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Blown tweeter: a question...

Instead of replacing the Avatar crossover capacitor, would it be possible to replace the crossover with a high quality Eminence crossover and plate?

The one that looks good for the Peerless tweeter is the Eminence px2-1k6, part number 290-620, a two-way with a 1,600 Hz crossover point.

The main question would be whether the crossover hole in the Avatar cabinets is the right size, which according to Parts Express is 6" x 3.875".

Seems that this would work even better than the stock crossover, while adding the lamp protection and current limiting to further protect the tweeter.
 
BruceWane said:
If Avatar's gonna charge you anything for the new attenuator.......Try PartsExpress part #260-265 instead. Handles 100 watts (plenty for a tweeter circuit), costs $6.35. They've got one that .50 cheaper without the knob & plate, but just in case your existing knob won't fit, I'd get this one. You'll have a hard time blowing this one.


Well, Bruce, as you may remember I went with a replacement avatar attentuator and today I ended up frying it again. So I just ordered that 100w L-pad you suggested from Parts Express which I think should solve this once and for all. The avatar is only 15w so I think that is the problem. It can't handle the juice I give it. I hope the tweeter isn't messed up...I love that thing!!
 
Schwinn, while you still have the Avatar crossover out, would you mind measuring the dimensions of the cutout in the cabinet and posting it here?

Enlarging the cutout to fit an Eminence crossover wouldn't be a problem, but if the cutout is too large in either direction, then this idea would not work. Let's see if this really is an option.

I think the Eminence would hold up better, and the crossover design is a real two-way instead of routing full-range to the 12's and highs to the Peerless. Plus you get lamp protection and current limiting at high volume for the Peerless.

I would send the cutout question to Dave Noss, but he's going on vacation this week!
 
MichaelVee said:
Schwinn, while you still have the Avatar crossover out, would you mind measuring the dimensions of the cutout in the cabinet and posting it here?

Enlarging the cutout to fit an Eminence crossover wouldn't be a problem, but if the cutout is too large in either direction, then this idea would not work. Let's see if this really is an option.

I think the Eminence would hold up better, and the crossover design is a real two-way instead of routing full-range to the 12's and highs to the Peerless. Plus you get lamp protection and current limiting at high volume for the Peerless.

I would send the cutout question to Dave Noss, but he's going on vacation this week!

Well I'm hoping to use the Avatar backplate still. The part I ordered is the attenuator which secures to the back of the original backplate. I hope it fits. As for a crossover, I'm using a simple capacitor to make things easier. But I can measure the cutout for you.
 
One way or another that attenuator will work. I'm pretty sure it'll be a bit larger in diameter, but it's got a 1" long shaft; you'll want to get a spacer of some sort from Home Depot. This will offset the body of the attenuator far enough from the jack plate so that it can clear the inside of the cabinet, just in case the larger size "overhangs" the edge of the plate. Since l-pads do get hot, you might want to avoid using a plastic spacer if possible. Try for metal or aluminum. Hard nylon would probably be alright. Just not plain plastic. Figure that at the absolute extreme, that attenuator could be burning off 100 watts of electricity, so it could get about as hot as a 100 watt light bulb.
 
MichaelVee said:
Schwinn, while you still have the Avatar crossover out, would you mind measuring the dimensions of the cutout in the cabinet and posting it here?

Enlarging the cutout to fit an Eminence crossover wouldn't be a problem, but if the cutout is too large in either direction, then this idea would not work. Let's see if this really is an option.

I think the Eminence would hold up better, and the crossover design is a real two-way instead of routing full-range to the 12's and highs to the Peerless. Plus you get lamp protection and current limiting at high volume for the Peerless.

I would send the cutout question to Dave Noss, but he's going on vacation this week!

Well, my humble opinion of course, but I tend to not put any frequencies through a tweeter that don't absolutely have to go there. I put as much frequency range as possible through regular cones, because they tend to sound the most natural. If a speaker's got good response up to 3K, I'm not inclined to cross it over at 1.6K, sending those frequencies instead to a tweeter. Even the best tweeters get kind of "honky" sounding in the lower part of their range, so it's usually best to let your woofer or mid handle as much high end as possible.

And in this particular situation, these two components complement each other really well. The 12's go high enough, and the tweeter goes low enough, so that a simple, cheap 1st order high pass filter is all it needs. You could certainly wire in a bulb for protection if you want, but since the tweeter handles 100 watts, I really don't think it's necessary. If it were a PA cab, maybe. But the most high end you're going to get out of a bass is going to be transients while slapping, not sustained wattage like you get from vocals or synth.

I dunno, I guess it's also 'cause I'm a cheap b*stard. Nothing wrong with Eminence crossovers, they are nice, but kinda overkill for this situation. Kinda hard to justify putting a $100 crossover into a $325 cab. Parts Express has their house brand (Dayton) for about half the price, so if I were to consider doing this, that'd be my choice. All the specs on them look good. Since the high pass is a 3rd order design, the crossover point is OK for this tweeter as far as protection from excessive low frequencies. 1.6K would be too low if it were a 1st order, marginal if it were a 2nd order. Also note that the Eminence crossovers only handle 400 watts, the Daytons 600.......that's due to the limitations of the coils used in low pass filters. You can build a low pass circuit that'll handle 1000 watts, but it ain't cheap. If you put either of these crossovers in an Avatar cab, you will be lowering your wattage capacity a good bit. If you let the woofers roll off high frequency response naturally, you don't place the additional limit on your wattage, and you save a few bucks, too.

Now, it could very well be that a different crossover scheme might sound better; if I had the time and resources, I'd play around with various crossover points and see what sounded best for each and every cabinet. But, time and resources being limited, the first thing I try is what looks good on paper. If it sounds really good, I don't put a lot of time and energy going for "great". You end up wasting way too much looking for that holy grail.

Again, all just my opinion, your mileage may vary......
 
The avatar-peerless combo with the simple crossover sounded fantastic. I don't want to change a thing except have an attenuator that can handle the peaks when slapping. Both times I've fried the attenuator were during a song where I slap and pop the whole time (same song ironcally enough :p ) The difference this tweeter makes is impressive. The cab sounds twice as good now (until last night :( ).
 
I've just ordered the same Peerless tweeter and the 6.8 micro-farad capacitor from PartsExpress. I plan to put these in my SWR Goliath Senior. I do have a couple of questions though, hopefully one of you can answer them.

In my SWR cabinet, the stock crossover frequency is 5khz to the Foster horn. If I use the 6.8uf capacitor in place of the stock one, despite the probable differences in filters between Avatar and SWR, can I expect to get a crossover frequency down in the 3khz range? I just ordered the capacitor because it was super cheap and I thought I may as well. If it won't work, that's fine. Any info on that would be excellent.

I'll post up results and pictures of my finished product when it's done.
 
BassIan said:
I've just ordered the same Peerless tweeter and the 6.8 micro-farad capacitor from PartsExpress. I plan to put these in my SWR Goliath Senior. I do have a couple of questions though, hopefully one of you can answer them.

In my SWR cabinet, the stock crossover frequency is 5khz to the Foster horn. If I use the 6.8uf capacitor in place of the stock one, despite the probable differences in filters between Avatar and SWR, can I expect to get a crossover frequency down in the 3khz range? I just ordered the capacitor because it was super cheap and I thought I may as well. If it won't work, that's fine. Any info on that would be excellent.

I'll post up results and pictures of my finished product when it's done.

As a general rule I like to go at least one octave above the tweeter's resonant frequency if I'm using a 12dB per octave filter, and at least 2 octaves above if it's a 6dB filter.

For this driver, 2 octaves above equates to 3.12K. You've got yourself a crossover point of just under 3K, more like 2.9K, and a slope of 6dB per octave. It's fairly close but 2.9k is not quite 2 octaves. It should still work but I can't guarantee it.

I would have paid the extra dollar and got a slightly smaller cap. 6.4uf or smaller.
 
Petebass said:
As a general rule I like to go at least one octave above the tweeter's resonant frequency if I'm using a 12dB per octave filter, and at least 2 octaves above if it's a 6dB filter.

For this driver, 2 octaves above equates to 3.12K. You've got yourself a crossover point of just under 3K, more like 2.9K, and a slope of 6dB per octave. It's fairly close but 2.9k is not quite 2 octaves. It should still work but I can't guarantee it.

I would have paid the extra dollar and got a slightly smaller cap. 6.4uf or smaller.

I may do that. I have a local store that I can get caps from. They sell audio-quality ones similar to the one I ordered. I simply ordered this one because it was the one suggested earlier and it was only a few bucks so even if it is wrong, it's no big deal. I'll have to experiment a bit, I guess.

Is there a formula derived from the basic capacitor formulas that allows you to determine the approximate crossover frequency?

*1st edit for grammar*

*2nd edit*: I just pulled the back plate off my Goliath Senior, and notice that there are TWO capacitors there. I will take a picture and post it tomorrow. I'm just wondering if anyone having experience with SWR's crossovers could give me tips on lowering the 5kHz crossover frequency, or if putting this 6.8uf cap in place of one of those do the job?
 
BassIan said:
I may do that. I have a local store that I can get caps from. They sell audio-quality ones similar to the one I ordered. I simply ordered this one because it was the one suggested earlier and it was only a few bucks so even if it is wrong, it's no big deal. I'll have to experiment a bit, I guess.

Is there a formula derived from the basic capacitor formulas that allows you to determine the approximate crossover frequency?

*edited for grammar*

If Bruce has tried 6.8 and it works, then go for it. It was always very close.

The formula to work out the capacitor valur for 1st order filter is:-

Cap(uF) = 1/(2*Pi*Ohms*Hz)*10^6.

So 1/(2*3.14*8*3000)*10^6 = 6.48uF


If you've already got the cap and want to know what the crossover frequency is:-

F = 1/(2*Pi*Ohms*Cap)*10^6

So for your 6.8uF cap, 1/(2*3.14*8*6.8)*10^6 = 2962Hz.


Now that you know how it's done, I find it just as easy to use the charts on Link Removed as a guide.
 
BassIan said:
*2nd edit*: I just pulled the back plate off my Goliath Senior, and notice that there are TWO capacitors there. I will take a picture and post it tomorrow. I'm just wondering if anyone having experience with SWR's crossovers could give me tips on lowering the 5kHz crossover frequency, or if putting this 6.8uf cap in place of one of those do the job?

I just noticed the second edit.

We'll need more info. Are the 2 caps wirered up so they're parallel to each other?
 
BassIan said:
*2nd edit*: I just pulled the back plate off my Goliath Senior, and notice that there are TWO capacitors there. I will take a picture and post it tomorrow. I'm just wondering if anyone having experience with SWR's crossovers could give me tips on lowering the 5kHz crossover frequency, or if putting this 6.8uf cap in place of one of those do the job?

You're probably going to need to remove both the existing caps and replace them with the single 6.8uf. But please do take some pics so we can see exactly what's going on there.

It'll be intersting to see how this combination sounds. Since I don't know how high the SWR 10's go, I don't know how much of a frequency gap you'll be filling with the lower crossover point. My guess would be that it's going to be roughly the same. Even though I'm pretty sure that SWR's drivers are going to have more low end response than the off-the-shelf Eminence drivers that Avatar uses, that doesn't mean that their high end roll off point will be correspondingly lower. I kinda think that most 10" speakers that have efficiency and low end suitable for bass guitar are gonna have high end roll-off point in the 3~4K range, not all that different from a 12, just a tad higher. There are 10's that go higher, but then they start getting weaker in the lows.

Since your 10's may go a bit higher than the Eminence 12's in Schwinn's "test" cabinet, you may be able to use a higher crossover point and still have good, even frequency response. So if the cab ends up excessively strong in the mids because of frequency overlap, you could pop in a different cap for a higher crossover point. But I wouldn't worry about needing to take it higher to protect the tweeter. Pete's rules of thumb are a good idea, and this crossover point is pretty much the absolute lower limit for this driver using a 1st order circuit. The 6.8uf cap puts you [email protected], [email protected], -15db@725Hz; so at the bottom of the drivers frequency range (1KHz), it's down about 11 or 12db, which means it's getting less than 1/10th of the input wattage. Even if you were to hit the cab with a 1Khz sine wave at 1000 watts, the tweeter would only recieve 100 watts of that, which is within it's rms rating. If this were a PA cab that would be reproducing vocals and synthesizers, it'd be a good idea to cross it over a bit higher, but I don't think it's going to be possible to harm it with a bass. Unless you're really into extreme harmonics.

BTW, thanks to Pete for the formulae; but if that math looks a little too intimidating here's an on-line crossover calculator..........

Invalid Link Removed
 
If you start designing your own filters/crossovers, one thing you will find is that they just don't make the caps and coils in the exact values that you want. You can use combinations to get the values you need (i.e. (1) 4.2uf cap and (1) 3.7uf cap in parallel = 7.9uf ........coils get hooked up in series, and there are other methods). But when you get into building a full-blown crossover, all the multiple caps and coils can get expensive and LARGE. You can end up with a crossover design that would dang near cover the entire back panel of the speaker. So often you'll compromise a little, moving your crossover point a few Hz either way so you can use fewer components.

In this particular case, I selected the 6.8uf cap because it was the closest available value in a single component; I was shooting for 3KHz, and this came up very close. Could have gone with a 6.2uf which would have put the -3db point at 3.2KHz, but that was getting further into the roll off curve of the 12's and I wanted to avoid a frequency dip in the overall response.
 
The SWR crossover is 18dB/octave highpass filter... I forget the exact values, but the network is a T...with the coil in shunt between the two caps.

There was a picture of the crossover in one of the BP shootouts a while back (either the 2x10 or the 4x10).

The SWR crossover also has a lightbulb to protect the tweeter and an L pad for level control.

The component values don't fit into the formulae for a 3rd order Butterworth filter...but it works...
 
BillyB_from_LZ said:
I have an SWR crossover in a homebuilt 2x10 of mine. I saw the board the other day and IIRC the caps are 2.2 uF and the coil is 0.17mH. I may be way off though... I turned 45 this year and developed a bad case of CRS (can't remember shi*).

That'd be in the 6K range for a 3rd order filter, which is appropriate for the horn they use. So maybe that CRS ain't as advanced as you thought. :)

Kinda interesting to think that you're probably getting practically nothing between 4K and 6K out of an SWR cab though.........