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Old 18th February 2014, 08:37 AM   #1
aluster is offline aluster  Ukraine
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Default impedance on PASS XP-10

hi, everybody

I want to buy pass xp-10, but I faced a question about out impedance
I Have active acoustic systems geithain me-901ka. From the preamp to the speakers will be used cable 4 m (13ft) long. My dealer, my friends, as well as numerous people on Hi-Fi Forum pointed out to me that the pass xp-10 output impedance is 1000ohm, my speakers have in impedance 10 kohm. They say when I will use my long cable between amplifier and speakers-I will have a loss in sound, have degradation, etc. All people say - do not buy this preamp for your speacers
. However, I really want to buy this pass.

(sorry for my bad Engl)
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Old 18th February 2014, 08:46 AM   #2
Mooly is online now Mooly  United Kingdom
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The spec mentions 1k for balanced operation, a more normal 150 ohms for single ended. What type of input are your active speakers, balanced or unbalanced ?
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Old 18th February 2014, 08:50 AM   #3
aluster is offline aluster  Ukraine
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balanced

Input impedance≥ 10 kOhm RC symmetrically
Electronic Crossover frequencies550 Hz and 2.8 kHz
Input ConnectorXLR 3F
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Old 18th February 2014, 12:04 PM   #4
Mooly is online now Mooly  United Kingdom
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Well in that case, and without knowing the details of the XP-10 (so taking the 1k output impedance at face value) I would suggest its not an ideal match over that lengh of cable run but having said that it doesn't mean it won't sound good though.

You've probably been told also that the high output impedance might affect the HF response due to capaciive loading... true but the effect is minimal. Even a 2n2 loading would still push the -3db point over 70kHz.

And maybe Nelson can answer this... is the 1k loading related to achievable voltage swing and drive ability rather than an output that is like an ideal voltage source in series with 1k. There's a big difference
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Old 18th February 2014, 03:13 PM   #5
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The schematic show 100 ohms (RCA) and 320 (balanced),
and the X power amplifiers of that time were 10K + 10K
input impedances.


Last edited by Nelson Pass; 18th February 2014 at 03:15 PM.
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Old 18th February 2014, 04:31 PM   #6
aluster is offline aluster  Ukraine
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Quote:
Originally Posted by Nelson Pass View Post
The schematic show 100 ohms (RCA) and 320 (balanced),
and the X power amplifiers of that time were 10K + 10K
input impedances.

diar Nelson , can tou tell me - once I buy PASS XP-10? the output impedance 1000ohm on preamp isn't critical?
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Old 18th February 2014, 04:32 PM   #7
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Mr. Pass,

I'm wondering what is the max output voltage of the XP-10? (I didn't see it on
the PL website). Is it adequate for an F4?

Thanks,
Dennis
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Old 18th February 2014, 04:50 PM   #8
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Quote:
Originally Posted by Dennis Hui View Post
I'm wondering what is the max output voltage of
the XP-10? (I didn't see it on the PL website). Is it adequate for an F4?
The gain stage has 32V rails, so probably will do +/-28 volts single-ended,
and twice that balanced. That will exceed the 21 volts peak you expect
from an F4.

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Old 18th February 2014, 05:12 PM   #9
Mooly is online now Mooly  United Kingdom
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Quote:
Originally Posted by Nelson Pass View Post
The schematic show 100 ohms (RCA) and 320 (balanced),
and the X power amplifiers of that time were 10K + 10K
input impedances.

Thanks. So based on that aluster is good to go
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Old 18th February 2014, 05:45 PM   #10
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Quote:
Originally Posted by Nelson Pass View Post
The gain stage has 32V rails, so probably will do +/-28 volts single-ended,
and twice that balanced. That will exceed the 21 volts peak you expect
from an F4.

Thank you, Mr. Pass.
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