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Using the same amp on an 'X.6' and an 'X.7'?

124.176.102.121

I'm asking this Qu because I've just read about someone who has the same amp running on 2 different Sonus Faber speakers - one which supposedly has a series XO ... the other a normal parallel XO.
Now these are different speakers, with different sensitivities - but the amp driving the spkr which had a series XO ran a lot cooler than the amp driving the spkr with a parallel XO.
So - as the difference between the two (apart from the use of foil on the mylar, instead of round-wire) is basically that the 'X.6' has a parallel XO whilst the 'X.7' has a series XO - I'm very interested in hearing if anyone has swapped:
* 1.6s for 1.7s, or
* 3.6s for 3.7s
... and still used the same amplifier.
And if so ... did you notice that the amp ran cooler?
Thanks,
Andy

Edits: 05/31/20

Follow Ups:

RE: Using the same amp on an 'X.6' and an 'X.7'? - Davey 15:46:36 05/31/20 (5)
Andy,
You can't infer/conclude that a parallel crossover is more demanding upon an amplifier than a series crossover....or vice-versa. Generally speaking. There are too many other variables at play here.
Simple example: In the case of these Magnepan X.7 speakers, the series crossover resulted in a somewhat flatter impedance curve in the crossover range. However, the 1.7 has a dip in impedance at higher frequencies the 1.6 doesn't have.
Dave.

Edits: 05/31/20
- RE: Thanks, Dave ... - andyr 16:57:43 05/31/20 (4)
  It certainly seemed to me that the guy was pulling a long bow when he said a series XO is an easier load to drive than the equivalent parallel XO ... but I wanted to get other people's input.
  
  Thanks,
  Andy
  - RE: Thanks, Dave ... - Roger Gustavsson 07:30:43 06/01/20 (3)
    Serial vs, parallel: https://sound-au.com/parallel-series.htm
    
    In the case of the 1.6 vs. 1.7, there is a different concept with the super tweeter. You need to compare speakers were the only difference is just if there is a serail or parallel crossover set for the same frequency response - not two differently tuned/voiced speakers.
    - RE: Sure, Roger ... - andyr 14:13:02 06/01/20 (2)
      That would be the ultimate test!
      
      The 1.7's super-tweeter idea means it is not the same as a 1.6. But maybe a 3.7 is pretty much the equivalent of a 3.6 (apart from the quasi-ribbon foil) - so that's a better comparison?
      
      I'm simply interested in determining whether the claim I read that the same amp into a series XO ran cooler than when it was driving a parallel XO ... is correct. Dave suggests not. :-))
      
      Andy
      - RE: Sure, Roger ... - Roger Gustavsson 08:11:03 06/02/20 (1)
        
        In Reply to: RE: Sure, Roger ... posted by andyr on June 01, 2020 at 14:13:02
        
        Magnepan 3.6 and 3.7 are voiced with their crossovers. If you switch the crossovers between them they will still sound a bit different. If you want to know what a series and parallel crossover sounds like, you need to build two versions for them.
        
        RE: Sure, Roger ... - andyr 17:35:48 06/03/20 (0)
        
        In Reply to: RE: Sure, Roger ... posted by Roger Gustavsson on June 02, 2020 at 08:11:03
        
        Actually, I'm not particularly (interested in what a series crossover sounds like, compared to a parallel XO) - all I wanted to do was get people's opinions as to whether the claim that I had read elsewhere, that a series XO was an easier load on an amp than a parallel XO, was valid ... or not. :-))
        
        And I thought that comparing 1.6s to 1.7s / 3.6s to 3.7s might be a good test. Obviously that was a wrong assumption.
        
        Andy
Take this with a whole teaspoon of salt. - wazoo 09:39:18 05/31/20 (3)
I'll resist other comments and questions, and just answer yours to the best of my ability - mind you, this information isn't exactly fresh. Back when I transitioned from 3.6s to 3.7s, my Pass X350 stayed put. That much is absolutely certain, but the following is less so. I don't recall any difference in either the bias needle movement or the heatsink temperature. Then again, even after introducing an electronic crossover to direct the very bottom end away from the 3.7s, I didn't observe an appreciable difference in the heatsink temperature, although the deflection of the needle reduced enough to get me contemplating tubes.
- RE: Thanks, waz nt - andyr 15:09:38 05/31/20 (0)
  .
- RE: Take this with a whole teaspoon of salt. - Roger Gustavsson 10:20:00 05/31/20 (1)
  The 1.7 seems to dip to Ohm at higher frequencies. The 1.6 is a far easier load.
  - RE: "The 1.6 is a far easier load" ... - andyr 15:11:34 05/31/20 (0)
    Aah, OK, Roger. So an amp should get hotter with a 1.7.
    
    Thanks.
    Andy
I suspect ... - Mike K 09:15:51 05/31/20 (0)
that the amp runs hotter in one case because the speaker attached is
less efficient, and/or is of a different impedance. Which means the
amp is underpowered for the load it is trying to drive.

I drive my LRS with a pair of PS Audio m700 class D monoblocks (700 wpc
@ 4 ohms). They never, ever get even a tad bit warm, at any volume level
or with any type of music I've tried so far. My Rogue Audio Cronus Magnum
II, otoh, was uncomfortably warm always - but it's a 100 wpc tube amp and
one should expect that.
Whether or not you can observe a thing depends upon the theory you use. It is the theory which decides what can be observed. - Albert Einstein

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