Mod your Beresford TC-7510

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Originally Posted by NRG

Stan, I'd be interested to learn more about these mods.

Update:
I ran my DAC continuously for 24hrs with the new 5v ALW reg and the sound has now settled IMO. I was still not happy with the low bass quality and went back to the original configuration as a sanity check...what I discovered is that the small (11R ?) surface mount resistor in line to the supply of the opamp is needed, feeding the 12v from the ALW reg via this resistor fixed the low bass.....I have no idea why but without it there was something missing...with it everything fell into place.

I also tried listening without the input PSU caps as you suggested, I didn't loose any bass but I found the sound stage became confused and muddled....very strange. I then tried a single 4700uF Blackgate as a replacement and I was taken aback...

What a difference this made, simply more of everything, I highly recommend to anybody replacing the two PSU caps with a good quality replacement it made a very noticable improvment in my system.

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Not knowing all the innards of this dac what other caps are after this 11R resistor Neil? is it just the SMD ceramic for the op-amp +v ? I wonder if it was some too low impedance or something the ALW didn't like and the 11R helps isolate it, also adds more impedance? I do know the ALW's can be picky whats on their output.
The ears are a good test tool for telling you theres a problem

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Originally Posted by Sensimilia

Don't get too carried away with external products that you feel might improve the sound of the DAC. My aim has always been towards trying to keep the changes internal since that is still the cheapest route.
There are loads more mods that can be done to the PCB, but many of them require extreme skills. Like swapping the PCM1716E for a WM8716. The two chips are pin for pin compatible, but the WM8716 has not got an analogue filter circuit built in, whilst the PCM1716 does. So to do that mod requires a few other associated mods. Then there is the CS8414 timing mod for reduced jitter. Etc. etc.

stan

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Hi Stan .
Can you tell us what the pico seconds are for jitter for the tc-7510 and if this value makes a difference to the transport you can use with it. :scratch:

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Originally Posted by NRG

what I discovered is that the small (11R ?) surface mount resistor in line to the supply of the opamp is needed, feeding the 12v from the ALW reg via this resistor fixed the low bass.....I have no idea why but without it there was something missing...with it everything fell into place.

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That will teach you wondering why I put it there:eyebrows:.

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I also tried listening without the input PSU caps as you suggested, I didn't loose any bass but I found the sound stage became confused and muddled....very strange. I then tried a single 4700uF Blackgate as a replacement and I was taken aback...

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You can use a 10000uF/16V, but be careful! There are two Hamei branded ones on eBay that I have tried. The one that is 25mm high is the one to choose. The 30mm version is too high to fit in the case. This cap is part of the Virtual DC power supply design I came up with, which relies on a double regulated power supply chain. The MK6 version was in its experimental stage. In the TC-7520 I managed to make some additional improvements.

Stan

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Originally Posted by leo

Not knowing all the innards of this dac what other caps are after this 11R resistor Neil? is it just the SMD ceramic for the op-amp +v ? I wonder if it was some too low impedance or something the ALW didn't like and the 11R helps isolate it, also adds more impedance?

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It's part of my Virtual DC circuit. Since I can't patent it, I can't tell you how it works;).

STan

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Originally Posted by Sensimilia

It's part of my Virtual DC circuit. Since I can't patent it, I can't tell you how it works;).

STan

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I wouldn't expect that Stan, I know how picky the ALW's can be so mainly wanted an idea what caps they would be seeing on the output, its not unusual for them to oscillate with low ESR types

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Originally Posted by kalozois100

Hi Stan .
Can you tell us what the pico seconds are for jitter for the tc-7510 and if this value makes a difference to the transport you can use with it. :scratch:

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i found out the jitter is less than 50 pico seconds if anyone is interested.

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Originally Posted by Sensimilia

That will teach you wondering why I put it there:eyebrows:.


You can use a 10000uF/16V, but be careful! There are two Hamei branded ones on eBay that I have tried. The one that is 25mm high is the one to choose. The 30mm version is too high to fit in the case. This cap is part of the Virtual DC power supply design I came up with, which relies on a double regulated power supply chain. The MK6 version was in its experimental stage. In the TC-7520 I managed to make some additional improvements.

Stan

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Thanks Stan! I take it the 11R provides some supply damping / decoupling of the LC cct formed by the PCB track and supply pin decoupling cap. Anyway it works.

I've made futher progress over the weekend, I've reinstated R11/R14. With all of my changes to the PSU I found the sound just little too strident and bright over longer listening, putting them back in has calmed things down. I think I'll try some more opamps as suggested previously.

Normally lowering the value of an op-amps FB resistors widens bandwidth, going by the pic it seems R11/14 are in the FB in series with R18/19

R11/R14 are part of a MFB filter. You can try lower values like 2K2, but don't leave them out otherwise the filter won't work as it should...

Stan

Hello Stan.
Today i recieved the LM4562MA opamp so i took the tc-7510 to elec. engineer and he is going to proceed with changing the opamp along with the mod21 part 1+2. I am really looking forward to the upgrades thanks for providing them in pdf form.
Kalozois.:):):)