PMC Twenty 21, listening fatigue?

It really depends. Even with a listenting position sufficiently far back, you may find that the amoutn of toe required vastly changes depending on how far apart the speakers are by just a few cm. I spent a lot of time playing with the positioning on 20.23 and even more time getting 25.23s right. The PMC manual says to toe in so that their imaginary axis converges a foot or so behind your head. I found this to be nonsense, but found firing straight ahead lost all soundstage. They can be a bit picky. Closer to a rear wall and they want a bit more toe it seems.

I finally got it right after many many goes nudging then a cm closer together, a few cm further out into the room and a tad less toe each time. Sounds easy but I'd spend an hour listening and positioning to get the soundstage locked in solid and then a day later would realise the total balance was off or that centre focus was spot on but everything else a bit vague. The Twenty series is a far more forgiving but follows the same basic rules. I found that the Twenty series benefits from careful positioning but doesn't really suffer dramatically from getting it wrong like the Twenty5 series does.

I'm using linn k20 cable with my 21's,on atacama moseco 6 stands three quarters filled with attabites and very slight toe in,14cm's from the wall and using a nait xs/flatcap 2x  fed primarily with a cd5i mk2 and project 2 xperience classic with at 33ptg ii/trichord mk3 /nc psu and it sounds sweet although I don't crank the volume very often about 10 o'clock is about as loud as I need.They fit my room well without any bass boom and a level of clarity that I've not heard before (these are my first speakers over the 1k mark)I really think that they thrive on a good recording though and they are a bit on the leaner side of neutral with lesser recordings which could come across as a bit bright to some.oh and if there's more to come from these little monitors when I get the urge and find the cash for something more exotic further up the naim ladder...I canny wait.

After listening since my last post I have lessened the toe in and removed the jumper leads and am now bi wiring the speakers. It seems to me there could surprisingly be an improvement or difference in what I hear. Bass and treble seem to be more refined and overall there is a bit more clarity of sound.

All very surprising really.

Bi-wiring is not good for Naim amps - OK OK,  if you think it sounds better who am I say its bad.   The fact remains that Naim amps need a high'ish inductance load to stabilize its output stages,  hence the way NACA5 is designed with its wide conductor spacing.    Bi-wiring halves cable inductance & doubles the capacitance.   I don't have the Rumour numbers but my Odyssey is aprx 0.6uH/m & Rumour is not far off the same;  whatever its not far off half that of NACA5 & bi-wiring halves that again.      Like I said,  if it sounds OK/better,  who are we to say otherwise,  just keep a hand on the amp,  any signs of running warmer or maybe when you detect a hard edge to the SQ,  I told you so.

GraemeH posted:

I'm sure PMC recommend the twenty range fire straight ahead for the best high frequency response. It's in an interview/review with Peter Thomas somewhere I recall.

As a practical example of what speaker manufacturers recommend versus reality here's what I've found:

After much experimentation with positioning I've got my Totem Sttafs toed-in directly at my listening position from eight-feet away and seven-feet apart, which is a rather acute angle and what I'd call well toed-in. This is the best sonic result I've obtained. In contrast, here's the recommendation from Totem;

 Due to the fact that all Totem speakers have great off-axis dispersion, toe-in is generally not needed. Imaging will therefore be more stable from any point in the room. If the speakers are placed very far apart (over 7 feet) then a slight toe-in may be experimented with. However if room geometry does not permit a straight-ahead aspect they will also perform very well with a slight toe-in.

So much for the manufacturer's recommendations. At some point you have to take the bull by the horns and frankly my speakers are about 95% great no matter what the toe-in. If you're struggling that much with placement, toe-in, and a need to bi-wire, etc, the speakers probably just aren't a match for your room and it's time to give up the ghost. All FWIW.

joerand posted:

GraemeH posted:

I'm sure PMC recommend the twenty range fire straight ahead for the best high frequency response. It's in an interview/review with Peter Thomas somewhere I recall.

As a practical example of what speaker manufacturers recommend versus reality here's what I've found:

After much experimentation with positioning I've got my Totem Sttafs toed-in directly at my listening position from eight-feet away and seven-feet apart, which is a rather acute angle and what I'd call well toed-in. This is the best sonic result I've obtained. In contrast, here's the recommendation from Totem;

 Due to the fact that all Totem speakers have great off-axis dispersion, toe-in is generally not needed. Imaging will therefore be more stable from any point in the room. If the speakers are placed very far apart (over 7 feet) then a slight toe-in may be experimented with. However if room geometry does not permit a straight-ahead aspect they will also perform very well with a slight toe-in.

So much for the manufacturer's recommendations. At some point you have to take the bull by the horns and frankly my speakers are about 95% great no matter what the toe-in. If you're struggling that much with placement, toe-in, and a need to bi-wire, etc, the speakers probably just aren't a match for your room and it's time to give up the ghost. All FWIW.

It will depend very much on the room, especially proximity of side walls and how absorbent or scattering of high frequencies are the side walls (+furniture etc).

Mike - B -  I don't understand the comment re bi wiring, the one set of  +/- terminals are used on the back of the amp, at the speaker end the bi wire cable is used on all four terminals rather than two and a connection from the jumper cables. And the point of "I told you so" is what ?

Joerand-  I feel that how the speakers are currently is better than ever, with toe in and with stands on granite slabs.

Innocent bystander - clearly the room is playing a big part, I've been playing with placement for two years.

Charles44 posted:

Mike - B -  I don't understand the comment re bi wiring, the one set of  +/- terminals are used on the back of the amp, at the speaker end the bi wire cable is used on all four terminals rather than two and a connection from the jumper cables. And the point of "I told you so" is what ? 

When you have two parallel cables from the amp output,  that halves inductance as seen by the amp compared to one cable going to the same speaker terminals .      Although you will probably not get to this point with your bi-wiring,  at some point, any amp given a low inductance & high capacitance load will be affected by capacitive reactance & its output stage(s) will oscillate (sometimes called HF ringing),  This condition is an overload across the entire frequency range & the amp will run hotter than 'normal'.   High'ish inductance speaker cable is recommended for Naim amps to give the required inductance load to stabilize the output stage & with most other amps the same is done with an internal inductor - plus whatever the installed cable load adds to that.   

If your amp runs hot or it has the hard edge which might be indicative of HF ringing,  I told you so  ........   just a friendly     Chances are you will be OK as IME the Naim integrated are very forgiving,  & none more so than my ol' SuperNait..