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Old 25th February 2010, 02:08 AM   #11
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Quote:
Originally Posted by DcibeL View Post
Perhaps somewhere that would be of some benefit to improve is the cabinet. Can you post some photos of that? How thick is the material? How much bracing is there? Does it sound hollow when you knock on the side with your knuckle?

You can always cut some dowels and insert them into the cabinet to improve bracing, as well you can always add some more damping material. These are simple and cheap tasks.
This is your best advice and the adding of extra damping material if what is there is degraded (or non-existent)
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Old 25th February 2010, 05:22 PM   #12
Lucky13 is offline Lucky13  United States
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Thanks for all the replies and helpful info. It seems there’s a consensus forming that I should leave the XOs alone…Guess I’ll have to find some other project to play with!

I’ll try to provide answers here to the questions some of you’ve asked:

- Yep, those are the original XOs. Definitely not electrolytic caps, though I haven’t been able to find any detailed info on their composition. I do know they were manufactured by Dahlquist. In the upgrade kit Regnar sells for ~$100 the included caps are made by SAS. So, new caps wouldn’t really provide better SQ then?

- So, what am I trying to improve? Excellent question. I dunno, probably just a case of upgrade-itis. My setup sounds pretty good to my ears, given budget and room constraints. If there’s anything I would try to improve upon, I would say perhaps the soundstaging, depth especially. Maybe someone can see improvements in placement or room setup based on the attached pics of my listening space? (Obviously it’s a living space, don’t have a dedicated A/V room.) FYI, the associated gear is: Parasound HCA-1000A amp, Parasound P/LD-1100 preamp, Logitech Transporter digital music server (using lossless source files).

- One of you asked about the drivers — the M905 has Vifa drivers, 8” woofer and 1” tweeter. They’re in excellent shape. Rubber surrounds on the woofers so no worries there. See attached pics.

- As for the cabinets, they have a nice walnut veneer over I’m not sure what base material (MDF? some kind of ply?) — Perhaps one of you can tell by looking at the additional pics I’ve attached? They don’t sound particularly hollow when I rap on the them with a knuckle, but neither is the sound completely “dead.” Walls are ~1/2” thick and there is some bracing inside (2 vertically placed dowels) and also some ~2” thick white material which looks to me like fiberglass insulation positioned to cover the entire rear wall of the speaker (I pulled it out of the way when I took the photos so it’s not in the pics).

- Any suggestions for improving the way the speakers sit on the hardwood floor? The floor actually is uneven in places so the speaker stands are not resting perfectly flat on all four corners. Problem?

- @DreadPirate (great handle, btw): You mentioned the smaller cap looks like 6uF to you. I ended up calling the guys at Regnar about this one, because it’s not marked except for the cryptic “Dahlquist 1060 Mexico” you see in the photo. They told me it’s 5-5.5uF (allowing for 10%tolerance). What makes you think it’s 6uF, or is this close enough not to matter? FYI, the larger cap is clearly marked “10k / 100V”.

Thanks again, any more ideas you can offer are appreciated!
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Old 25th February 2010, 06:32 PM   #13
DcibeL is offline DcibeL  Canada
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Sounds like adding a few more braces and some extra stuffing would help. It's cheap and simple. If you're still not satisfied, then I would look at finding a different speaker that you like better. The drivers and crossover look good, the crossover design may not be optimal (who knows), but without some fancy measuring equipment you're SOL for a crossover redesign.

By the way, that's a real nice home you have there.Good luck with your project.
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Old 25th February 2010, 07:14 PM   #14
Lucky13 is offline Lucky13  United States
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Quote:
Originally Posted by DcibeL View Post
Sounds like adding a few more braces and some extra stuffing would help. It's cheap and simple. If you're still not satisfied, then I would look at finding a different speaker that you like better. The drivers and crossover look good, the crossover design may not be optimal (who knows), but without some fancy measuring equipment you're SOL for a crossover redesign.

By the way, that's a real nice home you have there.Good luck with your project.
Thanks DcibeL. The place is great, should last us until it's time to have kids anyway!

I'll do some research on bracing and stuffing...might find myself coming back to the forum with more questions! As for new speakers, the Dahlquists sound pretty damn good -- I don't know what I'd have to spend to better them, but I suspect it would be a pretty large $$$ number. I've been toying with the idea of adding a sub...
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Old 25th February 2010, 09:13 PM   #15
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Look into room treatments also. May want to experiment with getting those tweeters up higher near ear level, but would affect bass.

Last edited by DreadPirate; 25th February 2010 at 09:15 PM.
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Old 25th February 2010, 09:35 PM   #16
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My immediate thought on seeing that tweeter is that a "Vifa D27TG05-06 1" Textile Dome Tweeter" from Madisound ($21) MIGHT be a drop-in replacement AND actually work OK with the same XO. I remember playing with both of these tweeters about 15 years ago....

A brace from the weakest point between the tweeter and woofer to the rear panel is probably the most effective single shot.

Some feet -- two in front and one center in rear -- might work for stabilizing them? Maybe even make them adjustable if you want to play with the tilt and height. The height is important, as already stated.

For more image depth, pull them away from the front wall (and perhaps also move your listening position closer).

DIY speaker cable is cheap and easy. (Surplus CAT5 available?)
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Old 25th February 2010, 09:58 PM   #17
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Room is nice, can't see the back wall but a few bass traps may work to improve over-all sound.
One thing that may work well is a cheap Bi-amp set-up with a pair ( or more ) of subwoofers, taking the LF ( Sub 100 Hz ) out of the main speakers could give a lot more clarity in the midrange and add to the overall SPL so you could actually turn the volume down a notch or two
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Old 24th August 2011, 08:37 PM   #18
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Reviving this old thread, I have a question about replacing electrolytics in my JBL 250Ti crossovers. In my case, there are two 24uFs in each crossovers. One is on the woofer shunt and the other is on the 108H lower midrange shunt.

My buddy replaced the corresponding 24uF woofer shunt electrolytic caps on his 240Tis with film caps, and we A-B'ed it against a pair of L250s (not the Ti version) and his 240Tis (same woofer and effective cabinet volume) had a lot more bass. It was dramatic, and it remained even when we moved the speakers to take each others' places in the room.

What effect does a dried-out cap have on a woofer shunt or Zobel? Would it decrease the bass or decrease it? Would it increase capacitance or decrease it? Just curious.
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Old 25th August 2011, 07:37 PM   #19
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If drying out a cap increased its capacitance, wouldn't you think we'd all be drilling vents in our caps?
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Old 25th August 2011, 07:44 PM   #20
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Good point. And then would air or a vacuum have the most capacitance of all?
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