Mpl

I have the cardiode woofers working with the 38cm Eminence woofers. After a lot of adjustments to my little Reckhorn crossover it sounds very good now. Maybe not as fast as my M-dipoles but with a very interesting rendering of the deep bass. The M - dipoles are very clean and tight and very even in tonality. The cardiode on the other hand definedly has a change in tonal colour when the tones get into the deepest octave. I do not know how to say it better but it sounds ripe and fruty there.
 
I have now build the slim version of the MPL. I think it looks much better then the wide baffle versions. I take care of the baffle step by blending in a second Enviee in the deeper midrange. That worked very well in the Mini MPL.
 

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Here is the bass response, the impedance curve and the FRD from 0°, 30° and 60° of the Bass-Midrange without crossover. For a 30cm driver i think the response is very extended, flat and has a low amount of beaming. The BBC slot may help..
 

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Great looking. What's inside the horn?

For some time I was wondering if there has been any progress going on with your open baffle/full range speakers.

I think it's a good idea to use another driver with narrower baffle. Do you still use whizzer version of upper full ranger? And if so do you still don't see any reason to add some front firing tweeter?

How does the rear firing tweeter sound when it comes to sound impressions, does it kind of feel similar to adding front firing tweeter?

I'm just about to start something new. For quite long time I have been using Fostex full range 20cm driver and Aurum Cantus G2si tweeter on top with just 2uF series cap (Siemens MKV PIO). I'm using fostex with series resistor/coil filter loosing few db and have it in 70 litres bass reflex box with Aurum cantus L-padded.

I have been planning to upgrade on this. My idea is in general to stay with full range driver. Right now I'm thinking of something like this:

1. Some two 15" OB bass drivers 12" Tone Tubby + some Lowther + some ribbon on top.

The Lowther would probably be second hand A series unit and I would low pass it at some point allowing the ribbon to get in earlier.

2. Also thinking of Beyma TPL-150 used with Tone Tubby or something similar and some OB bass drivers.

3. I was also thinking of some Onken style cabinet with Altec 416 with some horn on top of it although I have very little expirence at these kind of speakers.

In general I want the system to play loud and uncompressed with a big scale and large sound. i'm tired of small sound most full rangers do solo. i'm also tired of thin not extended bass and shy highs. I can secrefise the coherence of full range driver to get a really full range sound. I think I'm also tired of whizzer sound (at least of what I think is the whizzer but might be some other kind of coloration).

I was interested in the full range driver you designed Joahim but it is a little too expensive for me at this point. Although I feel it is one of very few drivers that can be used 3 ways only (or 3,5 ways) giving still exeptional results. I dont see a chance the Lowther to be used in 3 way system. Another I would go for would be PHY -HP, but these are complately out of my reach.

Please let me know how your system is evolving. How is the work on bass augumentation and if you really think you do not need the front firing tweeter?

Best regards

Bartek
 
Wolfs Dipole Horn uses 2 x 38cm Fieldcoil woofers. One only works in the bass so compensates for the loss in bass from the open dipole. The treble is a 75mm beryllium dome in a compression driver with horn. Sorry, i can not disclose any more details about the crossover. I can only tell you that this was hard work to get playing. The sound now is the least coloured of any horn i heard and in a big enough room ( at least 40qm ) it sets up a decent soundstage, free from the speakers. The most attractive for me is the midrange. It has tremendous substance and resolution. The voices are just standing there in front of you.
Concerning my MPL i found nirvana with the MPL slim. I started with widerange plus ribbon treble too but the Enviee wizzer sounds simple much more from "one piece" if you know what i mean. And that is not only tonally but also in terms of space, focus and soundstage. It simply sounds more real. With the equalization i use i do not miss any treble extension or resolution. That may have to do with the linear step response or time domain behavior if you wish to call it that way. Other say linear phase, phase coherence, linear group delay etc. I think many details in most speakers are lost because of all pass terms that swallow detail or add falls detail. Sound coming from one point in time and space sound more natural and easy on the ear in my experience. So i do not need a front tweeter and i do not want a front tweeter. When i switch on the G-Pole tweeter the sound gets more open, transparent and spacious without any loss of focus, at least to my ears. One listener ( Ward Maas ) found it more diffuse when the tweeter was switched on but that was an exception and more time before the MPL slim would convince him other wise maybe. Sitting close before speakers like that needs praxis anyway. People that visit me more often get more and more accustomed anyway and have trouble afterwards to listen to their highly resonant boxes. The back firing tweeter also gives you some control over tonal balance so a loss of treble on axis can be partly compensated by raising the volume of the back firing tweeter. Think of it : a life performance is quite similar with a lot of diffuse treble energy. As concerns more affordable widerange drivers i recommend the SEAS prestige over everything else. You really have to go up to the SEAS exotic or the Enviee to better that. Lowthers are simply to coloured for me but i heard that Nelson Pass got them working somehow.
 
I spend a fascinating evening on my system. the last days i had being working hard on my digital sound. I am using now an EUFL ESS9022 board an i have designed a filter-buffer to get rid of a small artifice i heard. The filter is now done but i could not find the right combination of harmonic extension and speed plus full tone and fleshed out images.
It dawned on my to the fist time that the resolution of my MPLs in the utmost treble was a tiny bit to gross. That never happened when i listened to vinyl but my setup is not shy in treble. In any MC cartridge a compromise has to be struck in the treble and the ones that are flat there ( over 10 kHz, that is ) have problems with tracking and dynamics because the moving system has to be damped more then is optimum for free movement of the cantilever-suspension system. Also there is more opportunity for tuning in a vinyl based system. A digital system is more rigid but also more accurate in terms of tonal balance. Do not misunderstand me, a CD player can sound thin and threadbare but this is not because of the mathematical incorrectness of digital per se. That has more to do with implementation like clocking, PSU and analog stage to name a few problem zones.
The sound of my CD system is spot on but there was this tiny bit of air missing or when i advanced the treble a small but audible tendency to sound artificial. I solved that problem now with integrating a super tweeter into the MPL. I will tell you more soon.
It is exiting to listen too BECAUSE it sounds so natural.
 
Here is a picture of the MPL with Mundorf super tweeter. I blend it in softly over 10kHz.
The minus 3dB point is even higher when i trust the simulation. Level is correct so i did not have to pad the Mundorf down. Crossover is very critical though and in the beginning i crossed too low. Resolution was spectacular but i lost a bit of a "one cloth" sound. Some treble energy came from too close from the baffles. I got i working though. Now the sound has much better resolution and air but the sound picture and not broken into separate pieces. What is really interesting is that musical instruments are now more easy to differentiate. That may be because of the overtones are better resolved. I checked the tonal balance with vinyl too and it is just fine. I am very satisfied and exited that i can still improve the MPL.
 

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I have now set up the MPL slim in my room. It sounds even more spacious then the 1.2m wide version. It is also arranged as a G-Pole with a back firing tweeter.

Here is a picture of the MPL with Mundorf super tweeter. I blend it in softly over 10kHz. ... I am very satisfied and exited that i can still improve the MPL.
What I can't see from the picture: Is the Mundorf added to the G-Pole or does it supersede the G-Pole version?

Rudolf
 
After around two years of continuos work i have decided on the final circuit for the crossover. This is a bit unusual because i normally do not need more then one day to design a crossover for a world class speaker. This may surprise you but when you have an
exact target modern computing does the job real fast. The MPL needed more time out of several reasons. One is that i changed the concept from 1,2 meter wide baffle to 0,6m wide baffle. The other is that i first worked with a wideband driver without wizzer plus horn ribbon tweeter, that was the famous Allen Wright Memorial Edition. It sounded very good too but ultimately i found it too ugly to look at. I have them still in stock so whenever Johanna wants to listen to them i can set them up. Third i added the G.Pole tweeters and forth i added the Mundorf Super Tweeters. Also the Enviee drivers went through a fine tuning phase and i had to check if the crossover constructed for one generation fits into the next. The work on the Enviee is done and surprisingly the crossover has not changed much. What took also some time is to adjust the G.Pole tweeter in level, response and phase. This and adjusting the super tweeter i did mostly by ear using simulation only as inspiration. Yes, i forgot : i listened a lot and did not measure much. That is an exercise for a mature speaker maker and reminds me of the good old times where we listened to music and not test signals. Mind you, the speakers measure great but the drive units are pretty decent to begin with. I had build the various crossovers mainly with parts from my junk yard so it was time to make something more professional. I did that the last days and have now mounted the very compact build into the MPLs. See a photo. The sound changed for the better but in a very supple way. Somehow it sounds more tidy and clean. Treble is more extended, midrange better resolved and bass is tighter and faster. Also the right channel balances better with the left. I always have to advance the right channel in volume a bit because my room acoustics are not totally symmetric by design to improve the bass and make the room more useful. I need less push on the right channel now and that makes the sound picture more symmetric. The higher resolution comes with a price. I heard more flaws in the recordings. I have my Titan i now run in well and i wanted to fine tune the cartridge setup anyway. To get more body into the sound i raised the down pressure somewhat and compensated the VTA accordingly. First i overdid it a bit but i found a good middle ground that sounds richer without loosing the resolution. I think i got the tonal balance back to neutral but the sound is better fleshed out like before but with a higher information content. I am satisfied and i await even better sound ones the xover boards have run in.
 

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I got a major boost i sound quality in my system today by just placing my MPL Slim Panels more optimally in my listening room. I am working at the same time on a second set of speakers with field coil drivers, the Sommerwind.
I had placed the Sommerwind behind the MPL Slims, so i can take away the panels and listen to the Sommerwind. That placed the MPL Slims very close to my listening seat and blocks part of the back radiation. I had already found that listening as far away from the panels as i can improved the soundstage but then i sit smack at the back wall.
Taking away the Sommerwind allowed me to place the MPL Slim some 15cm further away and i am sitting now maybe 10cm from the back wall. They radiate to the back now without blocking. The resulting sound is extraordinary. Much smoother and spacious without loss of focus. Wider, higher, deeper and more sweet without loss of detail or dynamics. Not so well recorded material sounds less hard and better resolved. Classical
sounds awesome. I can play now also old material from the 50th and 60th on Decca, EMI, DG, RCA, Mercury without listening fatigue where before was a slight and penetrating hardness. Violins, horns and percussion sound wonderful, so do voices and choirs. The sound is more balanced and better separated the same time. Tonal color of instruments are much more easy to differentiate, for example open against stuffed trumpet. The bass got better too because i sit somewhat less close to the back wall. I could advance the volume of my subs by some 1 - 2dB without any boomy-ness. So i have more bass in total, that is faster and cleaner. This is so far the best sound i got in this room. I am planing now to layout a floor plan that i will publish on my MPL thread for later reference. I really unlooked the magic of my room and that after living ten years in this building.
 
I am planning to build a loudspeaker that complements my MPP. I have build a preamp and Brianco is doing a poweramp so in the next month a system will be made of Phonoamp, Preamp, Poweramp and Speaker for DIY.
The speaker is based on a wideband unit in a baffle.
Under 80 Hz it will be complimented by a dipol woofer and over 7kHz there will be a horn loaded Ribbon.
The wideband driver got developped over a period of one year.
It has a classical paper cone and Alnico magnet.
I got the finished samples some days ago and did some measurements.
The driver is designed for very low distortion.
It is under 0.5% up to 100dB in 1m second harmonic. Thirs id under 0.1%.
Today i will post some measurements.
The driver is in a 90cm by 125cm baffle placed asymmetric due to golden cut.
I will pulish photos and drawings later.
Impedance is 6 Ohm Re and sensitivity is 96dB for 1W/ 1m.

Can you kindly point me to the post where the drawings (with dimentions and BOM) are given?
 
This is the diffuse field curve i try to implement.

Joachim, this is very interesting. Did you succeed with the implementation of it exactly according to the curve? Did you apply it only to rear driver or the whole speaker?

Please correct me - are authors suggesting to apply this attenuation curve to any diffuse sound field? Which actually would include almost any "normal", partially reflective room..

Also I can't get how to read the graph "the right way". Attenuation means "weakening", so positive values in curve must mean more attenuation, so level correction curve for diffuse sound field must be inverse to the shown. Is that so?

I remember Linkwitz write something like his Orions had to be reequalized 0.5 dB down at 4kHz after they were brought from open air into room and his surprise how dramatic was difference towards sounding "just right".
 
gannaji, i will post a photo of my current baffles and then we can talk.
PRTG, i will publish some more work on the diffuse EQ in Linear Audio 5 so i can not disclose all the details right now. What i found with dipoles is that the diffuse sound they add has usually too little presence, so in my G-Pole principle i BOOST the presence range. I found that it is not super critical to get the exact Zwicker curve. A simple soft dome with enough sensitivity does the trick just fine with a ca. 2uF cap. I will post what tweeter i use. Also is important to destroy the impulse response to the back while keeping the diffuse field FRD. That can be done with mechanical delay, simply mounting the tweeter some 10cm back and playing around with absolute phase on that tweeter.
 
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