Audio DAC Upgrade - The Beresford 7520 Audio DAC Upgrade offered by Tirna Electronics Ltd

It is generally reckoned that with DAC’s the upgrade of op-amps is the most cost effective upgrade & the one which could potentially bring the greatest improvement. After that, the replacement of the Burr-Brown DAC with the Wolfson DAC chip has been shown to bring further worthwhile improvements. We support following Beresford 7520 DAC upgrades

 

 

1. Upgrade to Wolfson WM8716 DAC chip

This upgrade replaces the Burr Brown PCM1716 DAC chip with the pin-compatible Wolfson WM8716 DAC chip.

 

Fig. 1 shows a 7520 with the old Burr-Brown PCM1716 DAC chip removed and ready for cleaning up the pads.

 

 

 

Fig. 2 shows the pads after they have been cleaned of old solder in preparation for soldering in the new Wolfson WM8716 DAC chip

 

 

 

Fig. 3 shows the 7520 after its “operation” with the new chip in place.

 

(Click Here To See Posts in The Art of Sound Forum)

 

 

2. MuRata Regs + Rubycon bi-polar Caps + WIMA Caps

 

This upgrade replaces the standard 5Volt and 10Volt Linear regulators with 5Volt and 12Volt MuRata Switch Mode Regulators and also replaces the six standard electrolytic signal coupling capacitors with six 47uF bipolar Rubycon capacitors. Also, two 47nF monoblock capacitors are upgraded to 68nF WIMA capacitors.

 

Warning Note:

This upgrade was originally developed for the new Caiman version of the Beresford DAC family, which is supplied with a 15Volt DC power source and this upgrade requires a 15 Volt DC source. If you apply this upgrade to your 7520, you must also change the DC source to 15Volts. If you buy a 15volt Caiman source from Stan Beresford, he will require confirmation from Tirna Electronics that you have indeed had this upgrade applied to your 7520. The reason for this is if you plug a 15Volt source in to your unmodified 7520 with the original internal linear 5volt regulator, you will risk damaging the 5Volt regulator. We are happy to provide confirmation to Stan Beresford on request from you.

 

(Click Here To See Post Number 264 in The Art of Sound Forum) - The link shows this upgrade applied to a Beresford Caiman DAC but is equally applicable to the 7520 DAC with the warning note above.

 

 

3. Additional for those who want to upgrade op-amps

 

You may want to upgrade one or both of the dual op-amps in the Beresford 7520 module with LM4562 dual op-amp upgrades. One dual op-amp drives the fixed/variable L & R RCA (phono) outputs at the back of the unit and the other drives the L & R headphones through the standard jack socket at the front of the unit. These 2 dual op-amps are to be found in sockets on a small circuit board over the volume control. The simplest upgrade is to replace either or both of them with LM4562’s which are available in the same type of “Dual-in-line” package as the standard dual op-amps which came factory fitted. Users who do not use headphones often just upgrade the fixed/variable output dual op-amp in the left hand socket looking down on board and viewing from the front of the unit. We can provide these upgrades as required when you send us your 7520.

 

4. Upgrading just the op-amps – an alternative to posting your 7520 to Tirna.

 

If you feel up to performing the upgrade yourself (we know some of you could “do it in your sleep”), then you can buy what you need from our EShop and perform the upgrade yourself, avoiding postage costs. If you do this, consider the following two points.

 

  • Please make sure you are “earthed” by wearing a conductive earthing strap. This not only protects your circuit, it also protects yourself. Earthing straps to wear on your wrist and plug into a standard UK 13A socket, picking up earth through the socket earth pin, are available from Maplin and similar electronics stores for a few pounds and are designed to connect you to earth through a 1 Megohm resistor (1,000,000 Ohms). This may not sound like a good earth contact (sometimes defined as less than ½ Ohm!), but it is low enough to discharge static from your body and, at the same time, is safe in that it limits the current which will flow through you if you touch live mains while connected to earth. (it’s the current which kills you, not the voltage).
  • Be sure you know where pin1 of the standard op-amp is BEFORE you remove it and place pin1 of the new op-amp (LM4562 ) in the same location. Op-amps usually have a semi-circular “cutout” between pins 1 and 8 on their top surface. Pins are numbered 1 to 8 anti-clockwise as viewed from above.

Send your Beresford 7520 to us for modification without it’s power supply to the address below

 

Dr Jimmy Dripps
Tirna Electronics Ltd
3 Roderick Place
West Linton
Peeblesshire

EH46 7ES

 

 

Purchase of this upgrade

 

Please purchase this upgrade through our EShop

 

We can also supply the Rubycon bi-polar and WIMA capacitors recomended for the above upgrades to customers who want to do their upgrades. However, customers wishing to do this themselves will have to source their own MuRata regulators, or contact us to obtain them via Tirna.

 

Please don't hesitate to contact us if you have any more queries. Click here for Feedback & Requests Form.

 

Jimmy Dripps

Tirna Electronics Ltd.