Where do I cross over a TB W4-1320SJ and a Dayton ND16FA-6?

[G]

Hi all. Really getting serious about building a set of Vampyrs using a TB w4-1320SJ with a small dome tweeter to add a little sparkle in the top end. I am looking at this tweeter:

http://www.parts-express.com/pdf/275-025s.pdf

The specs say that it will go up to around 27KhZ. Looking at it's response curve where would you cross the tweeter over? Also, should I use a 1st order or a second order crossover? Here is the datasheet for the W4-1320SD which should be close to the SJ:


http://www.mx-spk.com/image/W4-1320SD

[G]

This might be a nice tweeter to use also:

http://www.parts-express.com/pdf/275-200.pdf

All of the people that reviewed it liked it a lot. It is a Dynavox TD2801XL.

[G]

I think I will try first with a Fostex FT17H. I will try crossing it over at around 18KhZ with a 8 ohm Lpad to bring the dBs down. I'm going to build the test pair out of MDF so if they sound like crap with this driver no great loss.

[G]

After a little more searching for a worthy tweeter to use with the W4-1320SJ in a pair of Vampyre cabs I think that this one might get the job done:

http://www.swanspeaker.com/product/htm/view.asp?id=10

I want to cross this over very high and would welcome some suggestions on where to do it. I would like to use a second order but a third order might be in order? I'm also going to have to get creative with the bracing in the Vampyre cabinet to squeeze a tweeter in there. Any suggestions as to how close I should mount the tweeter to the driver? Any comments or suggestions from anyone at all? Here are the plans for the Vampyre cabinets in case anyone doesn't know which design I am referring to:

http://homepage.mac.com/tlinespeaker...1v1-010109.pdf

I think that Scottmoose designed them.

[Fast1one]

Why crossover with a steep crossover? Since you are crossing over high (somewhere around 8khz-15khz I would think with a full range driver) Just experiment with capacitors in line with the positive terminal (6db/octave) until you get satisfying results. You can also add an L-pad to the tweeter to fine tune the level.

Head over to radioshack and buy some cheapo caps to experiment. I would start with 2uF and go from there...

[G]

Originally posted by Fast1one
Why crossover with a steep crossover? Since you are crossing over high (somewhere around 8khz-15khz I would think with a full range driver) Just experiment with capacitors in line with the positive terminal (6db/octave) until you get satisfying results. You can also add an L-pad to the tweeter to fine tune the level.

Head over to radioshack and buy some cheapo caps to experiment. I would start with 2uF and go from there...

Well to be absolutely honest I thought I needed a steep crossover because I have no idea what a frequency response graph is showing me and I don't really know what I'm doing. I would like to build these speakers because I know that they are well designed. I want to use the W4-1320SJ because it has a better xmax that the FE103E and I want to use the ribbon tweeter because I like sparkle in the highs and I have heard that the TB driver I want to use leaves a little to be desired in the sparkle category but does everything else pretty damn well. I wasn't sure if a first order would do the job. The tweeter datasheet recommends a 2nd order but then again I doubt they normally use this crossed at 10k - 15k.

[awedio]

Absolutely use a first order Xover. Anything higher order than that and you will lose any benefits of a "full-range" type of sound. Keep it simple.

The TB 1320 sounds better if you low-pass it just because while the high-frequency response is there, it's quite directional and not that refined. I would try crossing over at 8-10Khz - my speakers use the 1320 and I cross them over to a 1" alu dome at 8kHz with a series first-order. But mine are time- aligned - you may have to crossover higher and experiment with driver polarity for the best matchup if you keep both drivers on the same plane.

As an option, I would consider mounting a tweeter on top of the cab or off to the side in a pod and time-aligning it.

The little dayton tweeter is cute and OK but you may blow it up easily at higher volumes with a 1-st order slope. Ask me how I know... depends on how loud you listen unless the xover is up over 12kHz.

[Fast1one]

Have you confirmed that the driver works in that cabinet? I would make sure it does...

As far as the tweeter goes, it will do just fine crossed over very high with only a 6db/octave crossover. Like I said, I would start 2uF for a crossover point and reduce the values. For an 8 ohm tweeter, that is a crossover point of 10khz. Halving the value doubles the crossover frequency. Doubling the value halves the crossover frequency.

Many have had success crossing the tweeter much higher than one might be led to believe. For example, many have used the Fostex FT17H with a 1uF capacitor or lower, effectively crossing over the tweeter at 20khz. This should give you the sparkle you desire, without disturbing the rest of the response of the full range driver.

All you really want to do is fill in the last 1/2 or 1/3 octave of the frequency response that is left out by the full range driver. Really, any tweeter that has an extended response to 20khz or more will work fine

[G]

Originally posted by awedio
[B]Absolutely use a first order Xover. Anything higher order than that and you will lose any benefits of a "full-range" type of sound. Keep it simple.

Sounds good to me.

Originally posted by awedio The TB 1320 sounds better if you low-pass it just because while the high-frequency response is there, it's quite directional and not that refined. I would try crossing over at 8-10Khz - my speakers use the 1320 and I cross them over to a 1" alu dome at 8kHz with a series first-order. But mine are time- aligned - you may have to crossover higher and experiment with driver polarity for the best matchup if you keep both drivers on the same plane.

Can you post a schematic of the crossover? Are you saying I need to run a low pass on the 1320 and a first order on the tweeter? So much for simple.

Originally posted by awedio As an option, I would consider mounting a tweeter on top of the cab or off to the side in a pod and time-aligning it.

The cabinet is about 52" tall so mounting on top is out. I suppose I could build in a enclosure on the side but then we get into the "how far away from the driver do I mount the tweeter?" problem and then there is the infamous "do I mount it above or below the driver" problem.

Originally posted by awedio The little dayton tweeter is cute and OK but you may blow it up easily at higher volumes with a 1-st order slope. Ask me how I know... depends on how loud you listen unless the xover is up over 12kHz.

I think I am going to go with the ribbon tweeter. Anyway the amp that will be driving these is a whopping 1watt 12B4A parafeed amp.

[G]

Originally posted by Fast1one
Have you confirmed that the driver works in that cabinet? I would make sure it does...

I have compared the specs between the 1320 and the FE103E and they are pretty close. The only minor difference (I think) is that the 103E has a vas of about 7 liters and the 1320 has a vas of about 6 liters. Other than that they are close except of course for the much larger xmax of the 1320 (3mm) compared to the 103E (.4mm).

Originally posted by Fast1one As far as the tweeter goes, it will do just fine crossed over very high with only a 6db/octave crossover. Like I said, I would start 2uF for a crossover point and reduce the values. For an 8 ohm tweeter, that is a crossover point of 10khz. Halving the value doubles the crossover frequency. Doubling the value halves the crossover frequency.

I understand the circuit part of the xover. It's the "blending" of the two drivers together that is less than intuitive to me. To say the least.

Originally posted by Fast1one Many have had success crossing the tweeter much higher than one might be led to believe. For example, many have used the Fostex FT17H with a 1uF capacitor or lower, effectively crossing over the tweeter at 20khz. This should give you the sparkle you desire, without disturbing the rest of the response of the full range driver.

I understand. I have a friend who uses a .22uF cap to xover a bullet tweeter with a pair of Fostex drivers. It works quite well. The ribbon I want to try is not 8 ohms but I can calculate the cap no problem. I am concerned about the time alignment issue though.

Originally posted by Fast1one All you really want to do is fill in the last 1/2 or 1/3 octave of the frequency response that is left out by the full range driver. Really, any tweeter that has an extended response to 20khz or more will work fine

That and it need to have good horizontal dispersion and a nice smooth presentation. I think the ribbon will provide that. "Think" was the key word in that last sentence.