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)
 

Strider

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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.
Definitely not, I've had the Little Bear for over a month and the Tisbury since last Wednesday.
The Little Bear is still a little cleaner sounding and has better bass but the Tisbury is a little smoother - good for a few of the poorly recordings I have.

I've tried several sets of cables with the Litle Bear and the only set that made things go haywire were an ancient pair I made years ago with Shark cable from Maplin.
When I plugged in the Tisbury I left the Van den Hull Wave (lurid green thungs) that have been in my system for years the Tisbury did not like these at all and the centre image would shift all over the place, certain frequencies were highlighted and would shift dramatically.
With the Tisbury I also tried Van Damme XDE patch, Chord C Line and finally the Mogami. It was the Mogami that did the trick!

As a side note I tend to make my own cables but the others listed above were freebies, you know what u think about spending silly money on cables...
 
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m7rso

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Okay. Tried my low cap cables between my passive Khozmo 64 step pre and my power amp which on this occasion is a modded Quad 303. It replaced an RFC MERCURY cable. The low cap gave more high end detail but I found it to be almost bright. Liked it for the first 30 seconds, put up with it for another two minutes, then took em out. Enough said. They would probably be good with my Castle Pembrokes which are rolled off and not bright at all so would probably give more life to the top end. I have put them in between the pre and my subs but the neighbours were back from work so gave that a miss Until tomorrow. Between the pre and subs they have replaced a pair of Acoustic reference pro. Update tomorrow.
 
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Strider

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Okay. Tried my low cap cables between my passive Khozmo 64 step pre and my power amp which on this occasion is a modded Quad 303. It replaced an RFC MERCURY cable. The low cap gave more high end detail but I found it to be almost bright. Liked it for the first 30 seconds, put up with it for another two minutes, then took em out. Enough said. They would probably be good with my Castle Pembrokes which are rolled off and not bright at all so would probably give more life to the top end. I have put them in between the pre and my subs but the neighbours were back from work so gave that a miss Until tomorrow. Between the pre and subs they have replaced a pair of Acoustic reference pro. Update tomorrow.
I get what you mean, when I first connected up the Tisbury with my regular cables it was rolled off bass was ok but 'soft' and lacking in punch.

With the Mogami cables in the soft bass has gone and the upper mid has sparkle and that annoying centre image shift has gone entirely, however bass is a little lighter, not in a bad way but doesn't do as deep as before. I don't mind this little trade-off though because I cant stand 'woolly' bass or curtailed higher frequencies especially in the strike zone where our hearing is more sensitive across the region of 2k to 4k.
 

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I get what you mean, when I first connected up the Tisbury with my regular cables it was rolled off bass was ok but 'soft' and lacking in punch.

With the Mogami cables in the soft bass has gone and the upper mid has sparkle and that annoying centre image shift has gone entirely, however bass is a little lighter, not in a bad way but doesn't do as deep as before. I don't mind this little trade-off though because I cant stand 'woolly' bass or curtailed higher frequencies especially in the strike zone where our hearing is more sensitive across the region of 2k to 4k..
I bought 4 mtrs of Mogami 2946 cable, and made up a couple of 1mtr pairs. I have to say they have brightened things up, in a good way (no harshness), in my 3 way active setup. I have used them from the dac, and phonostage to my Khozmo passive pre, very pleased with the results in that system. Not so good in my second system which is valve based into LS35a's, I found that a bit too bright.
Anyway thanks for pointer to that cable (y)
 
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Strider

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I bought 4 mtrs of Mogami 2946 cable, and made up a couple of 1mtr pairs. I have to say they have brightened things up, in a good way (no harshness), in my 3 way active setup. I have used them from the dac, and phonostage to my Khozmo passive pre, very pleased with the results in that system. Not so good in my second system which is valve based into LS35a's, I found that a bit too bright.
Anyway thanks for pointer to that cable
You'll be opening a shop soon, I think the 'Wam could do with a garden shed cabler, a bit of heatshrink and braiding and they'll fly out the door!😄
Glad you've found the Mogami cable useful and it actually does make an electrical difference.
 

newlash09

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Just out of curiosity, will lower capacitance cables make a difference even if using balanced connections via xlr.

And will there be a difference in cabling from source to passive or from passive to power amp. Thanks
 

Strider

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Just out of curiosity, will lower capacitance cables make a difference even if using balanced connections via xlr.

And will there be a difference in cabling from source to passive or from passive to power amp. Thanks
I don't see why not, My Little Bear passive pre has balanced I/O so I'll make a pair up and let you know!
I know the Mogami W2449 is very low capacitance at 23 pF/f, keeping the leads as short a possible is important because as you can imagine the capacitance increases with length (ooo errr)!
Mogami XLR

From Amazon you could buy a pair:
Looks good
 
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I don't see why not, My Little Bear passive pre has balanced I/O so I'll make a pair up and let you know!
I know the Mogami W2449 is very low capacitance at 23 pF/f, keeping the leads as short a possible is important because as you can imagine the capacitance increases with length (ooo errr)!
Mogami XLR

From Amazon you could buy a pair:
Looks good
Thanks sir 😁..
The idea of making my own custom cables of just the adequate length is indeed appealing and will be a nice weekend project.
Will await your findings in due time. Thanks
 

oldius

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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)
The Klotz I mentioned is even lower capacitance than the Mogami!
 

Strider

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Every cable I use is low capacitance.
Cables do make a difference if their electrical specification is different.

Here are the interconnects I use, and they are sold specifically on being ultra-low capacitance: https://shop.klotz-ais.com/mc5000-online.html#:~:text=MC5000 0.50 mm² conductor cross section (AWG 20),stabilising pair twisting for high end studio microphones
That is low! For XLR's that would be the doggies danglies but buying 30 m @ £180 is beyond scope here, If I were making 50 pairs it would make sense. To keep the capacitance low as possible the ideal length is 30 cm/1 ft.
Good call though
 
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oldius

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That is low! For XLR's that would be the doggies danglies but buying 30 m @ £180 is beyond scope here, If I were making 50 pairs it would make sense. To keep the capacitance low as possible the ideal length is 30 cm/1 ft.
Good call though
That's just the manufacturer's price because they supply studios and installers.

Check www.studiocare.com for more of a retail experience.
 
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Strider

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That's just the manufacturer's price because they supply studios and installers.

Check www.studiocare.com for more of a retail experience.
Thanks Geoff, in my day to day job I don't get to use many XLR's or zero phono/jack because everything is done in the digital domain (Dante) but I wired my studio and the early days at Chipping Norton every single cable was hand terminated to patch bays (before snakes were a thing) from the ground up, all 400 channels I/O plus a few odds and ends for single ended kit, I reckon I used about 8 miles of cables, 5 kilos of solder and a couple of litres of flux, kept Cranford in business! Fixing, repairing was a minute by minute job with a meter between spooling up tapes and checking FOH, fold backs, stacks, cabs, desk and stroking the swollen egos of too many artists.
After Chippy* died I opened my own studio and continued the analogue trend until ProTools gave my soldering iron a well earned rest, today I solder for fun despite my good ladies complaints of the mountains of cables (I reckon I could get a tidy sum for the copper I have in my garage let alone two sheds, storage and workshop.... 🤭
You and me are cut from the same cloth it appears!
*The place my heart, soul and sanity lived and died here
 
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