Pavel Dudek's (Upupa Epops) LM4780 amp

peranders said:
What does it mean in numbers? What is a high capacitance cable, I mean to regular ones?

The numbers are represented in pf capacitance per meter.:clown:
Don't remember the exact numbers of Kimber 4TC and 8TC (double capacitance of 4TC!).
Google a little and you'll find it.
The construction of the cable (crossed) gives it mid to high capacitance.
Low capacitance cables are figure-of-8 or flat cables, like Nordost and others.
That's why I initially had better results with cheap Supra 2.5, these chips don't like capacitive loads.
It's sorted, and I'm sure that if my amp works very well with a 5 meter pair of Kimber 4TC, it will work with almost everything.
 
Peter Daniel said:
It is very conservative approach, with a big concern on safety of operation and proper interfacing. It seems like sonic perspective is a little overshadowed
The safety circuits has nothing to do with the sound (or?) but I haven't got those because I think this integrated solution has got very good properties when it comes to reliability. Has anybody broken a correctly connected LM3886, LM3875, LM4870? Please report!

Pavel is right though: The parts cost nothing. They only take up a little space.
 
I am really looking forward towards a FAIR(and I do stress that) face to face comparison between a 47 style GC and a Pavel style GC...
Of course I would like to have a better design coming from europe, but I don't care where it comes from if it sounds better(us, canada, china, europe or any other place on earth) and doesn't cost a ton on c@sh nor does it consume 100watt+ at idle.
 
carlosfm said:


The numbers are represented in pf capacitance per meter.:clown:
Don't remember the exact numbers of Kimber 4TC and 8TC (double capacitance of 4TC!).
Google a little and you'll find it.
The construction of the cable (crossed) gives it mid to high capacitance.
Low capacitance cables are figure-of-8 or flat cables, like Nordost and others.
That's why I initially had better results with cheap Supra 2.5, these chips don't like capacitive loads.
It's sorted, and I'm sure that if my amp works very well with a 5 meter pair of Kimber 4TC, it will work with almost everything.


4 TC 144 pF per meter
8 TC 328 pF per meter

It means capacitance in a normal room of < 1 nF. Isn't this "small"? Nothing to worry about?
 
peranders said:
An amp should be able to take 100 nF, or at least 10 nF without problems. If not redesign it.

Tell that to National engineers.:clown:

I'm telling you that with direct output the amp sounds bad with these cables.
I'm telling you that with zobels it gets a little better, but not perfect.
I'm telling you that the solution I have is the best I found and solves it.
And I'm tired.:bawling:
Gotta go drink a cold beer.:D

Note: not every amp works fine with Kimber speaker cables, you know?
Or other high-capacitance cable.
And sometimes you change the speaker and the problem is gone.
Is it only the amp?
No.
Do you have answers for everything, P-A?
No.
 
Upupa Epops said:
cables : after many listening tests, which we do here, absolutely best results give hf power coaxials, such as Andrew and similars, belive or not ;) .

Interesting, but that reference is too cryptic for me. Is there another description for "hf power coaxials"? Sorry if this is dumb question.

Sheldon

Edit: Turns out that was a somewhat dumb question. Found it by searching Andrew Coaxial - duh. Ok, so here's a not quite so dumb question: Which of their cables are you referring to? I'm assuming the 1/4" variety?
 
Sheldon said:
Turns out that was a somewhat dumb question. Found it by searching Andrew Coaxial - duh. Ok, so here's a not quite so dumb question: Which of their cables are you referring to? I'm assuming the 1/4" variety?

Andrew cables apparently were the basis for the well regarded JPS cables. They have a solid copper shield, so are not easy to handle. The center conductor is a copper/aluminum solid wire, which shouldn't be trusted in most circumstances for audio. But it seems to work. The LFS5 is a good place to start.

That Andrew cable is mostly used for radio antennas, so getting a few meters to try shouldn't be hard.

If you follow the instructions on TNT's article written by Thorsten Loesch, using a coaxial cable to build a speaker cable, it's only a matter of replacing the original for the Andrew.

Such arrangement has a very low capacitance.



Carlos
 
carlmart said:

That Andrew cable is mostly used for radio antennas, so getting a few meters to try shouldn't be hard.

These guys seem to stock Andrew cable and sell by the foot:

http://www.cablexperts.com/cfdocs/cat.cfm?ItemGroup=11&itmsub=0&bskt=0&USA_ship=1&c=0

The type is LDF150. As you can see capacitance is low: 23.4pF/ft.

Price is reasonable, so it deserves a try.

There's a potentially even better cable, coaxial too, called Tflex 402. It uses teflon dielectrics and silver-plated copper. It's harder to find, but it's probably one of the best there is.

One of the few retailers might be this:

http://www.semflex.com/pdf/SM Series.pdf



Carlos