DIY Supertweeters

[JKent]

Just for fun.

My local electronics store (Wayne Electronics) had some surplus tweeters for sale so I thought I'd fool around with a pair.

The "cabinets" are black ABS 3" couplings from Lowes. I buffed them by hand with some white Scotch Brite to soften the appearance. The OD is about 4" and just a hair smaller than the tweeter mounting rings. Close enough. The backs are Masonite discs left over from making small speaker grilles for the KLH Model Eight. A wee bit smaller diameter than the coupling but again--close enough.

For the innerds I used my MicroStatics as a guide. The MS have a pot for volume and a 2-way switch to select the crossover point. The capacitors are two 1uF, used singly for the higher crossover or paralleled for the lower point.

I used parts from my parts boxes. Didn't use a volume control. The toggle switches had been bought form allelectronics.com for another project. Cheap. I experimented with caps and found that 2uF made the crossover too low (by ear) so I went with 1uF and 0.47uF. The banana jacks were purchased at steep discount when a local Rat Shack went out of business.

The biggest dilemma was how to put everything together. There was nothing to screw the tweeters to.

So I was putting together an order for Albany County Fasteners (great resource btw). Decided to get some 6-32 threaded rod, stainless acorn nuts and washers. The back plates were drilled with holes to line up with the face plate, then glued on with Permatex 81158 Black Silicone Adhesive Sealant. Then came the tricky part: I SHOULD HAVE bought brass threaded rod but I got plated steel. Cut four 4" lengths and pushed them through from the back but of course they stuck to the large magnet on the tweeter! Eventually, with cussing and using various picks I managed to get them together. Glad I didn't put the sealant on the front or I would have had a real mess.

So how to keep them from rolling off the shelf. I had a few thoughts but ended up wandering through Michael's (with my 40% off coupon! What a geezer!) and found some wooden beads. I selected a bag of ~3/4" diameter. They came drilled through for stringing so I drilled one end of each with a larger diameter drill so I could use screws to mount them as front feet. Put a coat of stain on them and will dip them in poly one of these days. For the rear I used a single self-adhesive rubber bumper so the base is a tripod and the tweeters are tilted upward slightly.

That's it. Hooked them up with my AR-91s and like the added sparkle, air or whatever.

[Aadams]

This is a good idea.  I have been trying to imagine a DIY way to make minimalist housings for individual drivers.

3 hours ago, JKent said:

The "cabinets" are black ABS 3" couplings from Lowes.

 

[ra.ra]

Hey Kent, I really enjoyed reading about this project. Your results look terrific - - very nice assembly details and material choices (except for threaded rod alloy) and the overall appearance is totally professional. Just a few questions:

• does this super-tweeter get wired in series from the AR-91 terminals? 
• is the switch a two-position device with a single resistor to provide two levels of output?

Great project.

[JKent]

ra.ra,

Thank you for the kind words. To answer your questions:

• No. I happen to have an Adcom speaker selector so I have them hooked up as Pair 4. BUT, using the MicroStatics and other add-on supertweeters as a guide, they would be hooked up in parallel with the main speakers.
• The 2-position switch switches between a 0.47uF cap and a 1.0uF cap to alter the crossover point. The volume seems fine but if I do another pair I may add an L-pad if space permits. The Microstatic (pic below) has both a volume control and switchable crossover level.

Aadams,

There are various projects on the interweb showing speakers made of PVC waste pipe. Some are very elaborate. The ABS does not seem to come in as many shapes and sizes, and PVC and  ABS are not completely interchangeable because of the thickness of the plastic. PVC would have to be primed and painted but the black ABS looked fine to me for a very simple little project.

Kent

[Aadams]

9 hours ago, JKent said:

There are various projects on the interweb showing speakers made of PVC waste pipe.

Yes, but yours aren't ugly.

 

[JKent]

1 hour ago, Aadams said:

Yes, but yours aren't ugly.

 

??

[ar_pro]

Great project - thanks for posting this, Kent.

Your work very closely resembles some commercially-produced supertweeters, and I'd say it certainly looks as good!

Here's what Fostex does with their model T90A - a cylinder, like your tweeter, and here's the rear panel of the Aperion ribbon supertweeter, which uses a jack & plug method to reduce ouput. It also incorporates a 6-position crossover switch, which is very clever.

So, how does everything sound?

 

[JKent]

Thanks, ar_pro

I think it sounds good. I don't know what the crossover points are but I like them with the 0.47uF cap. Planning another pair. I'll probably give one pair to the owner of the electronics store. He bought a pair of KLH Fives from me and he likes them but he rigged up an outboard piezo tweeter to augment the highs. My bullet tweeter-based ones sound much better than piezos IMHO.

That Fostex looks like high quality. I may try copying their double dowel stands. But for $215/pair they don't even include the capacitor or volume control! I like Aperion's approach with customizable xo's and volume but those are $300!

My cost breakdown was:

• 2) Surplus bullet tweeter $10
• 2) ABS 3" couplings  $3.66
• 3' 6-32 threaded rod $0.76
• 16) 6-32 plated acorn nuts $0.42
• 2) SPDT mini toggles  $2.50
• 2) chassis mount banana binding posts  ~$5.00
• 2) 0.47uF mylar capacitors ~$1.00
• 2) 1.0uF mylar caps  ~$0.50
• 2) rubber bumpers  ~$0.20
• 2) Masonite back plates (scrap)  $0.00

So what's that? About $25 for the pair? And except for the tweeters, ABS, threaded rod and wood knobs it was all stuff I had on hand.

For the next pair I think I'll eliminate the banana jacks. New ones from PE are about $3.50 each. Instead I'll use 8-32 machine screws and knurled nuts like the old AR, KLH and other vintage speakers (and the Fostex T90A). I have a good supply of those. And I may add L-pads, so that will add ~$11.00. And brass threaded rod is ~$7.50 so that pair may cost close to $40 but still relatively cheap.

[Martin]

Very nice job. Your ingenuity & creativity are admirable.

[ra.ra]

I originally misunderstood how these were meant to work, but now I get it. I appreciate the design aesthetic as much as I admire the budget cost breakdown, and for me, that's what makes Kent's solution superior to the several hundred dollar versions. (This is said, of course, with having no first-hand knowledge of the driver quality or sound performance.)

One suggestion: if you know that you prefer the 0.47uF cap setting, why not abandon the original idea of a second cap (and crossover point) and instead use the switch (with resistor) as an attenuation control (in lieu of L-pad)? And I like the idea of using the knurled nuts - - it worked well for me on this AR-18s project of mine that I displayed in this forum.   

[JKent]

1 hour ago, ra.ra said:

One suggestion: if you know that you prefer the 0.47uF cap setting, why not abandon the original idea of a second cap (and crossover point) and instead use the switch (with resistor) as an attenuation control (in lieu of L-pad)? And I like the idea of using the knurled nuts - - it worked well for me on this AR-18s project of mine that I displayed in this forum.

I like those on the AR-18s!

The resistor idea is appealing. What values would you suggest?

[ar_pro]

Ken, I really like how you took your surplus tweeters and visualized & executed this great end-result - and at $40, it's elegant & thrifty! 

I'd been playing around with add-on tweeters for my old AR-91/3a project speakers, and went through a couple of iterations of the Microstatic array, as well as some inexpensive piezo tweeters, and the Aperion ribbon model. None of these seemed to add what I'd been looking for - an increased sense of "air" on acoustic jazz & classical recordings; they were all too directional, and - to my ears, anyway - overlapped too much with the AR tweeters. The Aperion is a beautiful little tweeter, with the flexibility of switchable crossover settings.

I'd love to be able to try a pair of the Elac 4Pi ribbons that have a 360 degree output, but they tend to sell for well over $2K on the used market! 

Aren't they beautiful, though?

 

[JKent]

Those look nice but the price is pretty horrifying. Don't know about you, but at my age maybe using supertweeters is an exercise in futility. Haven't had a hearing test lately but I'm sure the high frequencies have "rolled off." 

[ra.ra]

On 3/10/2019 at 2:43 PM, JKent said:

What values would you suggest?

I wouldn't quite know how to design a suitable resistive circuit for this use - - the chief engineer in my studio workshop swears by the trial-and-error method when other options have run out.  I know many of the switched AR and KLH tweeters employ 2.5 or 3.0-ohm resistors, so I'd probably start in that vicinity. Did your tweeters come with any product literature?

And thanks for the heads-up on Albany County Fasteners - - it looks like a great catalog of parts.   

[JKent]

On 3/11/2019 at 6:50 PM, ra.ra said:

I wouldn't quite know how to design a suitable resistive circuit for this use - - the chief engineer in my studio workshop swears by the trial-and-error method when other options have run out.  I know many of the switched AR and KLH tweeters employ 2.5 or 3.0-ohm resistors, so I'd probably start in that vicinity. Did your tweeters come with any product literature?

No lit with the tweeters and not even any numbers on them.

I was rummaging through another parts box looking for some inductors and came across a nice pair of L-pads and a pair of pots. The L-pad are marked Violet AT40K L-8 Ohm. Think I'll use those. The pots are Clarostat CM40436 30 Ohm. They didn't seem to work well with the tweeters.

So the next pair will be like the first but with an L-pad and substituting 8-32 machine screws with knurled nuts for the binding posts. For the 0.47uF caps think I'll use some surplus Russian paper-in-oil caps from my collection. Then I want to experiment again for the other value. Maybe try 1.5uF again.

Expecting an order from PE in 2 days so I can finish up 2 pair of KLH Model Five crossovers for a CSP member. That order includes a pair of 49 cent terminal cups I thought might fit on the ABS coupling: https://www.parts-express.com/spring-loaded-4-1-2-round-terminal-cup--269-2182  We'll see. One reviewer wrote that at 49 cents, if you don't use them in speakers you may as well use them for coasters  edit: Guess they're coasters. 4-1/2" is too big for the ABS coupling.

Now here's a question: The ad for those terminal cups says "One set of leads includes a 2.2 µF 100 V providing a 9,000 Hz 6 dB per octave high pass crossover".  I was under the impression that the actual crossover point depends on the characteristics of the tweeter as well as the value of the capacitor. Can anyone help me out with that?

Edited March 19, 2019 by JKent

[JKent]

So further experimenting with the "found" L-pads and pots, they work fine. The Clarostat pots were salvaged from a pair of Rectilinear XIa crossovers.

Here are the innerds. I used caps that were on hand. For the pair with the Violet L-pads the caps are Madisound Surplus 2uF mylar (with the maddeningly short leads) and Russian 1uF paper-in-oil. For the pair with the Clarostat pots the caps are 2uF Carli and 1uF Russian PIO.

And for these 2 pair I used brass threaded rod and acorn nuts. Back of one shown below. Push-on knobs from ApexJr.com  On the other pair I'll use DakaWare knobs that match the AR-3 etc.

 

[ligs]

I have been using external tweeters to improve my main speakers for a while but I never came up with such elegant looking yet functional arrangement like yours! Thanks for sharing.

 

George

[ra.ra]

Really great work - - - what an enjoyable project! So if I understand correctly, in these two latest examples, you've basically doubled the value of the caps from your first effort, added the rotary control, and changed the rear wire terminals.  Can you describe your impressions of these latest revisions? And, do you have any pics of the backside of the tweeter?

[JKent]

Thank you all for the positive comments!

3 hours ago, ra.ra said:

in these two latest examples, you've basically doubled the value of the caps from your first effort, added the rotary control, and changed the rear wire terminals.  Can you describe your impressions of these latest revisions?

In the first ones I experimented a bit with the values. I had planned to do 1uF and 2uF, like the MicroStatics, but the effect was too much, so I replaced the 2uF with a 0.47uF. But I think the issue wasn't the crossover point, it was the volume. So with the attenuators in place I went back to the 1 & 2uF layout but I adjust the volume for a more subtle enhancement.

Nice hefty tweeters but no printing on the backs.

 

[ar_pro]

On 3/11/2019 at 6:25 PM, JKent said:

Those look nice but the price is pretty horrifying. Don't know about you, but at my age maybe using supertweeters is an exercise in futility. Haven't had a hearing test lately but I'm sure the high frequencies have "rolled off." 

Stereophile's Michael Fremer published something about maintaining one's listening skills while getting older & dealing with not-as-sharp hearing. I'm not unconvinced that it's whistling in the dark, though. 

[JKent]

Here are some more supertweeters.

Very "plain jane" but they were totally free! The BIC/010A horns came from my friend at the electronics store. When he saw the above tweeters he gave me a pair of the horns to see what I could do with them.

Couldn't find a convenient size plastic pipe so they just sat around for a while. Then I polished off a roll of bubble wrap and the cardboard tube seemed perfect--just cut it in half. I considered coating it with some black wood-grain vinyl leftover from another project but decided instead to spray them with truck bed liner (I use this on my Advent 400 "restomods".

I cut some 1/2" wood blocks and used Gorilla Glue to fasten them at 4 points inside the tube at the front. Back cap is a Masonite disc leftover from making baffles for KLH Model Eight speakers. Terminal plate was in my parts box. I don't like the spring clips so these were from a pair of speakers that got upgraded to 5-way binding posts. Each tweeter has a single 1.5uF film cap (also free from the electronics store). Feet are the wood beads from the other supertweeter project. Pics don't show all the screws installed but I used black #6 deep thread screws from PE.

No volume controls, so they can't be attenuated  but I listened to them on top of my AR-3a's and to my ears they were a nice enhancement, not unlike the MicroAcoustics.

In the end I gave them to my friend at the electronics store. So they're for sale but I don't know what he's asking for them.

Just a fun little project.

Kent

[Jim Pearce]

On 3/11/2019 at 5:25 PM, JKent said:

Those look nice but the price is pretty horrifying. Don't know about you, but at my age maybe using supertweeters is an exercise in futility. Haven't had a hearing test lately but I'm sure the high frequencies have "rolled off." 

See Wikipedia for pschoacoustics.

Ever since day one audio has been all about the tweeters for me and it was very gratifying to read this the first time I found it.