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In Reply to: RE: Going active on Tympani 1Ds posted by Roger Gustavsson on January 17, 2017 at 22:47:07
Roger,
Did some experimenting last night. Will start to plot some more graphs from REW.
I tried 500 for the mid and it just didnt sound good at all so went back to 1100.
I then tried 2200 for the ribbon and found it was a bit bright which was especially noticeable when it came to females singing at a higher pitch. It also sound tinny. It just didnt sound good.
When I bumped it up to 3000 it was a lot lot better. I am still getting a drop off from 10k onwards.
There are a lot of things one can play with on the minidsp plugin especially with the PEQ.
Follow Ups:
So when you lowered the XO to 500 hz the mid sounded strained and distorted or was it something else?
Satie very much so mate. Did not sound good at all.
I played around a bit and set the XO at 1200 for the mid.
For the ribbon I set it at 4000.
I didnt do any listening at these levels but rather relied upon REW and graph reproduction.
This is by far the most level graph I could get.
XO points are accompanied by 36 L/R.
I tried Bessel, 12db, 24db, 48dB and the "best" graph was with this configuration.
Could I get it smoother? Who knows. But the sound was quite pleasing.
Very clear and very revealing compared to before. Disregard sub 80Hz.
So you ended up with 36db LR as the final choice (for now)? at 1.2 and 4khz?
Results look very good. See if the Bessel sounds better or worse than the LR at the same order. The Bessel should give a less phasey sound - which either does or doesn't matter to you.
Did you run impulse response?
Okay this is the latest graph.
A big big difference from previous testing.
We identified a critical issue which was the ribbon falling down badly.
As a thought we decided to swap out the Quasimodo on the ribbon with the Plinius 8200 which has a lot of muscle.
Surprise surprise it resolved a big issue in that region. Put simply the Quasimodo wasnt dealing with a 3 ohm load
as well as the Plinius.
Whilst its not a perfect representation its certainly far better than where I was at before.
And it sounds damn good as well.
Changed from 36dB to Bessel. Much better outcome. Adjusted the gain in the line levelling and the result got better.
Didn't expect the amp to have that much of a problem driving the tweeter, though the Bryston 4B NRB I used on it for a while ran hot. Calsse DR 9 - closer design to the Plinius - did well and was just a bit warm.
Results look even better now. Did you run the Bessel filter at 6th order as before with the LR filter or did you lower the order?
Anyway, glad you like it.
Satie,
Look I spent many many hours trying every conceivable option I could muster to resolve that issue with the ribbon BUT the reality is it was falling away. Thats clear and unambiguous as indicated by the graphs I was getting.
When I swapped the amp out it made the difference you can see right now.
I am now convinced that I could do even better and across the board with a bit more grunt which clearly maggies are renowned for wanting.
I'm sorry I cant answer your question about Bessel filtering.
Are you familiar with the mindisp plugin? It gives you the option of what you want and all I sighted was 12,24,36,48 L/R and Bessel. How do I run Bessel at 6th order? Or is that assumed when you click onto it??
Appreciate the suggestions. They have helped.
XO for mid was 1200 and ribbons 4000. That seemed to get the best graph.
And trust me I tried every variant in between.
Bot expressing doubt or criticism on the amp/tweeter match just being surprised by the extent of the mismatch you had.
I am not familiar with the miniDSP interface, so from what you said I understand that their Bessel alignment option is for a single order option, I would guess 4th order but that is just a guess.
If you want more "grunt" what amplification is your baseline from which you want to upgrade? Any particular candidates in mind?
Satie,
In answer to your question I was using a custom built an amp called the Quasimodo.
Its rated at 40watts into 8 ohms and about 75 into 4.
It works really well but as we all know maggies need a tonne of power.
Bessel appears as a single order position on minidsp plugin.
I think I can get more out of the midrange with an amp with more muscle as well.
Low end is working quite well.
At the moment the system sounds better to my ears than before.
I have just levelled and adjusted the 2 Dayton Audio 12" drivers into mono. It has made a huge difference at the bottom end.
I have them cutoff at 80Hz but obviously I can play around with this.
My advice to anyone who wants to go active with maggies needs to start with a clear page and try everything. I did. Despite all the advice I was getting in the end that didnt translate to positive audible experiences and the graph reproduction was evidenced of that.
I ended up cutting the bass off at 1200 and then cut off the mids at 4000.
I tried every setting from 2000 to 5000. I tried everything from 12dB to 48dB and different variants in between.
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