Ants Beresford TC-7520 mods & guide

[Ant]

FWIW, when I had my modded by Stan 7510, I used a Maplin psu, similar price to the one suggested, if not the same unit, and IMO, it didn't make an audible difference, although at the time I persuaded myself it did.

That's the reason why 7 lines from the top I included the text: "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."

However - if you intend to implement discrete regulators and especially if you swap the 10v for a 12v you may need to allow as much as 3v dropout (dependant on regulator circuit/design chosen) - which the 12v OEM cannot deliver.

I intended to go 'discrete' from day one - hence the Maplins 15v PSU was added from the off.


Ant

[Reid Malenfant]

Hi Anthony, nice work chap I have a little suggestion for you that might be worth looking into. Regarding your LM317 regulator board, try removing the 10 ohm resistor & replacing it with a 1Amp or greater low value inductor I'd suggest somewhere between 30 - 100 micro Henry. In the standard StanDAC this resistor tends to reduce the dissipation of the 7805, but it also makes the supply feeding the regulator subject to voltage fluctuations if the output current varies (as the voltage dropped by the resistor will vary in sympathy)..

The LM317 should have no dissipation problems & is a much better regulator. If you replace the resistor with an inductor you'll virtually eliminate any switching spikes from the PSU reaching the regulator input, thus the output will be cleaner. There should also be less of a voltage fluctuation on the input & thus the output will be better regulated to..

Just a thought

[Ant]

Hi Anthony, nice work chap I have a little suggestion for you that might be worth looking into. Regarding your LM317 regulator board, try removing the 10 ohm resistor & replacing it with a 1Amp or greater low value inductor I'd suggest somewhere between 30 - 100 micro Henry. In the standard StanDAC this resistor tends to reduce the dissipation of the 7805, but it also makes the supply feeding the regulator subject to voltage fluctuations if the output current varies (as the voltage dropped by the resistor will vary in sympathy)..

The LM317 should have no dissipation problems & is a much better regulator. If you replace the resistor with an inductor you'll virtually eliminate any switching spikes from the PSU reaching the regulator input, thus the output will be cleaner. There should also be less of a voltage fluctuation on the input & thus the output will be better regulated to..

Just a thought

Quite right as you say - a 30-100µH inductor replacing the 10r would work very well indeed, I will do just that.

Thank you,
Ant

[Alex_UK]

Great guide Ant, thanks for taking the time to share it with our members.

[icehockeyboy]

That's the reason why 7 lines from the top I included the text: "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."

However - if you intend to implement discrete regulators and especially if you swap the 10v for a 12v you may need to allow as much as 3v dropout (dependant on regulator circuit/design chosen) - which the 12v OEM cannot deliver.

I intended to go 'discrete' from day one - hence the Maplins 15v PSU was added from the off.


Ant

Yeh but no but yeh but........... Not audible to not significantly better is still a big gap.

[chrism]

Yeh but no but yeh but........... Not audible to not significantly better is still a big gap.

The internal 5v and 12v regs are the limiting factor for any external linear PSU solution. They need sorting with something better if a quality linear supply is to be used and appreciated.

Your choices appear to be non-switching regulators like Dexa etc (not Muratas) or like me, removing the internal regs entirely and providing external linear 12v and 5v regulated supplies straight into the DAC.

As Ant says the bits add up!

Regards

[chrism]

Hi Ant,

Have you looked at swapping the pot out in the Caiman? It looks to be a 20k Alps type and I wondered if any improvement could be gained from the variable output from trying something else?

Noble types are just too big or I would give it ago.

Regards

Chris

[Ant]

Hi Ant,

Have you looked at swapping the pot out in the Caiman? It looks to be a 20k Alps type and I wondered if any improvement could be gained from the variable output from trying something else?

Noble types are just too big or I would give it ago.

Regards

Chris

Hi Chris,

I'm currently in progress with quite a few other bits 'n' bobs so I haven't looked into the pot as yet, although I don't use the variable or headphone so in my case it isn't really necessary but.... and a big but.... I have biggish plans for my 7520 so I suppose a stepped pot may be an idea whilst I'm at it.

So sorry, not as yet but soon.... maybe


Ant

[chrism]

Hi Ant,

Regarding stepped pots, has anything caught your eye that may be worth ago. Quite a lot of what appear to be original Alps pots on ebay for £10.00 but not sure if they would better Stan's original choice.

Would like to find something that fits the case rather than a stand alone lightspeed type.

Regards

Chris

[Ant]

Hi Chris,

As a replacement pot to fit in the STD case I'd go for the £15 Alps Blue aka "Blue beauty" here

Although in my case if plans go as expected the physical size of of the pot isn't the underlining requirement so I'm going to go for one of these or something like it.

Ta,
Ant