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Pass X150 and BAT VK3IXSE gain problem
Pass X150 and BAT VK3IXSE gain problem
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Old 12th September 2018, 11:35 PM   #1
Mark Veter is offline Mark Veter  Italy
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Unhappy Pass X150 and BAT VK3IXSE gain problem

Hi all. I have a Pass X150.
Previously I had a Mark Levinson 28 preamplifier and it was a near perfect match, both electric and timbrically

Now I bought a BAT VK3IX SE pre but I'm not happy about the matching with the Pass.

impedances should be ok:
1k Ohm output impedance the BAT and 22k ohms input impedance the PASS. The ratio is 1:22. Confirm?
It is a rule that minimum ideal ratio is 1:10?

However the Pass gain is too high (30db?) and therefore I can not increase the volume over 25/100 and 40/100 with SACDs

I also perceive a sense of fatigue and dirty sound. there is not a much black background like with solid state preamps.

I would like to know :

1. there is a way to decrease the gain of the Pass through internal switches?
2. Anyone has yet matched BAT preamps with PASS X series power amps ?

Please help me ,

Marco
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Old 13th September 2018, 01:16 AM   #2
Dennis Hui is offline Dennis Hui  Canada
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Pass X150 and BAT VK3IXSE gain problem
Marco,

I suggest you contact Pass labs (service@passlabs.com) with your amp's serial number.

Cheers,
Dennis
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Old 13th September 2018, 01:27 PM   #3
Mark Veter is offline Mark Veter  Italy
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Ok. I wrote them.
I’m waiting for a reply
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Old 13th September 2018, 02:35 PM   #4
Zen Mod is offline Zen Mod  Serbia
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Pass X150 and BAT VK3IXSE gain problem
open the lid , take photo of motherboard , post here
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Old 13th September 2018, 04:37 PM   #5
Nelson Pass is offline Nelson Pass  United States
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Pass X150 and BAT VK3IXSE gain problem
X250 gain is 26 dB last time I looked, and this is the first time the
subject has come up.

Single ended or balanced?
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Old 13th September 2018, 07:50 PM   #6
Mark Veter is offline Mark Veter  Italy
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Balanced
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Old 14th September 2018, 05:57 PM   #7
Nelson Pass is offline Nelson Pass  United States
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Pass X150 and BAT VK3IXSE gain problem
The amp has the same gain either way, but the source might easily
have twice as much running balanced.

You can reduce the gain arbitrarily by inserting resistance in series with the
to inputs. For example, 10 Kohm will drop it about 6 dB, 20 Kohm 12 dB and so
on. It won't hurt the performance of the amp, but it is necessary to have both
+ and - lines treated the same.
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Old 14th September 2018, 10:27 PM   #8
Mark Veter is offline Mark Veter  Italy
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Thank you so much Nelson.


So... just buy these attenuators to reduce the gain of my X150 Pass. Wonderful!

But ... what about input impedance?

It is still a "only" 1:22 ratio.

1KOhm BAT: 22KOhm Pass

It's enough ? This is a good sinergy?
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Old 15th September 2018, 07:55 AM   #9
Zen Mod is offline Zen Mod  Serbia
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Pass X150 and BAT VK3IXSE gain problem
if you add 10K in each input leg , Rin goes by 20K .... resulting in 42K
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Old 15th September 2018, 08:48 AM   #10
Mark Veter is offline Mark Veter  Italy
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Ok. Thank you!
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