Filter, super tweet for Coniston^2

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Having recently completed my first full range project - http://www.diyaudio.com/forums/full-range/175808-coniston-2-build.html

I thought I'd try some tweeks just for fun. I could be perfectly happy with the speakers just the way they are but you know how hard it is to stop fussing with a project:D Most of my listening has been done with the drivers wired up in series. I just ran separate leads out from the drivers and am currently listening with them wired in parallel, which I rather like. They seem more coherent and crisp this way. My amp (NAD C 275BEE ) seems to not mind the 2 ohm load either.

My thought was to add a super tweet to the rear of the cabinets but I wonder now if this possible with the parallel wiring or if I need to go back to series? I have 1 uF caps for the tweeters. I was also thinking of filtering the side drivers with 68 uF caps but with the parallel wiring this does not seem like it's needed.

So now ya'all know I'm pretty much all thumbs when it comes to electronics. Advice from anyone who has added a super tweet to a dual driver full range would be most welcomed. The parts should be here today.
 
So I forge ahead! Having all four leads outside the cabinet allows me to do some testing. What I've discovered is this: With only the front two drivers hooked up there is a big difference in the mids and highs. Much clearer. Big improvement. As you would expect, there is less lower mid and bass output. Apparently there is some comb filtering occurring with the second drivers in play.

So I'm going to wire these up in series through the front drivers and then use a 68uF cap across the side drivers. I can do this bread board style on floor outside the cabs easily. I will get the mid and base punch of the second driver without the deleterious effect of the "warbling" highs. I must credit Danny Richie from GR Research for this idea.

This is going to be stimulating............
 
Holy Smokes!!!!!!! The 68uF cap across the side drivers makes a huge difference!!! This is like a different pair of speakers. I'm not sure I need the ribbon tweeters now. The caps are jumbo size, kinda like a good ole fashioned "silver salute" if any of you is old enough to remember fooling with those. Once I dope out the mounting arrangement I'll post a pick or two.

I'm totally stoked by this little mod!!! My weekend (snowstorm and all) is shaping up nicely.
 
Okay, I've added ribbon tweets into the mix. These are HiVi RT1C-A Planar Isodynamic Tweeters available from Parts Express for about $35. So far I've just got them sitting on the floor facing me. I did not use the 1uF caps yet, and when I've surface mounted them on the backs of the cabinets I doubt I'll need to tame them down. I just wired them in parallel with the two CSS EL70's. Works great. They are nominal 6 ohm loads. The other drivers in series present an 8 ohm load. Not sure where this puts me now, about 7 ohms total maybe?

With these two simple modifications to the Coniston^2's, they are unrecognizable from their original state in terms of sonics. With proper recordings I'd venture we have a reference grade full range based speaker system. The backbone of this is Scott's (Woden Designs) masterful design of the box which emit perhaps the finest lower mid range and upper bass sounds I've ever heard from a pair of speakers. The two mods outlined above move the whole to heights I dared not expect when I was laboring with the cabinet construction.

These are just so fine and sweet!!! I wish you all could be here with me to give a listen.
 
frugal-phile™
Joined 2001
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I just wired them in parallel with the two CSS EL70's. Works great. They are nominal 6 ohm loads. The other drivers in series present an 8 ohm load. Not sure where this puts me now, about 7 ohms total maybe?

The 2 EL70 in series with a bypass cap on one will present an 8 ohm load down low, then drop to 4 ohms as the impedance of the cap drops to zero.

Running the planars with no cap puts them in danger of having the smoke let out.

4 ohms in parallel with 6 ohms gives 2.4 ohms. At high frequencies EL70 impedance rises to about 7 ohms, so once a cap is in place parallel impedance will be just over 3 ohms.

dave
 
The 2 EL70 in series with a bypass cap on one will present an 8 ohm load down low, then drop to 4 ohms as the impedance of the cap drops to zero.

Running the planars with no cap puts them in danger of having the smoke let out.

4 ohms in parallel with 6 ohms gives 2.4 ohms. At high frequencies EL70 impedance rises to about 7 ohms, so once a cap is in place parallel impedance will be just over 3 ohms.

dave

What Dave says, especially about the tweeters! They can be easily damaged and usually, from my experience, can sound pretty lousey if not crossed high enough.

Best Regards,
TerryO
 
Thanks Dave. So all the bass frequencies would fry the planar? I wondered how they were shrugging it off. I've unhooked them until I can get them mounted proper with the caps. You would have laughed to see all the wires and alligator clips and even clothes pins I had it all cobled together with on the floor.

I've got a bit of work ahead of me getting everything wired and mounted.
 
The 2 EL70 in series with a bypass cap on one will present an 8 ohm load down low, then drop to 4 ohms as the impedance of the cap drops to zero.

Running the planars with no cap puts them in danger of having the smoke let out.

4 ohms in parallel with 6 ohms gives 2.4 ohms. At high frequencies EL70 impedance rises to about 7 ohms, so once a cap is in place parallel impedance will be just over 3 ohms.

dave

Well, there is never a free lunch. My mods present a lower overall impedance that will no doubt have some swings across the frequency range. As always, more listening time will out any problems. Thanks for the heads up on direct driving the tweets.
 
Got everything installed. The mods are working wonderfully. Only one issue remains and that is a bit of upper harshness on some recordings. Probably from what I've read the way to address this would be EnAbling the two front drivers.

So the project met all my expectations and then some. They are impressive speakers. Almost architectural in their posture. And that I think, is where the good sounds come from. You can't get this kind of depth and sound stage from a small cabinet though the best of those can sound pretty good.

Back to the Pretenders from the Isle of View:)...............
 
frugal-phile™
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Is this accurate?

dave
 

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Yes Dave. I used a couple of 1/8" pieces of ply to mount the 1uF caps with the both leads threaded through it to keep the strain off the cap leads. Made a little blanket for it out of wool felt.

I hot melt glued a small piece of the same ply to each of the 68uF caps for "feet" and also glued some of the felt around them to cushion them from the zip tie I used to secure it to the under side of the holey brace. Removed the insulation from the center of a 2' piece of wire on each leg and covered the soldered connection with shrink tube.

Mounted the terminal cup 21-1/4" from the bottom of the cabinet and the ribbon tweet the same distance down from the top. Almost added a toggle switch to the terminal cup on the positive leg of the tweet so I could take it out of the mix because there is some music where it contributes little and I could increase sytem's resistance them. Could do this easily at some point.

BTW - how does the EL70 respond to your EnAbling process?
 
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Hi,

BTW - how does the EL70 respond to your EnAbling process?

Very nicely!

I had the priviledge of listening to En and non-En at CSS in some good tests. What does change really between the two is the clarity of the highs and high-mids.

With En, you can cross higher. A tweet adds a gorgeous "cherry on top". Without, cross a little lower for the same effect.

The EL-70 is one of the few speakers I personally can't say one is better when coupled with a tweeter, they are just different.

If you're running the EL-70 alone, go for the enabled.

Cheers!
 
It is an interesting full range driver. In this cabinet percussive sounds are fabulous as are mid range guitar sounds. The bass is taught and satisfying as well. The super tweet integrates seamlessly with that 1uF cap. I would like to build a fancier pair in regards to woodworking and I think the second EL70 could be mounted on the front of the baffle since the upper range has been removed from it. This should bring more mids forward and balance the highs from the unadulterated driver.

If I were more savvy with cabinet design I might experiment with removing the top horn mouth yielding a cabinet about 4' high. A slotted forward orientated aperiodic style vent could be use up top. But that change would be for aesthetic reasons only. You might just get away with one piece of 5' x 5' ply then. My wife noticed that the tall cabinet blocked the view of one of our paintings. I am rather attached to their stately posture at 5' high.
 
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Is this accurate?

dave

Dave,

I'm enjoying my speakers very much. There is one wrinkle that I'd like to sort out and I could use some help. The full range EL70 can sound "fierce" in the highs on some recordings. Looking at the above schematic, is there a way to incorporate a zobel to deal with this? I would be willing to revisit the whole wiring scheme if that would help. As stated above, I want to build a second really fancy pair with regards to woodwork. They are that good.

Erik
 
frugal-phile™
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The full range EL70 can sound "fierce" in the highs on some recordings. Looking at the above schematic, is there a way to incorporate a zobel to deal with this?

A Zobel isn't going to do much, the impedance of the EL70 is already quite flat, Remind me what amp?

Really long breakin might help (althou the biggest improvements that stood out for me where improved midrange finesse).

Perhaps the next set needs treated drivers? I have no complaints about the top end -- office system uses EL70eN.

dave
 

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Dave,

My amp is an NAD C 275 BEE along with their C 165 BEE pre. Have you found that an amp can cause this sort of anomaly? I listened to Albert King's Live Wire last night and it was pretty shrill on his guitar. I usually notice it in vocals if it's going to be there. I searched the forum and did not find others who've used this driver having the same issue so maybe it's me. The super tweet is far too subtle to be contributing to it.

At this point I will concentrate on listening to the wealth of music that plays so very well on them and forgo the "clinkers" as it were. I think it is an over saturation inherent in some recordings and not so much an issue with the driver. These full rangers like the good stuff.

Thanks for the reply.
 
I think it is 12 ga. run of the mill stuff. Internal wire is 16 ga. stranded, also run of the mill. I do have better low end inter connects. Have to admit to being from the "wire is wire" camp as long as it's resistance is not out of wack to the job. I'm willing to learn however;) This over saturation was far less noticeable on my previous 2 way speakers. I could really crank that Albert King without trouble though I don't need to have that kind of volume to bring out the details with the Conistons.
 
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