but after I tore the quite delicate ribbon cable after numerous 'in and outs' it was a necessary job. Not a lot to say other than I replaced the ribbon with cat5 solid core. I found the easiest way to remove the ribbon was to cut/separate the ribbon between each cable and de-solder each run individually.
No improvement noticeable other than a more forgiving/hardy connection.
Piccy:
No.10 “hard wired usb”
I removed the plug/socket from beneath the USB board and replaced with a tightly twisted soldered pair of solid core cat5 thinking the less 'connections' the better although no apparent improvement.
Piccy:
No.11 “the sockets”
I had a few spare quality “CMC” phono sockets so I thought 'while the case is empty'. I had to enlarge the case holes by 3mm so the connectors had enough room to sit side by side , no sonic benefit apparent but a 'better' mechanical connection none the less.
Piccy:
No.12 “the very cheap yet very effective 5v reg”
Another for the competent DIYer and IMO – the most beneficial and my favourite mod.
I used a very simple and very cheap discrete regulator circuit based upon the LM317 3pin here with superb effect, not only does it cut the passing HF noise from the SMPS but it cuts the noise from the LM317 itself.
I had to move the 1000uF 16v Cap through 90 degrees and solder to legs to fit the reg, the case closes with no fouling.
Here's my simple reg with the layout on a strip of veroboard:
Piccy:
And here's the complete (for now) product:
KEY:
SMPS: Switch Mode Power Supply
PSU: Power Supply Unit
Op-amp: Operational Amplifier
Reg: Voltage regulator
Cap: Capacitor
DAC: Digital to Analogue Convertor
BP: Bi-Polar
PCB: Printed Circuit Board
RC Filter: Resistor Capacitor Filter
I really hope this thread has been helpful,
Yours truly,
Ant
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Originally Posted by John
