Mod your Beresford TC-7510

[J B]

I'm planning on getting one of these hopefully in the next week or two and I'm just wondering if I could power it off my computer. Since it's gonna be used exclusively with the computer I was thinking I might as well run a twelve volt line out the back and into the DAC. What kind of effect would this have on the sound? Same as the stock psu or better like the Maplin?

Josh

[freddiecas]

I would guess worse since pc supplies are notorious for being full of interference from the various switching currents.

[ZebuTheOxen]

You'd have to go with something like a Corsair PSU. They use large Rubycon capacitors for the power stage, very low ripple.

If I read what you said correctly, you want to power the DAC from the PSU already running in the computer? I can't vouch for this but the amount of noise generated by a computer PSU is not conducive to a good quality listening experience.

If you used a PC PSU solely you would be burning 40w+ just to power a 12w(?) device, and even then it would offer no real benefit over the stock 7520 power supply.
Not to mention wasting a perfectly good PSU.

Better off buying a gang lead and plugging the stock 7520 PSU in seperately.

[J B]

I have quite a high end seasonic psu and was hoping to run both computer and DAC off it at once but if there's still going to be a lot of interference on the line I'll get the maplin psu

[ZebuTheOxen]

Sorry I didn't realise this was the 7510 thread, I should pay more attention when posting.

[YoG]

Does anyone know if the Maplin power supply pointed out by Stanley can be fixed with a different mains lead? I was almost sure it could but still took the opportunity to ask the Maplin fellow.. they denied its possible

I found this pic on eBay, someone is selling his Maplin PSU.. afaik this is the exact same one that can be used with the 7510?


It looks like he removed his mains lead... so would it be possible to replace this with an expensive power lead, such as Russ Andrews sells on their site? Or would that be total overkill in combination with the cheap PSU ??

[Stratmangler]

Does anyone know if the Maplin power supply pointed out by Stanley can be fixed with a different mains lead? I was almost sure it could but still took the opportunity to ask the Maplin fellow.. they denied its possible

I found this pic on eBay, someone is selling his Maplin PSU.. afaik this is the exact same one that can be used with the 7510?


It looks like he removed his mains lead... so would it be possible to replace this with an expensive power lead, such as Russ Andrews sells on their site? Or would that be total overkill in combination with the cheap PSU ??

The mains lead is a bog standard IEC kettle lead. So yes you could replace it with an expensive power lead from Rus Andrews, although why you would is beyond me. I reckon you'd be better off with one of these from Mark Grant cables.

Actually I really reckon that you'd be better off just getting a new psu from Maplin because that way you'd have the mains lead and the adapters to fit the DAC.

Chris

[snip]

That's a great result, well done. With the caps in place I predict it will sound even better!

I made another change last week, snowed in for the third time in a week I had time on my hands to finally implement a pulse transformer on the SPIDF output of my squeezebox:



Shameless borrowing of the idea!

Before, the SB SPDIF output as seen on the 'scope was a bit of a mess, with the cct in place the much cleaner scope trace confirmed what my ears where telling me...wow!

I am intrigued by this idea.
Any chance you can remember what chip it was that you attached the jumper cable to?, did the pulse trafo fit inside the SB casing or is it outboard?
I must admit I have never opened up my squeezebox, if anyone has a picture of the internals to highlight where this chip is I would be very happy to see it.

I suspect there is no room in the case so I guess it would be a small hole in the back of the device, piece of vero board with the components and a BNC socket on and then velcro it on the back or something?

//Jan

[leo]

The chip in the SB3 is just an Hex inverter , both the S/pdif and XO pass through that chip, ideally you want the pulse transformer as close as possible

[snip]

The chip in the SB3 is just an Hex inverter , both the S/pdif and XO pass through that chip, ideally you want the pulse transformer as close as possible

Ok, one of these days I should get around to opening it up, got a lot of things on at the moment though.

Also I am not sure I won't just flog it and get either a touch or a hiface, I have a whole lot of 24/96 material.

On the subject of the 7510, I recently got one of these from chrism, so far I have changed the opamp, performed the mod21 as set out by Mr. Beresford.

Right now I am using Panasonic FC caps in the input and output, I may change these to non polar Nichicon MUSE, also I have not found my bag of poly caps yet so have not changed C5/6 yet, I clipped a leg off CC1 and 2, clipped the L+R wires between the two boards and have replaced the LM7810 with an LM317. Check it out; Pardon the shook up picture, lamp in one hand, iPhone in the other.

I whipped it up with whatever was laying about, some tantalum's the connecting legs down to the board are their leads bent through the vero board, then the two regulating resistors and a 100pF disc fits pretty neat, gives out 9.68V and has lovered the noise on the 10V rail by 30 odd percent if memory serves.

I found that clipping the signal wires to the headphone/variable part really tightened up the sound of the fixed output.
In fact, I quite fancy sawing off the part of the board that deals with the headphone amp, if Stanley would be kind enough to give an authorized answer as to where it would be safe to place the cut, as it cannot be reversed. I could then use that space to fiddle about with a discreet output.
From what I can see right about where the G wire comes in from the ribbon cable looks safe enough provided I then ground to chassis at another point.

Has anyone had the DAC chip changed for the Wolfson and can comment on how that sounds? Personally the idea of oversampling does not sound that appealing to me, If I were to go for such an idea I'd properly get another 7510 and try it on. In a few days I am going to do a comparison of this modified one to a stock one at a friends house, I will naturally before then implement a 317 based 5V regulator as well and run it off a linear supply.

//Jan