tlawra... if you want mine email me, i have 10 sets of speakers right now. see my last build. shipping would be ok from lax to mil.. jon.parkhurst@mac.com. we could come up with a mutual agreement.. JP
You learn to work with what you can get. 15mm and 18mm BB is always available if you are willing to buy a skid and pick it up at some LCL freight terminal. 12mm BB is readily available because it is used by cabinet makers for drawer sides. Lately I have settled on a product known as "TigerPly" It is 11-ply 17-18mm and made of Paulownia wood. Plus side: Readily available, cheap, quite stiff. Down side: Layers are usually overlapped leaving minor voids at the ends of the layer and the internal layers are not always flat. The microscopically thin finish layers chip badly, particularly when routing. Using TigerPly as a finish surface is iffy at best.
Don't overlook good cabinet grade 3/4" 5(7)-ply. For a price, nearly void free is available. Core wood varies with region. What I get is pine. I understand the purist desire for BB, but if you can't get it, you can't get if.
When I really want BB for baffles and tops of large floor standers, I will laminate two sheets of 12mm BB. Talk about stiff and heavy....
Bob
Don't overlook good cabinet grade 3/4" 5(7)-ply. For a price, nearly void free is available. Core wood varies with region. What I get is pine. I understand the purist desire for BB, but if you can't get it, you can't get if.
When I really want BB for baffles and tops of large floor standers, I will laminate two sheets of 12mm BB. Talk about stiff and heavy....
Bob
Rarely is 15mm or 18mm material exactly this thick. In the US, and even here in Canada, 12 mm is often called 1/2", 15mm 3/8, and 18 mm 3/4".
Did you actually take a caliper or tape to the ply you are looking at?
Because of this one has to get the material, measure its actual thickness and adjust the plans to fit.
dave
Rear deflector/bass unit
I'm considering building the rear deflector shown here:
Frugel Horn v1 Maps 130307
I would make it the same height as the FH3 however. I'm looking at putting a woofer it, driven by a plate amp mounted in a separate enclosure. It looks like the internal volume of the deflector enclosure will be in the neighborhood of .7-.8 cu.ft. Any recommendations on a suitable driver for this size space? I'm thinking that the biggest driver I could possibly fit would be 8", and it my be 7" depending on the depth and size of the basket. I'm not looking to spend a fortune.
Suggestions?
Tom
I'm considering building the rear deflector shown here:
Frugel Horn v1 Maps 130307
I would make it the same height as the FH3 however. I'm looking at putting a woofer it, driven by a plate amp mounted in a separate enclosure. It looks like the internal volume of the deflector enclosure will be in the neighborhood of .7-.8 cu.ft. Any recommendations on a suitable driver for this size space? I'm thinking that the biggest driver I could possibly fit would be 8", and it my be 7" depending on the depth and size of the basket. I'm not looking to spend a fortune.
Suggestions?
Tom
Hi Tom, how will you connect your plate amp? I am interested to know if you will somehow connect it to your pre-amp output or are you using a modern amp with a sub-woofer output?
Tom: 'cause we had a bunch, the drivers we used in the "stealth" woofer is CSS SDX7 - not the cheapest candidate in this size but works very well in small sealed - not ported - boxes.
Others likely would be Silver Flute, Dayton and even perhaps Peerless HDS series - of those I'm not sure which particular model numbers to suggest.
Others likely would be Silver Flute, Dayton and even perhaps Peerless HDS series - of those I'm not sure which particular model numbers to suggest.
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Ah, good question. I obviously haven't thought this through completely. I was more focused on being able to use the internal adjustable crossover in the plate amp and never really thought about how to run the signal. My HT receiver has a sub output, so it was a no brainer. The FH3s are run off an MP-301 Mk2 integrated tube amp though, so no such luck.
Anyone have suggestions on how to best power these woofer units and run the signal? I haven't bought anything yet so it's a good time to figure it out!
Tom
You can use Y cables from the CD player and feed both amps that way. Another option is sending the CD player's analog signal to the MP while sending it's digital to a DAC and then from there to the plate amp.
Instead of a plate amp on one project I used an older Denon AVR in 2 channel mode to drive bass woofers using it's internal DAC to convert the CD player's digital signal ( coax or optical ).
Instead of a plate amp on one project I used an older Denon AVR in 2 channel mode to drive bass woofers using it's internal DAC to convert the CD player's digital signal ( coax or optical ).
I understand that a lot of guys like to use the high level inputs on plate amps to maintain the "sonic signature" of the amp driving the mains (particularly if a "tasty" SET etc), but doing so negates the overall advantages to be gain by High Passing the mains; increased dynamics, higher attainable SPL, and reduction of distortion.
Personally I'd use the line level inputs and since my audio only system has level controls on both the tube amp driving the mains and DAC/Pre-amp, matching levels is very straightforward.
Now of course if you're not using a plate amp with integrated XO, or miniDSP etc, things can get a bit more interesting - but even then, PLLXO are not that complicated or expensive (a separate chassis, in - out jacks and interconnect cables can easily cost more than the parts for low signal level filters)
Personally I'd use the line level inputs and since my audio only system has level controls on both the tube amp driving the mains and DAC/Pre-amp, matching levels is very straightforward.
Now of course if you're not using a plate amp with integrated XO, or miniDSP etc, things can get a bit more interesting - but even then, PLLXO are not that complicated or expensive (a separate chassis, in - out jacks and interconnect cables can easily cost more than the parts for low signal level filters)
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Nope, never even considered that, it's so you can make use of the high level outs on the plate amp, reducing the length and clutter of the wires.
Do you mean because the high level out on the plate amp is a fixed, single cap often around 100-150 µfd?
But that leaves the high levels outs dry as a Victoria creek bed this summer.
When driving the horns with a SET and using an AVR to power some Eminence Alpha woofers I've found this to be an inexpensive option to filter out the high frequencies.
80 Hz Low Pass 8 Ohm Crossover 266-442
It works as well for me as dual Dayton APA150 amps with built in crossovers.
80 Hz Low Pass 8 Ohm Crossover 266-442
It works as well for me as dual Dayton APA150 amps with built in crossovers.
To damp or not to damp - that is the question!
I am sorry if this seems a bit basic. I have recently built a pair of FHMK3's using 18mm, high quality birch ply. The drivers are Mark Audio Alpair 7 Gen 3 (with extra magnet attached.)
I have used 0.5 inch cotton damping to the upper walls as described but I am struggling with damping. I am looking for the maximum lower base without screwing up the lovely smoot midrange (I hate a boxy sound).
So my question is, firstly how do you describe the audible difference with heavy damping and no damping (excluding the cotton felt upper lining as described) I ask this because Lowther insist that their cabinets are not damped at all and I wonder if they could sound any good?
It appears to me that the lower bass is a little extended without damping but according to theory, it should be reduced? What effect can damping have on the lower mid range (bottom of the female human voice - for example)?
I am sorry if this seems a bit basic. I have recently built a pair of FHMK3's using 18mm, high quality birch ply. The drivers are Mark Audio Alpair 7 Gen 3 (with extra magnet attached.)
I have used 0.5 inch cotton damping to the upper walls as described but I am struggling with damping. I am looking for the maximum lower base without screwing up the lovely smoot midrange (I hate a boxy sound).
So my question is, firstly how do you describe the audible difference with heavy damping and no damping (excluding the cotton felt upper lining as described) I ask this because Lowther insist that their cabinets are not damped at all and I wonder if they could sound any good?
It appears to me that the lower bass is a little extended without damping but according to theory, it should be reduced? What effect can damping have on the lower mid range (bottom of the female human voice - for example)?
The FH3 design plans call for all drivers to use damping in the "apex" of the horn ( i.e. section behind the internal divider panel - if the horn was not folded it would easier to see that it's above the driver). Hopefully that was in place before assembly - it's pretty hard to access once buttoned up.
Damping below the driver is system (amp & room placement) dependent, and the conundrum can be that the quantity is a bit of a guess until drivers are fully broken in - and once again, access is rather tight. The two most brilliant solutions I've seen to that are building with removable top panel, and installation of light mesh netting approx 2/3 down the lower expansion to retain fiber in place.
I've built so many of these that I honestly forget if one has been with the A7s and how much fill we might have used. Without some, I'd imagine most of the MA drivers could be a bit "chesty" - not necessarily a bad thing with some vocalists
, (hmm, Sade) but I digress.
Damping below the driver is system (amp & room placement) dependent, and the conundrum can be that the quantity is a bit of a guess until drivers are fully broken in - and once again, access is rather tight. The two most brilliant solutions I've seen to that are building with removable top panel, and installation of light mesh netting approx 2/3 down the lower expansion to retain fiber in place.
I've built so many of these that I honestly forget if one has been with the A7s and how much fill we might have used. Without some, I'd imagine most of the MA drivers could be a bit "chesty" - not necessarily a bad thing with some vocalists
, (hmm, Sade) but I digress.
Chris, the original mules has A7 in them for awhile. Without any damping below the driver (and 3 ft out from the wall), the mid/upper bass was big, round, tuneful but too much quantity (some might like this) -- FH3 doesn't cover the low bass.
The FH3 with suprabaffle will be the 1st set you have built dedicated to A7/EL70.
dave
The FH3 does not go low enuff to have lower bass (defined as 20-40 hz). To cover that you will need some woofer support. With even a modest high pass on the FH3 as well, with the removal of it trying to reproduce the lowest notes, the whole system will be able to play louder.
dave
Chamfered edge on back of driver cutout
So I made a minor boo boo ... I glued the baffles in place before I chamfered the back edge of the drive cutout. How critical is it that this is chamfered? I'm using the CHP70 drivers if it matters. And if I do need to chamfer the holes, and suggestions on how to best do it at is point? I'm attaching a pic to show the stage they're at right now. Thanks for the help!
So I made a minor boo boo ... I glued the baffles in place before I chamfered the back edge of the drive cutout. How critical is it that this is chamfered? I'm using the CHP70 drivers if it matters. And if I do need to chamfer the holes, and suggestions on how to best do it at is point? I'm attaching a pic to show the stage they're at right now. Thanks for the help!
Attachments
Just use a rasp to get the same effect. It will take just several minutes per hole to do a really good job (considering it's plywood). It is challenging to rasp the part near the side panel (not much clearance), but that doesn't matter as long as you rasp out everything you can (while still leaving enough for the screws -- but the screws don't need much in my experience).
(Plenty of commercial designs don't chamfer / rasp at all, so whatever you do puts you way ahead.)
(Plenty of commercial designs don't chamfer / rasp at all, so whatever you do puts you way ahead.)
It also appears that the cutouts weren't rebated for flush mounting - whatever your opinion might be as to the effects of that, on drivers as shallow overall and with as thick a mounting flange as all of the MA, it will further emphasizes the constriction immediately behind the cone.
mr Bond is correct about many commercial products not being chamfered, but they're also more likely to be CNC machined with rebates, and many OEM drivers have much thinner mounting flanges
mr Bond is correct about many commercial products not being chamfered, but they're also more likely to be CNC machined with rebates, and many OEM drivers have much thinner mounting flanges