[Jose R.]

Hi everyone

As I mentioned previously, I use the Tact RCS in my system and one applies a correction after taking a measurement at the listening position.  The measurement showed a deep dip between 400-750Hz which puzzled me somewhat.  Initial listening was with a single amp with room correction and the sound was fairly good - I however preferred a x-over to my corner subs of 260Hz which was a lot higher than I used with other speakers.
I then moved on to biamping with a Tact S2150 digital amp driving the woofers (I use a separate S2150 for the subs) and a pair of 170W monoblock valve amps for the panels/tweeter.  I was very disappointed with the sound.  It sounded lacklustre and out of phase.  I checked all my connections to make sure that I had not inadvertantly wired out of phase but all seemed ok.  None of my components swap phase.
I then started to play around with the amps phase and the sound improved a lot.  I then ran measurements again with the woofers and panels/tweeter out of phase and the dip between 400-750 was practically gone.  This indicated that they were previously out of phase at the crossover point.  It also explained why I preferred the sound with higher crossovers to the subs - now a crossover of 100-120Hz is much better.

I checked the polarity of the the woofers with a 1V battery across the pos and neg and they were in correct phase as specified by the binding posts.  I don't however know how to check phase on the panels/tweeter - perhaps Brian can help here.

I doubt that the room or distance of measurement (10') could account for the crossover dip (about 8dB) that I found with all the drivers in phase according to the binding posts.  Perhaps the panels/tweeters were inadvertantly wired wrongly or does Brian design his crossover this way?

I can post the measurements I got if anyone is interested.

Any views would be appreciated.

Regards

Jose

[JoshK]

Jose,

What xo slope does the Tact use when biamping?  If it is 4th order LR then the upper and lower bands have to be antiphase, this is the xo in this case.   Brian uses *i think* a series first order crossover where the upper and lower passband on in phase.

[Jose R.]

Hi Josh

I am not using any crossovers in the biamping setup.  I am using the passive crossovers that came with the speakers.
I use a digital crossover in the Tact RCS between main speakers and subs - it is set at 120Hz but when doing measurements, it is not in the path - each speakers and each sub are measured separately.

Regards

Jose

[JoshK]

weird...

Does the TACT switch polarity on the second output? Many/most speakers use 4th O LR xo's so maybe they accounted for this by switching the second output's polarity?  I don't know, just a thought, probably not the case though.  

It just seems odd that if you used a battery to test the phase of the mid and woofer and they are in phase that they would be also with biamping passively. No idea really...

[jermmd]

Perhaps a simple way to check phase in the mid/tweeters would be to simply play the alternating phase white noise from Avia (or some other setup disk) with the bass speaker terminal disconnected?  If the speaker's upper panels are  out of phase it should be obvious.  On the other hand,  if the panels are out of phase with each other on the same speaker, this would be difficult to determine.

OT,  I just heard George's RM40's on the Tact system that you have and they were amazing.  Night and day difference with room correction.  Soundstage, imaging and clarity were dramatically improved.  It's very rare at this level to find something that makes such an obvious difference.  You don't need to be an audiophile to hear the difference in music when room correction is engaged.

Joe M.

[Brian Cheney]

You can measure phase of the panels with a fresh 9V alkaline battery.  Touch the (+) lead to the (+) terminal of the lowest panel and the (-) battery lead to the (-) terminal of the uppermost panel.  All three diaphragms should visibly move forward.

All drivers are in phase in the RM30 and typical semianechoic FR is within 2dB from 40Hz to 10kHz.

[Jose R.]

If the speaker's upper panels are  out of phase it should be obvious.  On the other hand,  if the panels are out of phase with each other on the same speaker, this would be difficult to determine.

OT,  I just heard George's RM40's on the Tact system that you have and they were amazing.  Night and day difference ...

Hi Joe

I will try the white noise test - listening to them, the speakers sound better with the panels/tweeter in phase.
I agree with you re the Tact RCS - I could not live without it.  The difference it makes to the RM30C is amazing.  Once you have used room correction, everything else seems dull and bloated.

Regards

Jose

[Jose R.]

You can measure phase of the panels with a fresh 9V alkaline battery.  Touch the (+) lead to the (+) terminal of the lowest panel and the (-) battery lead to the (-) terminal of the uppermost panel.  All three diaphragms should visibly move forward.

All drivers are in phase in the RM30 and typical semianechoic FR is within 2dB from 40Hz to 10kHz.

Thanks for the input Brian

I will try the battery test on the panels.  Is there any way to test the tweeter polarity?
BTW I am not doubting your design - what I am getting is very much influenced by my room set-up and conditions.  For example I have a +8dB peak between 100-200 but that is because I have the speakers about 6' from the front wall and 4' from sides.  I know that moving them closer to the walls would reduce this but I like the soundstaging I get in this position.  The Tact also can easily correct for this peak.

Regards

Jose

[jermmd]

Jose,

I have the same peak between 100 and 200 Hz.  So did the proffessional reviewer who loved the RM30's and so does a friend of mine.  I wonder if this is a common peak in all rooms or is this a speaker issue?

Let me know what you find on the phase tests.

Joe M.

[Brian Cheney]

It is not possible to do the battery test on the tweeter: the diaphragm moves too far and will break. We check phase at the factory.  In addition I took the RM 30C's for Jose to my soundroom and checked them out; no problems and they sounded excellent.

I believe most of Jose's measurements are misleading, as are most in-room measurements.  Room modes and cancellations due to time delays (reflected energy from side walls, floor and ceiling) in untreated rooms give microphones fits.

Room treatment yields superior results to EQ no matter how sophisticated.  Some users have combined a treated room and electronic correction with good results, however.

[JoshK]

Have to totally agree with BC on this one.  EQ without room treatments is like sweeping dust under the rug.

[John Casler]

Have to totally agree with BC on this one.  EQ without room treatments is like sweeping dust under the rug.

Didn't Jose mention that he is LEDE?  I could be wrong

[jermmd]

Well,  I have to admit,  I have neither room treatments nor EQ.  And  I truly enjoy listening to music with my RM30's.  If I hadn't done measurements I wouldn't have been aware of any anomolies.  I didn't even miss the deep bass until I listened to George's RM40's.  In fact I thought George's system was great until he A-B'd the system with and without EQ.  It's like watching TV on a giant screen: once you've seen it it's hard to be satisfied with the small screen you  were perfectly satisfied with a little while ago.   There really is a pathalogical side to this hobby and one needs to step back at times and just listen to the music without analyzing or comparing the sound to some perfect ideal.

Joe M.

[zybar]

It is not possible to do the battery test on the tweeter: the diaphragm moves too far and will break. We check phase at the factory.  In addition I took the RM 30C's for Jose to my soundroom and checked them out; no problems and they sounded excellent.

I believe most of Jose's measurements are misleading, as are most in-room measurements.  Room modes and cancellations due to time delays (reflected energy from side walls, floor and ceiling) in untreated rooms give microphones fits.

Room treatment yield ...

My room is treated with a combination of bass absporption (8 MiniTraps), HF absorption (8thNerver corners and seams), and first reflection points (4" 1'x1 acoustical foam).  The room treatments helped dramatically.

In the last week I added room correction via the Tact RCS 2.2x and as Joe already pointed out, the change is not subtle.  Although measurements are done from the main listening position, positive changes are absolutely audible outside of the sweet spot as well.

One of the things I noticed from my measurememts (and listening), was that one speaker was louder than the other (I noticed that over the summer too when I was playing around with a varioius Behringer models - 1024, 8024, and 2496).  This is no doubt because of the room, but it is still there and needed to be addressed.  I tried to address it as best I could via pots/putty, but could never eliminate it.  The Tact eliminates it and my imaging and soundstage have never been better.

Anyway, just wanted to say:

VMPS speakers + Room Treatments + Room Correction = AWESOME SOUND!!  

George

[jermmd]

VMPS speakers + Room Treatments + Room Correction = AWESOME SOUND!!

What he said.

Joe M.

[PeteG]

Sorry for being OT.

George,
I’ve been interested in the TacT RCS preamps for a while, never got one do to
the volume of vinyl and SACD I listen to, but the 2.2X  you can mix 1 or 2 sub’s
in your room, and I think that’s great. How does the DAC in it sound?

Pete

[zybar]

Sorry for being OT.

George,
I’ve been interested in the TacT RCS preamps for a while, never got one do to
the volume of vinyl and SACD I listen to, but the 2.2X  you can mix 1 or 2 sub’s
in your room, and I think that’s great. How does the DAC in it sound?

Pete

Pete,

I just posted some thoughts on the 2.2x over in the Critics Circle:

http://www.audiocircle.com/index.php?topic=14896.msg128897#128897

To quickly answer your question, I am going to sell my very good Audio Logic 24 MXL dac.

George

[jakepunk]

VMPS speakers + Room Treatments + Room Correction = AWESOME SOUND!!

I don't have any room correction, but you can add me to the list of believers in room treatments.  This week my new wall panels from Acoustics First arrived.  I am amazed at the difference they made.  I put them behind the live end of the room and one at the first reflection point (not visible in the picture below).  

One word: Clear.  Everything sounds so much clearer now.  I notice it especially in the high frequencies and percussion.  Each drum is more distinct, and cymbals sound like they have appropriate decay.  I can honestly say that material I have been listening to for years has a new level of clarity and detail now.  I wish I had done this a lot sooner.  If you look at the marginal improvement for the price, it's outstanding.



Don't worry, the red color matches another room in my house, so it all flows together.

[ekovalsky]

I don't have any room correction, but you can add me to the list of believers in room treatments.  This week my new wall panels from Acoustics First arrived.  I am amazed at the difference they made.  I put them behind the live end of the room and one at the first reflection point (not visible in the picture below).  

One word: Clear.  Everything sounds so much clearer now.  I notice it especially in the high frequencies and percussion.  Each drum is more distinc ...

I use the Acoustics First products too and they are a great value.  I have three 4' x 6' x 2" Respond panels on the front wall, behind the speakers; two 2' x 6' x 2" Respond panels on each side wall in the speaker-side of the room; and one quarter round 6' Geometrix bass trap in each corner.  These were wrapped in the fabric of my choice and looked quite nice, but not up to highly demanding WAF standards in this house.  So the walls were entirely covered with thick drapery fabric, double the square footage of the walls so they would properly "bunch up" and "puddle"    The fabric stealths the panels and adds some extra high frequency absorption too.

Needless to say the room is now well treated, except for the ceiling which is faux painted drywall.  Floor is carpet over slab.  Next step is room correction a la Tact  

[Jose R.]

As John mentioned, I have a dead-end/live end setup in  a purpose built sound room with a lot of acoustic treatment.  Even so, it seems to be a "difficult" room and before I got the Tact 2.2x, I went through the whole gamut of passive acoustic treatment without being able to sort out my problems.  The RCS was the first unit which made a huge difference.
I would agree with Brian that room treatment is essential but it can only do so much.
I do not listen to vinyl thus cannot comment on the effect of the Tact AD card.  I do however listen to a lot of SACD and DVD-Audio via the analogue inputs and it sounds great.  The benefit of room correction IMHO far outweighs any loss one gets in A to D conversion.  In the HiFi News review of the Tact system a few months ago, Ken Howard (I think) stated that vinyl via the Tact sounded superb.
In addition, using corner based subs (stereo) with the Tact doing the crossovers is a revelation.  I have tried a lot of "big" speakers in my room and all have proved problematic wrt bass boom etc and one then has to try to compomise between bass response and imaging/soundstaging.  All of these speakers have sounded better using the corner based subs with room correction.

Regards

Jose