Such (system) Q seems ideal for OB.
I got my system Q tuned to 1.1 with lo-Q driver and hi-Z amp, and I like the result very much, too.😀
BUMP!
Don't forget to come on by! I will be there tomorrow night. Set-up on Thursday.
Hope to see you there. 😀
Don't forget to come on by! I will be there tomorrow night. Set-up on Thursday.
Hope to see you there. 😀
End of day 1 at LSAF. I will post pix soon. Lot's of good stuff to hear. I do think that the Internet has helped raise the bar for sound quality. It's not just the big guys who have great sounding rigs now.
Yesterday was hell for me. Broken amps, missing tubes, power outages, crossover blues.
Had to call Parts Express and get a pair of 300B tubes overnighted. But all was up and working this AM. Day went fast. My rig is sounding pretty good, very laid back vintage style. Fun to listen to.
Will post photos as soon as I can. Great variety here. All good, all different. There have been a few forum members stop in.
I'm in room 215 if you happen to drop by.
Yesterday was hell for me. Broken amps, missing tubes, power outages, crossover blues.
Had to call Parts Express and get a pair of 300B tubes overnighted. But all was up and working this AM. Day went fast. My rig is sounding pretty good, very laid back vintage style. Fun to listen to.
Will post photos as soon as I can. Great variety here. All good, all different. There have been a few forum members stop in.
I'm in room 215 if you happen to drop by.
Hey panomaniac,
I came, I saw, and I heard the BIG OB with Altec coaxial.
I was privilaged enough to hear them back in 2008 when John Busch first brought them to LSAF. They sounded good then, and I thought they were even better this year.
I really think your introduction of EQ on the bass made a significant improvement as far as room control. In 2008 there was some room boom, to much bass for small hotel room.
It was great to hear these BIG OB's again. There is not much to complain about when it comes to OB sound, especially from the Altec.
It was great meeting you as well. I know it is a pretty long haul to come from your home in NC.
Speaking for myself and many others who discussed their thoughts about your OB speakers. Thanks for coming down to the Lone Star state, you brought more fun to the party, BIG OB fun.
Plus, I want to thank John Busch's for bringing his new OB creations, they were really good. John is a cool guy, we were glad that he came.
Now if Shane, myself and others could talk him into sharing. Many of us would love to have a pair of these beauties.
Oh yeah, we had the room right next to yours, 214. We could barely hear the loud music from your room. Thank goodness for thick concrete walls. We managed to get some much needed sleep.
This hotel has allot of positives design aspects about it, making it a good place for audio shows.
Looking forward to seeing all of you next year.
Norris Wilson
I came, I saw, and I heard the BIG OB with Altec coaxial.
I was privilaged enough to hear them back in 2008 when John Busch first brought them to LSAF. They sounded good then, and I thought they were even better this year.
I really think your introduction of EQ on the bass made a significant improvement as far as room control. In 2008 there was some room boom, to much bass for small hotel room.
It was great to hear these BIG OB's again. There is not much to complain about when it comes to OB sound, especially from the Altec.
It was great meeting you as well. I know it is a pretty long haul to come from your home in NC.
Speaking for myself and many others who discussed their thoughts about your OB speakers. Thanks for coming down to the Lone Star state, you brought more fun to the party, BIG OB fun.
Plus, I want to thank John Busch's for bringing his new OB creations, they were really good. John is a cool guy, we were glad that he came.
Now if Shane, myself and others could talk him into sharing. Many of us would love to have a pair of these beauties.
Oh yeah, we had the room right next to yours, 214. We could barely hear the loud music from your room. Thank goodness for thick concrete walls. We managed to get some much needed sleep.
This hotel has allot of positives design aspects about it, making it a good place for audio shows.
Looking forward to seeing all of you next year.
Norris Wilson
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Hi Norris, good to meet you, too. Thanks for the kind comments. Did I come over and visit you?
You're right about the thick walls. That hotel is really well built. As loud as it got in the rooms, it never seemed loud in the halls or in the next room. Really nice for this kind of gig.
I did add digital EQ and crossover to the OB rig - a Behringer DCX2496. I drove it simply off the 4 ohm taps of the lovely Grant Fidelity 300B amp. Went balanced into the analog inputs of the DCX. That worked well. The DCX allowed me not only to tweak the phase of the bass (I ended up at 45°) but also to kill the big hump that the rooms have at 34Hz.
Getting control of the bass and running the Grant amp on the Altecs I'm sure really opened up the sound.
John's new OB rig was really impressive. It sounded as big as it looked. More on that later.
Was nice to see so much innovative spirit at LSAF.
You're right about the thick walls. That hotel is really well built. As loud as it got in the rooms, it never seemed loud in the halls or in the next room. Really nice for this kind of gig.
I did add digital EQ and crossover to the OB rig - a Behringer DCX2496. I drove it simply off the 4 ohm taps of the lovely Grant Fidelity 300B amp. Went balanced into the analog inputs of the DCX. That worked well. The DCX allowed me not only to tweak the phase of the bass (I ended up at 45°) but also to kill the big hump that the rooms have at 34Hz.
Getting control of the bass and running the Grant amp on the Altecs I'm sure really opened up the sound.
John's new OB rig was really impressive. It sounded as big as it looked. More on that later.
Was nice to see so much innovative spirit at LSAF.
The Altec OB rig
OK, here some thoughts and images about the Altec OB rig that was in my room at LSAF.
First thing is a big "Thank You" to Grant Fidelity Home Audio for sending their lovely A-534B integrated amp to the show for me to use. It really did sound very nice. Great match for the Altec drivers.
The rig was a 3-way system:
The Altecs used a 2nd order passive crossover. No high pass or Zobel on the 15.
High pass and horn shaping on the 1" tweeter. The 18" was crossed with a DCX2496 in analog input mode. 3rd order, ~34Hz (IIRC). EQ used to kill room peak.
This all worked well together and integrated well. Like all open baffle speakers these had a big, open sound. But more than that, they had good depth. Not many of the speakers at LSAF could claim that. They also had a good, strong bass that did not sound too "speaker like" to me. Overall the system was easy going and laid back. Super easy to listen to and louder than you might think. I did get carried away with some Host Planets once, but mostly it was well behaved. 😉
As good as the sound was, I would have liked more resolution in the lower mids. I'm spoiled by big Altec horns, and the 15" paper mid just didn't have that cleanness. Perhaps a lower cross point to the horn would help. Something to work on....
You'll see a frequency response graph I did at the listening position and it's not too bad. It does fall a bit, as it should at the listening position. The top end falls off more than I would like, but that's the nature of the 605 horn. I did lift it with the crossover (C5/R1).
There is a big hole at 146Hz. Not sure what caused this, but John's big OBs had a similar dip. Perhaps reflections off the back wall?
Comments were generally favorable, but it was hard to tell what people thought. These are not "whiz-bang" speakers that catch your attention right away. They are more subtle. But in the long run very enjoyable and never fatiguing. Approaching the flavor of live acoustic music.
OK, here some thoughts and images about the Altec OB rig that was in my room at LSAF.
First thing is a big "Thank You" to Grant Fidelity Home Audio for sending their lovely A-534B integrated amp to the show for me to use. It really did sound very nice. Great match for the Altec drivers.
The rig was a 3-way system:
- High >2.3KHz = Altec 605 1" horn in the coax driver
- Mid 66Hz to 2.3Khz = Altec 605 15" woofer
- Low < 66Hz = Eminence 18" pro sound woofer (discontinued)
The Altecs used a 2nd order passive crossover. No high pass or Zobel on the 15.
High pass and horn shaping on the 1" tweeter. The 18" was crossed with a DCX2496 in analog input mode. 3rd order, ~34Hz (IIRC). EQ used to kill room peak.
This all worked well together and integrated well. Like all open baffle speakers these had a big, open sound. But more than that, they had good depth. Not many of the speakers at LSAF could claim that. They also had a good, strong bass that did not sound too "speaker like" to me. Overall the system was easy going and laid back. Super easy to listen to and louder than you might think. I did get carried away with some Host Planets once, but mostly it was well behaved. 😉
As good as the sound was, I would have liked more resolution in the lower mids. I'm spoiled by big Altec horns, and the 15" paper mid just didn't have that cleanness. Perhaps a lower cross point to the horn would help. Something to work on....
You'll see a frequency response graph I did at the listening position and it's not too bad. It does fall a bit, as it should at the listening position. The top end falls off more than I would like, but that's the nature of the 605 horn. I did lift it with the crossover (C5/R1).
There is a big hole at 146Hz. Not sure what caused this, but John's big OBs had a similar dip. Perhaps reflections off the back wall?
Comments were generally favorable, but it was hard to tell what people thought. These are not "whiz-bang" speakers that catch your attention right away. They are more subtle. But in the long run very enjoyable and never fatiguing. Approaching the flavor of live acoustic music.
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Hi panomaniac,
Thanks for sharing the x-over of your OB spkrs, I am curious about your x-over of the 1" horn, with 2 shelving capacitors, C2 and C5, can you explain?
146Hz could be floor bounce?
Thanks for sharing the x-over of your OB spkrs, I am curious about your x-over of the 1" horn, with 2 shelving capacitors, C2 and C5, can you explain?
146Hz could be floor bounce?
Could be floor bounce, I suppose. But 146Hz is equal to about 7.7 feet or 2.35 meters, so it might have been rear wall bounce. Should have done more poking around with the mic, but didn't....
The 2 shelving caps came about by experiment. It may not be optimum. To raise the natural roll-off of the horn I tried bigger caps at C2. They had very little effect. Neither did bypassing R3 or even R3+R4. Bypassing R1 did the trick. Hurray for clip leads! C2 stayed in place because it gave a little lift at the top.
The 2 shelving caps came about by experiment. It may not be optimum. To raise the natural roll-off of the horn I tried bigger caps at C2. They had very little effect. Neither did bypassing R3 or even R3+R4. Bypassing R1 did the trick. Hurray for clip leads! C2 stayed in place because it gave a little lift at the top.
Panomaniac,
I would be interested to know which eminence 18 driver that is you are using, and how it performs?
Also I am eagerly waiting to hear your thoughts on build using the Seas A26re4 and goldwood 18s. Madisound says that Seas driver has a natural roll off at 2k and im sure could make for a simplified crossover, and natural sound with that paper cone.
I would be interested in any other open baffle using larger coax'es if there were any at that event.
thanks in advance, and your open baffles are inspiring😉
I would be interested to know which eminence 18 driver that is you are using, and how it performs?
Also I am eagerly waiting to hear your thoughts on build using the Seas A26re4 and goldwood 18s. Madisound says that Seas driver has a natural roll off at 2k and im sure could make for a simplified crossover, and natural sound with that paper cone.
I would be interested in any other open baffle using larger coax'es if there were any at that event.
thanks in advance, and your open baffles are inspiring😉
Hi Brook.
Well there is bad news about that Eminence 18. It's no longer made. 🙁 It was an OEM product and the buyer does not use it any more. You can't get them.
Other bad news is that it's a great driver. Strong motor with great cone and suspension. Very little cone noise. See the graph below of it in use in this OB. Beside the little bump at 1.5K, (maybe voice coil reflection) there isn't anything. There are few 18s that can claim that.
But there are other 18s out there. This one happens to be "unsuited" for OB work because it's low Q. Qts is about 0.26 That low should mean no bass on open baffle. But there was plenty of bass. You just have to do the crossover right.
As for other big coax, there were 2. Right next door was the Hawthorn taking a similar approach. 15" coax and 15" powered sub. The Hawthorn Silver Iris 15 is not an Altec by any stretch of the imagination, but it costs about 1/4th what the Altecs go for these days. With the right crossover, it should make a very nice budget OB.
Danny Richie also had his V1 that uses a P.Audio 12" coax and 2x12" powered subs. The P.Audio coax line is really nice. They always have a bit of an edge, but otherwise are super dynamic and life-like.
Well there is bad news about that Eminence 18. It's no longer made. 🙁 It was an OEM product and the buyer does not use it any more. You can't get them.
Other bad news is that it's a great driver. Strong motor with great cone and suspension. Very little cone noise. See the graph below of it in use in this OB. Beside the little bump at 1.5K, (maybe voice coil reflection) there isn't anything. There are few 18s that can claim that.
But there are other 18s out there. This one happens to be "unsuited" for OB work because it's low Q. Qts is about 0.26 That low should mean no bass on open baffle. But there was plenty of bass. You just have to do the crossover right.
As for other big coax, there were 2. Right next door was the Hawthorn taking a similar approach. 15" coax and 15" powered sub. The Hawthorn Silver Iris 15 is not an Altec by any stretch of the imagination, but it costs about 1/4th what the Altecs go for these days. With the right crossover, it should make a very nice budget OB.
Danny Richie also had his V1 that uses a P.Audio 12" coax and 2x12" powered subs. The P.Audio coax line is really nice. They always have a bit of an edge, but otherwise are super dynamic and life-like.
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Yeah, I think so. They are big, bold and powerful. A little OTT for my tastes, but lots of folks like that kind of sound. Very rock & roll, in clean sort of way.
Comes down to a matter of taste, really.
Comes down to a matter of taste, really.
John's D-18s
OK, gonna talk a little about John Busch's big "D-18" open baffle rig.
Below you'll find photos and the in-room response measured at the listening position.
Here is a rig that Martin J King should enjoy. High Q woofers (about Q=1 on baffle) and a big paper midrange.
This is an all passive rig, 3 way. Open woofers and mid, sealed dome tweeter.
Drivers are:
Basically passive 2nd order on all three parts. No low pass needed on the 10", it rolls off just fine on the top. The crossover isn't published, and I don't know if it will be, but it's John's classic approach. BIG cap & coil on the woofers to fight the rising response on open baffle. Large spread to the midrange high pass for offset and phase, then bring in tweeter to match.
As you'll see on the graph below there is some shaping going on. Also a big peak at 32Hz that is the a room mode. What you don't see is a rise again at 16Hz. Remember, this is the actual listening position response of a crossover that was built in the hotel suite with NO measurements. All by ear. I measured Sunday just before we took it apart.
Will post baffle dimensions ASAP. IIRC, height is 46". Short side wings.
How does it sound? Well on Friday when we first fired it up, not great. The bass was badly boomy and the tweeter got into trouble fast. John rebuilt the crossover pretty much from scratch. The bass hump was tamed to a large degree and a new tweeter (TDFC) helped a lot.
These are big and they sound big. Probably too much bass for the small room. But they stay clean no matter how loud you get. And that's both impressive and surprising. With the TDFC tweeter, there was never a hint of strain throughout the entire range, even at 100dB average levels. (What??)
Soundstage is huge and open, of course. But there is also real depth and hight, qualities I find lacking in so many speakers. Midrange is clean and clear, better than most other cone midrange you'll hear. John says he can make it better. The sound can be very delicate if needed, or massive when the music calls for it. The 10" Seas A26RE4 makes a great midrange.
Overall a great success, I would say. there is still work to be done, but the basics are in place.
OK, gonna talk a little about John Busch's big "D-18" open baffle rig.
Below you'll find photos and the in-room response measured at the listening position.
Here is a rig that Martin J King should enjoy. High Q woofers (about Q=1 on baffle) and a big paper midrange.
This is an all passive rig, 3 way. Open woofers and mid, sealed dome tweeter.
Drivers are:
- Woofers - 2X Goldwood GW-1858 18"
- Midrange - 1X Seas Prestige A26RE4 (nominally a woofer)
- Tweeter - 1X Seas Prestige 27TDFC
Basically passive 2nd order on all three parts. No low pass needed on the 10", it rolls off just fine on the top. The crossover isn't published, and I don't know if it will be, but it's John's classic approach. BIG cap & coil on the woofers to fight the rising response on open baffle. Large spread to the midrange high pass for offset and phase, then bring in tweeter to match.
As you'll see on the graph below there is some shaping going on. Also a big peak at 32Hz that is the a room mode. What you don't see is a rise again at 16Hz. Remember, this is the actual listening position response of a crossover that was built in the hotel suite with NO measurements. All by ear. I measured Sunday just before we took it apart.
Will post baffle dimensions ASAP. IIRC, height is 46". Short side wings.
How does it sound? Well on Friday when we first fired it up, not great. The bass was badly boomy and the tweeter got into trouble fast. John rebuilt the crossover pretty much from scratch. The bass hump was tamed to a large degree and a new tweeter (TDFC) helped a lot.
These are big and they sound big. Probably too much bass for the small room. But they stay clean no matter how loud you get. And that's both impressive and surprising. With the TDFC tweeter, there was never a hint of strain throughout the entire range, even at 100dB average levels. (What??)
Soundstage is huge and open, of course. But there is also real depth and hight, qualities I find lacking in so many speakers. Midrange is clean and clear, better than most other cone midrange you'll hear. John says he can make it better. The sound can be very delicate if needed, or massive when the music calls for it. The 10" Seas A26RE4 makes a great midrange.
Overall a great success, I would say. there is still work to be done, but the basics are in place.
Attachments
Very big and powerful loudspeaker. Not easy to tune well, because the lowest woofer is near the floor and produces more bass. You do not need to fully compensate the OB lost of bass (I think 3dB less than normal).
🙂
🙂
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To help the 10" mid reach down a bit. There is a top shelf, but it does not go all the way across.
That answers the question i had for you. Yours?
I have a spare one of those up for grabs.
dave
Hey Dave. No, not mine. Rachel sent it to the show for me to use and show off.
Very nice amp. I almost brought it home with me.
But with my system I just don't need the power of the 300B tube. 2A3 or 45 is plenty for me. 110db/W will do that for you.
Very nice amp. I almost brought it home with me.
But with my system I just don't need the power of the 300B tube. 2A3 or 45 is plenty for me. 110db/W will do that for you.
I think they rate it at 8.8W which is not hurting a 300B. Most 2A3s I've seen are about 2 watts (if they're honest). I really only need 1 watt, but who's counting? 😉
But on this Altec rig I was running 16 ohm drivers on the 8 ohm tap. So 1/2 the power. Seemed to be plenty. FWIW, I was picking up signal off the 4 ohm tap and sending it to the DCX. Interesting that a lot of the new tube amps don't have 16 ohm taps.
But on this Altec rig I was running 16 ohm drivers on the 8 ohm tap. So 1/2 the power. Seemed to be plenty. FWIW, I was picking up signal off the 4 ohm tap and sending it to the DCX. Interesting that a lot of the new tube amps don't have 16 ohm taps.
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