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Old 21st January 2009, 08:38 PM   #1951
SamL is offline SamL  New Zealand
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Join Date: Jun 2004
Location: Wgtn
After over 48 hour, the silver mica on C1, C2 is a keeper. It not only added richness it also add soul to Op42 opamp that it feed. Cymbal from my OW1 tweeter has never been so good. Listening to songs from The Eagles show details in cymbal that I didn't notice before. The low end has also improve. You can easily follow the bass guitar.
Recommended mod if you using Op42 as this is what I used and not sure other opamp will have the same results. BTW, owner with metal dome tweeter may not like the added details in the high end as it can be too sharp.
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Old 22nd January 2009, 01:56 AM   #1952
SamL is offline SamL  New Zealand
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My mistake. A typo on my end. Should be C1, C3. Not C1, C2.
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Old 30th January 2009, 06:06 AM   #1953
SamL is offline SamL  New Zealand
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Join Date: Jun 2004
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Quote:
Originally posted by -ecdesigns-
--- first some information about pin numbering ---

SN74HC04 could be used for this, SN74HC04 pin numbering, notch to the top, top view:

pin top left is pin1, next one down is pin 2, and so on, until pin 7 (bottom left)
pin8 (bottom right), next one up is pin9 and so on, until pin14 (top right) .

ADDING THE INVERTER:

> Connect GND (SAA7220 socket pin 12) to the following pins of the SN74HC04: pin3, pin5, pin7, pin9, pin11, and pin13.

> Connect VCC (SAA7220 socket pin24) to SN74HC04 pin 14.

> Solder a 100nF decoupling capacitor between SN74HC04 pin7 and pin14.

> Connect pin1 of SN74HC04 to pin3 of J28 (DATA).

> Connect pin2 of SN74HC04 to pin3 of J25 (Inverted DATA).

John
Hi John or anyone who have done this mod. The SN74HC04 that come with the Thomas DAC is 16 pin version not 14.
Can someone please provide the conversion between 14pin and 16pin conversion or point to a datasheet that will provide such info. All the one I found doesn't.
http://rocky.digikey.com/WebLib/Texa...a/SN74HC04.pdf

http://www.diyaudio.com/forums/attac...amp=1194200446
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Old 31st January 2009, 02:51 AM   #1954
kokheng is offline kokheng  Malaysia
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Can anyone explain what are the functions of C7,R7 & R9 in the IV 1 board ( 4 single opamp board)? Will something bad happen if I shorted the S1 to bypass the C7,R7 & R9?
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Old 3rd February 2009, 05:24 PM   #1955
kokheng is offline kokheng  Malaysia
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Join Date: Oct 2007
Once again proved that signal decoupling cap is very important to use a good quality cap, I replaced the cap in the 4 opamp board from 100uf Elna e-cap to 0.1 film and foil cap, resulting a very clear and clean sound, better imaging, faster sound, more detail, the only down side is the bass quantity lesser but tighter.
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Old 8th February 2009, 03:04 PM   #1956
ccschua is offline ccschua  Malaysia
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Join Date: May 2008
Hi Kokheng,
Can I know what film and foil cap u use to replace elna 100uF?
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Old 10th February 2009, 03:26 AM   #1957
SamL is offline SamL  New Zealand
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Join Date: Jun 2004
Location: Wgtn
The nice people over Aspen Amplifiers form have point me to this link that some of you will find it interesting. Endless mod to try.
http://www.lampizator.eu/LAMPIZATOR/...r/TDA1541.html

They also advice to replace the C11 on the DAC board with silva mica and ground the digital ground, pin 14 of TD1541A with 100nF multilayer ceramic cap. Which I did with good results. BTW, silva mica do take min 30 hours to sound good.

Have fun,
Sam
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Old 10th February 2009, 04:13 AM   #1958
kokheng is offline kokheng  Malaysia
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Join Date: Oct 2007
Hi Chua,

I'm using vcap teflon o.1uf to replaced elna 100uf, the vcap will not reside there for too long. Once I start to mod the diy tube pre-amp, I will take out the vcap and try to jumper it with wire, or maybe try the obbligator cap, heard this cap sound quite analoge.

kokheng
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Old 20th July 2009, 08:10 AM   #1959
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Join Date: Mar 2005
Location: HK
I have a new unit to sell. Anyone interested please send PM to me. Thanks.


Regards,
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Old 23rd July 2009, 11:46 AM   #1960
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Quote:
Originally posted by chungtat
I have a new unit to sell. Anyone interested please send PM to me. Thanks.


Regards,

Just wondering how much you asking for it? I can't PM/email you...
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