Answered Do passive preamplifiers benefit from low capacitance interconnects?

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Strider

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Some of you know that I'm looking to build a passive preamplifier and I've already bought some bits and bobs to start me off.

I currently have two passive preamps feeding a pair of Extron class D monoblocs with varying success:
The Little Bear preamp has both balanced and unbalanced inputs and outputs, the Tisbury preamp II is unbalanced only.
The Little Bear preamp although cheap is rather good having a clean sound without any apparent nasties, the Tisbury however is a little bit soft and lacking in upper mids, it seems to have an odd issue that stereo balance isn't linear but shifts around depending where the volume control sits.
The Little Bear preamp has a 50k pot where the Tisbury preamp has a 10k stepped attenuator - would the difference in input impedance be the reason for the obvious difference in frequency response and balance?

I've read up that using low capacitance interconnects are a must for passive preamps to prevent upper frequency early roll-off, the Little Bear seems totally agnostic to cables but I'm wondering if the Tisbury would benefit from lower capacitance.

I've made interconnects with Van-Damme XPE patch cable that claims 50 pF/f oot core to core but 95 pF/foot core to core? So wich is it?

I've splurged out on a pair of Mogami 2964 interconnects that spec 19.8 pF/f - wow!

Both the Van-Damme interconnects and Mogami are 300mm (1 foot in old money)
 

Gizza

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Some of you know that I'm looking to build a passive preamplifier and I've already bought some bits and bobs to start me off.

I currently have two passive preamps feeding a pair of Extron class D monoblocs with varying success:
The Little Bear preamp has both balanced and unbalanced inputs and outputs, the Tisbury preamp II is unbalanced only.
The Little Bear preamp although cheap is rather good having a clean sound without any apparent nasties, the Tisbury however is a little bit soft and lacking in upper mids, it seems to have an odd issue that stereo balance isn't linear but shifts around depending where the volume control sits.
The Little Bear preamp has a 50k pot where the Tisbury preamp has a 10k stepped attenuator - would the difference in input impedance be the reason for the obvious difference in frequency response and balance?

I've read up that using low capacitance interconnects are a must for passive preamps to prevent upper frequency early roll-off, the Little Bear seems totally agnostic to cables but I'm wondering if the Tisbury would benefit from lower capacitance.

I've made interconnects with Van-Damme XPE patch cable that claims 50 pF/f oot core to core but 95 pF/foot core to core? So wich is it?

I've splurged out on a pair of Mogami 2964 interconnects that spec 19.8 pF/f - wow!

Both the Van-Damme interconnects and Mogami are 300mm (1 foot in old money)
Audio Synthesis certainly recommended low capacitance cables for their passives to avoid hf rolloff. They also recommended not using the highest 2 or 3 volume settings as these also caused hf rolloff.
 
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Strider

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The Mogami interconnects arrived 15 minutes and I put them in straight away, before the new cables the Tisbury was a little rolled off and a bit thick sounding in the upper midrange, there was also something odd with the Tisburhaving a 'wondering' soundstage where certain frequencies would cause a shift in the central image.
Well that's disappeared entirely and the image is central between the speakers, the slightly rolled off upper mid has opened up considerably - hurrah!
For once cables have made a difference in my setup* but I need to let them burn in to really appreciate their miraculous transformation of lifting veils, blacking the inks and making Dolly Parton sound like she's actually in the room....

*'tis electricalonics at play m'lord.
 

savvypaul

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The Mogami interconnects arrived 15 minutes and I put them in straight away, before the new cables the Tisbury was a little rolled off and a bit thick sounding in the upper midrange, there was also something odd with the Tisburhaving a 'wondering' soundstage where certain frequencies would cause a shift in the central image.
Well that's disappeared entirely and the image is central between the speakers, the slightly rolled off upper mid has opened up considerably - hurrah!
For once cables have made a difference in my setup* but I need to let them burn in to really appreciate their miraculous transformation of lifting veils, blacking the inks and making Dolly Parton sound like she's actually in the room....

*'tis electricalonics at play m'lord.
Just seen the thread and was about to say that...a passive is just a variable resistance (Lpad) in the signal path. So, using a high capacitance interconnect into a passive, you will create a tone control. You need low capacitance interconnects.

However, I'm now only thinking about Dolly Parton 😍
 

Strider

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Just seen the thread and was about to say that...a passive is just a variable resistance (Lpad) in the signal path. So, using a high capacitance interconnect into a passive, you will create a tone control. You need low capacitance interconnects.

However, I'm now only thinking about Dolly Parton 😍
Thanks Paul, back in the shouds of time I read something about low capacitance cables and did a little research but wanted to hear if anyone here had encountered a similar issue.

Just for your delectation I'm now enjoying Celine Dion cover of Nine Inch Nails greatest hits, it sounds like she's actually in the kitchen smashing plates with a Kenwood Chef.
 

savvypaul

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Thanks Paul, back in the shouds of time I read something about low capacitance cables and did a little research but wanted to hear if anyone here had encountered a similar issue.

Just for your delectation I'm now enjoying Celine Dion cover of Nine Inch Nails greatest hits, it sounds like she's actually in the kitchen smashing plates with a Kenwood Chef.
Yeah... she's always been a bunny boiler 😆
 
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George 47

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Thanks Paul, back in the shouds of time I read something about low capacitance cables and did a little research but wanted to hear if anyone here had encountered a similar issue.

Just for your delectation I'm now enjoying Celine Dion cover of Nine Inch Nails greatest hits, it sounds like she's actually in the kitchen smashing plates with a Kenwood Chef.
Oh God how the world has changed. Recording engineers telling us cables make a difference, whatever next....manufacturers agreeing. I need to sit down and read Oscilloscope Daily.
 

myles

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Good thread. I'd be interested to know which Mogami cables you used @Strider and if anybody can advise of any other good low cap cables - I want to ensure I'm giving my system the best chance!
 
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Strider

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Good thread. I'd be interested to know which Mogami cables you used @Strider and if anybody can advise of any other good low cap cables - I want to ensure I'm giving my system the best chance!
Hey Myles, the cables are:
Mogami 2964 from Amazon
They need a kick in the pods though. "Worlds best cables." Almost as bad a the "Worlds best Speakers."

They were a princely sum of 180 shillings and 22d.
81-8ZBwaJeL._AC_SL1500_.jpg
 
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toprepairman

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Have you not got Little Bear and Tisbury mixed up?
The lower impedance (10K Tisbury) stepped attenuator should be les affected by cable capacitance and balance issues, whereas the higher impedance (50K) pot will be more affected by those issues.
 

Amormusic

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Good thread. I'd be interested to know which Mogami cables you used @Strider and if anybody can advise of any other good low cap cables - I want to ensure I'm giving my system the best chance!
Agreed it's a good thread. Myles and I have same amp.

Myles, please let me know how you get on as curious as to your thoughts of how this goes. Ping me PM if you like so as to not busy the thread. Thanks!
 
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