"Into The Abyss", Tweeters in low places

[paulspencer16]

With 22uf cap

[paulspencer16]

Modifications

[paulspencer16]

Sorry missed the photo with the spacer inserted between the WG and tweeter front plate . I had to cut it up to get to the phase shield and then refill it with Bondo to get it to seat properly between the tweeter and WG That seemed to help a lot as it has the right diameter hole in it so you can apply Bondo on the wave guide up to the edge of that and when it's dried sand back to there. It obviously moves the dome further away from the phase shield as I think in the first instance it was too close and the tweeter had a very "honky" sound which dissapered with this back in place . Cheers

[augerpro]

Is the spacing between the dome and PS now the same as it was from the factory? What was the spacing when it was closer?

[TN Allen]

"...Think it's sounding pretty good but will wanna live with it for awhile to gain a better impression"

I like your approach to your research.

What is your testing software and setup?

[paulspencer16]

Hi augerpro I have not had time to check that yet but from a quick eyeball I'd say yes it's pretty close I will dismantle at some point and give you a more definitive answer . The change from the close to far would be the thickness of the spacer again I'd estimate 2.5/3mm but can measure once I have it in pieces again.

[paulspencer16]

Hi TN Allen.

Thanks for that.
I try to combine the measuring/ simulation with as much listening and A/B comparisons as possible. I find it's easy to get the "blinkers" on and think your on the right track when you could be heading down the wrong path.

This mod seems to be pretty good . It's very smooth and easy on the ear, the tweeter "disappears" but maybe lacks some zing and sparkle.

Testing software wise. I'm on a Mac mainly (always have been) so I'm running REW with Mini DSP's umik-1 for measuring. I have a turntable marked out in 5 degree increments, made from and old lazy susan bearing which is super handy. I have a Behringer UMC202HD sound card/preamp for impedance sweeps and a ACH-01 accelerometer for cabinet resonances. Simulation wise I have a old PC running PCD and Vituix CAD.

I'd like to be a bit more methodical with the measurement side of things and standardise all my measurements I'm getting close but still need to stick to the ground rules everytime. Sometimes I'm in in too much of a rush!!

All the best.

P

[300Z]

I finally got my Seos 8 for my Seas 27TDFC tweeters.
I measured them at 10cm from the mouth. The 3.53khz and 1.74khz were taken at different dates and I forgot to adjust the level to match the earlier measurement. Crossover and EQ done with a DCX2496.

[300Z]

Sample 1 and 2 + distortion.

[xmax]

So this Visaton WG is not modded in any way and the RST fits nicely, I will be remeasuring it in a test baffle hopefully tomorrow.
If I recall the sweeps looked real nice I was only seeing FR anomalies from the WG not mounted in a baffle (on a earlier page)

[KEtheredge87]

Looks good in that guide I hope the measurements look good too. Thanks for checking this combination out!

[xmax]

Update on the tweeters going low concept. Pete S and I came up with a design based around the B&C 8BG51 and the Satori TW29R,
With a 6X9" Elliptical WG in a small ported cab combined with the mighty Tymphany STW-350F in a sealed box using active xo between
8" and sub for now. The 3 drivers are going to live in a box exactly the same size as a Genelec 1038, creating a massive 3 way in a kind
of classic 3 way look. This concept came together after hearing about Pete's 2 way using the same B&C and a WG.

What I have learned so far... First and foremost SB tweets don't like going low even with the "discounted lunch" of the big 6X9", 1.5"
deep WG even though I have been listening them a lot and like many aspects of their sound the high distortion has to be fixed.
Why use a SB tweet that can't swing low in the first place? Because A: the dimple dome tweets seem to work much better in this
big deep WG and B: the extra little top end the Satori has helps with the normal loss you get in that region with a guide.

Great things about system thus far, awesome low end! Real "sub" box will end up being smaller (more ideal). Also
the B&C with the passive XO (5.6uh and .6uh and 22uf cap) has a bump in the 150 range which makes it very
easy to blend with the STW-350 which surprisingly plays nicely up to 250ish! From 30 to around 1K is perhaps
the most cohesive low/low-mid I recall hearing. Part of the design concept includes being able to easily "tune"
out boundary related nulls in the 80-250 range.

Back to "Tweeters in low places" a big WG (and soon) a tweet that can go low allows bigger mid-basses
which in turn allows lower XOs to woofs or subs. Pushing both XOs down makes possible a simplified
3 way full range system that can and will be played much louder that anybody should!

Also the deep WG very closely aligns the acoustic centers of the drivers helping this design image very well indeed!

Things to improve: Lower the "bump" at 150hz possibly making an adjustable Z correction circuit (Pete idea)
.Improve speed and or power response of 8" 800-2K range. Perhaps going to try Epique or looking at the other
B&C models in that range.

Biggest problem is the tweet distortion, perhaps a different woofer can play a little higher and be able to raise tweet
filter frequency. Pete Modeled the XO and I don't think it can be improved upon without changing 1 or both drivers.
I think the Satori 9.5 won't cut it but maybe the 7.5" version?

Pete's XO is 3rd order electrical at about 1.1K! And the THD is unfortunately about 20dB higher than it should be around 1.1K.

[xmax]

One tweet Pete says can play lower is the SB29RDAC

So I will be getting some asap.

[augerpro]

What is the 6x9 waveguide?

[TN Allen]

Please include the depth if possible. Thanks