Author Topic: Crossover upgrading  (Read 17324 times)

Offline Carlman

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Crossover upgrading
« on: August 28, 2009, 11:37:55 AM »
I'm in the process of rewiring and considering a cap upgrade.  I read great reviews about Duelund VSF-copper caps and thought, wow.. that sounds exactly like what I want..  They seemed a little pricey but I wasn't sure 'how pricey'.. but now that I've got the xo's out.. and I see I need a 47uF cap, they're in the $1,200 range, EACH.. in USD!  Do people really pay that per cap?  I mean wow.  If I were to replace all the caps I have (bass and tweeter), that's 6 per speaker... even at 1,k per cap, that's 12,k... in addition to the cost of the speakers... which wasn't small change either.

Sorry if I'm late to the high-price-cap party... but I just needed to vent and wonder aloud at how that's even possible that people use these to upgrade speakers.... ?

-C
I really enjoy listening to music.

Offline richidoo

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Re: Crossover upgrading
« Reply #1 on: August 28, 2009, 12:07:21 PM »
There are 10 caps in the mid/high filter each speaker and 3 each in the bass filter. 13 caps per speaker. They are 4th order crossovers with some impedance or EQ correction. The stock parts quality offers a good upgrade opportunity. I think you would be surprised with the improvement, even with Jantzen caps and coils, which are still premium parts. Use mundorf silver/oil on the tweeter high pass if you want to get fancy.

Duelund makes aluminum caps too, a lot cheaper, but same order of magnitude. And they make silver plate caps too. Special order only   :shock:

Offline BobM

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Re: Crossover upgrading
« Reply #2 on: August 28, 2009, 12:38:25 PM »
That big cap is probably on the woofers, right? I would keep the one that is there and just look to upgrade the tweeter crossover caps.  That's where you will get the biggest bank for the buck anyway.

If you really want to you could put a .1uF bypass on that big cap and get 90% of the improvement you would see with a full replacement. I would suggest using one of those inexpensive Russian Teflon's. It may or may not work, sometimes that bypass could bring too much to the top end and not sound correct at the crossover point. Your ears will have to be the judge.
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Offline Carlman

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Re: Crossover upgrading
« Reply #3 on: August 28, 2009, 04:27:04 PM »
I put photos in the gallery...   You can see what we're working with... Rich gave me a great analysis of what he saw (crap) and I appreciate it! :)  Thanks for your suggestions about the bypassing, Bob... I will check into it more.

Some curveballs to play with..
1 option:  Go with an actively amped system.. I think this makes sense but I've never heard it or dealt with it.. so it's a complete unknown and a steep learning curve, which sounds fun.

2nd option: Create new crossovers, keep them external, leave the stock xo's as-is for re-assembly/resale

3rd option: Stick with the plan and just upgrade some parts on the existing board.

4th option... some combo of 2 and 3.

I have one speaker on the floor with its guts hanging out and the xo's on my desk... decision time!

-C
« Last Edit: August 28, 2009, 04:28:48 PM by Carlman »
I really enjoy listening to music.

Offline stereofool

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Re: Crossover upgrading
« Reply #4 on: August 28, 2009, 05:21:59 PM »
Obviously...I'm going to follow this closely...since we have the same speakers   :-k !
Steve
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mgalusha

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Re: Crossover upgrading
« Reply #5 on: August 28, 2009, 06:07:06 PM »
That's a lot of parts, I'm guessing option 2/3 would be your best bet. One of the trouble with the good Jantzen's and Mundorf is the size. Both are double wound to cancel inductance but it also doubles the size for a given value.

The first thing I would do is draw up a schematic if you have not done so already so that you can determine which parts will have the most impact. At least the caps on the tweeter board look like polypropylene but kinda hard to say for sure.

Offline Carlman

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Re: Crossover upgrading
« Reply #6 on: August 28, 2009, 07:31:49 PM »
I'm taking my dissasembled speaker to our local xo master/guru Rick Craig and getting his opinion.. I'm fully capable of admitting when I'm in over my head!  :shock:  But at the same time I'm enjoying the learning! :)

Mike, I'm pretty sure I'll have to go outboard on the XO's... more to come on that.

So, I'll report more... and Steve, I'll be happy to let you hear what the improvements do.. Maybe we could do a direct comparison at some point... I did that once in the past with a couple pair of Usher 718's where I had the V-cap upgrade.. I think you were there, it was a long time ago.

I think the sub 1,k Usher's had a better xo design than these 15,k Piega's... so, I expect a bigger improvement but I'm not real pleased with what I've found so far... and some poor work has been identified by myself, Rich, and now Rick.  The cabinet is great and the drivers are mighty fine... but I'm really looking forward to this tweak/complete rework now.

-C


I really enjoy listening to music.

mgalusha

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Re: Crossover upgrading
« Reply #7 on: August 28, 2009, 07:43:52 PM »
Taking them to Rick will no doubt guarantee a good result. :D

Selah Audio

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Re: Crossover upgrading
« Reply #8 on: August 31, 2009, 06:23:56 PM »
First post here so I'll keep it short.  :D

I looked at the crossovers and went over everything with Carol on Saturday. First listening was today. If Carl approves I'll blog here as I go.

Offline bpape

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Re: Crossover upgrading
« Reply #9 on: August 31, 2009, 07:24:51 PM »
Welcome Rick.  Glad to have you hear.  Looking forward to your impressions.

Bryan
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Offline Carlman

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Re: Crossover upgrading
« Reply #10 on: August 31, 2009, 07:26:45 PM »
Welcome, Rick! :)
I wasn't sure if you wanted to 'go public' with this project so I was keeping quiet.  Blog away!  You can even use my comments/replies in email.

I'm excited about what Rick's doing and he's already found all the issues I had and is planning on how to work it out with a completely new, outboard crossover for these speakers.  I think the C8LTD's are great speakers but there has always been something holding them back.. and I'm starting to feel good about deciding to crack these babies open and take a peek.

Once these are done, (i.e. voiced, settled in/broken-in/etc.) I'd like to compare them to Steve's and hear what the real improvements are.

Thanks and welcome,
Carl
I really enjoy listening to music.

Offline richidoo

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Re: Crossover upgrading
« Reply #11 on: August 31, 2009, 08:04:13 PM »
Hi Rick!

Offline rollo

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Re: Crossover upgrading
« Reply #12 on: September 01, 2009, 05:35:16 AM »
First post here so I'll keep it short.  :D

I looked at the crossovers and went over everything with Carol on Saturday. First listening was today. If Carl approves I'll blog here as I go.




Welcome Rick, blog away.


charles
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Selah Audio

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Re: Crossover upgrading
« Reply #13 on: September 03, 2009, 05:50:37 AM »
Thanks for the welcome. Carl and I started with discussing how he wanted to improve the speaker and what things he liked about the sound. I tend to favor mods that just don't replace parts but also improve the execution / design of the crossover. In this case the crossover design is pretty complex, much more than you would typically see in a high end speaker. The parts quality was pretty much what is expected for a commercial speaker; however, the layout of the inductors could present some problems (mutual inductance). Small iron bobbin coils are also prone to saturation and the distortion from that smears the sound.

We talked about how much space would be needed for replacement parts and it became obvious that going outboard was the only solution. Fortunately the input terminals are bi-wire capable and the mounting plate will allow for a third set of terminals. Carl brought both speakers with one intact and the other open for inspection with the woofers and crossover removed. The construction of the cabinet is very good with excellent fit and finish. The first thing I noticed is that the crossover was so complex that you can tell this is going to be a difficult load to drive. Stay tuned...

 
« Last Edit: September 03, 2009, 05:54:11 AM by Selah Audio »

Offline Rob S.

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Re: Crossover upgrading
« Reply #14 on: September 03, 2009, 06:21:30 AM »
Hi everyone, this should be an interesting journey.  Rick did an excellent job on my crossover design- seamless transition, smooth and still very detailed.   Seems like a challenge to come in to an existing cabinet, drivers already there, and go at it from that angle.   Looking forward to hearing the updates.

Rob S.
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