Questions re: X350.5 specs

CP-Mike · 20th December 2005, 05:46 PM

Sorry for posting this here, my questions have nothing to do with DIY, but I can't find a good source of Pass Labs info anywhere else.

In the spec sheet for the X350.5, it says "Output Voltage: Maximum plus, minus approx. 80 volts" and "Output Current: Maximum plus, minus approx. 20amps". Why does it say "plus, minus approx"? Is the max current output approximate, plus or minus 20 amps? Or is it just 20 amps? It seems that 20 amps is very low compared to other amps out there, like the Musical Fidelity 750, which claims 250 amps max.

According to the specs online, the X250.5 doubles its 8-ohm power into 4 ohms, but there is no mention of a 4-ohm load in the X350.5 spec sheets. Does the 350.5's rated output also double into 4 ohms?

The damping factor is not stated for the X350.5. Anybody know what it is?

Nelson Pass · 20th December 2005, 06:53 PM

The damping factor as called out in the owner's manual is 240,
and the maximum output current is 20 amps. While we do not
spec the 4 ohm power, you can infer from the 20 amp rating
that it does not limit at 4 ohms, and with the supply lines
loading down, you can expect less than 700 watts into 4.

CP-Mike · 21st December 2005, 01:37 AM

Thank you, Mr. Pass, for your reply. Man. Where else does the lead designer of hi-fi gear regularly post in support of his/her products? Nowhere that I know of, that's for sure. At least not in a forum that's not owned/operated by the company that designer works for.

Is damping factor even important for solid-state amps? I thought it was only really a factor for tube amps.

How many watts can the X350.5 provide in class-a operation?

Nelson Pass · 21st December 2005, 08:26 PM

Last time I looked, it was a couple watts SE Class A, and it
leave PP Class A above 40 watts.

As to the damping factor, I have not found that it represents
the single number which determines the performance on the
bottom end. Anecdotally, I have examples of amplifiers with
high damping factors which do not control woofers as well as
some with much lower damping.

The most dramatic example would be comparing a pair of
Wilson Watt/Puppies with an Aleph 2 versus an X600. Both
amps had the same measured damping factor, but the Aleph 2
was inferior on the bottom end.

20th December 2005, 05:46 PM	#1
CP-Mike diyAudio Member Join Date: Dec 2005 Location: CA, USA	Questions re: X350.5 specs Sorry for posting this here, my questions have nothing to do with DIY, but I can't find a good source of Pass Labs info anywhere else. In the spec sheet for the X350.5, it says "Output Voltage: Maximum plus, minus approx. 80 volts" and "Output Current: Maximum plus, minus approx. 20amps". Why does it say "plus, minus approx"? Is the max current output approximate, plus or minus 20 amps? Or is it just 20 amps? It seems that 20 amps is very low compared to other amps out there, like the Musical Fidelity 750, which claims 250 amps max. According to the specs online, the X250.5 doubles its 8-ohm power into 4 ohms, but there is no mention of a 4-ohm load in the X350.5 spec sheets. Does the 350.5's rated output also double into 4 ohms? The damping factor is not stated for the X350.5. Anybody know what it is?

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20th December 2005, 06:53 PM	#2
Nelson Pass The one and only Join Date: Mar 2001	The damping factor as called out in the owner's manual is 240, and the maximum output current is 20 amps. While we do not spec the 4 ohm power, you can infer from the 20 amp rating that it does not limit at 4 ohms, and with the supply lines loading down, you can expect less than 700 watts into 4.

21st December 2005, 01:37 AM	#3
CP-Mike diyAudio Member Join Date: Dec 2005 Location: CA, USA	Thank you, Mr. Pass, for your reply. Man. Where else does the lead designer of hi-fi gear regularly post in support of his/her products? Nowhere that I know of, that's for sure. At least not in a forum that's not owned/operated by the company that designer works for. Is damping factor even important for solid-state amps? I thought it was only really a factor for tube amps. How many watts can the X350.5 provide in class-a operation?

21st December 2005, 08:26 PM	#4
Nelson Pass The one and only Join Date: Mar 2001	Last time I looked, it was a couple watts SE Class A, and it leave PP Class A above 40 watts. As to the damping factor, I have not found that it represents the single number which determines the performance on the bottom end. Anecdotally, I have examples of amplifiers with high damping factors which do not control woofers as well as some with much lower damping. The most dramatic example would be comparing a pair of Wilson Watt/Puppies with an Aleph 2 versus an X600. Both amps had the same measured damping factor, but the Aleph 2 was inferior on the bottom end.

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