Monoblock amps

[vcrpro3]

I recently obtained a pair of UPA-1 amps and they are great! If i managed to find a pair XPA-1L, would i like them more??? (can't afford the full size XPA-1 and have no room for them)

[garbulky]

I have used the UPA-2. I've listened to the UPA-1, XPA-2 and XPA-1 L and XPA-1. I suggest getting a pair of XPA-2 gen 2 amps (not gen 3) used.

[Gary Cook]

I have had an XPA-2 and an XPA-3, I still have an XPA-5 and I would rate my XPA-1L's above any of those as far as installed sound quality goes. Some of which I am sure relates to the physical advantages of monoblocks which allows for their placement very close by their respective speaker, something a stereo amp can never do.

Cheers
Gary

[leonski]

Jun 4, 2018 18:20:17 GMT -5 Gary Cook said:

I have had an XPA-2 and an XPA-3, I still have an XPA-5 and I would rate my XPA-1L's above any of those as far as installed sound quality goes. Some of which I am sure relates to the physical advantages of monoblocks which allows for their placement very close by their respective speaker, something a stereo amp can never do.

Cheers
Gary

IF you have long speaker runs and tend to use a wire which is a little small, like 16ga for 25' runs, than I'd say locate the amps to lower the run length.    But it's also possible to
up-wire and reduce resistance and reclaim some of the DF lost with higher resistance wire.
 
Sure, short speaker leads are attractive.   I'd also be concerned with a TOO LONG low level cable to each amp.   You kinda' have to balance one V the other.  Some interconnects with
high capacitance act as a high-cut filter and may adversly impact HF output.   

And I DO have my amps right in back of my speakers.   Maybe 2x of 3' speaker wires per STEREO amp running biamp to my panels.   My obvious path forward is to gut the speaker crossover
and go with a MiniDSP per amp.    
Those with HT gear and 5 channel and UP amps are sort of stuck and must make the best of location and run length.   

[Gary Cook]

Jun 7, 2018 15:01:24 GMT -5 leonski said:

Jun 4, 2018 18:20:17 GMT -5 Gary Cook said:

I have had an XPA-2 and an XPA-3, I still have an XPA-5 and I would rate my XPA-1L's above any of those as far as installed sound quality goes. Some of which I am sure relates to the physical advantages of monoblocks which allows for their placement very close by their respective speaker, something a stereo amp can never do.

IF you have long speaker runs and tend to use a wire which is a little small, like 16ga for 25' runs, than I'd say locate the amps to lower the run length.    But it's also possible to
up-wire and reduce resistance and reclaim some of the DF lost with higher resistance wire.

Sure, short speaker leads are attractive.   I'd also be concerned with a TOO LONG low level cable to each amp.   You kinda' have to balance one V the other.  Some interconnects with high capacitance act as a high-cut filter and may adversly impact HF output.   
And I DO have my amps right in back of my speakers.   Maybe 2x of 3' speaker wires per STEREO amp running biamp to my panels.   My obvious path forward is to gut the speaker crossover
and go with a MiniDSP per amp.    
Those with HT gear and 5 channel and UP amps are sort of stuck and must make the best of location and run length.   

To adversely affect the damping factor it only takes a very small amount of resistance/impedance, in my case I went from 5 metres (16 feet) of 14 gauge to 0.75 metres (2.5 feet) of 10 gauge. The 5 metre XLR balanced interconnects are Emotiva X series, which are a really nice cable at good value for money.

May 30, 2018 20:46:56 GMT -5 Gary Cook said:

Amplifiers with a HIGH damping factor have a LOW output impedance. As soon as we start adding speaker wire between the amp and the speakers, the damping factor at the speakers starts to fall. An amplifier with a damping factor of 400 into a 4 ohm load, has an output impedance of 0.01 ohms. If we use, say, 5ft of 14ga speaker wire, the total resistance of the wire is 0.016 ohms. If we add this to the output impedance of the amplifier the total output impedance is 0.026 ohms. This reduces the effective damping factor to 154. Longer runs of speaker wire will reduce the effective damping factor even more.

In summary, what we perceive as a small change in impedance can make a big difference in the damping factor.

For 2.1 stereo I have the 3 monoblocks located close by their respective speakers, the XPA-5 then powers the rest for HT use. There are ways to achieve a decent mixed use system, sometimes just have to be lucky with the room lay out.


Cheers
Gary

[leonski]

I'm glad you are in a happy place and especially with a 'mixed' system of HT / Stereo.

I really wish I knew what was better, but I suspect a LOT of factors, some of which are simply OUT of your control.    And than you add a couple 'it depends' to round it out.

DF is one of those third rail issues.   Nearlly irrelevent to my panels, since they store so little energy.   I'll default to what I understand is a good rule-of-thumb when considering
this and just say a NET DF of 50 or above is satisfactory.   Of course, a severaly underdamped speaker MIGHT benefit from a higher number, while a highly damped speaker might
not sound 'right' with such low output impedance from the amp.   'Old School' big box speakers might not (probably, even) sound right with such high damping.  

For those with a 'central' equipment location, the chat about speaker lead length V interconnect length is moot.    I've got the luxury of being able to locate one stereo amp
behind each speaker and little option to locate in the central cabinet, which would than turn into an OVEN.   The fact that my amps have In / Out jumpers, in effect a built-in
splitter, means only ONE run to each amp, and I low cut THAT using preamp bass management.    Not a big deal?    I don't think so, either.   Except for the result.  And the fact 
I needed only to add a pair of 18" jumpers to complete the setup.  

I'm running WAY overgauge wire, #10 Belden in 4x3foot runs, @2per amp.    I suspect some 'shotgun' runs of Canare 4S would work as well or even a good quality 'Zip' cord of
12ga.    I did my own terminations, the spade end of which I did at the store where I bought the amps.    I spent 45" or an Hour, clipping / trimming / crimping.     The store loaned 
me the 'crimper from hell' and MAN what leverage.   

I think I'll go back to and rely on fundamentals for setup.   Somebody who has a limit to WHERE they can put stuff has to maximize that setup.    One central place for electronics
means something different than for the guy who can locate amps nearby each speaker or SET of speakers.   Surround sound in any of the current flavors from 5.1 to nutty also 
bring their own constraints to each setup.  

I think the 1L amps might actually be a bump over some other choices, like the OP noted with hope?   As long as you feed it enough clean wall-power, you'll have it made.
I can't imagine the power demands of some systems i see around here.    I'm pushing stuff with my modest, by some standards, stereo setup.