Question on Monitor 10B crossover...

jon s

I took the crossover from the Monitor 10B out to see what parts are required to upgrade... I can see that there are two resistors, one 2.5 ohm 10% @ 5w and the second is 2.7 ohm 10% @ 5W. There's three caps, I think one is 34microf @ 50V (on the right) and I have no idea what the big yellow one is (labeled TI 0012-1 12j100V). I also cannot see what the value of the black resistor on the bottom is...can someone confirm that I have the parts correct? Since they do not seem to have 2.7 ohm resistors, can I substitute it with another 2.5 or do I go to a 3 ohm?

What parts do you think I should use to replace the stock items?

Thanks in advance...

jon s

I saw in another posting that the suggested parts are:
4 12uf Sonicaps (to replace the yellow one and the black one on the bottom?)
2 34uf Sonicaps (to replace the one on the right)
2 2.5 ohm resistors
2 2.7 ohm resistors (do they even have 2.7 ohm resistors now? can I use all 2.5s?)

are the mylar and electrolytic caps interchangeable...

F1nut

That is the correct part list.

(4) 12uf Sonicaps
(2) 34uf Sonicaps
(2) 2.5 ohm resistors
(2) 2.7 ohm resistors

jon s wrote:

are the mylar and electrolytic caps interchangeable...

Yes, but you want to upgrade to film/foil caps.

You can find a nice selection of caps and resistors here,

http://www.soniccraft.com/products/capacitors/film.htm

http://www.soniccraft.com/mills_resistors.htm

dcmeigs

Oh, come on! That's too easy.

There are many to choose from

jon s

The Sonicaps are way over my budget... I am looking at these... are they okay??

2 Mills 2.5 ohm resistors....
2 Mills 1.2 ohm resistors + 2 Mills 1.5 ohm resistors to make up for the one 2.7 ohm resistors (what wud be the issues if I used a 2.5 or 3 ohm resistor instead?)
2 Jantzen 22uF 400V crosscap cap
6 Jantzen 12uF 400v crosscap cap (I am planning to combine a 22+12=34uF crosscap)

I know I need to hook up the 1.2 and 1.5ohm resistors in series to make 2.7ohms
but my question is...are the crosscaps polarized? All this is setting me back about $100. About double what I paid for the speakers...

Thanks in advance.... but I am such a noob.... and I'd hate to see how much it wud cost me to upgrade the SDA1Bs!!!

Face

Crosscaps aren't polarized.

jon s

so, is my selection of parts okay? What about the 2.5 or 3.0 ohm resistors iso of the 1.2+1.5 in series?? Would these parts be sufficient for the upgrade? Thanks...

Face

Janzen makes a 33uf, that would be better than the 12+22 due to the lack of space.

F1nut

2 Mills 1.2 ohm resistors + 2 Mills 1.5 ohm resistors to make up for the one 2.7 ohm resistors (what wud be the issues if I used a 2.5 or 3 ohm resistor instead?)

I'm not sure what the problem is with you and the 2.7 ohm resistor. Sonicap sells them. You could also look at Dayton's since you're on a tight budget.

jon s

i'm just trying to buy everything from one source (parts express).

so going 34uF to 33uF is no biggie then...

McLoki

If you end up going with all cross caps, let me know what you think of the upgrade. I have thought about doing the same with my Monitor 10's. (upgrade cost for both crossovers should be under $60 or so)

Michael

McLoki

Face wrote: »

Crosscaps aren't polarized.

Seriously - is that important? (I am not sure either - for the record I would be upgrading Monitor 10's, Series II) I was thinking of going with all cross caps as well.

Boywonder

Speaker crossovers use non-polarized capacitors. It's only an issue with electrolytics (they come both ways). All film caps are non-polarized.

A 33 uf should work fine in place of a 34 uf; it's within 5% which is probably less/tighter than the tolerance of the original. If you want, you can bypass (parallel) a 1 uf with the 33 to get 34 uf.

I have Solens in my modified monitor 10's and they sound much better than stock.

dcmeigs

Jon, before you buy the Jantzen caps for the high pass you might want to read this Capacitor Review.

The reviewer claims that Jantzen has an issue with excessive silibance. That could be disqualifying if it is extreme. The Jantzen should be a fine budget cap in the low pass.

There is a thread here somewhere with links to several reviews in addition to this one (which was posted by F1nut, if that helps in your search).

I was planning on doing some monitor 10s with Jantzen all around but I'm reconsidering after reading that thread. I was wanting to do a cheap cap comparison but I now see that that road has been well traveled.

McLoki

dcmeigs wrote: »

Jon, before you buy the Jantzen caps for the high pass you might want to read this Capacitor Review.

Just to keep things in perspective. Jantzen crosscaps were rated at the same level as the solen caps that everyone thinks so highly of (both rated a 6.5) but not as good as the soniccaps (8.5)

jon s

Thanks for the heads up!!!

dcmeigs

Here is what the reviewer has to say exactly about the Jantzen Standard cap:

They do emphasise “S” and “T” sounds a little, so don’t use them in the signal path! Due to their low cost they are ideal for parallel capacitors in the low-pass of a woofer for example where in low budget systems electrolytics are often found

He says this about the Solen Ch

heiney9

Face wrote: »

Janzen makes a 33uf, that would be better than the 12+22 due to the lack of space.

Jon, Face is correct; its always better to use a single cap than it is to use (2) caps to attain a specific value. Most original parts in Polk x-overs are in the 10-20% tolerance range so using a 33uF in place of a 34uF is just fine and well within original tolerances.

If you have to use (2) caps to attain a specific value try to get caps that are as close to the same value as possible.

EX: if you need a 24uF cap using (2) 12uF is much better than using a single 2uF and a single 22uF.

If this helps here is the link for when I did my 5B x-overs.

5B crossover thread

ShinAce

Not all caps need to be top notch.

The caps for the tweeters need to be the best. The caps for the woofer can be of almost any quality.

Likewise, crossover coils on tweeters can get away with thinner wire. The crossover coil for a woofer should use the thickest wire within your budget.

I don't have time to look at the schematic and tell you which components need to be high quality and which can be downgraded.

jon s

OK, I am about to jump into recapping my Polk Monitor 10Bs... I got the caps, and I have a couple of questions...

1. I have to "stack" (parallel) a couple of caps to meet the value required. Do I need to glue the caps together?

2. What is the reason putting glue in the first place? All the caps in the crossover are glued to the board and I figure there's got to be a reason for that.

3. If required, do I have to use a heat glue gun or will plain old silicon glue work?

Thanks in advance...

F1nut

1. Yes.
2. Helps hold them to the board, to each other and helps with damping.
3. Use hot glue, NEVER use silicone.

dcmeigs

Question 2 - What F1nut said. Glue them well. The caps sit behind the PR and take a pounding from it. If they are loose they resonate with the bass frequencies and that can effect SQ. Glueing them down real well helps to reduce this.

jon s

All right!!! finished with the upgrade, used all Jantzen crosscaps from Parts Express... was relatively straightforward. The only issue I had was the inducter coil under the binding plate broke off from the crossover board... I had too stretch the coil pretty tight to the board and resolder it.

So far, the sound seems to be more focussed, imaging is more stable, depth is a bit deeper but the bass seems very light. Is this normal for the break in period?

BTW, I would take pictures of the upgrade, but my work was kinda sloppy and I'd be embarrassed to show them here...

F1nut

So far, the sound seems to be more focussed, imaging is more stable, depth is a bit deeper but the bass seems very light. Is this normal for the break in period?

I've never used Jantzen caps, so I don't know how they sound, but the bass should be there right off the bat.

Face

Let's see the pics.

ben62670

If it is one speaker, and not both It could be the large inductor wire wasn't clean enough for a good contact? Feel free to unwrap one turn of the coil.
Ben

heiney9

If found with the Solens in my 5B's, it took awhile for the bass to show up. Play the crap out of them to get them broken in and see if that doesn't help. Ben makes a good point as well.

In general replacing the caps should always give you some better bass response. Perhaps it's just much cleaner sounding bass and I can tell you cleaner more controlled bass takes some getting used to if the former amount of bass was bloated and had some overhang.

Give it some time and throw a lot of familiar music at them and re-evaluate in a couple weeks.

H9

jon s

I am thinking of replacing the speaker gaskets as a precaution. I also noted that both of the binding post cover plates do not have any sort of gasket which surprised me.

Face

PE carries it. Or you can pick up thin weatherstripping at Home Depot.

jon s

I replaced the speaker gasket on the passive radiator and the crossover plate. No difference. Tried playing some different CDs and noted something weird. If you ever listened to track 3 (Southampton) on the soundtrack of Titanic, it should rattle the house with deep bass from the bass drums. On the 10Bs right now, it seems mellow, not booming like it does on the LSi15s. Contrarily, while listening to James Taylor's song "Gaia" at about 4:15 into the song, there is a drum roll that also shakes the bass. On the 10Bs, the drum roll really booms. Yet, on the LSi15s, the drum roll is more subdued. Doesn't make sense, the bass is reversed on the two songs. Titanic is weak on the 10s and powerful on the LSi15s and James Taylor is strong on the 10Bs and weaker on the LSi15s...

F1nut

Two very different speakers, one using a PR and the other a port, resulting in very different bass.

As for the gaskets, there's nothing wrong with the originals unless they are torn or missing. The binding post plates came with gaskets, they are thin and perhaps hard to see.