Open Baffle Epiphany!
- Thread starter cptnCanada
- Start date
Poultrygeist
Lunatic Member
It's not unusual for folks to start their OB journey using car speakers.
David_NC
Super Member
I recently picked up a pair of EV 12-TRXBs to get started with an OB setup. One is near mint, and one has a small tear in the cone, which should be easy to patch. These are the apparently somewhat rare 8 ohm models. They were missing L-pads, so I added some replacements. Currently, they are set up in Amazon boxes without backs just so I can get an idea of how they sound. First experience hearing them was meh. I had them connected to an unrestored but functional HK 630 Twin, and they didn't really have enough space behind them. Mostly, they just sounded pretty lifeless. I tried them again last night with a restored HK A230 Ballad and was slightly happier with them. That amp apparently takes a little longer to sound its best than my other tube amps, but after 30-45 minutes, things had improved dramatically. I listened to them for several hours and was much more impressed. There was also a bit more room behind them in this setup, which probably helped. Bass is fine for many music types and songs, but I will likely use them with subs or added woofers, since much of what I listen to has a lot of deep bass. On a couple songs, deep notes were completely absent - no cone rattling or distorted sound but simply not there. Vocals were really good on them, and highs are fine. Nothing I played on them sounded bad at all, but certain tracks were pretty amazing.
My plan is to mount them to baffles made from 18" x 48" 3/4" MDF, with the tweeters centered at the 3' point. This should but the tweeters at a decent level. This will also allow me to mount bass drivers below, if I like the sound enough to continue with this. Since the EV's mount from the rear, I'm thinking running my router with a roundover bit over the driver cutout to improve the looks a bit. I'll probably do the same with the outside edges; sharp edges on MDF just don't hold up well.
It sounds like the dimensions I'm planning should work out well enough, based on reading through this thread. I don't see these drivers used a lot in OB setups, which kind of surprised me; are they not as well suited as others for this use? Any thoughts or suggestions are appreciated.
My plan is to mount them to baffles made from 18" x 48" 3/4" MDF, with the tweeters centered at the 3' point. This should but the tweeters at a decent level. This will also allow me to mount bass drivers below, if I like the sound enough to continue with this. Since the EV's mount from the rear, I'm thinking running my router with a roundover bit over the driver cutout to improve the looks a bit. I'll probably do the same with the outside edges; sharp edges on MDF just don't hold up well.
It sounds like the dimensions I'm planning should work out well enough, based on reading through this thread. I don't see these drivers used a lot in OB setups, which kind of surprised me; are they not as well suited as others for this use? Any thoughts or suggestions are appreciated.
Poultrygeist
Lunatic Member
David_NC
Super Member
I got the MDF and made two baffles 48" x 18" wide. To keep them stable but fairly portable, I built boxes for the base that a concrete block, jug of water, bag of sand, etc can be placed for weight. A router and an easy to make circle jig is perfect for cutting the driver holes. I listened to them on the same HK A230 Ballad tube amp; it's the easiest to get to in the garage, but I'll try a couple others to see how they compare.
Overall, I think the speakers sound really good with very good detail and no harshness from the tweeters. I had them 3'-5' from the back wall. Closer hurt the bass, but more than 4.5-5' away from the wall also hurt it; 4' seemed to be the best distance. I sat anywhere from 8' to 20' back from them, and about 10-12 was best. These things sound big! By that, I mean they really filled the backyard with sound much better than the ones I typically drag out of the garage (ADS L520s).
Sitting centered in front of them, I could pick out locations of individual instrument's sounds, and soundstage was huge. Farther back, there wasn't as much detail to locate individual sounds, but overall balance was good with no real 'dead spots' for the highs. They will definitely play loud with a 15 or so watt amp; I'll get some dB numbers next time to quantify loud.
Bass isn't up to par, though, which isn't surprising, especially outside. It's there and definitely present, but it's not as loud and clearly defined as I'm accustomed to (ADS L880/2, L1090/2, and M12 all with subwoofers). I know it's not fair to compare those setups, but that's the level of bass I'm looking for. This was a quick listening session yesterday, but I'll add one of my subwoofers next time to see how it goes.
I'm going to add some uprights to the rear to give it a bit more rigidity. If it goes well with an added sub and crossover, I'll work on making them look good. Fun times!
Overall, I think the speakers sound really good with very good detail and no harshness from the tweeters. I had them 3'-5' from the back wall. Closer hurt the bass, but more than 4.5-5' away from the wall also hurt it; 4' seemed to be the best distance. I sat anywhere from 8' to 20' back from them, and about 10-12 was best. These things sound big! By that, I mean they really filled the backyard with sound much better than the ones I typically drag out of the garage (ADS L520s).
Sitting centered in front of them, I could pick out locations of individual instrument's sounds, and soundstage was huge. Farther back, there wasn't as much detail to locate individual sounds, but overall balance was good with no real 'dead spots' for the highs. They will definitely play loud with a 15 or so watt amp; I'll get some dB numbers next time to quantify loud.
Bass isn't up to par, though, which isn't surprising, especially outside. It's there and definitely present, but it's not as loud and clearly defined as I'm accustomed to (ADS L880/2, L1090/2, and M12 all with subwoofers). I know it's not fair to compare those setups, but that's the level of bass I'm looking for. This was a quick listening session yesterday, but I'll add one of my subwoofers next time to see how it goes.
I'm going to add some uprights to the rear to give it a bit more rigidity. If it goes well with an added sub and crossover, I'll work on making them look good. Fun times!
Poultrygeist
Lunatic Member
Nice job. I'm in Charlotte every month visiting my daughter. If you're near by I'd be glad to give you a pair of 10" OB bass woofers that would work well on those baffles.
David_NC
Super Member
I'd def. take you up on those, but I'm in SoCal now and in the CLT area maybe once a year. Thanks much for the offer though!
Poultrygeist
Lunatic Member
The Seas Exotic is about $1400 for a pair. Probably sounds great.
z-adamson
Addicted Member
Who around here is using them though?
Poultrygeist
Lunatic Member
Don't know of anyone.
David_NC
Super Member
I'd be curious as to what speakers he thinks do image well, what OB's he's heard, and if the room was too small for them. If I had to guess, it'd be that much of the imaging comes from the driver itself but is affected by the baffle (and the room to a lesser extent). These remind me a bit of a friend's Altecs, but I can't recall the model... Hollywood is part of it. Anyway, there's an airiness that I get from these too, which I guess is what makes them sound so big. I'm going to try them with my sub later in the week to see how that works out. I'm betting it'll fill in what's lacking. 48x18 seems to be a good size. It allows one to center the main driver at ear level without having to mess with stands, etc.@David_NC
Nice write up.
On another forum a member (that has never had OB speakers) always says OBs don't image well,I have heard many OBs that do it very well.
My 1 and 1/2 way Viston B200 open baffles were 48x18, I started out 48x24 and cut them to improve imaging.
If you add some bass only drivers I think you will go fromto
fjdds
Active Member
That's more than my entire Zenith 852s OBs cost, including Maggie amp, Fx-Tube-03, ($31), Khadas Tone Board $89)and Alpha H-frames with plate amps. And lumber!
They'd better sound good!
z-adamson
Addicted Member
What is an Alpha H-frame?
David_NC
Super Member
I'm able to move the OB's into the garage temporarily. I'm using them with a Sherwood S-5000II tube integrated, RBH ported sub powered by a 400 watt QSC pro amp, Topping E30, and Amazon HD. There are many changed variables at play here - room acoustics, different amp, and addition of the sub. I'd say the Sherwood is an improvement, the room not so much, and the sub is huge help. These things sound really good bordering on pretty damn amazing, all things considered. Without the sub, they were most of the way there, but now, they sound like a complete set of speakers. I'll move them inside in a few days for more listening with different room acoustics and electronics and an even better sub. It'll be fun to compare them to the ADS M12's that are used in that room. As is, I cannot imagine a better sounding speaker for the price.
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fjdds
Active Member
Agreed. Although the H-frames bass is very precise and 'tight', low frequency output energy is much better on my flat baffles. (2 alpha 15inch/side). Digs down deeper, although occasionally a little boomy compared to the H-frames, depending on what I'm listening to.
Poultrygeist
Lunatic Member
H-frames are open ended cubes with high QTS woofers mounted in the center. They have more output than a single woofer on a flat baffle but as you might think they are a bit directional. One major advantage is once you build a pair you can try any number of OB's or box speakers on top. The ones pictured here I built many years ago and today I use them with the Zenith alnico's on top.
Poultrygeist
Lunatic Member
Doubled H-frame with opposed woofers
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z-adamson
Addicted Member
I know what an h frame is, but what is an alpha h frame?
