I've been enjoying 15" Alphas on open baffle for the past few months. They are mounted close to the floor. But i was wondering if anyone can tell me how adding a second woofer per side enhances the overall sound? I have seen systems where one 15 is on bottom and another is on top. I am concerned adding a top woofer will create problems sonically because it will be closer to ear height. Can anyone describe what they have heard when doing this?
Thanks,
Godzilla
Thanks,
Godzilla
Jeff,
If you keep them near the floor, you take advantage of the floor as an extension of your baffle...
dave
If you keep them near the floor, you take advantage of the floor as an extension of your baffle...
dave
Seems a bit of a waste to go MTM with drivers that size for the reason Dave mentioned, plus a few others. Still, one way to find out if it works for you...
Hi Jeff,
Speaking strictly as a newb, a second woofer in general would get you a higher max SPL, and more sensitivity. In MTM (or I guess, it's WFW), not only do you lose the boundary reinforcement for the upper woofer, but you'd also probablly have to worry about getting a null from its floor bounce? On the other hand, there might be a slight benefit to the diversity of woofer placement for froom modes, but I (newbily) speculate that it's a wash, and you don't gain any lower bass (just the upper part of the top woofer's contribution).
Personally, if I were doing it, I'd just get an 18" woofer with a lower Fs. A second (or fourth!) Alpha doesn't really get you more extension, right? Just sensitivity, but why not go for (a) a driver with an even lower Fs and (b) larger displacement (perhaps even equivalent to two Alphas?) I recall that MJK said the Goldwood 18" GW-1858 got him 20-something Hz in his room. One Goldwood is pretty cheap too ($90 last time I checked).
Speaking strictly as a newb, a second woofer in general would get you a higher max SPL, and more sensitivity. In MTM (or I guess, it's WFW), not only do you lose the boundary reinforcement for the upper woofer, but you'd also probablly have to worry about getting a null from its floor bounce? On the other hand, there might be a slight benefit to the diversity of woofer placement for froom modes, but I (newbily) speculate that it's a wash, and you don't gain any lower bass (just the upper part of the top woofer's contribution).
Personally, if I were doing it, I'd just get an 18" woofer with a lower Fs. A second (or fourth!) Alpha doesn't really get you more extension, right? Just sensitivity, but why not go for (a) a driver with an even lower Fs and (b) larger displacement (perhaps even equivalent to two Alphas?) I recall that MJK said the Goldwood 18" GW-1858 got him 20-something Hz in his room. One Goldwood is pretty cheap too ($90 last time I checked).
for me, GW-1858 did about "this" in H-baffle - subjectively phat bass
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Hi freddi, sorry for the OT but:
1. Obviously those two measurements weren't in the same room, right?
2. I'm thinking of getting TrueRTA. May I ask what mic and mic pre you're using, and whether it's necessary to have it calibrated? I want a setup just like yours 🙂
3. It's pretty cool that you paste in the cabs and label everything -- you are the most prolific builder, I think.
1. Obviously those two measurements weren't in the same room, right?
2. I'm thinking of getting TrueRTA. May I ask what mic and mic pre you're using, and whether it's necessary to have it calibrated? I want a setup just like yours 🙂
3. It's pretty cool that you paste in the cabs and label everything -- you are the most prolific builder, I think.
I built 3 sets of open baffle (Audio Nirvana 10" and Audio Nirvana 12") with both one alpha 15" in H frame and one Goldwood 18" in H frame in the last year.
All times I used a plate amplifier (B & K ) for the bass unit. Integration between the units was easy in all cases.
When plugged into my Moscode 600 amp, they could play so loud I had to leave the room and didn't sound strained.
When hooked up to a SET unit, the speakers would play very loud, but the max spl was limited to the SET not the choice of bass driver.
Both the 15" and 18" had similar bass in that with the correct setting ( for my taste) on the plate amplifier, they both had a rising bass response ~8 dB at 80 Hz which fell quickly so that relative to mid and highs, it was again flat at about 50 Hz, and -3dB at 40 Hz.
On both of the alpha 15 and, Goldwood 18 the plate amplifier was set at about 2/3 full to get my favourite settings. In my opinion, if you are going to use a plate amplifier, you don't need a second alpha 15, and not much reason to go 18"...
I made all of these for other people, and my Acoustats are mounted kind of permanantly, and therefore in the way for best listening spot for the open baffles I made. The room is 14' X 25' X 8 with cement floor and set up in the middle of the room.
Paul
x
All times I used a plate amplifier (B & K ) for the bass unit. Integration between the units was easy in all cases.
When plugged into my Moscode 600 amp, they could play so loud I had to leave the room and didn't sound strained.
When hooked up to a SET unit, the speakers would play very loud, but the max spl was limited to the SET not the choice of bass driver.
Both the 15" and 18" had similar bass in that with the correct setting ( for my taste) on the plate amplifier, they both had a rising bass response ~8 dB at 80 Hz which fell quickly so that relative to mid and highs, it was again flat at about 50 Hz, and -3dB at 40 Hz.
On both of the alpha 15 and, Goldwood 18 the plate amplifier was set at about 2/3 full to get my favourite settings. In my opinion, if you are going to use a plate amplifier, you don't need a second alpha 15, and not much reason to go 18"...
I made all of these for other people, and my Acoustats are mounted kind of permanantly, and therefore in the way for best listening spot for the open baffles I made. The room is 14' X 25' X 8 with cement floor and set up in the middle of the room.
Paul
x
I'm skeptical...
I haven't found a fullrange driver that sounds nice at high volume on all program material. There's too much cone breakup in the 1-4 khz area, more so with larger drivers.
And I use 2 15"s per side. One handles 60-200hz and the other is a sub on its own amp. I claim excellent results. 🙂
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I have 2 alphas per side, plus a visaton B200 on each baffle. I 'did' have an issue with a lack of bass (!) but that seems to be sorted now. In fact, I am having to turn down the gain on the Rane or the bass is a bit too strong to maintain a normal relationship with the neighbours...
I would recommend at least trying it, even if you dont like it you could offload a pair of alphas easily without making a great loss.
Steve
I would recommend at least trying it, even if you dont like it you could offload a pair of alphas easily without making a great loss.
Steve
Well, I rewired the drivers directly, ie, the speaker cable straight to the terminals rather than via the magnet wire flying leads I was using. then I finished the basic mods on the Arcam Alpha 5 CD that had been sitting on the bench for weeks. I am not convinced that any one of the minor things I have done has cured the issue, maybe just an accumulation of issues who knows?
Anyway I am a happy bunny now, thanks to everyone who offered advice and spurred me on!
Steve
IIRC ???, both the H-baffle and inverted taper transflex were in the same room and spot with equal drive - That 295070 15" woofer in the pipe is an old Dayton/Eminence with 109oz magnet slug. I did those traces on an ancient Celeron with little Behringer mixer (with phantom power) and mic - my kid took all the mixers. (Dell deleted use of audio input on some later pcs) Lapaire did the H-baffle - I made the ugly/lopsided flooring grade plywood pipe.
Hi freddi, thank you -- I think I'll get your exact TrueRTA setup. I guess I'll go the distance and get the mic calibrated.
Hi aquapiranha -- congrats!
Hi aquapiranha -- congrats!
You first might want to read about the basics of low frequency sound reproduction before deciding on a specific concept: http://harman.com/EN-US/OurCompany/Technologyleadership/Documents/Scientific Publications/13680.pdf
Best, Markus
>>> Jeff,
>>> If you keep them near the floor, you take advantage of the floor as an
>>> extension of your baffle...
>>> dave
Thanks dave, and everyone else, for your replies. You helped me think something thru. Having two 15's (one per side) sounds so good i just wondered how two might sound. I thought i saw a few designs in an MTM configuration but searching again seems to reveal this is not the case. There are a few tho. And there are several with two 15s one above the other. But my room is too small for something like this. I want to hear how 18s sound and if i do, im sure i'd also like to hear 21s... I must say, at first i thought 15s would just be too large and dominate the room visually. After several months having them in my listening room, they are beginning to look small! I just appreciate their contribution and wondered about having two per side. In the right room i'd imagine two per side would be amazing.
http://i44.tinypic.com/fmure0.jpg
Dave, you comment above made me think of the Snell Type 1 speaker i saw many years ago. It seems to try and take advantage of a large baffle plus the continuation of the floor. Not sure the tweeter benefits from the same treatment but interesting just the same. See pic in the link above.
Thanks,
Godzilla
>>> If you keep them near the floor, you take advantage of the floor as an
>>> extension of your baffle...
>>> dave
Thanks dave, and everyone else, for your replies. You helped me think something thru. Having two 15's (one per side) sounds so good i just wondered how two might sound. I thought i saw a few designs in an MTM configuration but searching again seems to reveal this is not the case. There are a few tho. And there are several with two 15s one above the other. But my room is too small for something like this. I want to hear how 18s sound and if i do, im sure i'd also like to hear 21s... I must say, at first i thought 15s would just be too large and dominate the room visually. After several months having them in my listening room, they are beginning to look small! I just appreciate their contribution and wondered about having two per side. In the right room i'd imagine two per side would be amazing.
http://i44.tinypic.com/fmure0.jpg
Dave, you comment above made me think of the Snell Type 1 speaker i saw many years ago. It seems to try and take advantage of a large baffle plus the continuation of the floor. Not sure the tweeter benefits from the same treatment but interesting just the same. See pic in the link above.
Thanks,
Godzilla
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