Noob question about external passive crossovers

Hoping for some guidance from the speaker builder experts here.

I have a new pair of Tekton Lores. They're still breaking in. But once broken in, I'd like to swap out the stock caps in the crossovers with some copper foil caps -- just b/c I like to play with stuff and I happen to have 2 of the 3 cap values in my parts bins. I'll order the missing value.

Issue: the stock 3.3 uF and 10 uF Dayton film caps are fairly small in size and weigh very little. The Audyn 3.3 uF and Miflex 10 uF copper foil caps that I plan to replace them with are huge and heavy. The same will be true for the 5.6 uF 'lytic that I plan to replace with copper foil. I'm not confident that the cross-brace supporting the stock crossover could take the additional weight - I estimate that the new caps will add about 10+ lbs or so. And I don't want to mess with the open volume of the cabinet. The 10 uF Miflex is truly enormous.

So I'm tentatively planning to rebuild each crossover in a box that I can put behind the speaker. I'll add an additional pair of binding posts, with one pair connected directly to the tweeter and the other to the woofer.

Questions for experts:

(1) Any obvious problem(s) with my plan?

(2) If the plan is workable, is there anything I need to pay special attention to? For example, regarding the wiring from the crossover to the drivers, do I need to keep the wiring as short as possible? Other things?

Many thanks in advance,

Derek
 

Wntrmute2

Not So Mediocre Member
Personal opinion only here. I don't believe the location of the crossover is critical. On my Altecs, the crossovers are a few feet away from the stock location. I just think the difference of a few feet of wire will be negligible. No proof though but plenty of really high end speaker builders offer stand-alone crossovers.
 

TubeHiFiNut

Administrator
Hoping for some guidance from the speaker builder experts here.

I have a new pair of Tekton Lores. They're still breaking in. But once broken in, I'd like to swap out the stock caps in the crossovers with some copper foil caps -- just b/c I like to play with stuff and I happen to have 2 of the 3 cap values in my parts bins. I'll order the missing value.

Issue: the stock 3.3 uF and 10 uF Dayton film caps are fairly small in size and weigh very little. The Audyn 3.3 uF and Miflex 10 uF copper foil caps that I plan to replace them with are huge and heavy. The same will be true for the 5.6 uF 'lytic that I plan to replace with copper foil. I'm not confident that the cross-brace supporting the stock crossover could take the additional weight - I estimate that the new caps will add about 10+ lbs or so. And I don't want to mess with the open volume of the cabinet. The 10 uF Miflex is truly enormous.

So I'm tentatively planning to rebuild each crossover in a box that I can put behind the speaker. I'll add an additional pair of binding posts, with one pair connected directly to the tweeter and the other to the woofer.

Questions for experts:

(1) Any obvious problem(s) with my plan?

(2) If the plan is workable, is there anything I need to pay special attention to? For example, regarding the wiring from the crossover to the drivers, do I need to keep the wiring as short as possible? Other things?

Many thanks in advance,

Derek
My opinions, in answer to your questions:

1. No problem with your plan at all. Just make sure that you get a good seal when you mount the second set of binding posts.

2. Use good wire and leave yourself enough length to be able to position your new external passive crossover.

I do have to ask the question: Are you sure you want to do this to your new speakers?
 
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About as passive as it gets. Maybe I move the HF L-pad a bit now and then.

View attachment 37773
Ya might want to think about the bolts at the centers of the Ls. Kinda defeats the air core - which won't saturate - with a bit of metal, which will. It'll also raise the value.

To Deke609 - caps are microphonic. Thier value varies slightly with pressure, so you're doing a good thing by moving them outboard.
 

Wntrmute2

Not So Mediocre Member
Ya might want to think about the bolts at the centers of the Ls. Kinda defeats the air core - which won't saturate - with a bit of metal, which will. It'll also raise the value.

To Deke609 - caps are microphonic. Thier value varies slightly with pressure, so you're doing a good thing by moving them outboard.
OK. I appreciate the advice. Does it matter that they are brass bolts? Or I might just hot glue them down.
 
Many thanks guys. That is very helpful.
... Use good wire ...

... Are you sure you want to do this to your new speakers?

Any recommendations on wire that is reasonably priced?

As to whether I want to mod the new speakers. Yeah, modding and tweaking stuff is a huge part of my enjoyment of this hobby. I like the tinkering as much as the listening. If all goes well, the only apparent physical change will be the addition of a new pair of binding posts on the back of the cabinet.

@Wntrmute2: I like your crossovers with Lpads.

I hadn't thought of using Lpads but adding one to the LF section of my crossover might address one of my concerns. Going by pics posted online, it appears that the stock LF section of the Lore crossover uses a 5.6 uF 'lytic in series with an inductor and a 6R2 resistor. I haven't opened the speakers yet and so haven't tested the cap, but I expect that, b/c it's a 'lytic, it has some non-trivial amount of ESR. On Mouser I found one example of 5.6 uF/100VDC cap with an ESR of 4.1 ohms! That's substantial. When I replace the 'lytic with a film cap that ESR will be pretty much gone. If I can't find a resistor that makes up the difference (e.g., 6R2 + 4R1 = 10R3), maybe an Lpad is the way to go. I have a handheld LCR meter that I'll use to figure out the ESR of the stock cap.

Does this make sense to people?

@Pat McGinty: many thanks for the confirmation. I appreciate your expertise in speaker design.

cheers and thanks, Derek
 

StevenZ

Pending Gold Star Member
I plan on doing external crossovers with my Audio Note speakers with upgraded parts as well so this thread is the info I needed. Thanks
 
I've built (rebuilt?) one pair of standmount speakers with external crossovers, for the same reason as you are thinking -- the components themselves are significantly larger than internal space allows. The crossover was built onto a piece of pegboard, about 12" x 12". I designed it with a set of barrier strip terminals, for relatively easy wiring. Mind you, these are audiophile grade barrier strips. Because the speakers are mine, I just ran the tweeter cabling out the rear reflex port hole. A bit tacky, but hey. It's my tacky. There's even a custom built set of cables (14g x 4) with quick-connect spades on the crossover end, and "other" termination on the speaker end. This way I can keep the crossover close to the amplifier, since both channels are on the same chunk of pegboard.

My only concern, other than my preternatural tackiness, is if someone were to inadvertently connect the speakers straight to an amplifier -- it would bork the tweeter in seconds flat.
 

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I don’t want to dampen anyone’s enthusiasm for DIY but I think some cautions are in order.

First, caps have a big impact on sound quality as I am sure you know, but the designer chose these particular caps for his speaker. If you like the sound of the stock speaker, you may find your “better” caps throw off the tonal balance and make the speakers less satisfying.

Second, most speakers take a good while to break in so you should wait a couple hundred hours before making any changes, just to make sure you can evaluate whether the changes are an improvement over the stock speakers or not.

Third, you should also allow sufficient time for the new caps, binding posts and wire to break in before making a final decision on whether the changes are an improvement.

Fourth, the modified speaker may not be easy to sell. The changes regarding outboard crossovers and an extra set of binding posts will permanently change the appearance of the speakers so the changes can’t be reversed without showing traces of the mods. You might want to try a single cap swap first, even if it’s a temporary lash up inside the speaker. That way if you aren’t wowed by the change you can go back easily. If you do like the change, then you can proceed with the whole plan.
 
My only concern, other than my preternatural tackiness, is if someone were to inadvertently connect the speakers straight to an amplifier -- it would bork the tweeter in seconds flat.
Thanks jhoyt. That's a good point. I think I'll add a warning/reminder label above the binding posts. If the speaker had rear ports, I'd be tempted to follow your wiring example. But the Lore has twin front ports. I like to think I'm a function-over-form kinda guy, but the mental image of wires coming out of the front of my speakers makes me shudder. So I guess I do have some aesthetic limits!

@Salectric: many thanks, and all valid points. I will follow 2 and 3 re break-in. Regarding the designer's choice of caps - in my case I think this is less of an issue. There is a cap "upgrade" option when ordering the Lore that get's one ClarityCap or Mundorf caps (depending on availability) instead of the stock Daytons. This leads me to believe that many different caps may work. I went with stock, knowing that I'd want to experiment with my own choice of caps. I can also experiment with ClarityCap CMRs in addition to copper foils - I already have the required values of CMR in my parts bins as well. Regarding resale value - totally true, but I won't be selling. When I let go of them they will either get passed on to my son or "sold" to a friend who will never get around to paying me. But I do agree with your cautions.

I've also made a bit of progress on the plan. After studying the pic of the xover a bit more, I realized the LCR LF section is in fact a simple first order jobby with the RC forming a Zobel network. Having done a bit of reading about ZL's I'm now inclined to leave the ZL as is. The ESR of the 'lytic cap may be playing a role in the woofer tuning. Since ESR varies with frequency (high at low frequencies, low at high frequencies), I'm guessing a fixed resistor in place of the ESR might compromise the ZL. Upshot: simpler plan and no need to buy caps! Awesomeness!

cheers, Derek
 
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