advertisement


Puresound P10 - Impedance Matching

L

Lefty

Trade: Amar Sood Photo
I've just recently picked up a Puresound P10 with the idea of it replacing my Trichord Dino.

I understand the P10 likes to see a 47kohm or greater load, but my preamp (a Benchmark DAC 2 HGC) is quoted as having an analogue input impedance of 20kohm.

My question is how much of an effect is this likely to have on the sound? Is it worth sourcing a separate preamp with a better matched input impedance (and just running the Benchmark as a DAC) or am I worrying over nothing?

Sound wise, the P10 is an improvement in the midrange and top end (more organic, transparent and effortless) and whilst the bottom is tighter, it does seem 'weaker' in terms of power and impact here. Could this be down to the impedance mismatch?

Lefty
 
Lefty said:
Could this be down to the impedance mismatch?
Click to expand...

Not in this case, if anything it would affect high frequencies, albeit only slightly. 'Tighter' bass (implicitly better-quality bass) can seem less impactful and room-filling because it may interact less with room nodes, and being more natural simply doesn't draw attention to itself so much.

If you want nice big wobbly 'bass-bins-in-a-Vauxhall-Corsa' style bass you can always bung a couple of cheap subwoofers into the mix ;-)
 
earlofsodbury said:
Not in this case, if anything it would affect high frequencies, albeit only slightly. 'Tighter' bass (implicitly better-quality bass) can seem less impactful and room-filling because it may interact less with room nodes, and being more natural simply doesn't draw attention to itself so much.
Click to expand...

Thanks for the info - my comments were made after a brief initial listen to the P10. I have just A/B'd it with the Trichord Dino and all is definitely not well. The Dino is outperforming the P10 across the board. After having listened to the P10 and then Dino and then cross referencing the track with the digital version (it's a 2021 album so I don't imagine the vinyl version will be mastered any differently to the digital version) it's clear the P10 is struggling with the 20kohm load).

At this point I wonder if it's worth just moving the P10 on as I can't really justify the purchase of a preamp to accommodate the P10.

If you want nice big wobbly 'bass-bins-in-a-Vauxhall-Corsa' style bass you can always bung a couple of cheap subwoofers into the mix ;-)
Click to expand...
Haha :D It's definitely not 'Vauxhall Corsa Bass' that I'm after!

Lefty
 
Lefty said:
I've just recently picked up a Puresound P10 with the idea of it replacing my Trichord Dino.

I understand the P10 likes to see a 47kohm or greater load, but my preamp (a Benchmark DAC 2 HGC) is quoted as having an analogue input impedance of 20kohm.

My question is how much of an effect is this likely to have on the sound? Is it worth sourcing a separate preamp with a better matched input impedance (and just running the Benchmark as a DAC) or am I worrying over nothing?

Sound wise, the P10 is an improvement in the midrange and top end (more organic, transparent and effortless) and whilst the bottom is tighter, it does seem 'weaker' in terms of power and impact here. Could this be down to the impedance mismatch?

Lefty
Click to expand...

It should have an output impedance of around 2K ish (from a quick look at the schematic).

A 20K load should not be a huge issue but distortion will rise somewhat, mainly 2nd harmonic.

There will be no problem with the high frequencies but if the output capacitor has been chosen to be the smallest practicable with a 47K load then there could be a slight bass roll off with a 20K load which can be corrected by fitting bigger output capacitors or adding capacitance in parallel to what is fitted.
 
Arkless Electronics said:
It should have an output impedance of around 2K ish (from a quick look at the schematic).

A 20K load should not be a huge issue but distortion will rise somewhat, mainly 2nd harmonic.

There will be no problem with the high frequencies but if the output capacitor has been chosen to be the smallest practicable with a 47K load then there could be a slight bass roll off with a 20K load which can be corrected by fitting bigger output capacitors or adding capacitance in parallel to what is fitted.
Click to expand...

Thank you for the info and reassuring to know that my ears and deceiving me re: bass.

Is the addition of bigger output capacicitors going to solve the issue or just mask it? I.e. Will it always be compromised into a 20k load?

Lefty
 
hifi-dog said:
I added bigger caps to mine a few yrs back ( don’t have bit anymore) and if improved it no end in the bass- message guy seargent at pure sound. He’s very helpful
Click to expand...

That's great to know - thank you! I don't want to let it go if at all possible, but at the same time, it has to work in my system. I will definitely look into this.

Lefty
 
Lefty said:
Thank you for the info and reassuring to know that my ears and deceiving me re: bass.

Is the addition of bigger output capacicitors going to solve the issue or just mask it? I.e. Will it always be compromised into a 20k load?

Lefty
Click to expand...

There are two separate issues.

Distortion will rise somewhat as I said but we are probably talking in terms of 0.05% going up to say 0.15% and it should be largely of the "valve sound" type of distortion anyway.

The output capacitors is an entirely different issue and has nothing to do with the phono stage itself.. as such...
The lower the load impedance being driven, the more capacitance required to go down to a certain point in the bass.
Hence IF the output capacitors are sized to only just go down to say 20Hz flat into a 47K load then they will need to be bigger to go down as low into a 20K load... they may be plenty big enough already... or may not. I don't know what is fitted to yours.
 
Arkless Electronics said:
There are two separate issues.

Distortion will rise somewhat as I said but we are probably talking in terms of 0.05% going up to say 0.15% and it should be largely of the "valve sound" type of distortion anyway.

The output capacitors is an entirely different issue and has nothing to do with the phono stage itself.. as such...
The lower the load impedance being driven, the more capacitance required to go down to a certain point in the bass.
Hence IF the output capacitors are sized to only just go down to say 20Hz flat into a 47K load then they will need to be bigger to go down as low into a 20K load... they may be plenty big enough already... or may not. I don't know what is fitted to yours.
Click to expand...

Understood - thanks again for the information, very much appreciated.

I have e-mailed Guy to see what he recommends and whether the situation is salvageable without resorting to the purchase of a new preamplifier...

Lefty
 
I had mine modified by Guy @ puresound a few years back to work better with solid state preamps with low input impedance. It made a worthwhile difference.
 
alanbeeb said:
I had mine modified by Guy @ puresound a few years back to work better with solid state preamps with low input impedance. It made a worthwhile difference.
Click to expand...

Many thanks Alan - do you know what modifications he made? Was it just the output capacitance or was it something else?
 
Guy told me thatthe recent versions of the P10 used 2,2uF output capscompared to the 1.0 uF ones my, presumably early version had fitted. So I took his advice and fittedsome of that value, Russkies recommended by Black Stuart of this parish. K73-16 I think they were. Job done. Mind you the input impedance on my Sugden integrated amp, which is the impedance of the volume pot, basically is 47K
 
Chris said:
Guy told me thatthe recent versions of the P10 used 2,2uF output capscompared to the 1.0 uF ones my, presumably early version had fitted. So I took his advice and fittedsome of that value, Russkies recommended by Black Stuart of this parish. K73-16 I think they were. Job done. Mind you the input impedance on my Sugden integrated amp, which is the impedance of the volume pot, basically is 47K
Click to expand...

Thank you - sounds like a change of output capacitors is the recommended course of action here (assuming mine isn't a more recent unit).

Lefty
 
I have a P10 and use it into a Puresound 2a3 amp, the output impedance of the P10 is about 5k so this works perfectly into the 2a3 which has 100k input, bass is full and extended.
My P10 is a more recent one though from 2018.
 
Lefty said:
Thank you - sounds like a change of output capacitors is the recommended course of action here (assuming mine isn't a more recent unit).

Lefty
Click to expand...
The more recent units have Puresound on the front, the older units it's Pure sound with a space and also a blue led ,new ones are orange.
 
chris@panteg said:
I have a P10 and use it into a Puresound 2a3 amp, the output impedance of the P10 is about 5k so this works perfectly into the 2a3 which has 100k input, bass is full and extended.
My P10 is a more recent one though from 2018.
Click to expand...

chris@panteg said:
The more recent units have Puresound on the front, the older units it's Pure sound with a space and also a blue led ,new ones are orange.
Click to expand...

Thanks for the info - looks like mine is a later model in that case. It has both 'Puresound' on the front and an orange LED. Not sure what output caps are installed though. I've called up the shop where I bought it, and they have kindly offered to take it back for full refund. A shame as I really wanted it to work in my system. Seems like I might be better served with a solid state phono stage.

Lefty
 
Lefty said:
Thanks for the info - looks like mine is a later model in that case. It has both 'Puresound' on the front and an orange LED. Not sure what output caps are installed though. I've called up the shop where I bought it, and they have kindly offered to take it back for full refund. A shame as I really wanted it to work in my system. Seems like I might be better served with a solid state phono stage.

Lefty
Click to expand...
Yes it's a very fine valve phono stage but the high impedance output means it won't work with a number of amps these days which seem to have 20k inputs, yes a good solid state phono perhaps the Trichord Diablo if you liked the Dino or possibly the higher end Rega?
 
You must log in or register to reply here.


advertisement


Back
Top