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In Reply to: RE: Going active on Tympani 1Ds posted by neolith on January 16, 2017 at 11:36:20
Neolith,
Thanks for your reply.
Okay I'll answer as best as possible.
Firstly, yes the tympanis sound very good at the bottom end. I've heard a pair of 20.7's and they dont come close to what the 1D's do in that range imo which is to confirm what you have said.
However I have put in a pair of Dayton Audio Reference HO 12 inche subs in mono in the 20-80Hz range and I am sorry but there is no competition there.
So the objective here is to bring in the maggies in from the point onwards.
This is not set in stone as I am going to tinker with cutting the subs off anywhere from 50Hz or even lower to see what the result is.
Dont forget from previous thread that my ID bass panels are like no other in the sense that I did not have them rewired but utilised QR for this. Its the same QR that is used in the 1.7i/20.7i mids. These sound outstanding compared to the intrinsic setup.
You have me absolutely confused about the XO points for the bass panels.
There are 2 bass panels side by side. I believe they start off at 40Hz and are cut off at 1100 at which point the tweeter panel kicks and covers the entire spectrum from 1100 all the way through to 20,000. Is that your understanding as well.
The physical configuration of these panels is that they work as one. There are only 2 leads - one going in and the other one coming out as these panels have been linked in series. Just bear that in mind. When the panels were redone in QR it changed the impedance so EACH bass panel was 4.2 ohms so I had to either link them in series or parallel. Clearly for logistical purposes I went series.
The repairer who did this altered the capacitors and choke on the system to reflect the change in resistance.
So if I read correctly what you are saying how can one bass panel be HP 400Hz? As I said there is a single signal going in at one end feeding the panels which are bridged together to return on the way out. This means that they are working as one unit????
Follow Ups:
Sorry a little slow to get back to you. It looks from the other posts that you are going in the right direction. As far as the crossover @ 1100 Hz, that is between the woofer and mid, not woofer and tweeter. So I believe the crossover points should be 1100hz and ~3000 hz.The mid-bass crossover is 1st order (6 db) and probably symmetric but most of the models with ribbon tweeters use asymmetric 2nd order filters (mid LP and tweeter HP) around 3000 hz.
Certainly a symmetric 6db filter at 3000 would be easiest to implement, but you might want to use the T-IVa values (mid LP 2050, tweeter HP 2650 both 2nd order) which will cross at ~3000 hz.
Just to add to the confusion, the above 2nd order filters have "atypical" Q values of 0.65 (mid LP) and 0.60 (tweeter HP) rather than standard Butterworth (0.71) or Besel (0.58) and this will affect the crossover value. You may be able to dial these in on your mini-DSP but, if not, go with the Bessel.
And finally, watch your polarity. If you go 1st order it really doesn't matter but if you use 2nd order then one of the drivers needs to be inverted.
I married the perfect woman. The downside is everything that goes wrong is my fault.
Edits: 01/17/17
IIRC correctly, the XO is specified in the 1-D manual? I'd stick with Magenpan's spec and agree with Neolith that you should stick with 6 dB/octave, that will help maintain the seamlessness that is one of the 1-D's signature strengths, and also maintain phase coherency.
Agree too with Roger that you should raise the XO of the ribbon, you could overdrive it otherwise. And the ribbon should be as close to the mid as possible to minimize lobing at the XO point.
Really, what I would do since you have the ribbons now is get some Neo 8's and do Satie's Neo 8 mod. That would solve the problem Roger mentioned, that the 1-D's don't image precisely because of the 1100 Hz. crossover. That would be pretty amazing.
Hi mate,
Please give consideration to the following photo.
As you can see I have put the drivers in wooden frames with metal frames for support.
Now have a look at the smaller panel. This is the what used to be the tweeter - now midrange, and the ribbon. The distance between the two is approximately 45mm. This applies to both sides.
Please remember that prior to this the imaging that I was getting BEFORE going active was simply sublime! I cant stress that enough.
I have simply added in the pair of subs in mono and added the ribbon for the higher end.
I dont quite understand the suggestions particularly about the addition of the neo's. Sorry I should rephrase that I can see that there would be benefit however are we not forgetting that I am simply making these speakers into a 3 way from a 2 way. Is it not the case that the Tympani IVas are a 3 way as opposed to the intrinsic 2 way setup of the 1Ds.
Sorry I am a bit lost at the suggestions.
The whole point was to try and go 3 way active. That is to go from the 2 intrinsic 2 way setup and go active with a minidsp running the show.
The frequency response is listed at +/- 3dB from 40 to 20,000Hz.
The internal XO is at 1100Hz with a 6dB octave.
I read that as the TWO bass panels covering the frequency spectrum FROM 40Hz TO 1100Hz where they are cut off and the remaining tweeter driver then dealing with all frequencies above 1100Hz.
Is that how you read it.
I cant see it any other way because as I said the physical configuration is a single wire going into the bass panels which are bridged and then coming back out. There simply cant be - not as I can see it anyhow one bass panel dealing with signals from 40-400 and the other one from say 400-1100.
So lets go with 40Hz as a start point. Everything else underneath that would be covered by the subs.
Would I cut this pair off at 1100 which is the intrinsic XO as stated in the manual?
How would I know what to cut the mid off at and then introduce the ribbons for the HF? I cant go off any manual because the tympanis never had a ribbon so really I would be relying upon what the maggie ranges do when introducing the ribbons. Does that sound reasonable guys.
Nice job with the frames!
Yes, I'd use Magnepan's crossove points as a starting point. That would be 1100 Hz single pole for the woofer/midrange crossoer. The ribbon in my IVa's is crossed over at about 3 kHz with a higher-order XO. I wouldn't cross over lower than what Magnepan recommends to avoid excursions that could shorten the life of the ribbon, *however* if you are using a higher order crossoevr than Magnepan's you can likely lower it a bit.
The Neo-8's are high quality push-pull quasi-ribbon drivers and in a line can be crossed over lower than the 1-D tweeter. I'm not sure how much of a difference it would make in the setup since the 1-D tweeter was also push pull but wire, and you've redone your woofers with foil. So just an idea. If you're getting great imaging, then it sounds like you don't have a problem (I used to have 1-D's and had the same imaging problem Roger has).
Finally, Satie has pushed up the ribbon crosssover frequency on his Tympani IV/Neo-8 combination and crossed them over at 6 dB/octave or IIRC without a low pass on the midrange. But what works for him might not work for you since you're using a different tweeter. It might be worth an experment, though.
Hi mate,
Yes very nice job indeed. Obviously resolves the issue of distance between the midrange and ribbon doesnt it.
Okay did an historical search and found the following:
For 20.7s -
Low-pass (bass): 18dB Butterworth @108Hz
High-pass (midrange/tweeter): 6dB @330Hz
Crossover between midrange and tweeter is
approximately 3000Hz and is non-defeatable.
For 3.6 -
Crossover between bass and midrange is 200Hz
Crossover between midrange and tweeter is 1700Hz
Tympani IVA
Crossover between midrange and tweeter is 3000Hz
Maggie IIIAs
Crossover between midrange and tweeter is 3000Hz
It seems that XO to ribbon at 3000Hz is a fair number to work with.
What do you think based on this history. Highly suggestive that it is.
I'm not sure f the figure for the 3.6 is correct, given the fact that it's so much lower than the other specs. Did you get it off the historical table on this sie? that has some errors in it.
I do remember reading Jim Winey saying years ago that they'd tried running the ribbon at lower frequencies and had settled on the crossover they currently used for reasons of reliability. So I agree that 3000 Hz is a good starting point.
BTW, I've thought of doing what you did with the mid and tweeter in my IVa's. The closer the better an in my house they don't need the wider separation that Magnepan puts in their commercial models to maintain structural strength. But where would I ever find the time! Another project for the future (sigh).
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