New/upgraded TC-7520 power supply?

Does this mean the 7520 is or is not suitable for use with a 12V system driven by a large lead acid battery :scratch:

I would have thought the battery wouldn't care about the capacitance.

A battery would be fine. In fact, that's exactly what I am going to try on my TC-7520 this week. I used to have one of Doede Douma's fantastic 1543 based DDDAC kits which I found sounded best powered by a sealed lead acid battery, but as the thing drew in excess of 1A at 12V I ended up buying a golf cart battery (20Ah) and having to charge it once a week which was a bit of a pain. The Beresford as I understand it only draws around 100mA, so a modestly sized 12V SLA battery will last a good while.

I've been playing with power supplies for a while with both the 7510 and the 7520. I found the original wall wart OK, then tried the Maplin supply but didn't find it significantly better and returned it. I then got Stan's new supply and found that to be a good improvement over both the standard supply and the Maplin, but nothing to my ears even approaches my discreet supply which I built using a toroidal transformer outputting 18V - 0V, feeding a low ESR electrolytic, going into one of Teddy Pardo's TeddyReg boards from PFM. To me this just raises the DAC to another level (especially if you've changed the op-amps to your liking). The usual disclaimer about your mileage may vary applies. I'll be interested to compare it with a battery supply and will report back if anyone is interested.

I am really interested in your approach Lovejoy and would be grateful if you would publish details and piccies of your PSU in the DIY section. Isnt 18v getting a bit much?
I dont think Stan approves of talk about alternative PSU which is understandable given the effort he has gone into producing his new one. Its likely that very few people would go down this route however given the time and cost involved.

Completely agree. From Stan's point of view, he's trying to make the best DAC available for the best price, which in my mind he's achieved and then some. It would make absolutely no sense to make this kind of power supply to sell as even an option as it would be heading towards doubling the outlay. I've been lucky in that everything I've built has come from parts I either had lying around or cannibalised old dead projects.

Yes, 18V would be too high to feed straight into the DAC. The 18V AC from the toroid gets rectified and smoothed and ends up at about 25V which feeds the TeddyReg board which in turn outputs the 12V to feed the 7520. This solution is by no means perfect. Ideally a toroid which gave me something in the region of 12-0-12 so I could perform full wave rectification and a higher value low ESR cap would probably improve things further, but apart from the TeddyReg board itself I've not bought anything new.

The battery experiment will be funded by the £20 credit note I have from Maplins from when I returned their power supply.

Would it cost that much? The Super TeddyReg board built and shipped is only about £40.

The Super TeddyReg is £40 (I wish you hadn't mentioned that as that's another experiment for another day ;-)). Then you have to add the cost of a transformer and a bridge to feed it with. I guess you could use a simple mains transformer which wouldn't cost you much more than a fiver but I can't vouch for them. Toroids (which I am using) after a quick look at the Maplin website are around £20 and generally considered a better bet for audio. Then add a good quality low ESR (this bit is important) smoothing cap which is another few quid and either a bridge, or diodes (pennies) and a nice box to put it all into. The cost soon stacks up, not to mention all of the time gone into designing such a thing.

If you feed more than 15V into the DAC be prepared for an internal explosion inside the DAC. The power cap is rated at 16V.

It maybe worth editing the above post and the one on here http://theartofsound.net/forum/showthread.php?t=2658 which mentions 15v , as Stan says if the caps are max rated at 16v running them over 15v will make em go bang, running near max voltage is at least going to greatly reduce the lifespan may even leak,bulge and go noisy if run 24/7
Your best off giving them some headroom, 12v would be the best imo

Its funny Leo mentioning that. I was always a little bit wary of the comments about running the Maplin PSU at 13.5v. I wouldn't want to go any higher than the designed voltage.

The Maplin PSU was only recommended for the TC-7510 up to the MK5. From the MK6 upwards the internal PSU design was changed. That pronounced midrange boost on the higher voltages is due to the inability of the Maplin PSU to charge up the Virtual DC power supply high capacity capacitor inside the TC-7510 & TC-7520 within less than the minimum frequency one expects to reproduce. That means that the lower bass energy requirements are not fulfilled by the Maplin PSU.
In the case of lead acid batteries: these are unable to perform adequately once they are partially discharged. Their off load voltage might be 12V or more, but once on load they can drop below 12V. I did many measurements and even ended up abandoning my attempt to make a battery PSU. The sub woofer I bought off Dave_C clearly showed up a softening of the bass as the battery got discharged.

Stan