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In Reply to: RE: Looks great, and multiple pictures... posted by grantv on May 29, 2017 at 06:56:07
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I have been there now. What you see is the MG 20.7 with a set of Tympani Bass Speakers in the middle. It is the Bass Speakers that came with the Tympani III, serialnumbers are 062763-1/2
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The Bass Speakers are fed via a LAB.Group IPD 1200 poweramp/crossover. The crossover is set to 50 Hz, 24 dB/octave, both LowPass and HighPass. The 20.7 is amplified by a pair of Lamm model M2.2.
Preamp is an Audio Research Reference 5SE and the CD-player/DAC is an Audio Research CD9. Turntable is a Rega RP10 incl. cartridge and RIAA.
The room is about 4x7, ceiling is partly slanted. Behind the listenning position ceiling height is normal at 2.4 m and flat. There are quite a few acoustic treatments in the room, mainly from Svanå but also from Sounds of Silence. Originally the room housed a pair of conventional speakers, I think it were the Response Grand, http://matsaudio.se/node/10. Those speakers did not suit the room very well, mainly bass problems and Matts of Svanå Miljö Teknik (www.diffusor.com) adviced my friend to try some Magnepan dipol speakers.
He started with the MG 3.7 and later switched to the 20.7. Not that many sold over here...- Switch to Magnepan also ment a change of the orignal acoustic treament. There are not that many diffusors in there any more but still quite a few. You can see them behind the speakers, two transperent diffusors beside the speakers and maybe five about 2 m behind the listening position. Some damping panels have been added.
(Why is that picture not up-right?)
I had my usual CD with me, a collection of different types of music. The 20.7 stands rather close to each other with tweeters in, unlike my own 3.6 more separeted with tweeters out. Initially, it sounded similar to my own 3.6 (active crossover and biamped) but with a bit more control. I changed my listening position, more forward and got a bit wider sound stage more like my own system. I asked my friend to increase the level of the Bass Speakers (remeber below 50 Hz) as I found the overall tonal balance on the anemic side. Remember, he was lacking power below 50 Hz with the 20.7 alone.
My friend has noted a rattling/buzzing from the Bass Speakers, at least from one or two of its four bass drivers. Sure, with some loud bass this could be heard. The Bass Speakers have some awful looking greenish cloth, we cut it open to see what the drivers look like. I was expecting wire peeling as my own Bass Speakers (not in use) have it. Surprise, wires perfectly held in place! Unfortunatley, some spots of the Mylar had damages. Maybe from manufacture (mine have them too) or from overloading the drivers.
As only one channel of drivers (two in each stereo channel) had these damages, I think it is from manufacture. Very disappointing... These drivers also have the hated wooden crossbars the make rewiring impossible. My younger Bass Speakers do not have the wooden crossbars and can be re-wired.
As we continued listening, everything sounded fine except for loud low frequency passages that slapped the Mylar against the magnets.
Back home, I had to run my CD...- Sure, there are some differences. My room/system seems to deliver most of my friends setup/room. I was expecting less extended bass from my setup but it is not that clear. My setup has a little more pronounced bass but not as controlled as the 20.7/Bass Speaker. Sound stage is wider at my place but there is no hole in the center either. My system is not as laid back/polite sounding and cannot play that loud without loosing control/comfort.
Although there are differences between the 3- and 20-series, in the end it seem to be up to the combination of speaker/room/setup - as so frequent.
Now, my friend and I, will try to cure his Bass Speakers. I do not expect Magnepan will help us but they certainly know how to correctly tension the Mylar but as they do not use the copper wiring anymore, it will be different drivers. At best, they will convert them to I-D basses. Using the drivers still working fine as references will not help as they are brooken in after +40 years of use. I can read the resonant frequences on my own bass drivers and they have lowered a lot, from 46 Hz at the date of manufacture to 34 Hz.
Any comments?
Follow Ups:
I almost bought the 20.7s but I ended up with the Martin Logan CLXs because my friend is a Martin Logan dealer.The panels in the middle look like my old Tympani 4As which I still miss in certain ways.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
Michael...
Did you like the CLX better than the 20.7s? Or was it a good deal? I find the 20.7 to have a better lower-mid than the logan ... My opinion of course.... I have had logans for about 13 years or so.....
Also,from my demo of the 20s - I just don't know if I would need additional bass.... room dependent for sure ... but getting ready to pull the trigger on some 20s....
Timm
I got my CLXs from the insurance when a small water pipe ruptured in my basement and sprayed my old Monolth 2s. It didn't touch my two ML Descent subs but anyway,I got the CLXs because I like ESLS and I was already setup for them.I could have got the 20.7s for much less however,the store wrote all the stuff up and they were ML dealers plus I ended up with a nice chunk of change having replacement cost.
You are right and the bass is better on the 20.7s.I use the subs so I'm good but I would love the 20.7s as well.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
Oh nice!! My stuff is going in the basement soon. I have no idea what my insurance would cover or if there is a limit on electronics etc. I would have got the CLX too!! :)
I ended up getting 48k with CLXs total.I got the CLXs at 20% off so they were a little over 20k and they didn't want old Monoliths or the IMF SACMs so I fixed them as only the midrange cabinet on one got wet. I had a pair of AR3s that were completly destroyed tho and they gave me 1800 for those.
I never had a claim in the 30 years I have been with them.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
That's what I call makin lemonade!!!
I think you have a problem with loud deep bass because the bass panels ate
1. too close to the front wall - so you are getting cancellation from early reflections.
2. The panels are not straight facing nor time aligned to obtain in phase reinforcement so you have a comb filtering problem that is preventing you from obtaining the best deep bass. The upside is that you are getting more uniform bass.
3. If you are using the high pass on the mains you are losing the bass panel reinforcement effects from having both the T III and 20.7 panels playing the same frequencies. However, even if you do have that wired so that the mains and bass play together, you still need to get them in phase so that you do not get a suckout near the crossover freq. So use the crossover in the bass amp to get that right - it should have a phase or time delay setting you can adjust, and you can place the bass panels more forwards to obtain better phase alignment.
4. The T III bass panels need to sit on sturdy feet and have a crossbrace going from the 1/3 point up the speaker to the back of the feet. Mye stands would do it but that is a big shipping cost. you can build wood and steel feet and put in a brace. In my case I could brace to the wall and it adds 6 db to max output below 50hz. Without the bracing the piano bass notes become anemic and the concert grand piano sounds like a baby grand.
5. If you have tears stretches and holes in the mylar you can use a packaging tape to seal them. Call magnepan and ask which brands or substrate and adhesive materials they suggest.
6. baffle and wall loading placement to reinforce bass. To really get what your friend is looking for in bass reinforcement for the 20.7 you need to place the TIII panels between the 20.7 and the wall forming a line or arc with the 20.7 panel from the sidewalls into the room. As a preliminary attempt you can place one set of TIII basses between the outside edge of the 20.7 and the sidewall with a concave V - keep the speakers in their precise current location, and just squeeze in the bass panels in the gap to the sidewall so that the deep bass panels are at the sidewalls and roughly equidistant to the rest of the speaker (use a tape measure to obtain equal distance from each driver center to the listening seat for each TIII and 20.7 bass panel.
@ DrChaos:
Well, the Tympani Bass Speakers go lower than the DWM. The 20.7 on their own does not deliver as much bass as wanted in this particular room. The Tympani Bass Speakers fill in nicely what is missing. Just a pity they have damages.
@Satie:
1. It is not my impression. I think it is also a matter of having the panels angled in relation to the wall.
2. Time alignment from panel-to-panel is not a problem at these frequences, below 50 Hz.
3. Yes but you need a complex crossover to just fill in below 50 Hz.
4. When folded, they are stable.
5. The damaged Mylar has lost its correct tension in the spots where the Mylar is mended with tape. I do not see any easy way to correct it. Magnepan has already been contacted, waiting for advice.
6. Wall loading helps but the room is a bit narrow. It has also been proposed by the distributor (since the very first Tympani!).
Main focus is on rebuilding the Bass Speakers!
1. It still makes a difference if you leave more room to the front wall. The angled drivers in this close to the wall setup are a benefit.
2. Without the time or phase adjustment to get phase alignment the LR4 crossover can leave a big hole.
3. You don't need a complex XO for bass augmentation just a good phase adjustment and placement (time alignment) to match up with the -180 deg phase of the bass at the XO freq. so that there is no cancellation at the listening seat. A simple Rane 22 will have a delay/phase adjustment on the low pass section. You just need to get the phase difference to go -90 deg to +90 between bass and mains Instead of -180 to 0. If you want a smoother transition you can do a symmetrical 1st order and add the LR4 crossover about half to one whole octave above.
4. Not enough to get the most bass output out of them. The difference is substantial with rigid bracing.
6. Do a preliminary trial with rough placement to just see how it works out and whether it is acceptable space wise.
The DWM's would be the modern replacement for the bass panels. But the 20.7 might be able to run nearly full range.
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