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

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.

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 with our THS4032 dual op-amp module or, alternatively, you may wish to have LM4562 dual op-amp upgrades fitted (See explanation below).

• Upgrades to One or Both of the Dual Op-Amps

There are 2 dual op-amps used in the Beresford 7520. 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.

• Upgrade to LM4562 Dual Op-Amps

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.

• Upgrade to THS4032 Dual Op-Amps

Alternatively, we can fit THS4032's in the fixed/variable output and headphone output sockets. These are surface mount devices mounted on our adaptors to make them go in the existing sockets.

Comparison of these Two Alternative Upgrades

We don’t know the relative merits of the LM4562 & the THS4032 upgrades.  You will have to rely on the Artofsound forum discussion & similar sites to decide which you want

Upgrading just the op-amps – an alternative to posting to us.

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 e-Bay shop 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 )or pin1 of the adaptor (THS4032) in the same location. On our adaptor, we mark pin1 with a “blob” of black marker pen. 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.

Upgrade to Caimen class”A” output configuration

The new limited edition “Caimen” DAC from Beresford has a class"A" output stage. We think this is for the headphone output but it may be on both outputs. We have been asked by several people if we have an upgrade which would take the 7520 to full Caimen spec. We cannot do this as we cannot perform an upgrade to either of the dual op-amp based circuits to make them class “A” configuration outputs. To do this would probably require a redesign of the PCB. We can only perform the Wolfson DAC chip upgrade and upgrade of the dual op-amps to better dual op-amps as detailed above. This is not the same as providing an upgrade to a class “A” output configuration.  You’ll have to buy a “Caimen” to get that.