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Open Baffle Epiphany!

The 16" woofers in this picture were harvested from a pair of Sansui SP speakers left on the curb. Surprisingly enough they work well in open air and sound better than they ever did in their congested enclosure. Those old Kabuki's may be a good source for OB woofers. The full range driver is PE's 8" GRS and not one of favorites.

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"The full range driver is PE's 8" GRS and not one of favorites." What is your opinion of the faults of the GRS driver?
 
Katalyst said:
"The full range driver is PE's 8" GRS and not one of favorites." What is your opinion of the faults of the GRS driver?
Click to expand...

It's billed as a clone/replacement for the famous Pioneer BoFu but it falls short in terms of detail and smoothness. The GRS lacks highs, refinement and really needs a tweeter whereas many 8 inch full range speakers can go it alone.
 
I'm launching off into an OB project. I'm using the following drivers:

Woof er = GRS 112 SW-4
Mid-Bass = Peerless (Vifa) NE123W-08 (love this driver)
Tweets = HiVi Q1R

x-over between the Mids and Tweets will be passive @ 2.8kHz at 12dB/octave (L-R alignment) and mid/tweet will be physically time aligned.
x-over between Woofs and Mid/tweets will be active and will be time and phase aligned. I have DSP EQ, phase, time, etc. and have proper measurement equipment to work with the x-over between woofer and uppers - and to adjust woofer (as well as the mid/tweet) EQ.

I'm thinking of mounting it all on a 2' x 4' piece of 3/4" MDF. Or should I use 3/4" plywood?

I'll be augmenting the bottom end with at least 2 powered subs - all driven with DSP available.

I use the drivers (mids and tweets) in a more conventional array (box) at the moment and they are fantastic. Any advice regarding things to do to make this all work out well as an OB project?
 
I need some help choosing a coil to filter out the highs from a 15" woofer I'm putting into an H-frame.

It's a Heppner driver that is pretty efficient but I have no specs. The 8" full range driver is also a Heppner. So how do I choose a coil to filter out those highs?
 
Wow, when I originally posted this "epiphany" some 3 years ago I would have never thought it would generate 84 pages of conversation and 130,000 views. I'm tickled! Big props to Poultry and the others who have kept the convo going!

Well the Epiphany is still going strong. During the three years, we bought our first house, completely renovated the main floor and I got a new job, but one thing consistent is I am still running open baffles. The system itself has changed quite a bit. I am now running a Marantz 8 into various vintage full range and using a 130 wpc home theater receiver to power the Alphas. A few things I have learned along the way..

DSP (such as minidsp) kills the magic in the full range, so now I only run it to the woofers.
The Alphas are very nice in open baffles, but if I had some extra cash, I would like woofers that handle more power and a solid state amp that can feed them more power.
I have liked every vintage oval speaker I have tried.
I have a growing affection towards piezo tweeters for some reason.
Alnicos are nice, but so are ceramic magnets.
Most of these old full range speakers can benefit with a little help in the top end. On axis a lot of them perform well, but the tweeter really helps with the off axis response.

Here is my current concoction. Motorola horn piezos over Electro Voice Wolverine LS-12 over Alpha 15's. Not pretty at all, but that will change when I find the time.

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Canada, it's good to hear from you and all you've learned along the way. Really like your current OB's.

I too have learned that once I added upstream devices to the signal the tube magic was lost. Some might consider the results more technically accurate but at what cost? That's the reason my two active crossovers are gathering dust in a closet. Give me the unadulterated sound of a full range driver running full range warts and all.
 
Neff,

I had a pair of of the 1808's and liked them a lot. I ran them full range from a flea watt SET amp with nothing in the signal path. With the woofers I used a Yung SD100 plate amp or a pair of Dayton APA150's with crossover set around 80hz. If you want to do a passive filter on the woofers check out the link in #1668 post. I think the Fmods are available in 70hz low pass. A pair is all you need and unlike most passive filters these install between the source and the amp or between the preamp and the amp.

The Fmods offer the same advantage of active crossovers in that they change the frequency before the signal is amplified. This way you get a cleaner signal and a bit more power.

There are several ways to split that signal and simultaneously feed it to two separate amps which I'll cover if anyone is interested.

Bi-amping OB's is easy compared to conventional 2 way box speakers.
 
CptnCanada how did you wire the piezo tweeters you are using? Are they the vintage motorola or newer ones? Thanks for starting the thread.
 
In this set-up they are currently just running full range, although its not because that is the best method, its just that I slapped these together last Friday and have been on the road since Sunday so I have not had a chance to design a proper xover. They do work well full range, I really like these tweeters. They are the old motorolas, I pulled them out of some filthy car subwoofer box that someone was discarding, probably built in the 80's.
 
Poultrygeist said:
Neff,

I had a pair of of the 1808's and liked them a lot. I ran them full range from a flea watt SET amp with nothing in the signal path. With the woofers I used a Yung SD100 plate amp or a pair of Dayton APA150's with crossover set around 80hz. If you want to do a passive filter on the woofers check out the link in #1668 post. I think the Fmods are available in 70hz low pass. A pair is all you need and unlike most passive filters these install between the source and the amp or between the preamp and the amp.

The Fmods offer the same advantage of active crossovers in that they change the frequency before the signal is amplified. This way you get a cleaner signal and a bit more power.

There are several ways to split that signal and simultaneously feed it to two separate amps which I'll cover if anyone is interested.

Bi-amping OB's is easy compared to conventional 2 way box speakers.
Click to expand...

I'm not yet ready to commit to buying more amps/receivers for OB... key word is "yet." But until then, I'd like to know if/how I can run these full range 8"s with the 15" using my quad/4 channel vintage receiver. If so, I'd be interested to know how. Thanks. Oh, and I'm not into designing a xover... just wanted to perhaps filter out some of the highs in the 15" so it will perform in an H-frame.
 
Well I guess it's time to dip my toes in the OB waters. Late last year I got this Zenith console
20170109_173742

20170109_173742

  • Media owner bigaltx24
  • Date added
Record Storage and Speaker Stands
I pulled the tube amp and modded and rebuilt it. While I was researching the tube amp I looked up the speakers just for kicks, seems they have a following.
20161118_205600

20161118_205600

  • Media owner bigaltx24
  • Date added
Found they guy at Glow In The Dark Audio had made some OBs with them. That piqued my interest, I wasn't done with the amp yet so I wired my Sansui 881 into the console and fired her up. One tweeter wasn't working at all and the other was cutting in and out (bad caps) so I unhooked the tweets and let the 12s run full range, which in this setup they do anyway. I can't say I was blown away or anything, the bass was subdued and they were a touch shouty, but I could tell they had potential. I also know from experience that old speakers that haven't been run in decades need time to loosen up. I left the back off of the console and moved it out about 10" from the wall so I'm kind of getting a OB effect. In the console the 12s are only about 4" of the floor and 6" apart but they are starting to sound real nice and giving me a surprisingly open sound with great imaging. I'll probably do something like the Glow In The Dark guy did, seem fairly easy for a first try, any other suggestions will be welcomed.
 
Poultrygeist said:
Neff,

I had a pair of of the 1808's and liked them a lot. I ran them full range from a flea watt SET amp with nothing in the signal path. With the woofers I used a Yung SD100 plate amp or a pair of Dayton APA150's with crossover set around 80hz. If you want to do a passive filter on the woofers check out the link in #1668 post. I think the Fmods are available in 70hz low pass. A pair is all you need and unlike most passive filters these install between the source and the amp or between the preamp and the amp.

The Fmods offer the same advantage of active crossovers in that they change the frequency before the signal is amplified. This way you get a cleaner signal and a bit more power.

There are several ways to split that signal and simultaneously feed it to two separate amps which I'll cover if anyone is interested.
Great advice. Thanks!
The price for a pair is lower than one coil would be!
I guess your experience tells you that the two driver's play nice together in their frequency overlap..

Bi-amping OB's is easy compared to conventional 2 way box speakers.
Click to expand...

Thanks for the advice!
Fmods are cheaper than one coil.
 
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FWIW 1950's full range drivers like the Zeniths were voiced for flea watt tube amps and that's the combination that will offer the best sound.
 
Yea, I got the amp from the console done about a month ago. It's now very similar to a Decware SE84. The Zenith's sounded nice with the Sansui 881, but they sound better with the tube amp.
 
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