The B&C DCM50. Can it replace the K55 driver?

[Al Klappenberger]

Rudy,

I saw your Universal networks on eBay. The serial number was visable on the pictures. Good luck!

The Trachorn 420 is available now. Check my web site.

A driver that goes solidly down to 400 Hz is all you need. One that goes lower just gets you a bigger price tag!

Al K.

[Rudy81]

Al, I'll check it out. Yes, those are the universal crossovers on eBay. I'm not sure if they will sell or not. If they don't, I'll just store them for possible future use. I have been on a long journey putting in an active crossover. I truly loved the ALK universal, it was a tremendous improvement. However, the actives sound fantastic and it gives me great flexibility. I'll see if the Trachorns can be sold. I know the JBL's hold their value very well. I would have to recoup most of that expense prior to dropping another grand+ on the 2". Man, I need to win the Lotto!

[Al Klappenberger]

Rudy,

Going active definitely has it's advantages, but in the end, you will find yourself back to a 400 Hz crossover if you are working with a Khorn. This is the right place for the woofer to start to drop. Moving the squawker down just puts a heavier load on the mid-range the lower you go, especially with a gradual slope on the crossover. The farther down you go with the crossover the steeper you need the slope to be to keep the lows below the horn Fc from getting through the filter. A bigger horn and driver just winds up the exact same problem, but lower in frequency requiring more expensive stuff. It also moves away from the woofers natural roll-off above about 450 Hz that adds to the crossover slope. You gain nothing but more driver interaction and the satisfaction of knowing that you have spent more money!

Al K.

[Rudy81]

Al, I have suspected that for some time and originally started my active experiment thinking at some point I might want to use a jub bass bin to be able to bring the bass bin up to the mid range comfortably. That led me to a full active setup.

[Al Klappenberger]

Rudy,

I see.. One point though. The Jube bas bin is simply a folded horn that will go higher than the Khorn will. The only reason active was used was because the high section required equalization. You can't do that properly with a passive network because the Jube is so efficient. If you use the kind of horns and drivers we have been using, that don't require EQing, a passive network crossed over at a higher frequency, say 600 Hz, will do fine. You also get to keep the 1-inch horn and move to a better driver as well. Of course, an active crossover will do all that too.

Al K.

[Deang]

When I had Jubilees, and for live listening sessions (loud), I needed a 4 ohm series resistor in line with the K-69s to prevent the drivers from running away from the bass bins (perceptually speaking). If you EQ out to 15kHz instead of 20kHz, I think you'll find plenty of sensitivity left over on top to meet up with the bass bins.

[Al Klappenberger]

Dean,

Exactly. The efficiency of the woofer defines how far up you can equalize. It's the frequency were efficiency of the driver being equalized equals the efficiency of the woofer. Above that, the curve must start down.

Al K.

[Rudy81]

Without a doubt the efficiencies are a huge issue. In my active setup the mids are way more efficient than the woofers or tweeters. I have the amp powering the JBLs 1 click next to the absolute minimum sensitivity to even get close to the SPL or the bass bin. The tweeter amp runs almost wide open. Although the amps are not all the same, they are similar enough to make the efficieny differences readily apparent.

Al, have you tried putting a K69 in your 2" horn? What do you suppose would be the result? Just thinking out loud. As usual, just enough knowledge to be dangerous.

[Al Klappenberger]

Rudy,

I think the K69 would do well on it. When I ran curves on that driver it was on a horn that required EQing. I don't think it would need that on the Trachorn. I would have to actually try it to know for sure though.

Al K.

[Rudy81]

Al, I would love to see you run some testing on the K69 and your 2" horn. You never know, It could end up a good fit for a 2 way setup.

[ClaudeJ1]

Passive network with bi amping sounds like the answer to me. Just turn up the full band gain on the top end. I have all passives on my 3-way top and and a subwoofer plate amp on the white MWMs clone bass bin. I'm NOT EQing the any of the horns, but using their natural rolloffs to the the next horn up. I know this goes against much of what you have written here, but it sounds really good. I find myself listening about 10 db lover than I ever did.........in the less the 80db average at the sweet spot with efficiencies up around 109/110 in the tops and the bottom at about 104. So it's about +6 db on the bass bin crossed at 180 Hz. to the big midbass horn. This has yielded incredible definintion between 200-400 Hz that was missing in the Khorns and LaScalas I had for 30 years. I prefer straight axis horns for as much of the sound as possible and as few folds as possible, which take the Khorn out of the running for me now that I know better

JC,

I figure you have to EQ constant directivity horns with active equipment. That's the only way you can add to the high end. The only way to Eq passively is to subtract from the low end. I actually did three different eq networks for that driver. That one was the most agressive of the three and it still has sag in the high end. The only time I ever did a serious EQ on a possive network was for my own den speakers. It used a Beyma CP-09 tweeter. The K24 12 inch woofer in it limited the efficiency. That gave me the room to do it with a passive network. It's the same sereis L-C circuit I used on yours.

Al K.

.

[consistent]

Hi Al,

Some great work again with some excellent follow up by others. I too have experimented with drivers and the Atlas is not a bad driver for what it does. I was wondering if you had ever come across the BMS 4592ND, it's a coax dual voice supposedly from 300hz to 22k hz???

Cheers

[Guest David H]

I was wondering if you had ever come across the BMS 4592ND, it's a coax dual voice supposedly from 300hz to 22k hz???

Here we go again.... and this thread was so peaceful.

Dave

[Al Klappenberger]

Yes,

I did tests on the BMS coaxial. I also did a 2nd order crossover to operate the two halves. It was for Dana Moore. It's a very impressive driver. In case you were not aware of it, the B&C DCM50 driver also comes with a coaxial version. It's the DCX50. I have not seen it though.

Dave,

Yep, Some people just can't leave sleeping dogs lie! [8-|]

AL K.

[whatever55]

As long as we are waking the dogs....

Al,

Could your 420 be used with either the K69 or even the EV DH1A with a jub base bin in a 2 way set up ? Without any EQ...

[ClaudeJ1]

I figure you have to EQ constant directivity horns with active equipment. That's the only way you can add to the high end. The only way to Eq passively is to subtract from the low end.

That is true if the HF transducer is equal or lower in sensitivity compared to MF and LF. If it is higher in sensitivity, the HF will be padded to match the MF and LF already. Then one can install a bypass network around the HF crossover filter and pad the bypass network to provide the necessary rise in freq response to correct for the CD horn rolloff. This correction is usually 6 dB/octave above 3kHz-4kHz, so often this can be done with just one added cap in addition to the pad. I think it was a Peavey PA speaker where I first saw this done like that. JBL also uses this method in some of their passives.

So what does that section look like, schematically, with the added cap? How is the value determined?

[Rudy81]

Al,

Could your 420 be used with either the K69 or even the EV DH1A with a jub base bin in a 2 way set up ? Without any EQ...

That is what I want to try at some point. I don't mind EQing the setup, but that could sound really good. I think I had asked Al about the K69 in his horn a while back.....don't recall seeing any data on that combo. Great idea though.

[Al Klappenberger]

--55,

The 420 horn has the standard 2-inch driver mounting scheme. I think any 2-inch driver would fit on it. It's a Tractrix expansion which I doubt needs any EQing no matter what driver is mounted to it.

Al K.

[Don Richard]

So what does that section look like, schematically, with the added cap? How is the value determined?

Basically you go from the + input with a cap sized for 6dB/oct hi pass where freq response begins to roll off (approx 4 kHz), bypassing the existing HF network and connecting to the + HF driver terminal thru a padding resistor which adjusts for proper response. Note that there must be a sufficient difference in sensitivity between the other driver(s) to allow for CD compensation.

[whatever55]

--55,

The 420 horn has the standard 2-inch driver mounting scheme. I think any 2-inch driver would fit on it. It's a Tractrix expansion which I doubt needs any EQing no matter what driver is mounted to it.

Al K.

So will it go to the limit of the driver, on the high end ?

DO you plan on running any test on this. I would really like to go back to passives... Trying to keep it simple.