Filter, super tweet for Coniston^2

[motosapien]

Having recently completed my first full range project - Coniston^2 Build

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 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.

[motosapien]

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............

[motosapien]

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.

[kristleifur]

Nice! Keep the updates coming.

[motosapien]

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.

[planet10]

Originally Posted by motosapien

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

[TerryO]

Originally Posted by planet10

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

[motosapien]

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.

[planet10]

Originally Posted by motosapien

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.

No i wouldn't. You should have seen the mess that was the XO for the MA#6 MTMs. Still pretty ugly even thou a bit of soldering eliminated quite a few clip leads.

dave

[motosapien]

Originally Posted by planet10

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.