Vintage Monitor 10B tweeter replacement does not get ride of buzz

movtarget

Hey, NMS

Although I'm no expert, I would like to join in the fun. Need to upgrade my SRS's down the road and could possibly help and learn at the same time. We could even get Fireman involved and call it a mini.

Movtarget

John in MA

lightman1 wrote: »

Fair enough. But wouldn't a cap lose it's speed to discharge voltage over the years?
Fishing.

Not sure about speed, but they can change in value and resistance. Incorrect crossover frequencies and lower tweeter levels result. In speaker crossovers they're used as filters and not intentional electric storage. Keep in mind that it's not a set thing, not all caps will degrage, and some will more than others. Electrolytics go first, even though they can last forever in limited situations. Mylar, poly, etc are slower to deteriorate.

Unless you're shooting for name-brand parts or have a bad one, I don't think I'd fuss with replacing resistors. Especially the big wirewounds used heavily in crossovers. Probably most problem resistors used in audio are ones that get cooked or blown up in power amp stages.

lightman1

John in MA wrote: »

Not sure about speed, but they can change in value and resistance. Incorrect crossover frequencies and lower tweeter levels result. In speaker crossovers they're used as filters and not intentional electric storage. Keep in mind that it's not a set thing, not all caps will degrage, and some will more than others. Electrolytics go first, even though they can last forever in limited situations. Mylar, poly, etc are slower to deteriorate.

Unless you're shooting for name-brand parts or have a bad one, I don't think I'd fuss with replacing resistors. Especially the big wirewounds used heavily in crossovers. Probably most problem resistors used in audio are ones that get cooked or blown up in power amp stages.

I can dig it. I am, by far, not an expert on x-overs.
Brain Poot! Cap value in series with a small speaker will take out the low Hz
(6db i.e.)
Thanks John
Back to you nms

F1nut

A bad cap is a bad cap regardless. Distortion is a tell tale sign. However, swapping the crossovers is easy enough to try first. A bad connection could cause a "buzzing" as well.

Especially the big wirewounds used heavily in crossovers.

The ones in the Monitor/SDA series are spec'd 5 watt, not very big at all. Since a typical Mills cost @ $2.50 or so and in fact are much better, I think it's a smart choice to upgrade them as long as one is in there anyway.

nms

Alright guys help me out here, I feel stupid asking this but here goes.

So I go to the parts express website and start looking for parts for the X-over. The first part I need is a 12uF electrolytic cap (according to the wiring diagram that I've matched with the X-over). So I click on electronic parts in the sidebar, and then click on electrolytic under capacitors. Well the first thing I see is that there isn't a 12uF cap listed, and it seems their search function is broken.

I know they've got to carry 12uF caps; how do I find them?

Thanks.

nms

movtarget wrote: »

Hey, NMS

Although I'm no expert, I would like to join in the fun. Need to upgrade my SRS's down the road and could possibly help and learn at the same time. We could even get Fireman involved and call it a mini.

Movtarget

Are you proposing a physical get-together? Sounds good, but I have exams for the next 2 weeks, so I doubt I'll get around to doing mine until I'm home for Christmas.

John in MA

nms wrote: »

Alright guys help me out here, I feel stupid asking this but here goes.

So I go to the parts express website and start looking for parts for the X-over. The first part I need is a 12uF electrolytic cap (according to the wiring diagram that I've matched with the X-over). So I click on electronic parts in the sidebar, and then click on electrolytic under capacitors. Well the first thing I see is that there isn't a 12uF cap listed, and it seems their search function is broken.

I know they've got to carry 12uF caps; how do I find them?

Thanks.

Here for a non-polar 'lytic:

http://www.partsexpress.com/non-polorized-electrolytic-capacitors.cfm

Or here for a poly:

http://www.partsexpress.com/dayton-metallized-capacitors.cfm

Poly caps are usually regarded as sounding "better", but they can change the voicing of the system that was designed for the electrolytic. Brighter.

nms

Thanks!

nms

Another dumb question: what's the replacement type for mylar caps? I've got a large yellow 12uF cap from "Mexica" (that's what it says on it) that needs replacing.

Make that 2 dumb questions. Can I use a 33 uF elect. cap to replace a 34 uF one?

nms

I've done some searching and haven't found an answer to what replaces a mylar cap in the current crossover. Anybody have an answer?

thanks

jakelm

2 of these:

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=027-572


and 2 of these:

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=027-592

The resistors are here:

http://www.partsexpress.com/mills-crossover-resistors.cfm?CFID=3401716&CFTOKEN=87204174

Follow the specs, remove and do NOT replace the bypass cap that goes along with the smaller 2ohm reistor.

2 to purchase, 1 for each xover...

The new caps are bigger but will fit just fine...

Your 10's will sound better than ever...

F1nut

^Excellent advice, IMO.^

nms

jakelm wrote: »

Follow the specs, remove and do NOT replace the bypass cap that goes along with the smaller 2ohm reistor.

OK, it took me a minute to figure out what you were saying but I think I got it. You're talking about the 2 ohm resistor and the 12uF cap that are wired in parallel. What you're saying (I think) is that the polypropylene caps are higher quality, and so we don't need the extra "filtering" provided by the 12uF cap wired in parallel. Am I correct?

On the resistor page, I don't see a 2.7 ohm resistor that is shown in the wiring diagram for the speaker. Is it OK to use the 2.5 ohm resistor, or is it necessary to wire 2 resistors in parallel to get exactly 2.7 ohm of resistance?

Thanks for the direct links, and sorry I keep asking so many questions.

jakelm

nms wrote: »

OK, it took me a minute to figure out what you were saying but I think I got it. You're talking about the 2 ohm resistor and the 12uF cap that are wired in parallel. What you're saying (I think) is that the polypropylene caps are higher quality, and so we don't need the extra "filtering" provided by the 12uF cap wired in parallel. Am I correct?

On the resistor page, I don't see a 2.7 ohm resistor that is shown in the wiring diagram for the speaker. Is it OK to use the 2.5 ohm resistor, or is it necessary to wire 2 resistors in parallel to get exactly 2.7 ohm of resistance?

Thanks for the direct links, and sorry I keep asking so many questions.

I did an A/B comparison, using the bypass cap and not using it. The bypass cap created a roll off in the fr responce, that I didnt care for. I found it best with out it..

Yes, a 2.5 will do just fine. The high the resistor value the softer that tweeter will become. If you find the tweeter to "overbearing" then raise the resistor value.

nms

Alright, I think I've got it. Thanks again for all the advice.

Hmm... Total for all of this stuff comes out to a little over $50 including shipping! Ouch!!

F1nut

Wait a sec. The bypass cap is used with the 12uF, not the resistor. Because you are using a better cap, you no longer need the bypass cap. Clear? Another thing, you don't wire resistors in parallel, you wire them in series. So, a 2ohm plus a .7ohm wired in series will give you 2.7ohms. Clear?

nms

F1nut wrote: »

Wait a sec. The bypass cap is used with the 12uF, not the resistor. Because you are using a better cap, you no longer need the bypass cap. Clear? Another thing, you don't wire resistors in parallel, you wire them in series. So, a 2ohm plus a .7ohm wired in series will give you 2.7ohms. Clear?

I'm not sure we're on the same page here, so I'll try to clarify.

I have a 12uF cap and a 2.0 ohm resistor wired in parallel. When he said bypass cap I assumed he was talking about leaving this cap off. (So the bypass cap is a 12uF cap.)

I know the resistors are wired in series. I mentioned wiring them in parallel because doing that allows you to get different total resistances. So to get 2.7 ohm you could have a 2.5 ohm and maybe 2 1 ohm in parallel to add .2 ohm more (just a random example). Since 2.5 ohm is ok, there's no need to do this. Sorry about the confusion.

Clear?

I hope so

rskarvan

Uhmmmm... have you tried a different amp/receiver/etc... to see if the problem goes away? The problem may not be in the speaker at all!

nms

rskarvan wrote: »

Uhmmmm... have you tried a different amp/receiver/etc... to see if the problem goes away? The problem may not be in the speaker at all!

Long story, but it is (in the speaker). If you search in speakers and vintage speakers I have couple threads on the entire process. The crossover is certainly NOT the first thing I looked at in this problem. First: receiver; Second: speaker wire (false positive for a while); Third: tweeter (eliminated when tested new RD0s with same result); Fourth: crossover.

avguytx

How about a picture of this capacitor with the resistor that's wired in parallel....

nms

Attached. Two views. The capacitor/resistor in question is circled in red in the first one.

avguytx

Ok. You don't have a bypass cap so you're good to go there. Of course, it's your call on changing out any or all of the crossovers but if it were me, I would replace the 3 caps and however many resistors there are per speaker. I think those speakers are worth it especially if you have already gone to the expense of getting the replacement RD0 tweeters for them. Just my $.02 of course.

nms

avguytx wrote: »

Ok. You don't have a bypass cap so you're good to go there. Of course, it's your call on changing out any or all of the crossovers but if it were me, I would replace the 3 caps and however many resistors there are per speaker. I think those speakers are worth it especially if you have already gone to the expense of getting the replacement RD0 tweeters for them. Just my $.02 of course.

I'm going to look at (and probably buy) a pair of SDA-2As tomorrow morning, so the RD0s will go in them. I'm going to hold off on upgrading the crossovers for a while because I've spent way too much money on stereo equipment in the past week!:eek:

At some point I will probably upgrade 'em. If it weren't for the cost of the components ($50) I'd go ahead and do it. And actually that'll go up again since I need two more caps @ $7 ea... oof.

And unless I'm playing classical or piano music I can't really hear the tweeter buzz anyway...

Thanks for all the help guys, words cannot describe how lost I would be without you.:o

jakelm

I dont want to sound ugly here, but NOW YOUR NOT DOING IT AT ALL??????/

OK...I got that out of my system....

When you do decide, just do what I said and you'll be 10X's better.:D:D

You have nothing to loose but a better sounding speaker...

nms

I know, I know, sorry. But up until I knew what parts I needed and was actually in the process of ordering them I had no idea how much it was going to cost (I thought like 20 bucks tops). So I wasn't stringing you guys along on purpose, I swear!

And I will do it at some point, just not now.

jakelm

nms wrote: »

I know, I know, sorry. But up until I knew what parts I needed and was actually in the process of ordering them I had no idea how much it was going to cost (I thought like 20 bucks tops). So I wasn't stringing you guys along on purpose, I swear!

And I will do it at some point, just not now.

Its all good.

Lets us know when you do...

F1nut

It's only $50.00!!! Man, some of us spend 10 times that and more upgrading our crossovers.

lightman1

I'll loan you the fiddy at 87.1%.;)

nms

F1nut wrote: »

It's only $50.00!!! Man, some of us spend 10 times that and more upgrading our crossovers.

Yeah, and most of you have jobs and steady incomes.

I'll loan you the fiddy at 87.1%.

Let's see... $50 times 1.871 equals... ooh, um, I'll pass

lightman1

$93.55... Damn this hobby. Don't give up on the re-build.