I'm planning on documenting my latest DIY effort here and hopefully use this thread to pick the brains of others as the project progresses 
I chose to call this latest project 'Perceive' because I hope it will offer a clarity and insight into music that is amongst the best available from commercially available loudspeakers.
Going with a 3-way, tri-amplified design with onboard triple mono amplifiers and all active Linkwitz 4th order network.
Just running through a quick synopsis of the components used for each speaker:
Drivers:
1 x Scan-Speak R2904-7000 Ring Radiator
1 x ATC SM75.150 3" Dome Midrange
2 x Seas Excel W22 8.5" Bass
Electronics and amplification:
1 x 3-way Linkwitz 4th order XO with transform,EQ and delay circuits
1 x Active XO power supply
1 x 16v Toroidal transformer for XO power supply
1 x Input/Output board with Balanced XLR and unbalanced RCA inputs
1 x 2 x 120w(8ohm) solid state amp for treble and mid drivers.
1 x Dual PSU for the treble and mid amps
1 x 120w(8ohm) solid state amp for bass drivers
1 x PSU for bass amp
3 x 18v Toroidal transformers for amp power supplies
All of this will be going in to a time-aligned, decoupled sat/sub type arrangement. With the Scan and ATC in the upper cabinet which sits on the bass cabinet containing the two Excel drivers.
Current candidates for crossovers frequencies are 400hz, 2.5Khz. These figures are subject to change after testing but are good starting points.
Most of the above components such as the Scan rings, ATC mid and all of the electronics and amplification I have or am awaiting delivery. The cabinets are in the late planning stages so are virtually ready to built. This will hopefully start in the next week or so. The only thing I haven't ordered or have is the bass drivers which leads on to a question.
Question:
I'm undecided on the bass drivers to use with the design, initial thoughts are the Sea's Excel W22. I'm limited to 8.5" drivers at the most because I'd like to keep the baffle slim.
What I'd appreciate from others are potential candidates to be used in the transmission line enclosure sub enclosure.
Will post details and other questions as the project progresses.
Thanks for looking.
I chose to call this latest project 'Perceive' because I hope it will offer a clarity and insight into music that is amongst the best available from commercially available loudspeakers.
Going with a 3-way, tri-amplified design with onboard triple mono amplifiers and all active Linkwitz 4th order network.
Just running through a quick synopsis of the components used for each speaker:
Drivers:
1 x Scan-Speak R2904-7000 Ring Radiator
1 x ATC SM75.150 3" Dome Midrange
2 x Seas Excel W22 8.5" Bass
Electronics and amplification:
1 x 3-way Linkwitz 4th order XO with transform,EQ and delay circuits
1 x Active XO power supply
1 x 16v Toroidal transformer for XO power supply
1 x Input/Output board with Balanced XLR and unbalanced RCA inputs
1 x 2 x 120w(8ohm) solid state amp for treble and mid drivers.
1 x Dual PSU for the treble and mid amps
1 x 120w(8ohm) solid state amp for bass drivers
1 x PSU for bass amp
3 x 18v Toroidal transformers for amp power supplies
All of this will be going in to a time-aligned, decoupled sat/sub type arrangement. With the Scan and ATC in the upper cabinet which sits on the bass cabinet containing the two Excel drivers.
Current candidates for crossovers frequencies are 400hz, 2.5Khz. These figures are subject to change after testing but are good starting points.
Most of the above components such as the Scan rings, ATC mid and all of the electronics and amplification I have or am awaiting delivery. The cabinets are in the late planning stages so are virtually ready to built. This will hopefully start in the next week or so. The only thing I haven't ordered or have is the bass drivers which leads on to a question.
Question:
I'm undecided on the bass drivers to use with the design, initial thoughts are the Sea's Excel W22. I'm limited to 8.5" drivers at the most because I'd like to keep the baffle slim.
What I'd appreciate from others are potential candidates to be used in the transmission line enclosure sub enclosure.
Will post details and other questions as the project progresses.
Thanks for looking.
Right pictures of the drivers now:
The R2904 treble units come as a matched pair and just to make sure you realise that you've spent £550 on a pair of tweeters they come in a presentation box - wow, good to know my money is going into sound quality and not useless trinkets :roll:
Whats this! Someones stole one
These things look downright dangerous with that extremely sharp phase plug in the middle. Wouldn't like to have these around with young kids otherwise there could be a nasty accident :? Build quality is faultless on these drivers. Very weighty too for HF units.
An externally hosted image should be here but it was not working when we last tested it.
The R2904 treble units come as a matched pair and just to make sure you realise that you've spent £550 on a pair of tweeters they come in a presentation box - wow, good to know my money is going into sound quality and not useless trinkets :roll:
An externally hosted image should be here but it was not working when we last tested it.
Whats this! Someones stole one
These things look downright dangerous with that extremely sharp phase plug in the middle. Wouldn't like to have these around with young kids otherwise there could be a nasty accident :? Build quality is faultless on these drivers. Very weighty too for HF units.
Here's a few early designs I've knocked up using CAD.
In the end I chose to go with non of these and decided on the decoupled sub/sat arrangement.
I thought I post these here though just to give an idea of the direction I'm heading in.
Once the final design is complete I'll post a schematic of it.
An externally hosted image should be here but it was not working when we last tested it.
In the end I chose to go with non of these and decided on the decoupled sub/sat arrangement.
I thought I post these here though just to give an idea of the direction I'm heading in.
Once the final design is complete I'll post a schematic of it.
Active 3-way LR 4th order XO
Power Supply for the active crossover:
Amplifier input and output stage with balanced and unbalanced connections
An externally hosted image should be here but it was not working when we last tested it.
Power Supply for the active crossover:
An externally hosted image should be here but it was not working when we last tested it.
Amplifier input and output stage with balanced and unbalanced connections
An externally hosted image should be here but it was not working when we last tested it.
Treble & Midrange Amplification and PSU
Dual mono amp with 2x120w into 8ohm. Used for treble and mid drivers
Treble and mid amplifier PSU 2 x 56V/2 x 14A continuous current capacity (2 x 70A peak) for the amplifier and 2 x 30V/2 x 0.2A for the input/output stage circuit.
Dual mono amp with 2x120w into 8ohm. Used for treble and mid drivers
An externally hosted image should be here but it was not working when we last tested it.
Treble and mid amplifier PSU 2 x 56V/2 x 14A continuous current capacity (2 x 70A peak) for the amplifier and 2 x 30V/2 x 0.2A for the input/output stage circuit.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Bass Amplification and PSU
Mono amp with 1x120w into 8ohm. Used for bass drivers
Bass amplifier PSU 56VA 14A
Mono amp with 1x120w into 8ohm. Used for bass drivers
An externally hosted image should be here but it was not working when we last tested it.
Bass amplifier PSU 56VA 14A
An externally hosted image should be here but it was not working when we last tested it.
Heh, world class project you've got going here =). Did you design these boards yourself or can they be purchased some where? What made you decide to go with an analog active crossover as opposed to a digital one? One solution to your bass driver problem would be mounting the driver on the side of the enclosure instead of the front. If you're only using the driver below about 120Hz or so then it isn't important for the driver to face the listening position (anyone feel free to step in an correct me on this if I'm wrong). It's my understanding that these frequencies are below the point where sound becomes "unlocalizable".
I'm very excited about seeing this project progress. Your pictures are really excellent. Thanks so much for taking the time to document your effort.
I'm very excited about seeing this project progress. Your pictures are really excellent. Thanks so much for taking the time to document your effort.
m0tion said:
Thanks
I wish I could design PCB's like that!
They were bought from here:
http://www.bmm-electronics.com/Producten_B.asp?Productgroep_ID=7
They are Nederlands based but will ship worldwide and supply either bare PCB's and schematics, kits or fully assembled and tested PCB's. So depending on your confidence/skill with electronics you can tailor the whole effort to match.
Personally I've gone for the fully assembled and tested to avoid any headache's. I really want to concentrate all my efforts into what I'm good at and thats active XO's and cabinet making. So not having to worry and expend time reaseaching amplifier design and perfecting my soldering skills, not to mention a considerable outlay in time to build all 14 PCB's for a speaker means I can dedicate myself to the parts I'm intimate with.
Some of the amp builders and designers will be shaking their heads
but I wanted a tailored solution without the hassle.Again I'm very familar with analogue active XO's. Because of this I can quickly add extra PCB's such as transform, delay, EQ, notch. shelving etc. and know instantly how to use them to correct problems in the measured response during crossover testing/tweaking.
Unfortunately the XO point between the bass and mid will be set no lower than 300hz with 400hz more probable. The reason for this is my choice of mid driver, the ATC 3" dome. Its simply not comfortable playing down to something like 120hz.
The side firing bass driver would of course ruin the lower mid's/upperbass and the response curve would suffer as a result.
So the bass drivers have to be used on the front baffle because of the 400hz XO point. Also note that I've chosen to use 2 bass drivers because of the high sensitivity of the mid and treble units - 94dB.
Also I wish to get more accurate, yet extended bass by using two smaller bass drivers such as the 8"ers in a TL loaded sub cabinet.
Its a pleasure and I thank all who share their idea's on here and give inspiration to others.
tiroth said:
Choice of order was entirely decided upon because of the time and phase coherency requirement.
The LR 4th order affords both of these in the electrical domain as well as flat amplitude through the pass band and the acoustic sum of the drivers is unity at the XO point.
If I'd gone with butterworth etc I'd would have had an extra notch filter to correct the 6dB summed gain at the XO point.
Of course there will be phase differences since the natural acoustic rolloff of the drivers will cause this. An all pass filter will correct these phase discrepencies.
The Scan Ring will definitely require an all pass but the mid and bass will have very close to what is a 4th order acoustic rolloff at their XO point because the drivers have a flat and large overlapped response.
I also have a preference for 4th order when it comes to active XO's. But I wouldn't sacrifice the sound of a design just to keep within this preference. So of course this choice will be evaluated when testing and tweaking the crossovers and may change based upon the results. For now though these are going to be the starting points.
Just to illustate the quality of the ATC dome mid:
The ATC certainly offers more material value than the Scan ring. Also note the irregular rear on the Scan, most likely to minimise reflections passed into the rear of the cabinet. Nice touch.
This thing weighs in at 9kg, more than most so called subs
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
The ATC certainly offers more material value than the Scan ring. Also note the irregular rear on the Scan, most likely to minimise reflections passed into the rear of the cabinet. Nice touch.
This thing weighs in at 9kg, more than most so called subs
The excel driver isn't the natural choice here, rather this new seas driver is (understanding that power input will need to be increased to achieve flat bsc response):
http://www.seas.no/seas_line/woofers/H1252.pdf
Only two things bother me with HiFi woofers: dynamics and distortion nearing fs. Provided you have the skills I'd be more inclined to mass load the Beyma 8G40 (but the result would be even less efficient) vs. the Seas driver - but the easier choice is still the Seas (and it will provide much greater spl).
The ONLY 8 inch driver I can think of that has enough eff. (even with a bit of mass loading to lower fs) is more expensive and probably has worse distortion nearing fs (though superior dynamic capability and far more "transparent" upper bass and lower midrange):
http://www.supravox.fr/haut_parleurs/215_GMF.htm
It would be my first choice (a pair with a bit of added mass), though costly. (note the csd at 300 Hz, there is about 9db of clean signal, almost like a Manger driver this low in freq..)
http://www.seas.no/seas_line/woofers/H1252.pdf
Only two things bother me with HiFi woofers: dynamics and distortion nearing fs. Provided you have the skills I'd be more inclined to mass load the Beyma 8G40 (but the result would be even less efficient) vs. the Seas driver - but the easier choice is still the Seas (and it will provide much greater spl).
The ONLY 8 inch driver I can think of that has enough eff. (even with a bit of mass loading to lower fs) is more expensive and probably has worse distortion nearing fs (though superior dynamic capability and far more "transparent" upper bass and lower midrange):
http://www.supravox.fr/haut_parleurs/215_GMF.htm
It would be my first choice (a pair with a bit of added mass), though costly. (note the csd at 300 Hz, there is about 9db of clean signal, almost like a Manger driver this low in freq..)
Its funny you should mention the Sea's L22, it was in my mind as a potential condidate.
Here's the short list so far that look suitable:
Sea's L22RXP
Sea's Excel W22
Volt B220.2
Volt B250.8
Scan-Speak 22W
The supravox are very difficult(second hand market only) to get hold of here in the UK and I would never consider shipping another speaker from a different country ever again after the hassle I've had previously.
Here's the short list so far that look suitable:
Sea's L22RXP
Sea's Excel W22
Volt B220.2
Volt B250.8
Scan-Speak 22W
The supravox are very difficult(second hand market only) to get hold of here in the UK and I would never consider shipping another speaker from a different country ever again after the hassle I've had previously.
My aim isn't floor pounding bass like some would pursue.
I want these to be about imaging, detail, speed and transparency.
I don't think I could have made a better choice regarding treble and mid units, they're the best that's available in the UK. The bass driver however is always more trouble.
I can boost the low end of bass drivers using a linkwitz transform circuit or maybe that's a little too drastic and could further increase distortion.
I want these to be about imaging, detail, speed and transparency.
I don't think I could have made a better choice regarding treble and mid units, they're the best that's available in the UK. The bass driver however is always more trouble.
I can boost the low end of bass drivers using a linkwitz transform circuit or maybe that's a little too drastic and could further increase distortion.
Banned
Joined 2002
ShinOBIWAN said:
Hmm, to bad then about the Supravox - that would be their forte (and better dynamics to "boot").
The 8/800 37Hex looks pretty good. (a little higher Qts is a good thing for the T-Line, though fs isn't quite as low as the Seas). I'm guessing though that the driver will be a little dynamically "stunted" (as would the Seas). Excursion isn't much - so spl's would suffer. At least they publish distortion figures - it sure would be nice to see what the distortion was like on the Seas. Between the two I'd opt for the Seas (which is virutually tailored for a T-Line).
The Volt drivers don't do anything for me - nothing special on the TS param.s and no distortion figures (and the smaller one doesn't have the "Q" neccesary for a T-Line).
As for the Scan Speak, the Q is a little low BUT the response seems to "take up the slack". Like the Seas you are missing data on distortion, but this is Scan Speak.. Excursion is lower than the Seas while MMs is higher. Again, between the two I'd opt for the Seas.
Hello again folks.
I've had quite a drastic turnaround regarding the loading in the bass cabinet. Originally I had planned a TL loading but after modelling using MJK's excellent MathCAD sheets I'm now having second thoughts.
My proposal is for a sealed box design both heavily braced and stuffed. Then apply a Linkwitz transform to lower the response.
This of course means a totally different look at potential drivers used for the sub enclosure.
Right here are the requirements for the driver:
-Driver must be flat to at least 500hz+ as it will be crossed over at around 400hz.
-The lower the Fs the better.
-The higher the efficiency the better - less power required.
-The higher the excursion the better - less distortion
-Enclosure volume is likely to be 70 liters.
I would really appreciate any suggests on the types of driver(s) to be used. I'm also going to consider drivers upto 10" instead of the 8" previously.
Once I've got this bass situation sorted I can start work.
I've had quite a drastic turnaround regarding the loading in the bass cabinet. Originally I had planned a TL loading but after modelling using MJK's excellent MathCAD sheets I'm now having second thoughts.
My proposal is for a sealed box design both heavily braced and stuffed. Then apply a Linkwitz transform to lower the response.
This of course means a totally different look at potential drivers used for the sub enclosure.
Right here are the requirements for the driver:
-Driver must be flat to at least 500hz+ as it will be crossed over at around 400hz.
-The lower the Fs the better.
-The higher the efficiency the better - less power required.
-The higher the excursion the better - less distortion
-Enclosure volume is likely to be 70 liters.
I would really appreciate any suggests on the types of driver(s) to be used. I'm also going to consider drivers upto 10" instead of the 8" previously.
Once I've got this bass situation sorted I can start work.
I'm curious about how the plan to use LT interacts with the statement that "floor pounding bass" isn't needed. How low do you want? In my experience, F3 around 50 can be quite authoritative in a sealed alignment. The advantage being, there are a lot more drivers to choose from in the Fs ~40 range that will deliver this performance at high efficiency. Also, I think it limits excursion and thus distortion.
I hope you don't object to me picking your brain as you work through this process; it's of particular interest to me as I am also working on a TMWW design that seems to stem from similar design principles: high efficiency, a wideband true mid, coherent woofers, all active. I've already got the basic design done but I am still playing with the XO...I'm interested in 4th order because of the phase alignment benefits, but since I have a good-sounding 2nd-order XO, I'm afraid of the supposed sonic penalties of higher-order designs.
I hope you don't object to me picking your brain as you work through this process; it's of particular interest to me as I am also working on a TMWW design that seems to stem from similar design principles: high efficiency, a wideband true mid, coherent woofers, all active. I've already got the basic design done but I am still playing with the XO...I'm interested in 4th order because of the phase alignment benefits, but since I have a good-sounding 2nd-order XO, I'm afraid of the supposed sonic penalties of higher-order designs.
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