Poor Man's High-End Monitor - SB/Vifa 2-way

[Andy_G]

OMG.. a design on PE that I can actually get the drivers for at a reasonable cost. (with the current exchange rate, I will not be ordering from the US for a long time) !!

WES Components stock the SB drivers and that Vifa tweet !!.

So, I shall certainly be looking at this this thread with interest.

[jkim]

Jay,
I reduced the series cap like you suggested and that did the trick. I put the series resistor back to 4.7 ohms too. Now it is a lot smoother.

I discovered something else; I can listen a lot lower levels because it is so free of distortion and it is so clear.

Thanks for the design!

Thanks for reporting back. BTW, what kind of resistors do you use for the tweeter padding? And how did you experiment with padding resistance in small increments? I'm just curious.

-jAy

[ctbowman]

Yes, at $45 it will be interesting to see how the new Fountek will fare against our long time favorite Dayton RS. But given the fact that it's a metal cone, my hope for its midrange performance is not that high. Let's see.

I think zaph has already measured a pair of these. They did quite well and look pretty sharp too IMHO.

[ctbowman]

Huh. Just seems like that L2 is kind of low...

Going to play w/ some ClarityCaps and mundorf resistors I got today. Since this is the last project for a while, thought I'd mess around w/ whether these pricier components make an audible impact (aside from my wallet)...

I've been interested in trying some claritycap px series caps lately. Supposed to have some extra tech to limit microphonics. e-speakers has good prices and free shipping right now.

[philiparcario]

OMG.. a design on PE that I can actually get the drivers for at a reasonable cost. (with the current exchange rate, I will not be ordering from the US for a long time) !!

WES Components stock the SB drivers and that Vifa tweet !!.

So, I shall certainly be looking at this this thread with interest.

not to hijack the thread

yeah I grabbed two of these amps from ska-audio when the rate got nice and low or high depends on where you are.

http://www.ska-audio.com/

gb150d stereo kit

the rate was so good i asked greg to assemble them due to my cataract surgery.

[critofur]

DQ25... It's funny how it took Zaph's measurements to really draw attention to this driver. It was Zaph's ZMV5 that really convinced me to use it.

Well, usually when I've heard metal domes / metal mids/woofers in the past there's always been something unpleasant about them.

The fact that this tweeter is:
A) Reasonably cheap
B) Small flange, good for closer C-T-C
C) Tested well and highly regarded (by Zaph)
But most of all,
D) All of the above AND can crossover at/below 2Khz with 2nd order electrical, how could you not at least try it?

If somebody else besides Zaph had used this tweeter, measured it, and posted measurements showing that it worked well crossed at ~ 2Khz w/2nd order electrical, then, that too, would have been enough to make it interesting.

But, add in the fact that there's a tested well thought out small inexpensive design posted by Zaph on his website, ready to build with parts that you can get (now that the woofer is back in stock at MCM), then why wouldn't you build one if you A) can afford it and B) have time to spend in the garage and enjoy building...

[jkim]

But most of all,
D) All of the above AND can crossover at/below 2Khz with 2nd order electrical, how could you not at least try it?

Take a look at Zaph's distortion test. Compare DQ25 and XT25. The only reason why the DQ25 may not be used at a low xover point is its a bit highish 2nd order products. But as you can see, they are lower than XT25's. Many people used XT25s at 2.0 - 2.2 kHz with acoustic 4th order rolloffs with satisfactory results---it usually needs a 3rd order electrical filter due to its shallow natural rolloff at the low end. No problem using 2.0 kHz LR4 for the DQ25. And a 2nd order electrical filter is all you need to achieve it.

[lunchmoney]

jkim,

are there any published plans for these? gotta link?

thanks!

[jkim]

jkim,

are there any published plans for these? gotta link?

thanks!

An email sent to you.

-jAy

[johngalt47]

To answer Jay's question publicly, I use Mills resistors. If I need a small or oddball value, I parallel two or three of them.

[Wushuliu]

Hrm, any chance we can cajole an MTM design out of you Jay?

Can't believe it's almost a year already since I first started building these...

I use Mills as well. The Daytons resistors can be a bit 'tizzy'...

[jkim]

My job search never ends... This design's actual build and measurement have been held off... All the components are getting dust.

May I ask why you need MTM?

[Wushuliu]

My job search never ends... This design's actual build and measurement have been held off... All the components are getting dust.

May I ask why you need MTM?

Bummer! Well, I hope you land something soon...

I'm just curious as to how an MTM w/ these drivers would sound compared to the TM. Also, an MTM may even help w/ the acoustic issues of my living room which sucks out a chunk of the lower mids/bass at my listening position of 11ft. from the speakers (glass coffee table, bookshelves, carpet, and surrounding futons don't help).

Plus, a potentially more sensitive design would be useful down the road. I have some unfinished tripath amp kits I'd like to try out
and the MTM I'm sure would be far more forgiving than the TM.

And I need to build something

[benchtester]

Something that has bugged me for a long time. The picture in the original post, as well as Zaph's ZMV5, show the phase shield on the tweeter horizontal. Is this preferred?

I would think that it should go vertical to improve horizontal dispersion and decrease vertical dispersion. Or am I missing something about how the phase shield works?

[dlr]

Something that has bugged me for a long time. The picture in the original post, as well as Zaph's ZMV5, show the phase shield on the tweeter horizontal. Is this preferred?

I would think that it should go vertical to improve horizontal dispersion and decrease vertical dispersion. Or am I missing something about how the phase shield works?

I believe that it should be horizontal. The purpose of a phase shield is to block the output near the tip so that at high frequencies, where there is a phase issue between output near the voice coil and output near the tip, there is reduced cancellation. The horizontal position will block a bit more, so the response both on- and off-axis should be a bit better in that position.

dlr

[Wolf]

I believe that it should be horizontal. The purpose of a phase shield is to block the output near the tip so that at high frequencies, where there is a phase issue between output near the voice coil and output near the tip, there is reduced cancellation. The horizontal position will block a bit more, so the response both on- and off-axis should be a bit better in that position.

dlr

I always thought it like Benchtester too. I guess I wil place them the other way from now on....
Wolf

[romanbednarek]

I believe that it should be horizontal. The purpose of a phase shield is to block the output near the tip so that at high frequencies, where there is a phase issue between output near the voice coil and output near the tip, there is reduced cancellation. The horizontal position will block a bit more, so the response both on- and off-axis should be a bit better in that position.

dlr

Sorry about the tangental subject, but my curiosity is too strong... I never spent much time thinking about tweeter properties too much but please correct me if my logic is wrong in my statements below regarding tweeter dispersion properties (I've probably thought about these things in the past but never put all of the pieces together, and I may still have things mixed up).

Larger metal dome tweeters tend to roll off at the top end due to off axis cancellation between the sound originating from the center of the dome with the edge of the dome when the distance between those points relates to wavelengths that are out of phase with each other (in combination with a stiff diaphragm that doesn't flex).

Larger fabric dome tweeters don't roll off, or sometimes have a peak, in this region due to flexing or damping properties of the dome?

Ring radiator tweeters tend to have an extended top end response due to the shape of the radiating surface and the presence of the small "phase plug" in the middle but I suppose that dispersion is still limited due to wavelengths originating from opposite sides of the radiating surface which still can cancel off axis.

I'm sure that my descriptions fall short in some way or another but please let me know if my assumptions are on the right track.

[dlr]

I'm sure that my descriptions fall short in some way or another but please let me know if my assumptions are on the right track.

You're right on the mark. That's precisely how they operate.

That's why tweeters with wavy response above 10k may look nearly ideal just off-axis. Even Morel has this issue with their soft domes. They're way to tall, so-to-speak. They look close to being hemispherical in shape rather than being catenoid (old Peerless were described as that) or truncated hemisphere (if that description fits).

It's also why the XT25 can extend to 40KHz on-axis, yet is overall more directional than the equivalent diameter dome. A detriment in one way, yet it means that there will be less diffraction from an XT, since there is no dome that occludes the radiation from the far part in the off-axis as occurs with a dome.

Most hard domes, even with a phase plug, have a characteristic droop in response below breakup. This is due to the gradual change in the phase relationship between tip and surround. It's worse without a phase plug or a non-optimal one.

The RS52 midrange is a good example as well. The curves below resulted from experiments near the surround and with a felt disc at the tip in place of the plastic one.



dlr

[ontariomaximus]

An email sent to you.

-jAy

An old thread I know, but I love to look at the plans for this one

[gowa]

I can't see your pictures.