First trials of active horn speaker

[Robh3606]

Hello Duke

Thanks!! Yes magnesium and JBL used in their synthesis line up. Figure a souped up 2450SL. The waveguides are readily available as are 2216nd and 2216nd-1s, do a search lots of goodies!

https://reconingspeakers.com/

 

[Duke LeJeune]

Hello Duke

Thanks!! Yes magnesium and JBL used in their synthesis line up. Figure a souped up 2450SL. The waveguides are readily available as are 2216nd and 2216nd-1s, do a search lots of goodies!

https://reconingspeakers.com/

Wow, VERY cool!!

I had no idea Speaker Exchange carried so much cutting-edge stuff. Looks like they have not only the waveguide for the M2, but also the woofer and a dual-diaphragm compression driver, though I think it's not quite the same one.

I had figured M2 parts were unobtainium. Wonder why more DIYers don't take advantage... or maybe they do.

 

[morricab]

Wow, VERY cool!!

I had no idea Speaker Exchange carried so much cutting-edge stuff. Looks like they have not only the waveguide for the M2, but also the woofer and a dual-diaphragm compression driver, though I think it's not quite the same one.

I had figured M2 parts were unobtainium. Wonder why more DIYers don't take advantage... or maybe they do.

Might not be such any easy waveguide/horn to implement as JBL uses DSP with it.

Also, I think Rob’s choice of CD is better than this dual diaphragm rebadged BMS CD.

 

[Robh3606]

Might not be such any easy waveguide/horn to implement as JBL uses DSP with it.

Hello morricab

That is simply not the case. Most of the high Q DSP is all used for the 2430 driver. You can take any of the 2450 family of JBL drivers and get a good passive network that gives you a smooth and extended response on the waveguide. Your best bet would be using the smooth Ti coated diaphragm drivers like a 2450SL. What you are looking for are the SL diaphragms. They are the best Ti versions to use. Much smoother up top than the un-coated ribbed versions.

Here is a base schematic for a passive compensation network that works very well with the M2. Just take away the protection capacitor and drop a high pass in front of it. You can also easily add stepped attenuation by adding a parallel resistor @ R7. This is what the attenuation looks like in my M2 network.

Rob

 

[morricab]

Hello morricab

That is simply not the case. Most of the high Q DSP is all used for the 2430 driver. You can take any of the 2450 family of JBL drivers and get a good passive network that gives you a smooth and extended response on the waveguide. Your best bet would be using the smooth Ti coated diaphragm drivers like a 2450SL. What you are looking for are the SL diaphragms. They are the best Ti versions to use. Much smoother up top than the un-coated ribbed versions.

Here is a base schematic for a passive compensation network that works very well with the M2. Just take away the protection capacitor and drop a high pass in front of it. You can also easily add stepped attenuation by adding a parallel resistor @ R7. This is what the attenuation looks like in my M2 network.

Rob

Ah, so it is more the driver than the waveguide...makes sense.

 

[morricab]

Yes, the CP385-Nd has a Mylar diaphragm (or some type of polymer diaphragm). I didn't catch that yours is the Ti version; didn't realize they made one.

In my R&D phase I went through something like nineteen compression drivers before the CP385-Nd. It was recommended to me by Al at US Speaker.

I've probably sold more home audio speakers with the CP385-Nd than all others combined.

https://usspeaker.com/beyma CP350Ti-1.htm

Just FYI

 

[morricab]

new drivers are here!!

 

[Audiophile Bill]

new drivers are here!! View attachment 67559 View attachment 67560

When is the install Brad? Look forward to comments.

 

[Robh3606]

Great when you hooking them up!

Rob

 

[morricab]

When is the install Brad? Look forward to comments.

Probably sometime this weekend depending on family stuff.

Based on curves from Radian, this driver rolls off quite steeply so it might require a fair bit of EQ to not sound rolled off. I will measure as I have the xover and EQ set now and see how different it is from the Beyma drivers, which are quite flat requiring only a bit of EQ.

 

[morricab]

Update:

Now have the WE91 derived monoblocks. These are LD+ MK2 91 monos that use a 274A rectifier, 310A input/driver and 300B output tube. This circuit was a modified WE91 design by Thorsten Loesch that gives a wider bandwidth. First trials are very promising...really nice sounding on my bigger black horns! Nice quality chassis and the parts quality inside is quite good (Obligatto and even some Audio Note caps).

I think this will be a ideal amp for driving the horns only part of the speaker but I will also try it in other uses (like the SUpravox part and/or my Athos 10s.

Still haven't had time to install the Radian Be drivers but this will have to wait until after my holidays....

 

[Alrainbow]

Thanks for the posts very good info. Love horns

 

[morricab]

Amp photos

 

[morricab]

Interestingly, the noise level was acceptably low attached to my 110db horns...I was a bit fearful that they would be too noisy like my Mastersound (which is great on the SUprvoxes but was just too noisy for the horns).

 

[morricab]

Further trials with the new 300b amps shows they were a good move...much more engaging and now the sound has expanded well beyond the speakers. i don't know how they would fare full range but as a horn amp they are superb.

 

[Robh3606]

Hello Morricab

How are your new compression drivers??? Get a chance to power them up and get some listening impressions??

Rob

 

[morricab]

Hello Morricab

How are your new compression drivers??? Get a chance to power them up and get some listening impressions??

Rob

Hope to have first trials this coming week. Stay tuned...
How is your project going?

 

[Robh3606]

How is your project going?

Which one?? My speakers are doing fine. Finally got my 1.8 Meg resistors to Charge Couple my caps in the crossover. Took a look at the impedance curve and added and imp comp circuit from parts on hand to limit the phase shifts to mostly +/_ 30 degrees and narrow the magnitude imp to 5-15 ohms over most of the range.

Got a pair of Emotiva XPA- HC-1 mono-blocks to power them so plenty of clean power all in all OK. Happy with how they turned out!

Rob

 

[morricab]

Update:

Installed the Radian 475pbBe drivers yesterday and if you were all expecting heaven and earth to move with the change in drivers, well you might be disappointed. As I suspected, the Beyma drivers are REALLY good and don't exhibit what many people claim to hear with Ti diaphragms, which is a kind of "hardness" to the sound. I think this comes a lot from the JBL drivers that switched from Al to Ti and people found they preferred the old Al diaphragms.

That being said, I can hear what people like about these drivers and Be as a diaphragm material. It is very precise and resolved...perhaps more so than the CP350Ti. I will switch back though to compare because I found that the CP350Ti with the Iwata 600 was a bit more detailed overall than the CP755Ti + XT1864, so I am not sure if it is really the driver upgrade I am hearing. What I do notice is the gentleness in the highs. Now, this driver is rolled off at the upper end and I have given the same compensation as for the CP755Ti (the CP350 needs less it seems) and the gain was nearly the same. Until I can do detailed measurements though I am not sure if this gives the optimal response yet from the Radian.


So, a very good start, no bad surprises (in fact it sounds really good) but I am not sure it is the huge upgrade that I was sort of hoping but kind of doubting would happen. I will let you all know more soon once i have done some measurements.

 

[Robh3606]

Hello Morricab

Glad you like them!

Installed the Radian 475pbBe drivers yesterday and if you were all expecting heaven and earth to move with the change in drivers, well you might be disappointed.

Exactly it's not. What you get is better low level resolution like the the noise floor suddenly getting lower.

I think this comes a lot from the JBL drivers that switched from Al to Ti and people found they preferred the old Al diaphragms.

Well you have to remember the when they originally went with the "diamond" surrounds it was done with aluminum. The problem with the aluminum was the surrounds added a lot more stress and they were failure prone. That's what lead to the use of titanium which is much more fatigue resistant but not as well self dampening as the Aluminum they replaced.

To take some of the harshness away from the Ti all you have to do is add aquaplas to damp the diaphragms. Makes a definite difference for the better.

Rob