@Wolf said:
The old way was half inch mdf, a saw kerf 'crossed' around the perimeter, and some screen spline and roller.
Like a screen door - that’s interesting. My dog, after trying to run after a squirrel, though the screen door, gave me an ‘opportunity’ to give that approach a go…
Time to take some sweeps! The Celestions (FTX0617) are now back into a new (slightly smaller) open back box, and while I could go with the previous 2nd order Xover, what fun is that? As mentioned, I’ve been playing with (online) a MOD 1st order Series (with a notch pre-Xover) so after my bin box parts I can finally get an order (albeit a bit small) over to JFcomponents. We’ll see if real life (vs software) I can get the tweeter to roll-off at the down 6dB area as it seems to work in the mock-ups. If so, this will be outside of the 3dB crossover range with the mid keeping the phase of the mid and tweeter intact (or at least ‘rhyming’ - maintain parallel curves). I’ve been adding felt to the woofer box, waiting for a final delivery of some more poly fill… So time for some mid/tw crossover work.
Fyi, the Xover will go on the bare wall in the top box (per IMG 3669).
Depending on the volume you like to listen, that xover might be fine. The capless serial xover always seemed to sound good, till you crank up the levels. Ya really need some good candidates to pull 6dB xovers off.
Best-laid plans for the crossover... while the 1st order mod series mocked-up and sounded good, I'm a bit concerned about the longevity of the tweeter at high(er) listening levels.
But it does look possible (at least per VituixCad2) to set-up a 3rd order on the tweeter and let the mid run w/o a filter, as I'll be placing active notches before the coax filter/Xover (there are some common peaks on these drivers, looks associated to the coaxial design?). Back to pulling parts from the parts bin.
Final unit values selected (per listening) for Xover (IMG 3727), and placed order for needed parts.
As mentioned, bottom inverted woofer with protective metal grill in place (IMG 3707). While about a 3/8ths spacing, added a few clear rubber spacers biz the strength of the magnet (IMG 3713), also as seen, reverse wiring for inverted driver. Additionally used speaker gasket material to keep the grill tight.
I got the metal screens and cloth material from Parts Express- make the frames myself and stretch the speaker cloth. That being said I don’t see the square metal grill material on their website ?, but cut and bend the metal screen material (when appropriate) to fit. I.e. made amp and pre-amp tube tops for my tube projects.
@Steve_Lee said:
Love the amp chassis - do you have a bending brake or just use boards clamped and bend away and hope for the best?
I wish. Neither.
I use my little ~3inch vice, bend down a small angle amount across the 'crease line' and go back, and back, and... until very close. I found a hammer on concrete floor with a solid good edged board helps with the hammering of the corners and bends as well (and a little black rattle can when done, as necessary). And a couple more pics of the amp build.
I put blue on one and green on the other > just for when I'm listening by myself sans grills. If you noticed in my previous posted pic of the amp build (took a kit and redesigned the chassis with horizontal tubes) I painted the iron blue and internally some orange - Gulf Racing colors. Can't keep the status quo.
I thought the stands could use a bit more stability- put in a thin metal strip up front (not visible with speakers in place). The felt provides a little leveling / scratch protection for the speakers, and hides my ‘dremel work’ for imbedding the metal strips.
This week the Xover components are scheduled to be delivered.
Coax filter built and in place. Fingers crossed I don’t have any dry solder connections. I needed to unwind the coils (to 0.26mH) and have a hard time getting the insulation off at the one end. Q: how do you guys remove the insulation? It’s too late tonight unfortunately, to test and/or check anything.
IMG 3795 pic of top of bass unit with the connection for the coax box (put a bit of felt into the indentations for the top box feet- the rubber feet weren’t as soft as hoped for). IMG 3804 shot from the top with coax box. IMG 3799 with grills.
Ran a few initial sweeps. I’m not real sure how the distortion harmonics stack-up with what you guys see? but 3rd @2.35% for this push-pull build vs 7.53% (also 3rd) for my previous build, which used the same 8in woofer but matched to a 10in PR make sense in that the PR (as with a port) is a reactive system.
Also posted the frequency graph, and for some reason I could not get a copy of 5dB verticals (I do have a screen shot if any interest) but what is posted is 10dB spread. Unlike my shrinking box tests, this does not (yet) have any eq enhancing the low end - either via extension or boost. I did, however, place a slight notch btwn 70 and 80Hz to pull down a bit of a bump (room?). Also, I pull down 3000Hz +/- (so ranging from sub 1000 towards 7000) approx 1.5dB.
I’ll be listening more of course, but so far I’m pretty happy with its low-end extension. I also ran a sweep with the Aperiodic Vent closed off- very little difference (which I take as indicating I’ve got the AV almost shut off). The fs listed for these drivers is 29Hz.
So far, I’m finding this to be my best low-end (previous systems; PR, ports, and open back). My dual 12in beyma’s per-side in my open backs would be right up there but they didn’t play as low. And I’m a fan of a slower roll-off > no sense of one-note bass. Which I’ll give credit partially to the ~closed box push-pull design, and the balance to me not getting the port lengths and/or PR weights perfect.
Also, I just used a speaker wire cover to clean up / blacken the cables, and fyi these things can expand significantly. I run two sets of cables per speaker (bi-amped) and ordered both ¼ and ½ inch. The ¼ inch was clearly large enough- could have possibly used ⅛ to keep things even tighter.
Comments
The old way was half inch mdf, a saw kerf 'crossed' around the perimeter, and some screen spline and roller.
InDIYana Event Website
Like a screen door - that’s interesting. My dog, after trying to run after a squirrel, though the screen door, gave me an ‘opportunity’ to give that approach a go…
I tried grill cloth once. Ugh real fiddly. I'd be super excited to have em come out like yours!
Time to take some sweeps! The Celestions (FTX0617) are now back into a new (slightly smaller) open back box, and while I could go with the previous 2nd order Xover, what fun is that? As mentioned, I’ve been playing with (online) a MOD 1st order Series (with a notch pre-Xover) so after my bin box parts I can finally get an order (albeit a bit small) over to JFcomponents. We’ll see if real life (vs software) I can get the tweeter to roll-off at the down 6dB area as it seems to work in the mock-ups. If so, this will be outside of the 3dB crossover range with the mid keeping the phase of the mid and tweeter intact (or at least ‘rhyming’ - maintain parallel curves). I’ve been adding felt to the woofer box, waiting for a final delivery of some more poly fill… So time for some mid/tw crossover work.
Fyi, the Xover will go on the bare wall in the top box (per IMG 3669).
Depending on the volume you like to listen, that xover might be fine. The capless serial xover always seemed to sound good, till you crank up the levels. Ya really need some good candidates to pull 6dB xovers off.
Best-laid plans for the crossover... while the 1st order mod series mocked-up and sounded good, I'm a bit concerned about the longevity of the tweeter at high(er) listening levels.
But it does look possible (at least per VituixCad2) to set-up a 3rd order on the tweeter and let the mid run w/o a filter, as I'll be placing active notches before the coax filter/Xover (there are some common peaks on these drivers, looks associated to the coaxial design?). Back to pulling parts from the parts bin.
Final unit values selected (per listening) for Xover (IMG 3727), and placed order for needed parts.
As mentioned, bottom inverted woofer with protective metal grill in place (IMG 3707). While about a 3/8ths spacing, added a few clear rubber spacers biz the strength of the magnet (IMG 3713), also as seen, reverse wiring for inverted driver. Additionally used speaker gasket material to keep the grill tight.
And a couple pics of bass and top box.
Where do you source your grille materials and do you cut them down to size yourself?
I got the metal screens and cloth material from Parts Express- make the frames myself and stretch the speaker cloth. That being said I don’t see the square metal grill material on their website ?, but cut and bend the metal screen material (when appropriate) to fit. I.e. made amp and pre-amp tube tops for my tube projects.
Love the amp chassis - do you have a bending brake or just use boards clamped and bend away and hope for the best?
Those look great! Did you add the blue to the top plate on that bottom driver?
I wish. Neither.
I use my little ~3inch vice, bend down a small angle amount across the 'crease line' and go back, and back, and... until very close. I found a hammer on concrete floor with a solid good edged board helps with the hammering of the corners and bends as well (and a little black rattle can when done, as necessary). And a couple more pics of the amp build.
I put blue on one and green on the other > just for when I'm listening by myself sans grills. If you noticed in my previous posted pic of the amp build (took a kit and redesigned the chassis with horizontal tubes) I painted the iron blue and internally some orange - Gulf Racing colors. Can't keep the status quo.
I thought the stands could use a bit more stability- put in a thin metal strip up front (not visible with speakers in place). The felt provides a little leveling / scratch protection for the speakers, and hides my ‘dremel work’ for imbedding the metal strips.
This week the Xover components are scheduled to be delivered.
I don't see any metal strips [in those pics] so you have hidden them well.
the first pic is pre, the second is with the strip/bar across the front -
Ahh ha
toyz
follow-up: both inductors measured out to 3rd decimal place 0.300mH, very nice (and if I didn't have to jump on a work call I'd measure the caps)
…and the JF caps, 6.64 vs 6.65 (both w/in 2.5% of stated) and as closely matched as the ClarityCaps PUR.
(gosh I hate it when work gets in the way)
👀👀👀🍺> @tajanes said:
Coax filter built and in place. Fingers crossed I don’t have any dry solder connections. I needed to unwind the coils (to 0.26mH) and have a hard time getting the insulation off at the one end. Q: how do you guys remove the insulation? It’s too late tonight unfortunately, to test and/or check anything.
IMG 3795 pic of top of bass unit with the connection for the coax box (put a bit of felt into the indentations for the top box feet- the rubber feet weren’t as soft as hoped for). IMG 3804 shot from the top with coax box. IMG 3799 with grills.
I use a razor blade as a scraper and go at it like I'm peeling a carrot. Then before soldering, hit it with some 400 grit.
I just scrape it off with an X-Acto knife.
Acetone, otherwise I use a knife and scrape, scrape, scrape.
I seem to remember it being common to use a lighter to burn off magnet wire insulation and just clean off the leftover residue.
This is my method. I use a small torch tho.
Scrape with a knife.
InDIYana Event Website
Just use sandpaper...
Solder pot makes life a lot easier.
same as w/o the solder... ha
Watched pot doesn't boil.. Nor does it smoke itself.
Ran a few initial sweeps. I’m not real sure how the distortion harmonics stack-up with what you guys see? but 3rd @2.35% for this push-pull build vs 7.53% (also 3rd) for my previous build, which used the same 8in woofer but matched to a 10in PR make sense in that the PR (as with a port) is a reactive system.
Also posted the frequency graph, and for some reason I could not get a copy of 5dB verticals (I do have a screen shot if any interest) but what is posted is 10dB spread. Unlike my shrinking box tests, this does not (yet) have any eq enhancing the low end - either via extension or boost. I did, however, place a slight notch btwn 70 and 80Hz to pull down a bit of a bump (room?). Also, I pull down 3000Hz +/- (so ranging from sub 1000 towards 7000) approx 1.5dB.
I’ll be listening more of course, but so far I’m pretty happy with its low-end extension. I also ran a sweep with the Aperiodic Vent closed off- very little difference (which I take as indicating I’ve got the AV almost shut off). The fs listed for these drivers is 29Hz.
So far, I’m finding this to be my best low-end (previous systems; PR, ports, and open back). My dual 12in beyma’s per-side in my open backs would be right up there but they didn’t play as low. And I’m a fan of a slower roll-off > no sense of one-note bass. Which I’ll give credit partially to the ~closed box push-pull design, and the balance to me not getting the port lengths and/or PR weights perfect.
Also, I just used a speaker wire cover to clean up / blacken the cables, and fyi these things can expand significantly. I run two sets of cables per speaker (bi-amped) and ordered both ¼ and ½ inch. The ¼ inch was clearly large enough- could have possibly used ⅛ to keep things even tighter.