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Tisbury Audio.....
Posted: Wed Oct 04, 2017 11:46 am
by cybot
Anybody here know anything about these? Two items featured : a phono pre catering for both mm and mc and a passive pre featuring an SMD Stepped Attenuator. Ridiculously priced too ;)
http://www.tisburyaudio.co.uk
Re: Tisbury Audio.....
Posted: Thu Oct 05, 2017 12:10 am
by nige2000
Seems like they use a stepped dact like here
https://m.ebay.com/itm/2-pcs-of-20K-D-s ... Ciid%253A7
Bout 14e each
Rotary swiches are bout the same
Wouldnt be expecting too much magic
Re: Tisbury Audio.....
Posted: Thu Oct 05, 2017 1:09 am
by cybot
That's all I need to know :) Thanks Nigel......
Re: Tisbury Audio.....
Posted: Thu Oct 05, 2017 1:17 am
by nige2000
Well tbh these dact attenuators aint the worse preformers either
They are relatively decent as far as passive vol control goes
And there's far worse ways of doing it out there
Re: Tisbury Audio.....
Posted: Thu Oct 05, 2017 11:49 am
by cybot
If truth be told I was more interested in the passive pre option as I've never heard what a passive pre can bring to the table. When I think of passive I think airy highs, transparency and no bass ;) Anyway I honestly can't see a use for either in my system. So I don't really know exactly where they actually fit into a system that's already been assembled with care......and, more importantly sounds good!
Re: Tisbury Audio.....
Posted: Thu Oct 05, 2017 2:14 pm
by Rob
cybot wrote: ↑Thu Oct 05, 2017 11:49 am
If truth be told I was more interested in the passive pre option as I've never heard what a passive pre can bring to the table. When I think of passive I think airy highs, transparency and no bass ;) Anyway I honestly can't see a use for either in my system. So I don't really know exactly where they actually fit into a system that's already been assembled with care......and, more importantly sounds good!
The conventional wisdom is that passive pre-amps can be very good if well matched without long interconnects. I think I read on your link that the Tisbury has a 10k pot so should match well with quite a few power amps except some lower input impedance transistor and Class D amps, as long as they have a high sensitivity, perhaps below 1 volt for use with CD or phono stages, or a much higher sensitivity if using cassette decks (remember them?) and tuners because they tend to have a fairly low output. If bass is an issue then another option is to use a transformer volume control which have a low impedance output. These can be especially pricey but recollect that the Hifi Collective had a relatively inexpensive model.
Re: Tisbury Audio.....
Posted: Thu Oct 05, 2017 6:36 pm
by cybot
Rob wrote: ↑Thu Oct 05, 2017 2:14 pm
cybot wrote: ↑Thu Oct 05, 2017 11:49 am
If truth be told I was more interested in the passive pre option as I've never heard what a passive pre can bring to the table. When I think of passive I think airy highs, transparency and no bass ;) Anyway I honestly can't see a use for either in my system. So I don't really know exactly where they actually fit into a system that's already been assembled with care......and, more importantly sounds good!
The conventional wisdom is that passive pre-amps can be very good if well matched without long interconnects. I think I read on your link that the Tisbury has a 10k pot so should match well with quite a few power amps except some lower input impedance transistor and Class D amps, as long as they have a high sensitivity, perhaps below 1 volt for use with CD or phono stages, or a much higher sensitivity if using cassette decks (remember them?) and tuners because they tend to have a fairly low output. If bass is an issue then another option is to use a transformer volume control which have a low impedance output. These can be especially pricey but recollect that the Hifi Collective had a relatively inexpensive model.
Thanks for that Rob! It's all starting to make sense....
Re: Tisbury Audio.....
Posted: Thu Oct 05, 2017 10:12 pm
by nige2000
this sort of passive volume control is kinda like a no win scenario
it loads the input signal and weakens the output signal
the attenuator itself adds a little colouration at best aswell
i have had good results with a volume control unit with two jfet buffers (powered by lifepo4 cells) one before and after the attenuator
this strengthens the signal before it's loaded by the attenuator and then again on output
i havent come across a commercially available device with a similar idea
transformers have an input impedance too
so its not a bad idea to know what that is when looking at tvc
personally if going with transformer volume control id be looking at a large step down 3:1 or greater
meaning its input would need to be amplified to maybe 4 or 5v
on my list of stuff to try
Re: Tisbury Audio.....
Posted: Fri Oct 06, 2017 1:03 am
by cybot
nige2000 wrote: ↑Thu Oct 05, 2017 10:12 pm
this sort of passive volume control is kinda like a no win scenario
it loads the input signal and weakens the output signal
the attenuator itself adds a little colouration at best aswell
i have had good results with a volume control unit with two jfet buffers (powered by lifepo4 cells) one before and after the attenuator
this strengthens the signal before it's loaded by the attenuator and then again on output
i havent come across a commercially available device with a similar idea
transformers have an input impedance too
so its not a bad idea to know what that is when looking at tvc
personally if going with transformer volume control id be looking at a large step down 3:1 or greater
meaning its input would need to be amplified to maybe 4 or 5v
on my list of stuff to try
It all makes sense when you put it that way. I'm so glad I asked the question. Good luck with it :)
Re: Tisbury Audio.....
Posted: Fri Oct 06, 2017 1:11 am
by abraxalito
nige2000 wrote: ↑Thu Oct 05, 2017 10:12 pm
this sort of passive volume control is kinda like a no win scenario
it loads the input signal and weakens the output signal
the attenuator itself adds a little colouration at best aswell
I agree - they're a lose-lose proposition in most cases.
i have had good results with a volume control unit with two jfet buffers (powered by lifepo4 cells) one before and after the attenuator
this strengthens the signal before it's loaded by the attenuator and then again on output
I think the primary benefit of the passive pre is the lack of external power. An active pre running on batteries has the isolation of the passive but no downside that I can see. If you use a JFET buffer with a TVC you can dispense with the second buffer - the input impedance of a TVC does benefit from buffering but none is needed on the output. Isolation (raising the impedance of AC ground loops) is another benefit of a TVC.