John - according to that review, it will match any input impedance from 25 -200K. They claim it will match just about anything so impedance matching isn't a problem.
Are you saying that using the lower level output, there is still too much gain? My own valve pre has a very high gain but I can use it OK with the Charlize or Autocostriure amps!
Are you saying that using the lower level output, there is still too much gain? My own valve pre has a very high gain but I can use it OK with the Charlize or Autocostriure amps!
I believe thats after their output mods Nuuk. One output is left as-is, the other has been tinkered with.
I own the stock unit, which has two sets of outputs, both of which give gain of x22. Way too much for the Autocostruire.
- J
I own the stock unit, which has two sets of outputs, both of which give gain of x22. Way too much for the Autocostruire.
- J
How often do you need to change over pre-amps?
It only takes a short time to piggy back a parallel resistor onto the feedback resitor and reduce the gain! My Autocostriure is set up like that with a gain of only 8.
(I can't believe that I have been replying to diyAudio posts for over an hour without a break! 😱 )
It only takes a short time to piggy back a parallel resistor onto the feedback resitor and reduce the gain! My Autocostriure is set up like that with a gain of only 8.
(I can't believe that I have been replying to diyAudio posts for over an hour without a break! 😱 )
Well that's true, but as the Ming Da contains two sets of outputs I'd like to (once and for all) change one of the sets so I can use either solid-state or valve power amps without having to do any soldering again - just change the outputs.
haha Nuuk you are too good for your own - er - good!!! If you're ever in London drop by and I'll buy you a pint or three ;-)
- J
haha Nuuk you are too good for your own - er - good!!! If you're ever in London drop by and I'll buy you a pint or three ;-)
- J
hahaha! Who says audio nuts have no sense of humour?! tsk! ;-)
TA2020-020 Gain Setting...
I cant remember the Formula for choosing the gain-setting resistors on the input stage of the Tripath chip, but its in the Data-sheet at
www.tripath.com
Check out the data-sheet, for the TA2020-020 the formula is in there as well as all the other goodies...! (as I remember, the data-sheet is a little hard to find, on the site, as its now 'No Longer Recommended For New Product Designs' The next stage is 'Obsolete...but it was there as of last week.....(Shame, as its a pretty good chip once you get used to its hideous pin-out when designing round it!)
I have been thinking of using a 6SN7 base pre- in my car, but lack the time currently to build it!
I cant remember the Formula for choosing the gain-setting resistors on the input stage of the Tripath chip, but its in the Data-sheet at
www.tripath.com
Check out the data-sheet, for the TA2020-020 the formula is in there as well as all the other goodies...! (as I remember, the data-sheet is a little hard to find, on the site, as its now 'No Longer Recommended For New Product Designs' The next stage is 'Obsolete...but it was there as of last week.....(Shame, as its a pretty good chip once you get used to its hideous pin-out when designing round it!)
I have been thinking of using a 6SN7 base pre- in my car, but lack the time currently to build it!
Re: TA2020-020 Gain Setting...
should be: gain setting in dB = ((12 x Rf/Rin)log x 20)
Alastair E said:
should be: gain setting in dB = ((12 x Rf/Rin)log x 20)
If i need 2.55x gain from this amp but with higher input impedance, can i use 470k for Ri and 100k for Rf? 47k input impedance is too low for my application.
The input impedance isn't Ri, but rather should be dominated by whatever input impedance of the input stage inside the amp chip. Tripath datasheet doesn't show any info about that however.
So i am mistaken to assume that the input stage is an inverting op amp? Nevertheless, can i carry out with the aforementioned plan?
You're right, the input stage is inverting and the input impedance is dominated by Ri.
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