Some thoughts on your 2905 based system
Looking at the actual acoustic response curve generated by several big inductors on the Peerless using ARTA in a medium sized room at 10' listening distance (13-18 MH), I would start around 70 Hz. Maybe as much as 100 Hz. The bass output and balance will be reasonable and the woofer will reach up a bit higher taking some low end load off the tweeter. However, the woofer break up at 1,850 Hz may become audible enough that you may have to trap it. And the lower you go in inductor size, the less grunt you get out of the Peerless. But you to gain a bit of over all efficiency with the lower inductor values.
The tweeter is where the work is going to be. (Assuming you are sticking with the 2905 for the moment).
Two strategies. A first order electrical way up in the 2,300 Hz to 2,600 Hz area and of course a resonance trap. IIRC, most of the 2905 units will exhibit a resonance right around 500 Hz. And they tend to rise more up top than the published slopes indicate. Anyway, you end up with a second order acoustic function somewhere around 1300 Hz. This will couple with the final roll off to form a 3rd order acoustic response. Your series pad will be in the 15-25 ohm area.
The other way is a second order electrical with odd staggered values. (Large cap and small coil similar to the original TDFC set up). I would also trap the tweeter resonance to protect it. The 2905 will sound way better with the trap too. Again you will end up in the 1,200 - 1,400 Hz area.
I don't think you can achieve a flat summation with out risking damage to the 2905. As with the original Manzanita small tweeter format, you will have to settle for a broad midrange dip from around 500 Hz up to 1,600 Hz. This dip will be 2-4 db deep and look like a very shallow, wide bowl.
Some of the dip is filled in by the rear radiation of the Peerless, especially if you can stay with the equivalent of a 13-15 Mh inductor.
I look forward to seeing what you come up with.
Looking at the actual acoustic response curve generated by several big inductors on the Peerless using ARTA in a medium sized room at 10' listening distance (13-18 MH), I would start around 70 Hz. Maybe as much as 100 Hz. The bass output and balance will be reasonable and the woofer will reach up a bit higher taking some low end load off the tweeter. However, the woofer break up at 1,850 Hz may become audible enough that you may have to trap it. And the lower you go in inductor size, the less grunt you get out of the Peerless. But you to gain a bit of over all efficiency with the lower inductor values.
The tweeter is where the work is going to be. (Assuming you are sticking with the 2905 for the moment).
Two strategies. A first order electrical way up in the 2,300 Hz to 2,600 Hz area and of course a resonance trap. IIRC, most of the 2905 units will exhibit a resonance right around 500 Hz. And they tend to rise more up top than the published slopes indicate. Anyway, you end up with a second order acoustic function somewhere around 1300 Hz. This will couple with the final roll off to form a 3rd order acoustic response. Your series pad will be in the 15-25 ohm area.
The other way is a second order electrical with odd staggered values. (Large cap and small coil similar to the original TDFC set up). I would also trap the tweeter resonance to protect it. The 2905 will sound way better with the trap too. Again you will end up in the 1,200 - 1,400 Hz area.
I don't think you can achieve a flat summation with out risking damage to the 2905. As with the original Manzanita small tweeter format, you will have to settle for a broad midrange dip from around 500 Hz up to 1,600 Hz. This dip will be 2-4 db deep and look like a very shallow, wide bowl.
Some of the dip is filled in by the rear radiation of the Peerless, especially if you can stay with the equivalent of a 13-15 Mh inductor.
I look forward to seeing what you come up with.
Thanks Pano and John,
I will try your ideas and listen to what comes out of it. I have done some experiments with the 2905 and an 8” woofer in an OB as a test. I could run the 2905 down to 1400Hz with the miniDSP 2nd order filter and it survived! I will definitely make a passive design with the original drivers in the end! The biggest challenge for me is the measuring exercise. I mainly use it to get even output from the two amplifiers.
I will try your ideas and listen to what comes out of it. I have done some experiments with the 2905 and an 8” woofer in an OB as a test. I could run the 2905 down to 1400Hz with the miniDSP 2nd order filter and it survived! I will definitely make a passive design with the original drivers in the end! The biggest challenge for me is the measuring exercise. I mainly use it to get even output from the two amplifiers.
Guys, I have a couple of construction questions.
- Based on a panel mounting idea that I'm considering, I'd like to place the crossovers in self contained boxes. Ideally these boxes would be as small as possible.
Any concerns with crowding the cross over components?
- How important are the side(s) and bottom panel? Could they all be eliminated? How about just the bottom?
- I'm considering constructing two 1/2" mdf skins with a 1/2" sand filled void between them (overall thickness,1-1/2", drivers would be protected with 1/2" mounting spacers) Unless you tell me this is a waste of time, I'm hoping for suggestion on which side(s) of the panels to mount the drivers on. I plan to router in relief. Which side of the panel(s) would you suggest mounting the driver(s) on.
Thank you,
Marko
- Based on a panel mounting idea that I'm considering, I'd like to place the crossovers in self contained boxes. Ideally these boxes would be as small as possible.
Any concerns with crowding the cross over components?
- How important are the side(s) and bottom panel? Could they all be eliminated? How about just the bottom?
- I'm considering constructing two 1/2" mdf skins with a 1/2" sand filled void between them (overall thickness,1-1/2", drivers would be protected with 1/2" mounting spacers) Unless you tell me this is a waste of time, I'm hoping for suggestion on which side(s) of the panels to mount the drivers on. I plan to router in relief. Which side of the panel(s) would you suggest mounting the driver(s) on.
Thank you,
Marko
I too have pondered the base plate and it's functionality aside from stability. Astheticaly it has a "soap box derby" look to it that I'd like to avoid ( no offense John ). Four or so layers of birch ply across the bottom between the wings, say 4" x 15" would make for a solid mounting area.
I have all the parts in hand but find myself compelled to take a month or two for a camping road trip to get a loved one out of harms way ( domestic abuse ). Southern Illinois here I come. My build will have to wait.
Last night I gave my Coniston^2's a pretty good workout with Dick's Picks #14. Stunning performance from the dimminutive EL70 drivers. It makes me wonder if the Manzi's can best them. I really would like to bring the Connies to a gathering in the upper midwest to get other's impressions of them.
I ramble on a bit here but look forward to making dust with my usual light heart later.
Moto
I have all the parts in hand but find myself compelled to take a month or two for a camping road trip to get a loved one out of harms way ( domestic abuse ). Southern Illinois here I come. My build will have to wait.
Last night I gave my Coniston^2's a pretty good workout with Dick's Picks #14. Stunning performance from the dimminutive EL70 drivers. It makes me wonder if the Manzi's can best them. I really would like to bring the Connies to a gathering in the upper midwest to get other's impressions of them.
I ramble on a bit here but look forward to making dust with my usual light heart later.
Moto
A couple more comments
Mnsouthpaw
You can experiment with the crossover physical layout all you want as long as you keep the inductors separated by at least 6" and keep the resistors up in the air where they can remain cool.
As for the side panels, I do recommend you keep them on the baffle, they are there for a reason, both sonically and structurally. However, the speaker will of course play without the side wings, but the tonal balance may not be as intended. As far as an engineered sand filled baffle goes, that is up to you. I don't think the extra work will be worth the effort, but you never know. The drivers should be mounted on the front of the baffle. I would not change that.
Again, part of the charm of the Manzinita, it's simple and easy to experiment. Just hope you report back what you learn.
Motosapien....
The base plate is also there for a reason. A place to mount the crossover and obvious structural reasons. I tried to keep it as simple and roomy as possible. However, you can completely eliminate it if you want to. I assume there would be little or no effect on the overall system sound other than some potential lower mid range reflective changes. May actually improve a bit, don't know until you try.
Also hope you share what you learn as you tailor your personal Manzinita to suit your whims and priorities. Will be interesting to read your impressions of your Manzinita's relative to the performance of other speakers. Good luck on your trip!
Mnsouthpaw
You can experiment with the crossover physical layout all you want as long as you keep the inductors separated by at least 6" and keep the resistors up in the air where they can remain cool.
As for the side panels, I do recommend you keep them on the baffle, they are there for a reason, both sonically and structurally. However, the speaker will of course play without the side wings, but the tonal balance may not be as intended. As far as an engineered sand filled baffle goes, that is up to you. I don't think the extra work will be worth the effort, but you never know. The drivers should be mounted on the front of the baffle. I would not change that.
Again, part of the charm of the Manzinita, it's simple and easy to experiment. Just hope you report back what you learn.
Motosapien....
The base plate is also there for a reason. A place to mount the crossover and obvious structural reasons. I tried to keep it as simple and roomy as possible. However, you can completely eliminate it if you want to. I assume there would be little or no effect on the overall system sound other than some potential lower mid range reflective changes. May actually improve a bit, don't know until you try.
Also hope you share what you learn as you tailor your personal Manzinita to suit your whims and priorities. Will be interesting to read your impressions of your Manzinita's relative to the performance of other speakers. Good luck on your trip!
Moto,
I just used baltic birch plywood built to the drawing except no 2 x 2's in the corners or base. Yellow glue and a few brads from the nail gun. I did double up on the base - 2 pieces glued together. I haven't mounted the x/o yet.
I tried 15R for R1 and like it much better than 8R.
Hope everything goes well on your trip. Take care!
I just used baltic birch plywood built to the drawing except no 2 x 2's in the corners or base. Yellow glue and a few brads from the nail gun. I did double up on the base - 2 pieces glued together. I haven't mounted the x/o yet.
I tried 15R for R1 and like it much better than 8R.
Hope everything goes well on your trip. Take care!
John,
Thank you for answering my construction questions. Regarding the sand, I’ve seen some information on dampening enclosures and baffles which talks about reduce panel vibrations and driver energy loss. Although I must say I was very surprised at the amount of bass output the Manzi’s have, considering the open baffle design without larger side wings. Maybe a better question is, do you think dampening the baffle with sand will have an adverse effect?
While it may not be obvious, from some of my recent questions and comments, I do understand the original idea of keeping the approach simple and cost effective. This was the very reason that I chose Manzi’s over other projects which were considered. However, now that I have a sense for their potential, I can’t leave well enough alone. I’m also on Moto’s page in that, a little styling might be in order.
Along this line, in an earlier response you said;
“Hopefully as more Manzi's are built there will be enough of them to reach a critical "mass" if you will and a lot more music lovers will be exposed to and enjoy what a simple, musical speaker can do”. This would be an interesting discussion… maybe someplace down the road.
Thanks again John for your input, I will definitely report back along the way.
Kec, do you mind sharing what you liked more about the R15?
Thank you for answering my construction questions. Regarding the sand, I’ve seen some information on dampening enclosures and baffles which talks about reduce panel vibrations and driver energy loss. Although I must say I was very surprised at the amount of bass output the Manzi’s have, considering the open baffle design without larger side wings. Maybe a better question is, do you think dampening the baffle with sand will have an adverse effect?
While it may not be obvious, from some of my recent questions and comments, I do understand the original idea of keeping the approach simple and cost effective. This was the very reason that I chose Manzi’s over other projects which were considered. However, now that I have a sense for their potential, I can’t leave well enough alone. I’m also on Moto’s page in that, a little styling might be in order.
Along this line, in an earlier response you said;
“Hopefully as more Manzi's are built there will be enough of them to reach a critical "mass" if you will and a lot more music lovers will be exposed to and enjoy what a simple, musical speaker can do”. This would be an interesting discussion… maybe someplace down the road.
Thanks again John for your input, I will definitely report back along the way.
Kec, do you mind sharing what you liked more about the R15?
Hey mnsouthpaw,
I tried 15r for R1 based on John's notes. I thought 8r was a little too bright for me.
I tried 15r for R1 based on John's notes. I thought 8r was a little too bright for me.
Parts availability
Just placed an order with Parts Express. The Vifa TC9FD drivers are back ordered on Madisound and Parts Express. The 2.0mH 18 AWG Perfect Layer Inductor is also back ordered on Parts Express. The expected dates are in May.
Not a big deal for me as it will probably take until then to build the baffle.
John
Just placed an order with Parts Express. The Vifa TC9FD drivers are back ordered on Madisound and Parts Express. The 2.0mH 18 AWG Perfect Layer Inductor is also back ordered on Parts Express. The expected dates are in May.
Not a big deal for me as it will probably take until then to build the baffle.
John
Summary of plans
I collected the posts and pictures regarding the latest plans and pictures for the Manzanita. I thought it might be helpful to post a link for others who are interested in building a pair.
http://www.evernote.com/shard/s3/sh...e9e605c166a5/18b6b9b42bc1c1cd5d7a17468a9ce8c3
John
I collected the posts and pictures regarding the latest plans and pictures for the Manzanita. I thought it might be helpful to post a link for others who are interested in building a pair.
http://www.evernote.com/shard/s3/sh...e9e605c166a5/18b6b9b42bc1c1cd5d7a17468a9ce8c3
John
Keeping up with subtle driver changes
Jcowling
Thanks for putting together the summary.
Things continue to evolve. Seems the latest Vifas have a bit more high frequency rise. I have noticed it and so have others.
So for new builders I would recommend the following resistor values as standard.
R1 = 15 Ohm
R2= 5.0 Ohm
This will provide a smoother, flatter and sweeter balance. Current Manzi owners may also want to try the above. I think some will benefit and the cost to experiment is just a few dollars.
John
Jcowling
Thanks for putting together the summary.
Things continue to evolve. Seems the latest Vifas have a bit more high frequency rise. I have noticed it and so have others.
So for new builders I would recommend the following resistor values as standard.
R1 = 15 Ohm
R2= 5.0 Ohm
This will provide a smoother, flatter and sweeter balance. Current Manzi owners may also want to try the above. I think some will benefit and the cost to experiment is just a few dollars.
John
Maybe mine are not far behind. The rest of the shipment, without the Vifas and the inductors, arrived today.
On another note, what do people think of the idea of adding some kind of fabric cover to the back for a more finished look? If I used speaker grill cloth, would that be transparent enough not to impact the sound? I could run it over the top of the wings and diagonally down to the back of the base. Or, what if I added a thin frame covered with cloth to make the speaker look rectangular?
I know exactly what look I will get from the wife when I bring these babies in from the garage.
John
On another note, what do people think of the idea of adding some kind of fabric cover to the back for a more finished look? If I used speaker grill cloth, would that be transparent enough not to impact the sound? I could run it over the top of the wings and diagonally down to the back of the base. Or, what if I added a thin frame covered with cloth to make the speaker look rectangular?
I know exactly what look I will get from the wife when I bring these babies in from the garage.
John