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DIY Tympani basses?

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Posted on April 23, 2013 at 05:36:03
AkuAnkka
Audiophile

Posts: 167
Joined: February 3, 2013
 Is there something totally different on Tympani IV(a)'s bass units, compared other large Magneplanars? I mean, would it be possible to get IV- like basses by combining bass units from some other older Magneplanar models, such as MG1, MG2. 1.x, 2.x or what ever there are..?

IV's are quite rare anyway.

 

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RE: DIY Tympani basses?, posted on April 23, 2013 at 06:15:31
Roger Gustavsson
Audiophile

Posts: 2055
Location: Huskvarna
Joined: February 12, 2010
 The Tympani-basses are different. The two drivers each side have differnt tuning. One panel use to be without tuning buttons, that is the low bass driver. The second driver has two or three tuning buttons or one button and a strip across the driver (I-D), that is the mid bass driver. Older drivers has Mylar 9"x57". Tympani IV and IVa are different. Low bass is 10.5"x57" and mid bass 9"x57". MG 2.5 and 2.6, are 10"x57" but have double mass wiring compared to Tympani I-D, IV and IVa.

If you can find four bass drivers of the MG 2.5 or 2.6, you could build your own Tympanis. Yes, it would need some experimenting with the tension of the Mylar....

 

RE: DIY Tympani basses?, posted on April 23, 2013 at 18:06:02
john65b
Audiophile

Posts: 326
Location: Chicago
Joined: July 19, 2005
 The T-Id I had did not have the same slam as the T-IVa.

I have had two T-IVa and a single pair of T-Id. I always cruise CL for an inexpensive set that needs refurbishment...they are out there...just gotta dig a bit.
I VOID WARRANTIES

 

RE: DIY Tympani basses?, posted on April 23, 2013 at 22:43:21
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 One of the panels on each side would have to have the buttons taken off. That would be the deep bass panel. The second would retain its buttons and would be the midbass.

I also thought of stacking 3 MMGs sideways on top of each other and taking their buttons off for a deep bass DWM panel to supplement smaller maggies. I thought they would have the tweeter wires hooked in series and paralleled to the bass sections, that would be wired two parallel and one in series. That should provide the bass sections with 3/4 of the current.

 

RE: DIY Tympani basses?, posted on April 24, 2013 at 02:04:41
Roger Gustavsson
Audiophile

Posts: 2055
Location: Huskvarna
Joined: February 12, 2010
 If you use the lighter wiring of the Tympani I-D/IV/IVa on a MG 2.5 or 2.6 bass driver, it is a must to tension the Mylar for a good low frequency response. The curvature of the backplates might need to be changed too.

 

RE: DIY Tympani basses?, posted on June 18, 2013 at 11:58:44
AkuAnkka
Audiophile

Posts: 167
Joined: February 3, 2013
 What actually is the purpose of these "tuning buttons"? Why a driver without any buttons will go lower, and is there any potential risk on removing them?

"One of the panels on each side would have to have the buttons taken off. That would be the deep bass panel. The second would retain its buttons and would be the midbass."
-> Did I understand correctly that there wouldn't be any crossover between the mid- and deep bass drivers anyway? I.e. those buttons would just change their frequency range correspondingly.

 

RE: DIY Tympani basses?, posted on June 18, 2013 at 13:55:41
Roger Gustavsson
Audiophile

Posts: 2055
Location: Huskvarna
Joined: February 12, 2010
 The tuning buttons divide the diaphragm into different zones, each with its own resonant frequency. A large portion of the diaphragm will have more moving mass and therefore a lower resonant frequency.

It is also true that the two bass drivers run together, there is no crossover between them. Sure, the low bass panels could have been cut off at a lower frequency but that is not the case.

Removing the buttons will change the resonant behaviour and the frequency response. There will be a risk that the diaphragm might hit the magnets earlier if the resonant frequency in decreased. The lower the frequency, then larger the peak.

 

RE: DIY Tympani basses?, posted on November 18, 2014 at 12:18:36
AkuAnkka
Audiophile

Posts: 167
Joined: February 3, 2013
 Has ANYONE actually tried removing the buttons from any Maggie model?

And is there anyway to remove buttons in such a manner that they could be inserted back, if things go wrong??

I'm still trying to find IV- basses, but it seems that they are very rare here in Europe... :=(

 

RE: DIY Tympani basses?, posted on November 18, 2014 at 14:12:21
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 I have come across one case where the buttons were removed and put back on with nut and bolt and a spacer instead of the original rivets. Should work ok. But I don't know that for a fact.

T-IVs and T-IVa's are rather rare in Europe since they are so big. Best market to look at is Germany. I would get a complete one rather than just work on finding the bass panels. There is a T-1D for sale by Herr Schmitz. He does maggie repairs in Germany and should be a good contact to find a T-IV or IVa when one comes on the market he would likely know of it first. He is on the maggie user group on FB.

 

RE: DIY Tympani basses?, posted on November 19, 2014 at 10:48:22
Roger Gustavsson
Audiophile

Posts: 2055
Location: Huskvarna
Joined: February 12, 2010
 What do you want to achieve by removing the buttons? I would really like to know how the double sided tape between the Mylar and the magnets can be romved without destroying the Mylar. If you remove a button, you will change the resonant behaviour of the diaphragm.

You can buy some MG 2.5 or 2.6 and replace the Mylar+wiring, re-arrange the buttons and the tension . Then you can come closer to Tympani basses. For sure this will be expensive and a difficult work... You will also need to find two pair of speakers.

Herr Schmitz use to be expensive... There is a strange pair of T-IVa in Great Britain. Not correctly restored but I think they can be corrected.

 

RE: DIY Tympani basses?, posted on November 19, 2014 at 12:41:36
AkuAnkka
Audiophile

Posts: 167
Joined: February 3, 2013
 Well Roger, I would like to achieve best possible planar basses, just like IV's have. But I'm also aware it might be impossible to make such drivers from any other Maggie driver, just as you said.

Darn.

Could someone from USA please send me a pair of IV's via UPS, thank you! ;=)

 

RE: DIY Tympani basses?, posted on November 19, 2014 at 13:18:41
Roger Gustavsson
Audiophile

Posts: 2055
Location: Huskvarna
Joined: February 12, 2010
 There is a pair of IV for sale in the US since quite a while. Shipping to Europe is expensive, by sea is cheaper. Forget UPS, Fedex etc....

 

RE: DIY Tympani basses?, posted on November 19, 2014 at 13:53:21
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 We were talking about converting two pairs of 2.x maggies into one tympani like speaker and we speculate that taking the buttons off one bass panel would get you lower resonance freq.

Btw. the set in uk was looked at by our Davy (uk) and the repair is not reversible. The wires are 2 gauge numbers too heavy and are glued with PVA glue which is not removable. the tweeter foil was cut short and magnets removed. The repair guy is not aware that he destroyed the speaker. He thinks he improved it by making it more sturdy and using "real furniture grade" glue.

 

RE: DIY Tympani basses?, posted on November 19, 2014 at 22:28:58
Roger Gustavsson
Audiophile

Posts: 2055
Location: Huskvarna
Joined: February 12, 2010
 Satie,
Yes, I ment that set in the UK could be restored. I have friends that can replace the Mylar, they can use my T-IVa for checking the tension. Sure, all shipping is expensive even within Europe but far from the cost of shipping them from the US. I know as I did import mine a year ago.

Strange thing about the ribbon drivers. It looks like something from the factory. Maybe they did things like this before going for an external resistor? My Tympani ribbons still have the original wide 3 ohm ribbons. Magnepan went to wide 2 ohm ribbon+series resistor after that. I think the original ribbons were fragile. Since 20-25 yeras or so, they use a narrower 3 ohm ribbon and thicker magnets. The ribbon cage have the same measurments. I asked Sheila at Magnepan if they can supply the original wide 3 ohm ribbons as spares. She had never heard about them...

Best way is to remove the drivers from the baffles and just ship the drivers in a crate.

http://www.forumbilder.se/DEL87/shipping-crate-3.jpg

 

RE: DIY Tympani basses?, posted on November 19, 2014 at 23:30:47
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 The wide 3 ohm tweeters are probably before her time.

I missed your T-IVa import story. Did you post about it?

How did you end up placing it? Did you leave it stock or mod it?

 

RE: DIY Tympani basses?, posted on November 19, 2014 at 23:47:28
Roger Gustavsson
Audiophile

Posts: 2055
Location: Huskvarna
Joined: February 12, 2010
 I had damages in shipping... This is why I recommend crates.

They will be modified. All drivers are out their baffles and will become a single baffle each side, mid/tweeter decoupled from basses. Frame of steel profiles and wood. Low basses touching side walls. Mids have new Mylar and foil conductors. Testing will be done with the original crossovers (internal+external). Goal is biamping with active low pass + low level passive high pass (within the Power amplifier circuits)+ high level mid-to-tweeter. Basses were re-wired by former owner (not very good looking).

When I have this up and working, I will post a story. Right now, I am rebuilding my living/listening room and I will use my 3.6 to begin with.

 

RE: DIY Tympani basses?, posted on November 20, 2014 at 11:12:43
Norman M
 Hi Mr. Gustavsson,
If you have this information, might you please post the mm width sizes of the so called "original wide 3 ohm" and "narrower 3 ohm ribbons". (It also wouldn't hurt to learn about wide 2 ohm ribbon.)

Wouldn't any 'IV-A ribbon' available from Magnepan be identical to that used in the 3.6, and possibly the 3.7(i) as well?

Thanks so much,
Norman

 

RE: DIY Tympani basses?, posted on November 20, 2014 at 22:57:41
Roger Gustavsson
Audiophile

Posts: 2055
Location: Huskvarna
Joined: February 12, 2010
 Norman M,

There are some confusing data on the ribbons. Originally they were 6.35 mm wide (1/4") and 3 ohm. These were replaced by 6.35 mm wide ones with a resistance of 2 ohm. As this raised the level and made it difficult for some power amplifiers, a resistor of 1 ohm had to be inserted. Unfortunatley, the suggested place to install the resistor slightly changed the frequency response of the ribbon driver. I think the reason for the switch from the thinner 3 ohm ribbon to the thicker 2 ohm, was to make the ribbon more reliable. If your 3 ohm ribbons need replacement, you get the 2 ohm with a 1 ohm resistor. The slot between the magnets are about 7 mm wide.

With the MG 3.3 (I think), a narrower ribbon was introduced. It is 4 mm wide (5/32"), 3 ohm and a little longer (60.6" vs. 60"). The mounting of the ribbon is also altered. Thicker magnets are used, the gap is 5 mm wide. This ribbon driver is also used in the 20-series.

The ribbon cages are all 1524 mm long (60") and of the same profile (Davy /UK and I checked), even if you find different numbers in the manuals/brochures. The different mounting of the ribbon need a little bit more space in the baffle.

(There is also a shorter ribbon driver, used in the 2.5 and 2.6. It is 40" long, ribbon is always wide and with a series resistor.)

 

RE: DIY Tympani basses?, posted on November 21, 2014 at 07:49:33
Norman M
 Mr. Gustavsson,
Thank you very much for the information you so kindly provided.

Best regards,
Norman M

 

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