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Class D Switching Power Amplifiers and Power D/A conversion

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Old 8th November 2006, 09:01 PM   #21
phn is offline phn  Sweden
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Quote:
Originally posted by t.

The UCD uses MBR10100 schottkys, DNM T-network psu capacitors, LM4562 input op-amp and no coupling caps, theres a few other mods added to the pcbs.
The caps are always going to be the limitation of the T amp. Just compare a transformer-coupled tube amp with a cap-coupled tube amp. There's no comparison.

I have two AMP3 kits I haven't gotten around to. I hope to make one without coupling caps. Without a "reference amp" I won't know what the improvement is.
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Old 8th November 2006, 09:11 PM   #22
t. is offline t.  United Kingdom
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Quote:
Originally posted by phn


The caps are always going to be the limitation of the T amp. Just compare a transformer-coupled tube amp with a cap-coupled tube amp. There's no comparison.

I have two AMP3 kits I haven't gotten around to. I hope to make one without coupling caps. Without a "reference amp" I won't know what the improvement is.
Don't you have to use coupling caps though because of the Tripaths input bias?
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Old 8th November 2006, 09:17 PM   #23
t. is offline t.  United Kingdom
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Quote:
Originally posted by thomaseliot
I own both Ucd180ad and Tripath Ta2022 2x50W 8ohm. I've too a couple of t-amps and a Tripath TA0102a 2x100W 8ohm amp.

Low power Tripath chips can't compete with higher power ones: I have Fostex FE206E 96dB sensitivity and t-amps sound loud enough to shake windows, but with high power tripath chips higher and lower dynamic extension are dramatically improved, while sound quality and detail is similar to t-amps, but with more solid sound.

Please, don't ask who's the winner between Tripath and UCD. More useful to discussion is to tell what are good experiences with both.

UCD is unbeatable for clean sound and timber fidelity of instruments (I listen to classic music only): it is like a good valve amp but quieter. I identify this amp with solo violin sonatas and Bach.

Tripath high power amps are unbeatable for dynamic extension, transients and detail: they go lower and higher than UCD and in between it looks like there are more sounds. When the bass section of an orchestra is sounding loud with thick basses, you can still hear distinctly a violins pizzicato at right volume, and the sudden hit of a timbals or drums still detaches from this loud background with great force.

I use UCD when I want fidelity, Tripath when I want live emotions.


P.S.

I'm the guy with 106 MPP cores, 60 perm, 13 turns I calculated with a software that they don't saturate.
Thanks for letting us know thomaseliot
Are these MPP cores available?
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Old 8th November 2006, 09:17 PM   #24
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Old 8th November 2006, 09:31 PM   #25
PWatts is offline PWatts  South Africa
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Well you have to bear in mind that the UCD modules' power ratings are specified into 4ohms, and thus the UCD180 cannot be considered a power monster. Rather go for UCD400 for a better comparison when it comes to dynamic extension and such.

Winding your own cores isn't a terribly good idea. The windings have to be coupled very close to the core for optimal coupling, and any crosscoupling of the windings lead to interwinding capacitance. That's also the reason why toroids aren't preferred since the shape of the toroid makes it difficult to create an even spacing and coupling of the thick wire. Bar cores wind easily, but are not very efficient due to the large air gap, and thus you often need multiple winding layers leading to... capacitance again. That is why the potted cores work the best, or otherwise the SMD ones I mentioned earlier. Merely calculating that the cores don't saturate is only one of the factors that need to be calculated.

Since parasitic elements are usually very small measuring it isn't easy; so unless the specs are published it is best to rather follow the guidelines for what arrangement works best than try and measure what you have.
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Old 8th November 2006, 09:32 PM   #26
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Quote:
Originally posted by t.


Thanks for letting us know thomaseliot
Are these MPP cores available?
You can buy small quantities online from following:

http://www.coilws.com/c_winding_main...Core_types.php

https://www.arnoldmagnetics.com/v2/s...ct.aspx?id=164

Cost is about $3 each. They sell wire too.

Here you'll find software:

http://www.mag-inc.com/software/software.asp
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Old 8th November 2006, 09:36 PM   #27
t. is offline t.  United Kingdom
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Quote:
Originally posted by thomaseliot


You can buy small quantities online from following:

http://www.coilws.com/c_winding_main...Core_types.php

https://www.arnoldmagnetics.com/v2/s...ct.aspx?id=164

Cost is about $3 each. They sell wire too.

Here you'll find software:

http://www.mag-inc.com/software/software.asp
Thanks again Thomas
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Old 8th November 2006, 09:45 PM   #28
t. is offline t.  United Kingdom
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Since upgrading the UCD's PSU (thanks Chris ) changing the AD8620 to LM4562, changing the resistor biasing the zeners in the regulation circuit to CRD's, changing the cap in the output filter the UCD's performance has really improved in my setup

Both the coupling caps and psu upgrade improved the Amp6.
I'll give these coils a try if I can get chance order some just to see if they improve this amps performance
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Old 8th November 2006, 10:00 PM   #29
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Quote:
Originally posted by PWatts
Well you have to bear in mind that the UCD modules' power ratings are specified into 4ohms, and thus the UCD180 cannot be considered a power monster. Rather go for UCD400 for a better comparison when it comes to dynamic extension and such.
UCD180 are 2 mono ~90W 8ohm, twice TA2022 and same as TA0102A. I read somewhere that there's no difference between UCD180 and UCD400 in small rooms like mine (16 square meters). Jan-Peter agreed. In larger rooms and less than 96dB speakers I don't know.

Quote:
Winding your own cores isn't a terribly good idea. The windings have to be coupled very close to the core for optimal coupling, and any crosscoupling of the windings lead to interwinding capacitance. That's also the reason why toroids aren't preferred since the shape of the toroid makes it difficult to create an even spacing and coupling of the thick wire. Bar cores wind easily, but are not very efficient due to the large air gap, and thus you often need multiple winding layers leading to... capacitance again. That is why the potted cores work the best, or otherwise the SMD ones I mentioned earlier. Merely calculating that the cores don't saturate is only one of the factors that need to be calculated.

Since parasitic elements are usually very small measuring it isn't easy; so unless the specs are published it is best to rather follow the guidelines for what arrangement works best than try and measure what you have.
In another thread I was the volunteer for this experiment, just executed other members hints.

Click the image to open in full size.

Experiments are still in progress, when I've time, but this is a good one with respect with T80 low perm 36 turns 1mm wire. I'd like to try lower perm MPP with more turns of smaller wire.
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Old 8th November 2006, 10:11 PM   #30
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Quote:
Originally posted by t.
Since upgrading the UCD's PSU (thanks Chris ) changing the AD8620 to LM4562, changing the resistor biasing the zeners in the regulation circuit to CRD's, changing the cap in the output filter the UCD's performance has really improved in my setup
I have the Hypex supply HG, so nothing to upgrade for the PS. What output caps you used?

LM4562 is an upgrade for AD8620 on the UCD modules? I payed already for AD8620 upgrade with respect with standard opamps

For Amp6 I think the best improvement would be.... power. So strange, but I've tried Tripath chips with 5w, 45w and 100w and, while sound character is similar, thikness and dynamics grows up greatly an proportionally.

Think that Audio Research made e 2x150W Tripath based amp, and one year later, after customers requests, 2x300W. Belcanto started from 2x100w to go to 2x500w bridged.
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