Stereomour and Klipsch La Scala

[croc]

Hey there,
i'm looking for some time to replace my trusty EL34 based SET with something better.
The speakers are Klipsch La Scalas with type A xover and various upgrades.

Recently i've tried Audio Note's 300B based SET monoblocks and i felt some "whole" somewhere in the midrange.

Yesterday i've got for audition the Stereomour and i felt very similar thing.
i mean low bass is great, some midbass feels perfectly fine but sometimes some midbass notes sound very lean and lacking body and punch that i'm used to.

so this time i've measured in room frequency response (with radioshack SPL meter) and i clearly see ~10db less in the 65-80 Hz range.

what do you guys think happens here?

perhaps there is something with La Scala's xover at those frequencies that make it hard on the amps?
but somehow my EL34 cheap amp is doing fine...

many thanks,
Gennady

[Grainger49]

I wonder what the speaker response without a sub looks like.  Or what the sub response without the La Scala looks like.

Then are the La Scala and sub in phase?

There are so many things that affect the frequency response in the range you have graphed above.  The room dimensions and speaker placement are huge factors.  The speaker responses without room effect are another and finally phase.

I don't think you can draw a scientific conclusion without more data. 

Sorry!

[croc]

the sub adds few DBs at 30Hz. that's it.
the difference is the same when the sub is disconnected completely.
speakers placement and room don't change.
the amp is the only difference....

usually i would say that the amp is running out of steam.
but that Audio Note is note supposed to be less powerfull than this EL34 based SET...
and also it doesn't happen very low bass - there is no problem there.

so this gets me wondering what kind of interaction happens with the amp and those speakers at this 65-80 Hz range...

[Paul Birkeland]

Posting more information about your EL34 SET might help a fair amount.

IMO - I'd repeat the measurements without the sub.

[Grainger49]

To know what standing waves and nulls your W, D & H of your listening room is need.  That gets calculated against the woofer height, distance from front wall and distance from side walls.

Like I said before, there is a lot of things happening here that you are not taking into account.

[croc]

yes - i get it.
once again - measurements without the sub were done and they are identical to those with sub at range of 35-120 Hz.
standing waves should be the same as the room, speakers, their location in the room and the measurement point are all constant.

the EL34 amp is Norh SE-9 with all possible parts replaced (stock transformers retained):
http://www.tnt-audio.com/ampli/norh_se9_e.html

preamp is VTL The Ultimate heavily moded.

[Grainger49]

    .   .   .    perhaps there is something with La Scala's xover at those frequencies that make it hard on the amps?  .  .  .   .     

This might be a factor.  See if you can find the impedance curve for the speaker with your crossover (there are others out there other than the stock crossover). 

SET amps react to impedance peaks and dips.  They prefer a smooth curve.  If your EL34 amp has feedback that can help with impedance peaks and dips.

[RPMac]

Try wiring one La Scala reverse polarity. May be a miswire of OPT to speaker terminals.

[Chris]

I am thinking a little like RPMac, reverse the polarity (simple things first), and have to say, even though Klipsch speaks are supposed to be efficient on paper.. They are famous for LOVING higher power amps like McIntosh (a famopus pairing), HK Citation II etc.... I think 3ish watts isnt enough for them....

[Paul Birkeland]

It's pretty tough to get the impedance curve of the La Scala, but you might try going down to the 4 Ohm tap and retrying the test.

[croc]

Try wiring one La Scala reverse polarity. May be a miswire of OPT to speaker terminals.

done.
didn't help unfortunately.
this could be an easy fix 

[croc]

La Scala's crossover is the same as Klipschorn (untill mid 80's anyway) and same drivers.
so impedance shoulld be the same.
still i haven't seen good and clear measurement of it...

it's interesting ypu're mentioning Citation II - i own one for 10 years.
IMO it's a comple overkill for the La Scala.
i drive with it JBL L300 and at the past some quite hugnry modern speakers...

i had once 45 based Yamamoto A08 for few hours - and it sounded like it could handle the La Scala's OK.
but perhaps the audition was too short...

is there any updgrades available that can make Stereomur more impedance tollerant?
on my past amps upgrades of caps in power supply and the rest always made sound more solid/stable/powerfull.
what about better/bigger iron?

[Paul Birkeland]

is there any updgrades available that can make Stereomur more impedance tollerant?

Yes, you go down a tap in impedance.

[smithanh]

I've been using. Stereomour with LaScalas for the past two years and have not found any problems other than those of the LaScalas themselves, mainly, lack of low end. I do not use a subwoofer (often tempted, but concerned about interaction). I have the Crites tweeters and appropriate Crites crossovers which lowers the crossover frequency for the tweeters to 4500 Hz which reduces demand on the mid-horn.  This has made the mid ranges considerably smoother. Considering a sub and wood appreciate any input.

[corndog71]

http://www.rythmikaudio.com/F12G.html

This is a very fast and powerful sub.