More horn madness

[peterbrorsson]

Playing around with wide banders in my HM4750SLF, I used Visaton FRS5X for a long time. I have now tested Monacor SPX-20M and it's excellent for home use. The Monacor have better output in treble and "feels" more detailed.

Anyone able to make a 3d printed phaseplug, it would be even better!

Green is Visaton, yellow Monacor

 

[Pano]

Hey Peter. Interesting. These little full range drivers are woefully inefficient. Does that matter to you, or is the Selenium horn adding some efficiency?

 

[peterbrorsson]

I do not consider these as inefficient for home use. 90db around 7Khz is enough for me, I have to knock them down with a low q -13db with peak at 900Hz. They don't break a sweat playing loud, the Visaton AL170 gives up first

X-over is at 360ish, haven't got dip deep enough yet. I have also SB65WBAC25-4 to play with, but these are a bit too low although excellent drivers. However maybe not in these horns...

MONACOR: SPX-20M

 

[Pano]

Thanks. Seems that you are getting some gain from the horn. I certainly hope that Monacor is better than the Vistaton - at 6X the price!

 

[peterbrorsson]

Thanks. Seems that you are getting some gain from the horn. I certainly hope that Monacor is better than the Vistaton - at 6X the price!

It's 4x in Europe, I got them for under 40Euro's. Quality of gluing and metal work was a positive surprise for me

 

[Pano]

Excellent!
And that's a good price.

 

[ErikdeBest]

Looks nice indeed, I am becoming curious about horns/waveguides and widerange/fullrange drivers, so all info is welcome!

you said xover is at 360Hz?

 

[peterbrorsson]

Yes 360ish, any attempt to x higher make problems with speech intelligibility.
I don't know if it is because too close proximity of divider in the BIB enclosures. Btw, these monsters are closed boxes now, couldn't stand them as "horns"

Anyone willing to take on a phase plug drawing? The wiggles up high are really not detectable, I compare with my Genelec's! Should though be interesting to find out if there's any audible improvement...

 

[AllenB]

Anyone willing to take on a phase plug drawing?

Do you have more details on the horn, maybe top and side projections and the driver?

 

[peterbrorsson]

Allen, the horn is questionable as the precision of work is made with an axe.
Of course it's fixable with some epoxy and some grinding, the driver is though measurable, I will see if I can pull out one of them tomorrow, it's sounds quite good right now, despite the warts)

 

[peterbrorsson]

X-over now as seen, in screen shot. The Monacor is not extending as low as Visaton driver. Due to lower q??

 

[peterbrorsson]

Managed to get rid most of the dip in the mids, a bit more delay on the bass driver and moving the center of the PEQ upwards makes it look better and voices seems to be clearer.

 

[AllenB]

Allen, the horn is questionable as the precision of work is made with an axe.

Maybe it's ok.

I'm thinking the outer of the cone will be 1/2" from the outer of the throat, and the middle of the cone may be a similar distance back. It appears to function past 12kHz. May be some standing waves. Polars might tell.

 

[peterbrorsson]

The distance to edge is around 5-6mm from half of surround and cone depth around 4-5mm. Haven't pulled them out yet.

I measured only in roughly 45 degrees, pretty much identical response at 60cm distance.

However the Monacors are trickier to get the x-over sound ok. Tinkering will continue...

 

[peterbrorsson]

These curves aren't for the weak hearted. These are settings for the last posted measurement. I first eq the drivers as flat as possible, then started play with x-overs

The x for highs is set at 400Hz, driver + horn starts to fall at 450Hz. With a 24 db Butterworth, I get a small boost under 400Hz straightening out the response a bit.

The bass x is set at 288Hz, with the rising response and non-optimal box this works excellent. The driver is also delayed 34cm, to be honest, I can't hear any difference going from 18cm and up. However, the dip after reversing one driver gets deeper with 34cm.

I can switch between my Genelecs and these easily, the horns are more detailed and have less room interaction. But the 40 degree angle is a bit irritating when walking around. 80x55 would maybe be optimal...

 

[AllenB]

These curves aren't for the weak hearted.

They don't seem to look unusual.

I can't hear any difference going from 18cm and up. However, the dip after reversing one driver gets deeper with 34cm.

Yes, combing tends to be sharp on the bottom but gradual on top. 18cm is within the threshhold, what you say is plausible.

when walking around.

The directivity plots give some limited clues.

 

[peterbrorsson]

They don't seem to look unusual.

Allen, it depends on the dogma of viewer

 

[peterbrorsson]

I discovered today when walking past speakers, sound changed slightly between them. Checking the x on both speakers, left one have 10db deeper dip when reversed. With an offset, the x slightly lower fixed the dip, now it is quite ok walking around. Driver tolerances?

Now to something else,

YouTube

 

[peterbrorsson]

Well, I'm going to continue my monolog I'm not going to post any measurements anymore. When measurements are not posted, all kinds of creatures shout for it, when posting...null, zip, zero and nadamente!

I know measurements are tricky to interpret in room as I've done. But I have no option and it seems to function quite good. I'm happy with result so far.

Now I want to raise a question. I cross the horn now at 300Hz to a 170mm midbass, this is not ideal according to theory. However, I can't hear any negative purely subjectively speaking as well as any horn issues. Can it be that the directivity doesn't have any impact in the low midrange. It would be interesting to hear Earl Geddes point of view as he claims it doesn't matter under 800Hz or so, I can't remember exactly...

I have a nagging feeling that some of the theories claimed on forums are a bit superfluous and pedantic

 

[Pano]

There are a lot of "How many angels can dance on the head of a pin" type arguments on the forums. It's often easier than actually building something. You might find that audio is more tolerant than the arguments would lead you to believe.