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Old 7th November 2012, 09:01 PM   #11
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Quote:
Originally Posted by lehmanhill View Post
I agree that working without a DC blocking cap is not advised.

The other thing, you didn't say which amp design you are working with. If it is one of the MyRef series, then the collected wisdom is that removing the cap also hurts bass response due to an interaction with the 318 opamp. Other designs, the interaction won't be a problem.

If you don't want to spring for the Mundorf in question, then look around for other, less expensive alternatives. Try one of the cheap Russian caps. Depending on the value needed, you could try a Sprague Orange Drop or any number of metalized polypro caps.
Why not just design the circuit so it swamps the nonlinearity of the capacitor?

Tubes, BJTs, and FETs are not linear. But with simple methods we can swamp that nonlinearity. Capacitors (even cheap ones) are far more linear than any active device. The same principles work with them too.
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Old 8th November 2012, 12:18 PM   #12
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I got the styroflex cap 1uf/50v I think we use this one as DC blocking cap..
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Old 8th November 2012, 12:47 PM   #13
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i plugged it in it sound awesome without any veil but i feel bass is a bit shy.... but highs and mids are awesome.... i could hear alot of details now....

when I was using polyester cap it was foggy how much was that got clear after plugging these in.... very nice and open sounding but I believe its pretty bright and too much open.....

or these caps need burning time?
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Old 8th November 2012, 01:02 PM   #14
AndrewT is offline AndrewT  Scotland
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What is the RC time constant of the high pass filter on the input?
What other RCs inside the amplifier could affect the LF frequency response of the amplifier?
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Old 8th November 2012, 08:51 PM   #15
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Use cheap polyester caps. Show us a schematic and we can advise their value.
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Old 8th November 2012, 11:54 PM   #16
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Quote:
Originally Posted by rhythmsandy View Post
i plugged it in it sound awesome without any veil but i feel bass is a bit shy.... but highs and mids are awesome.... i could hear alot of details now....

when I was using polyester cap it was foggy how much was that got clear after plugging these in.... very nice and open sounding but I believe its pretty bright and too much open.....

or these caps need burning time?
As usual, Andrew makes a good point. Check the input impedance and figure out the corner frequency to see if you are affecting the bass.

As for burn in time, my experience with K71 styrene caps is that they do need some hours of burn in, but nothing terribly long like teflon. From what I have read, that is the trade-off with the styrene caps, lots of detail but the bass is not as full as with some caps. Some say they sound a little cool.
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Old 9th November 2012, 02:30 AM   #17
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Quote:
Originally Posted by lehmanhill View Post
As usual, Andrew makes a good point. Check the input impedance and figure out the corner frequency to see if you are affecting the bass.

As for burn in time, my experience with K71 styrene caps is that they do need some hours of burn in, but nothing terribly long like teflon. From what I have read, that is the trade-off with the styrene caps, lots of detail but the bass is not as full as with some caps. Some say they sound a little cool.
yeah true bass is not that rounded and full... but mids and highs are phenomenal...

mids have some overtones which I didnt like it went off when I used the silmic decoupling caps... it was just awesome loved the sound...

I have the following circuit...

http://www.diyaudio.com/forums/attac...-ok-opa549.gif

Andrew which rc time constant are you talking about? input cap and R2?

Last edited by rhythmsandy; 9th November 2012 at 02:33 AM.
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Old 9th November 2012, 02:41 AM   #18
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After 14 hours I see the highfreq roughness has reduced but still the mids is pronounced....

but i would rather prefer musicality than details...

i have 4 x 4.7 metalized polyster film capacitor... i think i should try them...

I think the guys who like guitar will love styroflex at input....

i like the details in the mids and highs but
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Old 9th November 2012, 03:07 AM   #19
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added one more 1uf/50v styroflex at the input now total 2uf cap but no use the sound is cold couldnt improve it.... ... I think i can stick with polyester caps rather than going with styroflex. Probably will try Mundorf Silver oil caps soon 1uf costing about 60USD...
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Old 9th November 2012, 03:32 AM   #20
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i replaced back the old config 8600pf Polystyrne parallel with 1uf Polyster cap gave back that warm bass and mids looked more like tube sound than ss...

I have a doubt to use the polystyrene 1uf parallel with 1uf / 50 silmic cap... using back to back to get .5uf cap...

i know its strange to parallel silmic with a film cap at the input but can It give what I want? I read somewhere that somebody tried blackgates at input which was sounding better than the film cap.. may be sonically but not in detail...

I have 50 silmics 1uf /50v and 100uf/35 70units can anybody suggest me how to use them?
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