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Question for Satie

63.233.220.133
Posted on August 24, 2016 at 05:03:06
pwicca@cybermesa.com
Audiophile

Posts: 69
Location: Santa Fe
Joined: February 9, 2006
 Would appreciate it if you would describe how you measured the distances to your Magnepans/Tympanis to establish the arc from your listening position. More specifically did you measure from the the center of each panel or from the edges to the listening position. I have been trying to follow the guidelines in Jim Smiths book and am finding it very difficult to figure out where on the panels to measure from and how to measure such that each measurement is from a point that is perpendicular to the panel.I am trying to create an arc with a 3,7 and two bass panels from Tympani IIIa. Hope my question makes sense to you.Thanks in advance for any help you can provide. Joe Fagan

 

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That sounds like an intriguing combination!, posted on August 24, 2016 at 07:31:10
E-Stat
Audiophile

Posts: 37673
Joined: May 12, 2000
Contributor
  Since: April 5, 2002
 I am trying to create an arc with a 3,7 and two bass panels from Tympani IIIa.

I still have fond memories of hearing tri-amped T-IIIs back in '74. :)

 

Why not, posted on August 24, 2016 at 10:22:02
M3 lover
Audiophile

Posts: 6605
Location: SW Mich
Joined: May 29, 2005
Contributor
  Since: July 4, 2007
 post your question to Jim Smith? Are you aware he once worked for Magnepan/ARC and wrote the manual for the Tympani's?

"The secret of life is honesty and fair dealing, if you can fake that you've got it made." Groucho

 

RE: Why not, posted on August 24, 2016 at 10:48:09
pwicca@cybermesa.com
Audiophile

Posts: 69
Location: Santa Fe
Joined: February 9, 2006
 M3lover: I have posed the question to Jim Smith as these issues regarding Magnepans/Tympanis are not covered in his book Get Better Sound even though he previously worked at Magnepan. Presently I am waiting for his response.However, I am also interested in how Satie performed his measurements. Thanks for the suggestion. Joe Fagan

 

RE: Question for Satie, posted on August 24, 2016 at 12:08:09
Roger Gustavsson
Audiophile

Posts: 2058
Location: Huskvarna
Joined: February 12, 2010
 Which panels from the Tympani IIIA? There are four panels in IIIA, two are low bass and two are mid bass. These are connected in series. Time alignment at low frequences is really not very critical. Top, center and bottom of the driver will never be time aligned. The crossover also modifies the time alignment.

 

RE: Question for Satie, posted on August 24, 2016 at 13:08:19
neolith
Audiophile

Posts: 4842
Location: Virginia
Joined: February 21, 2002
Contributor
  Since: December 2, 2004
 You sound like me, a little too pedantic and sweating details that really aren't important. You can pick your poison, measure from the center of the speaker or the ends -- it will not matter because the final tuning is done with your ears. You may find using Room Equalizer Wizard which is available for free helpful. You will need a calibrated microphone and either a DAC or sound card.
I use a Behringer UCA-202 ($30) which is surprisingly good and UMM-6 (from PartsExpress) which is now about $80. Another cheaper alternative is to get a IMM-6 mic which works with an iPhone and use the built-in sound card of your computer and a free app. I haven't done that but it might be good enough for government work.



"Our head is round in order to allow our thoughts to change direction." Francis Picabia

 

RE: Question for Satie, posted on August 24, 2016 at 13:17:46
pwicca@cybermesa.com
Audiophile

Posts: 69
Location: Santa Fe
Joined: February 9, 2006
 Thank you for your interest. I have the IIIA a mid bass panel and the low bass panel to the outside of each 3.7. Not sure about the XO issue. I have the IIIA. bass panels connected to a Marchand XM9 with a 24 db XO set at 90 Hz. as per you very helpful suggestion some time ago. Unfortunately I have not been able to implement your other suggestion for rolling off the bass from the 3.7s. My concern about the method to measure distance from a panel speaker was primarily for the 3.7s.. Presently I have tried attaching a 6" block of wood to a small laser distance finder so that I could get a perpendicular distance reading from the 3.7 ( ribbon and woofer ) to my listening position. Not sure where to aim the laser beam for the ribbon and then for the woofer panel. Right now I have each 3.7 ribbon 10'6" from a place just to the side of my head. With this orientation of the 3.7s the lateral portion of the woofer panel is 10' 1" and points to a place 10" from the side of my head. Jim Smiths book indicates that the placement of the non-panel speaker is based on the tweeter but that doesn't seem to make sense to me with Magnepans. but maybe I don't understand the issues involved. I would appreciate you guidance. Joe Fagan

 

RE: Question for Satie, posted on August 24, 2016 at 14:08:39
pwicca@cybermesa.com
Audiophile

Posts: 69
Location: Santa Fe
Joined: February 9, 2006
 Sadly your character description is not very different from mine. But in my defense in Jim Smiths book he notes that an error of only 2" over 12 feet can cause problems. As I went through his reference CD for setting up systems ( Tears of Stone by Chieftains ) I found issues which he credits to error in speaker placement. Would like to see if more accurate speaker placement would resolve some of the issues. Joe Fagan

 

RE: Question for Satie, posted on August 24, 2016 at 19:11:23
neolith
Audiophile

Posts: 4842
Location: Virginia
Joined: February 21, 2002
Contributor
  Since: December 2, 2004
 No doubt slight errors in position can make substantial changes in the results. My point is that precise measurements with a tape ruler or laser ruler (been there, done that) will not get the results you want -- it's a starting pont. You need to fine tune with your ears and REW. Remember no room that humans live in is perfectly symmetric.
Give yourself some time -- 2 or 3 years is probably a good guideline :).



"Our head is round in order to allow our thoughts to change direction." Francis Picabia

 

If you *really* want to get serious ..., posted on August 24, 2016 at 21:12:04
andyr
Manufacturer

Posts: 12551
Location: Melbourne
Joined: September 2, 2000
 I suggest you buy a laser distance measuring device and a tripod. :-)) I bought a Bosch unbit.

And you measure to the centre of the bass panel.


Andy

 

RE: That sounds like an intriguing combination!, posted on August 25, 2016 at 03:56:11
rosendds@frontiernet.net
Audiophile

Posts: 599
Location: North East
Joined: November 13, 2010
 Please post Jim's Maggie set up tips here.

 

RE: If you *really* want to get serious ..., posted on August 25, 2016 at 04:12:03
pwicca@cybermesa.com
Audiophile

Posts: 69
Location: Santa Fe
Joined: February 9, 2006
 Thanks for the suggestion. I have been using a Bosch Laser Distance Finder and it is much better than my old tape measure. Have a tripod but have not found it easy to use. Reason for my questions is that I am trying to replicate the procedures outlined in Jim Smiths Get Better Sound. He recommends measuring to the tweeter for speakers in general and is less specific about Magnepan type speakers. As an example on his reference CD he points out a chime which should be localized behind the the right speaker. When I listened to the chime on my system it was located in the center of the two speakers. He noted that this was most likely due to the left speaker being slightly closer to the listener than the right. More specifically he noted that a difference as little as 1 to 2 inches over 12 feet could cause the position of the chime to move from behind the right speaker to the center of the two speakers. Given the number of installations that Smith has managed over the years I take his findings seriously and wonder if I am not measuring the distance from my listening position to the 3.7s correctly

 

RE: That sounds like an intriguing combination!, posted on August 25, 2016 at 07:24:42
pwicca@cybermesa.com
Audiophile

Posts: 69
Location: Santa Fe
Joined: February 9, 2006
 Good question. Wish I had a good answer. Jim's book is a comprehensive look at all aspects influencing the reproduction of music. He emphasizes making the distance from speakers tweeter to listeners ears exactly the same for both speakers. Primary assumption through out book is that the recommendations are for speakers with tweeter and mid/woofer being in vertical relationship. He recognizes that there are differences when the tweeter and the mid/woofer drivers are arranged horizontally as with Magnepans but does not address those issues. My question was and is how do I measure the distance from the Magnepan tweeter and midrange panel to my listening position. If I measure perpendicularly from tweeter and midrange panel they will never converge at my listening position. Do I disregard the midrange measurement? Do I compromise and split the difference between the tweeter and midrange such that each is on opposite side of my head but the same distance? I just wanted to replicate Jim's set up but can't seem to get to first base. Joe Fagan

 

RE: Question for Satie, posted on August 25, 2016 at 13:17:19
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 First of all. you have to eventually use REW or another program to check your results. The result should be a straight impulse response. The audible performance should be a wide and deep soundstage with well defined images with the images located in stable locations when they are immobile and track the slight or major changes when the are not (chamber music recordings often capture the swaying violin as the violinist sways and cyclically moves the center of the violin's output towards and away from the mic. Heifet does that on purpose to change the volume and tone of his instrument on the recording according to his interpretation, at times to the consternation of his engineers at RCA or DG who set him up differently from one take to the next even within the same piece going from one part to the next)

I use a tape measure because the laser can't compensate for the fabric offset from the driver, which is not really stable. The tape measure's loose end is sown to the center top of my recliner with about 20 loops of thread loosely enough so that the tab at the end does not get caught on the fabric.

I measure to the distances to the centers of each driver and compensate for the distance to the diaphragm from the contact point. I don't know what it would be for the 3.7 models and it depends on whether you have diaphragm front or magnet board up.

The panels are arranged perpendicularly to the tape measure by either using a T square or L square (I use the latter) and use the edges on the bass panels measuring the same distance (to each edge) since they are symmetrical relative to the center of the driver (should measure closer or the same than the edges).

I use a 3 way bubble level to straighten out the drivers to dead vertical and straight horizontal before doing the distance measurements.

I go for a 1/8" precision in the equidistant setup ( at this point I check for symmetry with a mono recording sarah vaughn or billie holiday with band or orchestra) and then fine tune the tweeter angle for the images to snap together and group images to separate out into components like cymbals on a drum set in a 1958 jazz recording. Or the violin section revealing individuation of the violins (only on older three or two mic recordings). The position of the 4 pianos in the Bach concerto is also very useful, as is the individuation of brass and reeds in big band recordings made in 2 or 3mic ballroom studio recordings..

Sorry I missed that yesterday. Hope this helps

 

RE: Question for Satie, posted on August 25, 2016 at 23:02:56
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 Crossing over from the bass panels to the 3.7 should be 1st order symmetrical in order for the equidistant setup to work. A good starting point is 100 hz and you can go down from there, the proper freq will probably end up being about 80 hz. The measurement to the center of the 3.7 bass panel should align with the bass panels. The other drivers should be aligned to the 3.7 bass by ear with the T3 bass panels not playing but placed near the 3.7 roughly where you intend to place them. The mids and highs are not crossed over symmetrically and you can not get them to align in the equidistant arc, since they are on the same plane as the bass on the 3.7. So first thing is to get the 3.7 aligned properly as a stand alone speaker and that will determine the exact locations for the T3 bass panels.

If you want to, you can easily do the crossover passive at line level as it would be just a single cap + optional resistor for the high pass and a cap and a resistor for the low pass. The high pass cap value will depend on your top amp's input impedance and the low pass will just depend on the freq unless your preamp has a high output impedance (tube preamp for example) in which case you would need to calculate for that. You can add a level adjustment pot on the 3.7 high pass filter before the cap - assuming it is more sensitive than the T3 and the amp gains are both close to standard. You can easily get these figures from the manufacturer spec sheets.

I suggest you don't use the LR4 Marchand at all. If you want to do equidistant and can't wait for the 1st order parts to arrive and to build the filters then use both the high and low outputs of the crossover to the top and bottom amps respectively so that the drivers can be both electrically and physically aligned. The phase change on the 3.7 bass panel may bother you, if it does, you definitely will be better off with a 1st order.

 

RE: Question for Satie, posted on August 26, 2016 at 05:23:13
pwicca@cybermesa.com
Audiophile

Posts: 69
Location: Santa Fe
Joined: February 9, 2006
 Thanks for your two posts. Reading your recommendations is always a humbling experience. Unfortunately the amp for the IIIA bass panels is a 1000 W4S amp which is much less sensitive than the Bryston 7BST that I use for the 3.7s. Both are mono blocks. Don't think that I could use a passive XO for either amp as my preamp is auto former based and as such the output impedance changes with the level of the passive preamp. Given this I can try to use my existing 24db XM9 and see if the phase issues you noted is audible. If so I will ask Marchand to either send me two circuit boards set up for 6 db which I could put in my existing XM9. If that is not possible I could get a XM9 set up for 6db. Appreciate your description of your methods of setting up your Magnepans. Your method seems to make a lot of sense. One question. Why not measure the IIIA bass panels in the center of each panel? Thanks again Joe Fagan

 

RE: Question for Satie, posted on August 26, 2016 at 05:28:34
pwicca@cybermesa.com
Audiophile

Posts: 69
Location: Santa Fe
Joined: February 9, 2006
 Yesterday Jim Smith sent me an email and generously offered a telephonic discussion of my questions about how to apply his method of measuring speaker distances with Magnepans. I am looking forward to the chance to speak with him. Joe Fagan

 

RE: Question for Satie, posted on August 26, 2016 at 06:20:02
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 "Why not measure the IIIA bass panels in the center of each panel? "

Obviously didn't come out clearly, You DO measure to the centers of the Tympani panels The 3.7 you are adding to them you are coordinating the bass panel outputs with the T3 panels so you are measuring to those bass panels too.
Where you don't adjust that way is with the mid and tweeter on the 3.7.

Just to be sure that we aren't talking across each other you are using a 3.7 and augmenting the bass with the bass panels from a T3a, Tell me if I got it wrong.

 

RE: Question for Satie, posted on August 26, 2016 at 10:39:15
pwicca@cybermesa.com
Audiophile

Posts: 69
Location: Santa Fe
Joined: February 9, 2006
 You have it right. Have been running the 3.7 full range and augmenting with the IIIA bass panels crossed over at 90 Hz 24 db. Bass response measured well but only with a RS SLM.

Probably will be better with a first order XO for both the 3.7 and the IIIA bass panels. Marchand can replace the 24 db circuit boards with boards for a 6db XO. Thanks again for your help. Joe Fagan

 

RE: Question for Satie, posted on August 26, 2016 at 10:53:14
Roger Gustavsson
Audiophile

Posts: 2058
Location: Huskvarna
Joined: February 12, 2010
 First order low pass on Tympani IIIA basses? I doubt it is a good idea, they are high mass drivers not doing that well over 150-200 Hz. A steeper cut-off will leave out the "problematic" high frequences.

 

RE: Question for Satie, posted on August 26, 2016 at 15:09:20
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 The issue is that the LR4 as part of a band pass on the 3.7 bass makes for 2 octaves of phase changes which would be ok on an earlier high order maggie but would make a difference in the coherence of the 3.7. The main point for him is whether he likes the one over the other, since the replacement cards for the XM9 are not expensive and he can try it out both ways.

In my case the TIV bass is far slower than the Neo8 mids so there is a slight degree of congestion that I didn't love in the 250-500 hz range with 1st order symmetrical but the problem with LR4 is that the entire 2 octaves around the XO lose their time coherence and sound phasey. Detail is more prominent and the bass panel's contribution of congestion, however small was gone. But the harmonic structure is disrupted and the time alignment is hurt and takes away from the really great imaging performance and instrumental texture. The latter was more important to me than the sort of disconnected detail you get with the LR4 symmetrical.

I think that at the 80'ish hz XO the heavy bass wire and membrane are not going to be so much of a problem even at 150 hz since the output would be down 8db.

 

RE: Question for Satie, posted on August 26, 2016 at 16:38:01
rosendds@frontiernet.net
Audiophile

Posts: 599
Location: North East
Joined: November 13, 2010
 After I located my seating position and distance from the 1.7's,I ran tape lines from the center of the sofa to the distance the speakers would be.I used a straight edge to track along the low pile carpet to make a straight line impression in the carpet that I could see,there by marking the speaker distance line.After setting the speakers the same distance from the side walls and positioned on the line impression in the carpet,I toed them in.I used a angle gauge to toe them in at the same angle.The line impression on the carpet allowed me to use the angle gauge.Having the center marked is good way to be sure that the speakers are equally spaced at the center seating position. I hope that helps your set up.

Dave

 

RE: Question for Satie, posted on August 26, 2016 at 18:44:50
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 I think that is a good idea, but I would still confirm with a mono recording that all drivers are positioned well and the tonal balance is even. If it can't be made to even out just by positioning then you need to start loading the sidewalls with "stuff" to even out the two sides. I am a firm believer in furniture and "junk" as room treatments.

 

RE: Question for Satie, posted on August 27, 2016 at 05:01:34
rosendds@frontiernet.net
Audiophile

Posts: 599
Location: North East
Joined: November 13, 2010
 I forgot about the mono listening test.I believe that you advised me to do it and it is a good idea. Best wishes,

Dave

 

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