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Pass XA Monoblock Amps

I know there have been many threads on these amps and the different levels of power with each set. To those who owned the Pass XA60.5 and went to the Pass XA100.5 monoblocks, did you feel that the change made a big difference in your system or was it not that noticeable whether played at low to mid level volume levels or high volume. I currently own the Pass 60.5 and am contemplating the Pass 100.5. Some people have suggested that it would take a move to the Pass XA160.5 for it to really make a difference but that would unfortunately be out of my price range. The room is 12 by 24 and the speaker load is 2 ten inch seas woofers, 2 seven inch mids, and the tweeter. They are 4 ohm with a sensitivity of 91 but a big speaker. Any thoughts from Pass owners of these amps would be appreciated. The other direction i can go would be to upgrade my Pre-amp from the Rowland Capri but my initial thought was that the Pass amp change would be more of an upgrade. Thanks for your thoughts.
pettyfeversk
rtn1
535 posts
 
I agree with "some people". Get the XA160.5s. Particularly if you like orchestral music. It's not just about loudness, but playing complex and large pieces without strain. I also have 91 dB sensitivity speakers into 4 ohms, and I can still get the meter to bounce a little when all 100 musicians are playing at the same time.

The only downside to having too much power with these amps is the heat. The big ones sound beautiful as well. I still can't think of an amp I'd rather have. Except for maybe the Pass XS300...
pettyfeversk OP
87 posts
 
I wish i could afford the XA160.5's but i can't. It is a 2.25 db increase from the Pass XA60.5 to the PassXA100.5. How much that will affect my headroom as well as the capacity to play loud without going into class a/b is probably unknown until i have them in my system as the room plays a part also.
charles1dad's avatar
charles1dad
10,250 posts
 
Hi,
Pettyfeversk, something does`nt seem right here. According to Nelson Pass the XA.5 series is "pure Class A" and is an ultra high current design(factor of 5x compared to the previous series current output capabilities) his words.It has a very stout power supply(obviously).
Your speaker is`nt a difficult load. At 4 ohms your amp will have plenty of current reserve(per design objective). Unless you want ear damaging volume your amp should really be fine for any type of music.

I`d speak with someone at Pass Labs before I`d follow the advice of some here to move up to a larger amplifier. Have you done that yet?
pettyfeversk OP
87 posts
 
Hi Charles,

Thanks for responding. The XA.5 series has a very strong class A power supply but if you have the volume up to a high level, you reach a point where they transition from pure class A to classA/B. That happens with all the amps in the XA series and definitely happens to me with my speakers which can take a good amount of power. You can see the bias need move as you go up the volume level and they move to AB.
almarg's avatar
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almarg
9,670 posts
 
A point that might be relevant is that speaker sensitivity is often defined with respect to 2.83 volts, rather than 1 watt. For an 8 ohm speaker that would make no difference, since 2.83 volts into 8 ohms corresponds to 1 watt. But 2.83 volts into 4 ohms corresponds to 2 watts, so if the 91db figure of your 4 ohm speakers is defined with respect to 2.83 volts, they would be 88db/1W/1m speakers, not 91db/1W/1m.

I did a quick Google search, but couldn't determine how the 91db is defined.

Beautiful system and setup, btw.

Regards,
-- Al
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