Open Baffle Epiphany!

[ODYOFAEL]

Open baffles were akin to a religious experience for me also.

Using University Diffaxials
100 db efficiency.
12 inch woofer.
5 inch mid.
Superb silk dome Sphericon super tweeter.
Getting the great coherency that one gets with point source.

No real lack of bass.
Don't care about all the people pointing at graphs and saying look at the rolloff.
I am not experiencing any big loss of bass.
And the bass is really something special.
Feel like I'm on a first name basis with Ron Carter.

I used them with 6bq5 mono blocks (3 or 4 wpc) and a t-amp (15 wpc) with great success.
They sounded so good with low wattage I went and picked up one of Don Garber's Fi-X Super 300b amps.
Woo-hoo.
No turning back now.

SET amps and efficient speakers in open baffles have given me the best sound I have ever had.

Can't stop listening.
Up late every night.
Not eating properly and losing weight.
Can't focus at work.
My wife is angry with me every day.
Even listening to opera now.

It all just sounds so good.

Art

I have a pair of UC -123 University speakers and not sure where to start with the OB route. Do you happen to have pics of your speakers if you still have them? I am currently using the speakers in a custom console stereo that i aquired from the original owner. It was in an enclosure so while experimenting, I decided to remove the back cover of the cabinets. Now i get a more balanced sound and the brightnesskinda lessened.

 

[Poultrygeist]

On a whim I bought this $59 Nobsound passive preamp from Amazon and it arrived today. It has three inputs and it's two outputs make it ideal for bi-amping open baffles. A compliment for any passive is that it sounds like "nothing" and that's true with this Nobsound. Comes in a very attractive metal case, has a powered switcher and the volume control seems to be high quality. Substituted the passive for my tube pre and I'm pretty sure I'm getting more detail. But I had to back off the treble on the old EL84 to compensate for the smoothness lost from the tube pre.

 

[Poultrygeist]

Here's a new update from "Glow In The Dark" regarding the Zenith 49CZ series. He's hearing what I'm hearing from these incredible OB drivers.

http://glowinthedarkaudio.com/zenith-49cz852.html

 

[sempai]

I have a pair of UC -123 University speakers and not sure where to start with the OB route. Do you happen to have pics of your speakers if you still have them? I am currently using the speakers in a custom console stereo that i aquired from the original owner. It was in an enclosure so while experimenting, I decided to remove the back cover of the cabinets. Now i get a more balanced sound and the brightnesskinda lessened.

Still have the drivers but had to take them out of the open baffles.
I live in a small house and don't have the space to set up more than 1 pair of large speakers at a time.
The baffles where 2' x 4' birch ply made stable with L-shaped iron plant hangers screwed to the baffles at the bottom. The drivers where mounted about 6" from the top (if I recall correctly) and slightly offset.

Pretty crude but sounded fantastic.
I kept these in my system for about a year experimenting with "wings" of various widths aligned at different angles.
No photos but the sales sheet for the University Diffaxial 312 Series 200 can be seen here:

http://audiokarma.org/forums/index.php?threads/open-baffle-epiphany.566879/page-73#post-8925991


art

 

[Roscoe Primrose]

I have a pair of UC -123 University speakers and not sure where to start with the OB route. Do you happen to have pics of your speakers if you still have them? I am currently using the speakers in a custom console stereo that i aquired from the original owner. It was in an enclosure so while experimenting, I decided to remove the back cover of the cabinets. Now i get a more balanced sound and the brightnesskinda lessened.

More info on the UC-123 can be found here: http://www.preservationsound.com/wp-content/uploads/2011/11/University_1963_p2.pdf in case you haven't found that yet. I had a pair on JEL style OBs with a 15" woofer on the same baffle (bi-amped) and they sounded quite good. Baffle can be seen here: http://dcaudiodiy.com/phpBB3/viewtopic.php?f=4&t=649 with 12" Tannoys where the UC-123s were...

They also worked quite well in some Altec Model 15 cabinets I converted as seen here:http://dcaudiodiy.com/phpBB3/viewtopic.php?f=4&t=761

I wasn't quite as happy with the HF on the UC-123s as I've been on some other speakers, but I never played with the stock crossover at all, and I'm sure there's room for improvement there...

Roscoe

 

[bigaltx24]

Here's a new update from "Glow In The Dark" regarding the Zenith 49CZ series. He's hearing what I'm hearing from these incredible OB drivers

I totally agree on the Zeniths, I need to build bigger baffles for mine. The baffles mine are in took about two hours to build and are too small, but they sound fantastic. I also really like the Bozak B800Bc I'm running in my workroom. They have nice bass for an eight inch, the mids are as good or better than the Zeniths and the high end is very detailed but smooth. I think a big part of their magic is the aluminum cones, the transient response is fast and the cones are stiffer than paper and don't distort when playing loud.

 

[Poultrygeist]

The Zenith OB's have a high ceiling and are good enough to demand the best amp I've got. So this past weekend I replaced the EL84 receiver with these Bottlehead 2a3s and now I'm getting even

better detail. If you crave the resolution of detail at low levels nothing does it like a direct heated triode.

For the last few years I've powered the Lowther DX3 OB's with the Bottleheads but for the time being they'll have to get by with the Miniwatt amp until I find something else.

 

[Poultrygeist]

Yesterday I picked up two of these to go under my OB's. They're effective in reducing some of the bass bounce I was getting from the hardwood floors. In spite of the low price these are heavy duty thick commercial quality mats and pass the WAF test.

http://www.homedepot.com/p/TrafficM...rcial-Door-Mat-60-885-1907-20000300/206498870

 

[Poultrygeist]

Acoustically dead with thick fiber over rubber, I could see them glued to baffles or to panels and used for room treatments.

 

[mkane]

Wouldn't fly here unless they were invisible. Mabey nestled between the wings. As soon as I'm finished with my wife bathroom remodel I'm going to construct another pair. Thanks Paul.

 

[H-daddy]

Many years ago my first experience with music was through a open back Magnavox 6v6 amp with fieldcoil 12" speakers. I always thought it was a beautiful sound even though it was mono. Anyway, these days I have a small garage and decided I would give open baffle a try. To make things simple, and for test purposes, I bought a 15 year old Sony low-end stereo with two el-cheapo speakers. I lopped off the back of the speakers and the sides and mounted them in the corners of the garage. Next I took two old Marantz speakers and cut the backs off those too. I mounted those towards the center of the wall. All four speakers are about 4-5 feet off the floor and with a slight downward angle. First play was quite amazing and with some slight adjustments in angle it sounds even better. Playing John Mayall's "Turning Point" (always my test recording of choice) I was impressed. The sound stage is perfect, the bass is fine, and the midrange not bad. I think for $15 and a little bit of work I have proved the concept (at least in my garage) so I am now thinking I can do better with minimal investment. But, as is, this system is really good.

 

[Poultrygeist]

Many years ago my first experience with music was through a open back Magnavox 6v6 amp with fieldcoil 12" speakers. I always thought it was a beautiful sound even though it was mono. Anyway, these days I have a small garage and decided I would give open baffle a try. To make things simple, and for test purposes, I bought a 15 year old Sony low-end stereo with two el-cheapo speakers. I lopped off the back of the speakers and the sides and mounted them in the corners of the garage. Next I took two old Marantz speakers and cut the backs off those too. I mounted those towards the center of the wall. All four speakers are about 4-5 feet off the floor and with a slight downward angle. First play was quite amazing and with some slight adjustments in angle it sounds even better. Playing John Mayall's "Turning Point" (always my test recording of choice) I was impressed. The sound stage is perfect, the bass is fine, and the midrange not bad. I think for $15 and a little bit of work I have proved the concept (at least in my garage) so I am now thinking I can do better with minimal investment. But, as is, this system is really good.

Sounds like we have another convert to the dark side

 

[Poultrygeist]

If you spend time on the AK tube forum you're likely to see posts touting those "Magnificent Magnavox" console pulls from yesteryear. After exchanging some correspondence with "Glow in the Dark" regarding amps to extract the most from the Zenith OB's I acquired this audio equivalent of a "resto-rod". This is a Magnavox single ended makeover with all new parts and sporting an updated circuit. Dennis Had, the founder and chief engineer of Cary Audio loves the sound of the old Maggies and in this build he retains the original power transformer and output iron. The sound is so clean and clear with the Zeniths I can't think about it too much without watery eyes. I only wish Diana Krall was here to hear how faithfully her voice is reproduced.

 

[Poultrygeist]

FWIW and for the time being I'm enjoying the Nobsound passive preamp with the Magnavox powering the Zeniths/tweets while the passive's second output ( pass through signal ) goes to an Ashly active crossover and then to a tube preamp and TPA3116 amp driving two Alpha H-frames. A sub connection on the Ashly goes to a plate amp driving a Dayton diy sub then cascading it's line out signal to another plate amp powering two bucket subs.

The Bottleheads are now back powering the Lowther OB's. I'd hate to be married to a single system as so much fun comes from switching things around.

 

[mkane]

Good stuff Paul. I'm giving a different amp a try today

 

[essNeff]

If you spend time on the AK tube forum you're likely to see posts touting those "Magnificent Magnavox" console pulls from yesteryear. After exchanging some correspondence with "Glow in the Dark" regarding amps to extract the most from the Zenith OB's I acquired this audio equivalent of a "resto-rod". This is a Magnavox single ended makeover with all new parts and sporting an updated circuit. Dennis Had, the founder and chief engineer of Cary Audio loves the sound of the old Maggies and in this build he retains the original power transformer and output iron. The sound is so clean and clear with the Zeniths I can't think about it too much without watery eyes. I only wish Diana Krall was here to hear how faithfully her voice is reproduced.

 

[essNeff]

Top notch stuff!
I would like Diana at my home for a slightly different reason.
Here's my "Little Maggie" in action. It's a rebuilt 9301 chassis.

 

[ScooterMcTav]

Hi all,

Apologies as I have not read all 96 pages of the thread - maybe 30 or so, and I started getting a bit lost.

Let's see if I can summarize what I believe I learned so far:

- You use a full range speaker on the open baffle
- If you would like to add a tweeter, you can either use a high pass filter, a capacitor, or bi-amp separately
- Bass may be lacking, but you can either bin the bass, eq it, or build a 10' wide baffle for it
- Passive x-overs are a no-no

Did I catch the main gist, and it's now up to me to source some full range speakers, a baffle, and figure out how to @#%$@&^ biwire the things?

I've got a set of Technics speakers in the the garage which can provide some donor parts for me. I like the idea here - seems like the OB concept would be great for a wide soundstage on orchestral music.

If I've missed any of the main bits, someone feel welcome to disabuse my of my incorrect thoughts.

Oh, and how would coaxial speakers work in this application (i.e. Kef iQ)

 

[Poultrygeist]

Top notch stuff!
I would like Diana at my home for a slightly different reason.
Here's my "Little Maggie" in action. It's a rebuilt 9301 chassis.

Love your Maggie. I bid on something very similar. You've got about 12 watts compared to my 4.

 

[ScooterMcTav]

In fact, I made a CAD drawing of my design - sort of Vandersteen in some ways.

I drew it, and I'm a CAD.

Thinking the key is the driver in the middle - the lower driver can have a low pass filter on it, and the tweet can have a high pass filter, while the full range driver in the middle handles everything from 100Hz to 10Khz.