Introducing me and my speakers

Hello everybody.
I posted a picture of my diy speakers in another thread.
To not capture the other thread, I will take the chance to say hello, introduce myself and tell a bit about my speakers here.

My name is Michael, I´m reading the diyAudioforum since 2004 but only made a few post. I really appreciate reading from you diy-pople from all over the world. I got some really good impressions from this forum.

I´m living in Dortmund, and I´m 28 young.
I´m totally into diy, mostly turntables, tonarms and speakers for about 6 years now.
I fooled around with some Lencos, my DIY turntable, some transmissionlines, single-driver-horns, frontloaded-conespeaker-horns and now ended up with compressiondrivers.

My latest projects are with the BMS4590 compression drivers (Mid/High coax).
There is a good friend of mine who also wanted to build speakers with the BMS, so we started to take the challenge together.
We learned a lot by comparing the different systems and had a lot of fun, as well as a lot of laphroaig. :rolleyes: :rolleyes:

My current system:
my system - click
Beyma 15LX60 in 130l vented enclosures, made from 40-80mm bended MDF, reinforced with fibreglass.
BMS4590 in elliptical DIY Horns, made from composite of fibreglass and polymeric-stone, wheight approx 35kg, quite dead.
The horns have a calculated f cutoff of roundabout 190Hz (Mouth 70*50cm, 43cm long), crossover with 24dB @ 400Hz. Mid/High crossover after all the really good bms serial crossover.
Bass/Mid crossover managed by DSP System from Sitronik.
The horns are fired by Peter Daniels LM3850 premiumkit , the bassdriver get their energy from SAC Igel.

My new system: (under construction)
the new system
The elliptical horns casted from flowstone + 2*12 midbass drivers per side in casted concrete enclosures + my 2*15LX60 working as subs. crossover sub/bass @ 70Hz, midbass/horns @400Hz

The first experiences with casted stone-horns:
pictures from the first try

The system of my friend:
my friends system
2*18´´ SPH450TC sub,vented, approx 25Hz-70Hz
4*10´´ A&D Audio R1030 in 40l closed from 70-400Hz plus the mentioned horn for the BMS4590.
The horns are composite horns (like mine) now, but will probably be substituted by the casted flowstonehorns.
Also DSP controlled (Lucius by Sitronik).

It has ben a long way, a lot of work but after all it was worth everything.
I´m in love with the systems. They sound very detailed and smooth, nearly fragile with nice femalevoices, really neutral with classical music.
But most fun is putting a good percussive jazz lp on the turntable and set the dsp on -0db.
They beat the sh** out of you and still are smiling.
They seem to say “What ? Is this the end with your ears ? Your kidding, I´m just getting started, I want more voltage…”
They are never getting harsh nor start to scream, no matter what happens.
I think the BMS is real bargain, it´s amazing, what you get for your money.
I´ve listened to commercial horn speakers like Avantgarde, Odeon and Cessaro at some acquaintances.
I think, my friend an me don´t have to bother…. :D

Best regards, Michael
Very inspiring for me your search for the optimum horn system!
I said that as a horn lover. Now, I'm dreaming of a cast stone mid horn with coaxial-compresion and a midbass strait like B.Edgar's 80Hz...

Michael, have you any feedback concerning new B&C coaxial compression driver DCX50? Beside BMS and B&C I didn't find any else manufacturing coaxial compression drivers.


2004-08-02 10:04 pm

I don't want to be offtopic but maybe this kind of information could help someone. One memeber of this forum posted a comparison between a modified BMS driver and crossover kit from BD-design (the same used in the new Oris horns) and the Radian PB950. He was clearly enjoing the Radian driver more than the coaxial and he even thought that a supertweeter is not needed. The tractix horns he used with the drivers where designed by him.

Pictures are here . You can see on that gallery a method of building horns.

Beside BMS and B&C I didn't find any else manufacturing coaxial compression drivers.
That are the only ones I´ve heard of, too.

Michael, have you any feedback concerning new B&C coaxial compression driver DCX50?

Unfortunately not, but I´m interested in that, too.

I'm dreaming of a cast stone mid horn with coaxial-compresion

So you have similar plans like me.

I´m in love with my caststone-horns. Eliminating any sound of material is a good way for me.

Where do you get the material, and how do you make the mold?

Material is ordered from construction material dealer (I´m construction engineer, my friend has it´s own building company )
Unfortunately it´s difficult to get it in small charges. They all want to deliver cement, fibres and additives for tons of horns. :bigeyes:

I constructed the horn in CAD, made layers of 10mm and with that the inner flare was built. From first blank casting of the flare
we made a complete prototype-horn from fibreglass and plaster
and out of that we built a fibreglassmold which consists of 3 parts (one inner and to outer parts).

very creative volume control.
:D thanks

I´ve also heard a lot of good reputations on the radian.
Seems interesting.
But I´ll have to finish some projects before thinking on further ones.
(restoration of my 1940s lathe, the concrete bassdesign with the midbass and subbass, amps for that, etc.)
"Beside" all that we are building a house this year.
And my better half is complaining, she only sees me when I´m coming in from the workshop to to go to bed in the evening. :smash: :xeye:
Hi Carl.
Perhaps it is inapropriate to answer in this thread and we should start a new one.

Absolutely not inapropriate, I started this thread to exchange experiences.

We pour special cement into our mold.
The procedure is the same as with normal cement.
But the blend is very sensitive, we´re still experimenting.
Ingrdients (percentage still vary):
white cement (high resistance, pressure about 100N/mm², tension without reinforcement 15N/mm²), sand, water, deaerate-additive, flow-additive, pigment if you wish to.

The base of my TT is of this black-pigmented concrete:

It´s not behaving like common concrete, less resonating, smooth (if the mold is), very rigid.

You can google for concrete-furniture.
Most of the manufacturers use similar cement/concrete.

It can be polished like natural stone, but it´s as difficult as with the natural stone, cause these concretes get very firm.
There is also another way for cast-stone.
In germany they call it polymeric-concrete.
It consists of resin, crushed rocks, sand or other surcharges.
I reinforced some of the blank-flares with 20kg of this
Very good material for horns in my opinion.
But not healthy to work with (casting, sanding etc.).
There is a guy in germany, who makes very nice and good sounding small horns of this polymeric-concrete:

As far as I know, David Haigners horns are made of a polymeric concrete, too.
further improvements

hi all

a customer from BD-design, which i exchanged emails, said the new Orphean horns perform much better than the version, i had. Here his words :

The first versions flawed regarding phase and did not have the mechanical mod implemented. The mechanical mod's were introduced 1/2 a year ago together with the one piston filter. Beside the new magnificant filter, which takes the standard BMS to an incredible high level, the mechanical mod is about the switch beteween 2nd and 3rd harmonics when you crank it up tp high amplitudes = No horn shout.

i never heard the MKII. However, the differerence between the BMS and the Radian was really substantive in my system, after the first comparative session, i sold the Orpheans.

after listening for some time the Radian 950pb with a jbl 2405 slot above 10khz, i bought a Coral H100 tweeter. The performance of the whole system improved dramatically. The best result i am getting , not lowpass the Radian, highpass the Coral at 10khz/6db, and reduce the output with a autotrafo. I tried lowpass the Radian at 10khz, but integration was not so good.

The result i have now, is the best until now. I cross the Radian too low, since the active bass amp does not drive the bass higher than 300hz/24db. So i highpass the Radian at 300hz/12db in the 49cm diameter horn, tractrix flare. Some music, like drum , or brass, is really impressive, with astounding dinamics, and no beaming , but open, detailled , sweet sound. However, voices have horn coloration , that can be clearly heard.

This week i got a big wood lathe ready, and will start making MDF horns up to 1m diameter. First i will turn a horn with 65cm diameters for a friend, and next will be a big midbass horn, with 88cm diameter, which will be driven with Fane Studio 8M. But i will try out other drivers, like B & C 8" er. It will work between 150hz and 800hz. For the Radian i pretend making a Mid Horn with LeCleac'h flare, to work above 800hz. This should resolve the problem of horn coloration.

As more i listen with the Beyma 15" LX60 Bass, more i like it. Very fast and dry, and going enough deep, no subwoofer needed. Michael probably will agree with me. Magnetar has mentioned the qualities of the JBL 2226h. The Beyma LX series are a copy of this woofer. Extremely low distortion.

I like the way, Michael placed the woofer, at some distance from the floor. This is something, i do not like so much in my first design. The low frequencies reflect too much on the floor, the bass gets directional. I think the best would be making a row, with > 4 woofers, to get a homogenous load in the room of these frequencies.
Hi Carl.

Do you mean the mold for the concrete or the very first mold for the fibreglass-flare ?

This are all the steps in shortform:

- plot cross-sections of every 10mm of the CAD-flare-model
- draw the cross-sections on 10mm wood
- cut the wood and glue it
- after a lot of sanding and modelling with plastic, this inner flair is ready to get a paintjob

like this one for my round horns:

- polish and wax the inner mold
- make fibreglass-castings of this inner mold – you get a thin (5mm) horn without flange and curves at the hornmouth
- take this thin model, glue a bigger elliptical piece of wood to the mouth, make the curves and reinforce it properly, glue a flange on it

(we made 4 horns this way, measured it, took some weeks to listen to it and decided, that those horns were worth the further steps….

- Take another raw flare, glue sticks with desired thickness of the lateron horn all over it , get everything smooth with plaster, make a flange on the lathe an glue it to the blank and modify everything for an easy casting (roundings etc.).
- Again a lot of sanding and filling and again a paintjob
- Now we have a 1:1 prototype of the later cast-stone horns
- Make a dividing-plane from throat to mouth and another one round the mouth, laminate half of the outer part of the horn with fibreglass (1st part of the mold)
- After 1 day, remove the dividing plane from throat to mouth (the 1st part remains at the blank) and laminate the other half of the outer side (this gives the 2nd part of the mold)
- The next day, remove the dividing plane round the mouth (part 1 and 2 remain) and laminate the inner part of the horn

In the end you have a 3-part-mold, which is very sealed, no concrete gets to the outside.

I hope, this can be understood, some technical terms are hard to describe for me in english.
Unfortunately I don´t have pictures of all steps.

It´s similar to my inner-mold for the round horns, but the sanding for the elliptical mold has been done by hand.

Neither a CNC was available, nor such a big lathe with a “elliptical-gearbox” (don´t know the word in english).
To construct such a gearbox and a big lathe would have been impossible for us, cause relation between bigger and smaller radius of the horn varies (1:1 at the throat = circle, 1:1.5 at the mouth).
Besides that, to rotate such a heavy mold on a excentric chuck is very hard to handle.

Best Regards, Michael
Wow Michael,

Making a mold is a lot of hard work but it looks like the results are worth it! Congratulations.

I may try my hand at casting a more traditional radial horn. Are there limits as to how thick of a layer you can pour? In other words could I cast something 3 inches thick at it's deepest dimension in one pour or do I have to limit each pour to a lesser thickness and build up to the 3 inch depth? I know with some plastic pour systems you are limited due to its thermal qualities.

Best Regards,
Carl Huff
Hi Carl.

I know with some plastic pour systems you are limited due to its thermal qualities.

Yes, the resin must not get to warm/hot (exothermic).
For the polymeric-concrete I cooled down the sand and crushed rocks beforemixing it wiht the resin.
I tried to make a mixture with as least resin as necessary, so I got much cooling stone with not so much heating resin.
Anyhow, you could feel the warmth with the hands on the inner flare.
So I cooled it with water from the outside.
The walls of this pouring were about 3 inch thick.