Mod your Beresford 7520

[Gazjam]

in other words....

trust the Designer to know a thing or two about a thing or two...

[therockst4r]

I did. I tried a set of Burson discrete opamps. The results were:
1. It didn't work
2. The case couldn't close

Added to that, the distortion figures for the U$100 Burson discrete opamps are 0.001%, compared to the U$5 LM4562 0.00003%.

If you are however hell bent on going discrete, even though the sound will be more distorted than the LM4562, let us know how you get on.

Stan

I am not that interested in the Burson due to costs, but im curious as to why it didn't work. Any ideas? I would be more likely to try the Moon discrete opamp.

[StanleyB]

I am not that interested in the Burson due to costs, but im curious as to why it didn't work. Any ideas? I would be more likely to try the Moon discrete opamp.

It didn't work because the minimum operating voltage required is far more than the available operating voltage in the TC-7520 and the Caiman.

The distortion figures quoted for the more expensive Moon discrete opamp is 0.0003%. That is still ten times more than the LM4562.

I don't know which opams are used in each and every DAC out there, but I doubt that there are many that have a lower distortion figure than the Caiman. And the ones that do are no doubt uber expensive.

[therockst4r]

It didn't work because the minimum operating voltage required is far more than the available operating voltage in the TC-7520 and the Caiman.

The distortion figures quoted for the more expensive Moon discrete opamp is 0.0003%. That is still ten times more than the LM4562.

I don't know which opams are used in each and every DAC out there, but I doubt that there are many that have a lower distortion figure than the Caiman. And the ones that do are no doubt uber expensive.

The Moon seems to be much cheaper than the Burson, unless I misread something, and its operating voltage should be low enough to work in the Caiman. An engineer told me that anything under .001% is inaudible anyway, so I am not too concerned. The Moon is specifically designed for high fidelity audio, whereas the LM4562 is not, so it would be interesting to try it.

[StanleyB]

The Moon seems to be much cheaper than the Burson, unless I misread something, and its operating voltage should be low enough to work in the Caiman.

The operating voltage of the Moon is +/- 9V minimum. That is higher than the maximum the Caiman can handle.

The Moon is specifically designed for high fidelity audio, whereas the LM4562 is not, so it would be interesting to try it.

Moon only mentions on their website that their opamp uses audiophile grade resistors. It does not mention the same about the transistors they use.

The LM4562 is specifically referred to as a high performance audio opamp.

[leo]

Interesting pdf here on op-amp distortion, theres quite a few tested including those discrete Audio-GD jobs http://www.sg-acoustics.ch/analogue_...mps/index.html

[therockst4r]

The operating voltage of the Moon is +/- 9V minimum. That is higher than the maximum the Caiman can handle.


Moon only mentions on their website that their opamp uses audiophile grade resistors. It does not mention the same about the transistors they use.

The LM4562 is specifically referred to as a high performance audio opamp.

What is the maximum the caiman can handle? I thought the Caiman could handle 10V. Their website is kinda lacking in details I must admit, so I cannot comment on their transistors. As for the LM4562, it is not a bad opamp, its just more geared to integrated devices like CD Players and such. Discrete opamps are more geared to Hi-Fi use. I have never done a direct comparison, but I know people who swear by them, so I would be interested in doing a head to head comparison.

[leo]

The Caiman is +10v but as Stan already mentioned the Moon requires +/-9v ( +9v to ground and -9v to ground) total is 18v

Only other thing is run it from a seperate supply

[prenzlberger]

You guys are amazing!!
When I last read this thread ... before getting the LM4562s for my 7520 ... we were at 78 pages, and now look!

I am truly happy with my purchases. The 7520 is everything I hoped for, driving my STAX Lamdas just wonderfully.

What I also love is the fact that this small unit can fullfil so many tasks.

For the STAX, which have their own amplifcation, it serves as AD converter. For my AKG701s (which I use as "guest phones"), it is a fabulous amp, which runs in parallel to the STAX. Nifty!
And with a pair of M-Audio powered speakers, the 7520 even handles the task of background music.

Few products have been as thoroughly satisfying as this small unit.

Carry on folks, I'm perfectly happy, but it I'll keep reading the thread, because who knows, perhaps the modding bug bites again!

[Gazjam]

The Moon seems to be much cheaper than the Burson, unless I misread something, and its operating voltage should be low enough to work in the Caiman. An engineer told me that anything under .001% is inaudible anyway, so I am not too concerned. The Moon is specifically designed for high fidelity audio, whereas the LM4562 is not, so it would be interesting to try it.

Your talking to a couple of engineers here too.
One even designed the Dac.

Its a balance really, and Stan's approach to it is really hitting the mark in my opinion - hence the large following his products have.

I've a Tirna modified 7520 (thanks again guys) and I had another spooky listening moment earlier tonight...

LastFm was on in the background playing random favourite tracks of mine, (my Dacs still running in as I've not had the time since I got it to listen to it much till recently) and I was pottering about the house when I stopped what I was doing and had go into the living room.

A live recording of Bill Hailey "Rock around the clock" from the 1950's no less...and the recording acoustic was spooky.
VERY realistic "life size" images playing along the front wall of my room.

I guess its like what someone said earlier about being ruthlessly revealing of the recording?
It works for good recordings as well Im glad to say.

I call it the "Fleet Foxes" effect!
That is one SPOOKY album, with close miked harmonies 2 inches from your nose...

Anyway,
One thing Ive noticed the Caiman doing as it ran in was helping the speakers disappear more and more.
Everythngs rock solid now, sound just comes from the wall now, and occasionally from the sides of the room too
.
Stan how DID you do manage that????