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Hi all,
Thanks for bearing with me these last couple months as I have joined in here at PE TT and asked some probably odd questions. I'm going to be posting periodically regarding a build I am doing. It is a large 3 way using pro sound type drivers. It will be actively processed (probably with a BSS DSP) and powered by some old pro amps I've found for sale from a church that isn't using them anymore.
By way of retroactive introduction I am a physician by trade and have been a sound freak since high school. I have built DIY speakers as kits only in the past (Seas Embla and the AV1 from Danny Ritchie). I've built several home and prosound subwoofers. I enjoy live sound reinforcement which I get to participate in at our fairly large church. Anyway on to the subject at hand.
I, like I assume many of you here, am not a tweaky audiophile type. I appreciate good quality sound but I don't spend tons of time sitting and critically listening for how some nuance of a recording changed because I am now sitting 10 degrees off axis. For me it is more about being enveloped by the music and drawn into it by a system that sounds right and doesn't distract me by doing annoyingly wrong things. In any case my design goals for this speaker are the following.
1) Full range with as flat/even/smooth of a magnitude response as possible. By full range I mean as close as possible from 20hz all the way to 20khz (I fully realize at 40 I don't really hear 20khz anymore).
2) Low distortion. Part of the reason I chose a 3 way is to avoid having to push drivers into ranges where their distortion starts to rise. That is tough to avoid with a 2 way design. 2 way designs can obviously sound excellent but there are limitations with a 2 way that a 3 way avoids. A different set of tradeoffs I suppose.
3) Dynamics need to be excellent. To this end I wanted relatively high efficiency coupled with good power handling to result in very high output capability (for a home system that is). If a speaker is operating 30 db below it's max continuous output then there is plenty of room for all the dynamic range of almost any movies or music while avoiding any compression of the transient peaks...for example if playing at a relatively loud average level of 80 or 85 db on a system capable of 115db cleanly there is really not much likelihood at all that dynamic peaks will be compressed or have their impact lessened.
4) In less specific terms I want a system that is at once powerful, authoritative and dynamic but also with the ability to do all of that with clarity and subtlety when needed.
So the cabinet design is a large bass enclosure for the 15" woofer and then a truncated pyramid shaped enclosure on top of that which will house an MTM mid-hi section. (See very crude sketchup drawing below). I envision crossover points in the 200hz to 300hz range and again in the 1500hz to 2000hz range (obviously subject to change).
The tweeter is the Beyma TPL150H which is a hornloaded AMT type unit http://www.google.com/url?sa=t&rct=j...44158598,d.eWU
It appears to have very good distortion measurements, flat extended response and quite high efficiency. The hornloading should minimize the diffraction effects in the range of the tweeter.
The mid is the 18Sound 6ND430 as seen here http://www.eighteensound.com/index.a...simple&pid=243 and as tested by Zaph here http://www.zaphaudio.com/6.5test/ . It appears to have very low distortion, useable frequency response and good efficiency. A pair of these will be used on each side.
The chosen woofer is the B&C 15BG100 http://www.bcspeakers.com/products/l...o/15-0/15bg100 which should provide mid 20's extension in 135 liters vented and have sensitivity in the 91db range. I figure this driver should easily be safe for a crossover up to 300 hz or so. I have frankly perseverated more about the woofer choice more than the mid or tweeter. I have considered the RSS390HF which would give more infra-bass response but would be less efficient and have less maximum output capability (again except in the VLF realm say below 25 - 30 hz). The other one I have considered is the AE TD15S which would work in the enclosure I have built tuned quite low to give a vented alignment with a shallow sealed box type rolloff and F3 in the 35hz range. The AE would be an additional 2 db or so more efficient than the B&C. As it is the B&C have been ordered and are in transit so I probably will just end up sticking with them.
Pics of some of the box progress and of the drivers are included.
Feel free to offer any and all thoughts/advice/comments.
Loren Jones
Thanks for bearing with me these last couple months as I have joined in here at PE TT and asked some probably odd questions. I'm going to be posting periodically regarding a build I am doing. It is a large 3 way using pro sound type drivers. It will be actively processed (probably with a BSS DSP) and powered by some old pro amps I've found for sale from a church that isn't using them anymore.
By way of retroactive introduction I am a physician by trade and have been a sound freak since high school. I have built DIY speakers as kits only in the past (Seas Embla and the AV1 from Danny Ritchie). I've built several home and prosound subwoofers. I enjoy live sound reinforcement which I get to participate in at our fairly large church. Anyway on to the subject at hand.
I, like I assume many of you here, am not a tweaky audiophile type. I appreciate good quality sound but I don't spend tons of time sitting and critically listening for how some nuance of a recording changed because I am now sitting 10 degrees off axis. For me it is more about being enveloped by the music and drawn into it by a system that sounds right and doesn't distract me by doing annoyingly wrong things. In any case my design goals for this speaker are the following.
1) Full range with as flat/even/smooth of a magnitude response as possible. By full range I mean as close as possible from 20hz all the way to 20khz (I fully realize at 40 I don't really hear 20khz anymore).
2) Low distortion. Part of the reason I chose a 3 way is to avoid having to push drivers into ranges where their distortion starts to rise. That is tough to avoid with a 2 way design. 2 way designs can obviously sound excellent but there are limitations with a 2 way that a 3 way avoids. A different set of tradeoffs I suppose.
3) Dynamics need to be excellent. To this end I wanted relatively high efficiency coupled with good power handling to result in very high output capability (for a home system that is). If a speaker is operating 30 db below it's max continuous output then there is plenty of room for all the dynamic range of almost any movies or music while avoiding any compression of the transient peaks...for example if playing at a relatively loud average level of 80 or 85 db on a system capable of 115db cleanly there is really not much likelihood at all that dynamic peaks will be compressed or have their impact lessened.
4) In less specific terms I want a system that is at once powerful, authoritative and dynamic but also with the ability to do all of that with clarity and subtlety when needed.
So the cabinet design is a large bass enclosure for the 15" woofer and then a truncated pyramid shaped enclosure on top of that which will house an MTM mid-hi section. (See very crude sketchup drawing below). I envision crossover points in the 200hz to 300hz range and again in the 1500hz to 2000hz range (obviously subject to change).
The tweeter is the Beyma TPL150H which is a hornloaded AMT type unit http://www.google.com/url?sa=t&rct=j...44158598,d.eWU
It appears to have very good distortion measurements, flat extended response and quite high efficiency. The hornloading should minimize the diffraction effects in the range of the tweeter.
The mid is the 18Sound 6ND430 as seen here http://www.eighteensound.com/index.a...simple&pid=243 and as tested by Zaph here http://www.zaphaudio.com/6.5test/ . It appears to have very low distortion, useable frequency response and good efficiency. A pair of these will be used on each side.
The chosen woofer is the B&C 15BG100 http://www.bcspeakers.com/products/l...o/15-0/15bg100 which should provide mid 20's extension in 135 liters vented and have sensitivity in the 91db range. I figure this driver should easily be safe for a crossover up to 300 hz or so. I have frankly perseverated more about the woofer choice more than the mid or tweeter. I have considered the RSS390HF which would give more infra-bass response but would be less efficient and have less maximum output capability (again except in the VLF realm say below 25 - 30 hz). The other one I have considered is the AE TD15S which would work in the enclosure I have built tuned quite low to give a vented alignment with a shallow sealed box type rolloff and F3 in the 35hz range. The AE would be an additional 2 db or so more efficient than the B&C. As it is the B&C have been ordered and are in transit so I probably will just end up sticking with them.
Pics of some of the box progress and of the drivers are included.
Feel free to offer any and all thoughts/advice/comments.
Loren Jones
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