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Old 18th November 2010, 02:25 PM   #1101
smithie is offline smithie  United Kingdom
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chokesrule
if your using lampys tube output stage as a filter directly wired to the dacs then those caps are doing more then what first appears,if i remember rightly they act as loading for the dacs and the circuit...or something like that,depends what dacs and design your using i guess...i dont know enough to be of any help other then point out that i remember reading that value was quite important for some dacs.
maybe better starting a new thread regarding the lampizator and its use with these amps as its more to do with that side of things and you may get more help that way...it would be a shame to damage your dacs
all the best
smithie

Last edited by smithie; 18th November 2010 at 02:27 PM.
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Old 18th November 2010, 02:36 PM   #1102
benoar is offline benoar  France
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Quote:
Originally Posted by hifimediy View Post
Hi, we actually use 1k/14k on T1, so don't worry about that, 30V is ok for T1.
Nice. Could you update the schematic then, please ? And is there any other change ? Thanks.

Quote:
And for the feedback caps, I think some one has answered.
Well, I don't see that, only other people wondering why this choice of yours. Stereo bridged (T1) and single BTL (T2) are quite similar theorically in the feedback circuit design, I think. I just wonder why you change the value between the T1 (390pF/150pF) and T2 (470pF/390pF, same as datasheet). You say in another comment that it's because it's "better" : could you elaborate on that ? What does warrant this choice ? At this stage, output impedence shouldn't matter, and recommanded supply voltage is the same between T1 and T2.

Quote:
The output filter is determined by calculate and listening test, I think they are both ok for T1 and T2 design. But for T1, it's ok if change caps to 0.47uF as someone prefer.
Could you elaborate on your calculations ?
With the T1 values, the output filter cutoff is at 1/(2*pi*sqrt(11uH*220nF)) = 102kHz. With T2 values (11uH/470nF) we have 70kHz. Tripath datasheet recommands 15uH and 220nF which gives 88kHz, even if they state further in the datasheet that TK2050 "works well" with 10uH and 470nF (close to T2's values). Please correct me if I'm wrong.
I'm planning to try changing them, and I'll report here.

Also, even stanger, ST datasheet on STA5XX has a different output filter design: what do you think about it ? Why do you prefer Tripath's one ? (and ST has kept the design until today, as even the march 2010 updated STA510A datasheet keep this design; so they must think it's good, even after having seen Tripath's design at the time)
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Old 18th November 2010, 02:44 PM   #1103
alkasar is offline alkasar  France
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a T2 review Hifimediy TK2050 Amplifier | Headfonia
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Old 20th November 2010, 10:14 PM   #1104
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Dunno if this has been asked already, but I find it to be very, very important:

What is the output impedance of this amp?

And has anyone done other (sound quality related) measurements?
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Old 21st November 2010, 02:48 AM   #1105
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Out of curiosity, are there any plans for a version of the T2 board with an ALPS pot, just like the T1?
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Old 25th November 2010, 08:27 PM   #1106
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I have recently purchased T2 version of amp with Meanwell power supply. It has been playing now constantly for 10 days.

It has a very pleasant mids, warm but detailed - great, however the higher frequencies are not that good - they are very laid back and lack resolution. My LM4780 based amp delivers much more "air", details and something that gives live and space to the overall sound.

Has anyone had similar experience? Is there something I can do to improve this?

Another questions: is it possible to remove input caps? The Amp is fed from a Tube stage which has high quality output caps so I guess if this makes sense to have two caps one, after other?
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Old 26th November 2010, 09:56 AM   #1107
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Afaik, having caps at the output and right again at the input is not a good idea at all.
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Old 27th November 2010, 06:26 PM   #1108
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Quote:
Originally Posted by Spacejack View Post
- they are very laid back and lack resolution. My LM4780 based amp delivers much more "air", details and something that gives live and space to the overall sound.

Has anyone had similar experience?
Yes I can confirm that. In my case in comparison to a sure board. But the rest values added its still a great performer for this price. I also wished it would project a bit more space into the soundstage.

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Originally Posted by Spacejack View Post
Is there something I can do to improve this?
Yes. Take a source with higher resolution. Not that type of CD Players which sound like vinylrecords or analogue/warm whatever ...
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Old 27th November 2010, 08:15 PM   #1109
sendler is offline sendler  United States
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Default 2050 sound

Quote:
Originally Posted by Spacejack View Post
I have recently purchased T2 version of amp with Meanwell power supply. It has been playing now constantly for 10 days.

It has a very pleasant mids, warm but detailed - great, however the higher frequencies are not that good - they are very laid back and lack resolution. My LM4780 based amp delivers much more "air", details and something that gives live and space to the overall sound.

Has anyone had similar experience?
My TK2050 amp sounds much better than my 3875 amp which is better than my 3886 amp. More transparent with explosive dynamics. What you are hearing is not the sound of the chip. You can try rewinding your output coils with less turns or better yet, replace them with Wurth XXL at 4.7uH. If you jump your input caps you must also remove the input pot. The amps actually sends dc back out the input.
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Old 2nd December 2010, 08:53 AM   #1110
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Default T3 and meanwell

I got myself a Meanwell SE-600-48 to try with a pair of T3 and T3e psu boards. That was a big dissapointment, the se-600 runs its fan constantly. It's very loud so it's unusable for living room audio.
I then tried to connect one S-350 36V meanwell onto two T3's with each their T3e. Hadn't tried this exact combination before, last time used the two channel T3e psu board.
But it was the same issue, some high frequency shhh noise, quite audible on my 99db speakers. maybe it will not be a big issue on something like 88db speakers. When I disconnect one amp so that one meanwell only powers one T3, then this noise disappears.

So it seems like 2 x s350-48 is still the way to go to be sure to avoid this noise.
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