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In Reply to: RE: Absolutely! ... posted by Satie on September 07, 2016 at 06:42:37
Hi Satie,
In answer to some of your questions -
If you look carefully in the photo you will notice that the ribbon is placed in the same channel that the original wire occupied. It goes along the same track so the spacing will be slightly narrower given that the the QR is wider physically. Where there were originally double runs are single runs. If you have a look at a TID bass panel it should be self evident as to why that is the case.
In terms of sonics take what I say with a grain of salt because my filter, that is my ears will be different to yours. However I can see the response thus far from colleagues of mine has been very noticeable.
It needs to be pointed out that I had the opportunity to listen to a fresh pair of rewired Tympanis and then listened to mine the following day. The response from the repairer was that I would not need a sub woofer. Now we all know that a sub has its place but what the repairer was alluding to was the fact that the bass response was jumped out at you. It was chalk and cheese. It is so much tighter, faster with a lot lot more slam. As an example I put some music on and spoke to a friend on the phone. I put the phone on speaker and played a small section where a bass element kicks in and even he could detect kick in the response. This is a terrible way of listening to music but it shows under such conditions what someone else could detect.
At the minute the system is 2 way. The true ribbon is there and will be used to make it 3 way in an active system controlled by an 8 x 8 minidsp. This means then that the existing tweeter will be the midrange. I am still learning about frequency ranges so I can't answer your question about 1st order. The repairer double the size of the inductor coil and also included a bank of capacitors totalling 34.1 uf to account for the resistance change.
Would you like me to post additional photos particularly of the ribbon layout?
Let me say this. I had an opportunity to choose between this and panels which were done in wire. I would challenge anyone to listen to my system with the QR and choose the original wire. It was a no brainer. This was an experiment by the repairer who had been the principal repairer of Maggie's in Australia for many many years. He had had it in his mind to try something like this and I guess I was the lucky recipient. I would have no issue whatsoever in leaving the panels as is without the true ribbon. If there is a suggestion that doing this should in theory result in a poorer sonic response then to my mind it doesn't translate into physical reality. Just my opinion of course.
Cheers Ozzie
Follow Ups:
Still, this modification is not a straight comparsion between round and flat wire!I am not surpriced that the sound of the basses changed, a move towards a lower register as this would be normal as you increase the moving mass. The original I-D is not the very best midrange performer, that is why the IIIB with its separate midrange driver was introduced. Your modified basses are probably good up to about a few hundred Hz but not all the way up to the tweeter. The tweeter is not very suited to go that low.
I have a set of Tympani IIIA. They have an even heavier copper wiring and the magnetic structure is indentical to the I-D. They measure flat up to 4 kHz but it does not sound that way.
The mass of the bass wiring is:
I-D: 19 g
QR-modified I-D: 24 g
IIIA: 82 g
at Bolder Bob:
QR is the Magneplanar type of driver with a flat wire (foil) instead of the normal round wire. The flat wire i this case is the same as used in the 3.7/3.7i. It measures 0.075" x 0.005". If you go that path, the crossover need to be modified as well.
Satie wrote: "How much of a free mylar strip do you have left to act as suspension?"
Sure the foil conductors cover a larger area than the round wire - there will be less uncovered Mylar than can strech. The Mylar is 9" wide. The round wire covers about 0.54" of the Mylar versus the foil 1.95". I think the foil will limit the maximum bass SPL quite in bit versus round wire.
Edits: 09/07/16
Roger,
You said:
"Still, this modification is not a straight comparsion between round and flat wire!"
I dont know what you mean by this. We had an established reference point to make a comparison against.
Let me explain a little. The repairer is a chap who has been the principal repairer of Magnepans here in Australia for a very long time. He is formerly in retirement but greatly assists the new repairer. He has a pair of Tympani 1Ds himself. Both his panels and mine were repaired in FULL - that is they were completely rewired - tweeter panels as well which is something that Magnepan do NOT do. Magnepan do NOT rewire the tweeter panel. They simply replace it. The bass panels they will rewire.
Upon completion I had an opportunity to listen to both sets of speakers. It was a no brainer. Without going into too much detail but the repairer wanted to keep my speakers with the QR. He didnt. I have no hesitation in saying that they are a step above the intrinsic set up. And on a complete level. So to my mind it is a fair comparison. Its comparing one set up with another to determine efficacy. I did not was not compelled to choose one over the other. It was completely my choice. I chose the QR variant. If you havent listened to 1Ds with this modification then you are speculating as to what you may think the result will be. I would urge anyone out there to undertake this type mod and then see for yourself.
Yesterday I went into a noted hifi specialist store and listened to a pair of $40k B&W speakers to get an idea of where my speakers are at. I left feeling very satisfied with what I have. I understand the principal of confirmation bias and I get that we are all attached to our speakers on some level but I know I have a good set of speakers. I get what it means to be a maggie owner.
Please note that I also have a pair of MMGs, MGMC1s and IIIAs. Does that get me in the club :)
Ozzie
And another
Great looking set of Tympani!!
What is the black material at the ends of the foil runs? It almost looks like tar.
Left channel. As you can see the true ribbon on the very outer edge with the existing tweeter.
Ozzie: "Please note that I also have a pair of MMGs, MGMC1s and IIIAs. Does that get me in the club"
Yes! I have only three sets... Tympani IIIA (modified, in storage), Tympani IVa (modified, in storage) and MG-3.6 (biamp via an active crossover).
Another photo
Well, I think you have quite a heroic bracing effort. The driver frames are supported by steel slats from the back? And the wood is backed by steel beams and that goes into the back struts and big feet. That may have more to do with the increased performance than the QR - which Roger is right to question regarding resolution into the midrange/ However, when you get the DSP running you can compensate by lowering the XO to the md/tweet and use a steep slope.
You are far more into the club than I am. The T IV are my first and only maggies, I just went for what I wanted when I could afford to and had the space. But my mids are not maggie mids so I am standing with one foot out of the club, though the BG Neo8 are planar .and in a line source fitting into the midrange slot on the TIV
Satie,
You can attribute whatever increases in performance to the designer Peter Keenan who worked on both the wooden frames AND the metal stands. What I like about the stands is that there is no welding. It's all bolted together. If you want to make the stands wider for whatever reason to accommodate bigger Maggie's then you simply get a longer cross brace. That's it. The drivers are fixed directly onto the wooden frames. The metal uprights then fix to the wooden frames. It is extremely solid in design. The length of the stands at the base is only 450 mm. They can easily go down to 350 mm in my opinion. I can position a 100mm masking tape at the back of the base to tilt the entire system forward and the speaker holds down. No issue.
My intention was to go even further than this. I am hoping to rewire the existing tweeter, again in QR with foil from what you would find on the 20.7 mid. That was supposed to happen but ideological differences crept in. I will keep everyone posted as to whether this takes place or not. As I understand it there were no changes to 1st order frequencies.
Ozzie
Ozzie wrote: "My intention was to go even further than this. I am hoping to rewire the existing tweeter, again in QR with foil from what you would find on the 20.7 mid."
The foil used in the mids of the 20.7 is too wide (0.0005"x0.1") to be a direct replacement for the round wire in the Tympani I-D tweeters. In your case with a ribbon tweeter, it might be a step in the right direction as, in theory, it shifts the original tweeter into a slightly lower register (8 ohm=Tympani I-C and Tympani IIIA). I am using that foil in my T-IVa mids. You could also think about the use of thinner Mylar for your tweeter rebuild.
Roger,
I just want to reiterate that I was not in a position to confirm either way whether that foil at that dimension was not only a good physical fit but translated into good music. I am hoping that in the next couple of months I can come back and report on this.
I believe the black stuff at the top of the panels is certainly NOT tar but another type of glue to prevent delamination. I will try and get this information for you all. It feels quite "rubbery". Its something that the repairer has been using for a while to great effect. It is not standard to the repair.
Ozzie
Roger,
You are correct in the sizing. You are however not correct that it is too wide. It can be done and was done. The only issue was that working with it was problematic.- it kept breaking. The only reason why the job wasnt completed was due to circumstances that I don't really want to get into at this stage. To be fair we didn't get to the point to be able to test for efficacy.
You are quite correct about Mylar thickness. We were heading down that route but the repairer was short on Mylar. One of the channels had to have the mylar replaced due to damage. Magnepan do NOT provide Mylar the customers for purchase. It would have meant sourcing it from elsewhere which we could have. However, again and frustratingly so, ego got in the way and the work didn't go in the direction I had hoped for. But yes the repairer did comment that thinner Mylar would have been a good direction to head into. At the time he didn't want to create a disparity between the two. It's also a pain in the ass to replace. Magnepan won't repair tweeter panels on the 1Ds. They replace them. In fact they strongly advise you even attempting to remove the driver. I did. Luckily I had no issues. It's all about getting the correct tensioning of the Mylar which without proper setup is not easy. Luckily the repairer was willing to have a go and it worked.
I would have still liked to have at least tried t see what the result would have been like. But at no stage did the repairer think that size of the ribbon would be prohibitive. It was worth a shot and still so.
Cheers Ozzie
Well, it is not too wide to use but it will give a different impedance /resistance. The I-D tweeter is originally about 4.8 Ohm. With the smallest size foil Magnepan can offer, you will have about 7.4 Ohm, you loose about 2 dB and the mass is higher. Yes, this foil easily breaks but it is still doable. My T-IVa uses more of this than any tweeter.
I have been workning on my Tympani IIIA tweeters. Replacing the Mylar with a thinner one, cutting down the width of the driver in order to place it closer to the midrange driver etc. The driver is 20 cm wide but the diaphragm is just 6 cm. I ended with 10 cm wide drivers. I still did not like the very closed sheet metal in front of the driver. There is just about 11% of open area.
Roger,
That figure of 7.4 ohms that you state - is that something that you have measured yourself using that specified foil size for the T1D tweeter?
Cheers Ozzie
I have that foil on my Tympani IVa mids. It has the same cross sectional area as a round wire with AWG 32, 0.032 mm2, or 0.85 Ohm/m. In the Tympani tweeter there is 8.8 m, about 7.5 Ohm in total. That is what the earlier tweeters, before the I-D had.
30 years ago, that is before Magnepan started to use foil conductors, I cut 10 m long strips of foil, 1.5x0.018 mm. Wanted to use it for modifying my Tympani tweeters. Also had 6µm Mylar. Never finished the project as I wanted a more open area in front of the diaphragm.
Hi Roger,
Thanks for that. Okay you have convinced me that I should pursue this further and perhaps do the relaying on the existing tweeter with the foil. Bear in mind that with the addition of the version 2 true ribbon the old tweeter would be my new mid range.
cheers Ozzie
Thanks Ozzie for the fine detail. Very useful. Just a day out of cataract surgery so can't give the pic any more careful attention for the time being, but I am sure others would appreciate them,
I have no trouble believing that the flat wire would provide better tighter deeper response and cleaner response because it creates a better damped diaphragm and a stiffer moving surface so is more pistonic. It is also consistent with results reported by others for 3 series speakers. So another winner for the flat wire.
For the ribbon integration I would try first skipping the DSP altogether and joining the ribbon tweeter in with a first order filter like the ET LFT 8 at somewhere between 10 and 15khz - probably easier to do at speaker level with just one series cap with the ribbon and the circuit in parallel with the wire tweeter - if your amp can handle really low impedance loads (2'ish ohms) at lowish power. Do not use a low pass on the original wire tweeter and just play it as high as it will go. That way you can maintain identical polarities on the wire tweeter and the ribbon supertweeter. I absolutely love that alignment. Also used by some Apogee models to great effect
I would be very curious to see how this compares with your DSP when you implement it.
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