and its very easy to make: with a template of e.g. oval shape, a 40mm guide bush for the hole, a 20mm guide bush for the peace that goes into the hole, and a 10mm straight router bit for both (that's the 20/40/10 trick). The combination 24/40/8 does the same job. And the template can be any shape, as long as the smallest radius is >20mm.You have to sand it a little bit, otherwise it will fit too tight and you won't get it out again.
BTW: Trend and others (sautershop.de in Germany) sell collets that convert a 20mm guide bush into a 40mm guide bush, so you don't even have to change it.
Ring für Kopierhülse - www.sautershop.de
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Felt damping material
Hi, I bought some of this Speaker Carpet - Light Grey - Jaycar Electronics which turns out to be a synthetic felt rather than wool/cotton. I was planning on using 4 layers which gives around a 1/2" mat.
However given its synthetic (you can tell when you burn a small piece) should I be using it or try and fine some wool/cotton felt? Having trouble finding any locally tho I may look to pulling up some carpet and using the old style wool underlay.
Thanks
Hi, I bought some of this Speaker Carpet - Light Grey - Jaycar Electronics which turns out to be a synthetic felt rather than wool/cotton. I was planning on using 4 layers which gives around a 1/2" mat.
However given its synthetic (you can tell when you burn a small piece) should I be using it or try and fine some wool/cotton felt? Having trouble finding any locally tho I may look to pulling up some carpet and using the old style wool underlay.
Thanks
Surely scissors and a passing sheep would supply the necessary fibers
you ever worked with raw sheep's wool? - not an experience you'll soon forget
I had read,and tried, the packing, sealing with weather stripping,listening, adjusting and then sealing method
weather stripping with an adhesive back is the **** to remove, i resorted to the belt sander and then had to remove stuffing! I a little wiser as to re-stuffing, BUT
Make the top panel removable.....Its the best solution
weather stripping with an adhesive back is the **** to remove, i resorted to the belt sander and then had to remove stuffing! I a little wiser as to re-stuffing, BUT
Make the top panel removable.....Its the best solution
Anybody building these and wondering about how much punch they have, just finished Motorheads "ace of spades" album. Last track "the chase is better than the catch", thru a 50 year old 10 watt valve amp.I could FEEL the bottom end, see it in my wine glass. Not my first choice of music but it was TIGHT thumping bass, no mush. I wonder what it would be like with really stiff cabinets.
Mark audio chp-70
I received a pair of chp-70s from Madisound last week with the intent of trying them in folded Tabaqs, but after reading this thread and listening to the drivers in some old BR enclosures, lined with 1/2" cement board, I will be making a pair of FHs using my plentiful supply of oak boards.
The chp-70s sound absolutely gorgeous in their temporary housing driven by my Starfish pre and Pass F5 clone. Initially,I tried them with my MF B200 integrated and they were so-so. Maybe they are breaking in rapidly?
Has anyone here made their FHs with hardwood and/or used hardibacker lining?
Peter
I received a pair of chp-70s from Madisound last week with the intent of trying them in folded Tabaqs, but after reading this thread and listening to the drivers in some old BR enclosures, lined with 1/2" cement board, I will be making a pair of FHs using my plentiful supply of oak boards.
The chp-70s sound absolutely gorgeous in their temporary housing driven by my Starfish pre and Pass F5 clone. Initially,I tried them with my MF B200 integrated and they were so-so. Maybe they are breaking in rapidly?
Has anyone here made their FHs with hardwood and/or used hardibacker lining?
Peter
There is at least one hardwood build, with cherry IIRC. No hardi backer or similar, that should not be necessary since they have specific stuffing details. In fact, I believe cement board lining in the FH3s would be a huge mistake. Lots of satisfied builds, to the specs, why mess with that?
slow typing this post, as I'm donning my kevlar vest and flame proof jumper, but I'd like to offer the opinion that hardibacker cement board, or any very high density material intended for enclosure damping should be reserved for other projects
edit: fastbike beat me to it
if you're confident enough with your fabrication / assembly skills to build these with solid hardwoods, by all means , but keep a couple of things in mind;
- The Mark Audio drivers will need some break in time ( at least 100hrs), and adjusting the final damping fill for acoustic tuning of bass response, or for that matter any passive or active EQ, should await completion of that period
- Damping fill level to apex (behind the internal divider) remains the same for all drivers, but the area immediately above, and below the driver can vary depending by system, and access to these areas can be very tight once the enclosure is buttoned up. More than a couple of builders have fabricated with a removable top panel to allow access - a brilliant solution - keep in mind that this needs to be airtight.
For the love of heaven don't do that Peter. You'll push the panel Fs right down, slap bang into the middle of the cabinet's operating BW. You'd also need to redesign the cabinet, thanks to the loss of internal volume.
Half way there!
I have planed the oak, cut, assembled and sanded the first of my FHs - the second will be finished similarly this week.
The CHP-70s have been playing 10 hours+ a day for a week in some lashed up BR boxes. I transferred one of the drivers to a folded Tabaq that I finished last month, and, with it playing the left channel, and the FH the right, I had a quiet session while indulging in a bottle of merlot.
The only known construction deficiency in the FH is a lack of felt lining behind the driver. I live very close to the carpet capital of the world, but unable to find felt locally, except under the carpet of my F-150. I used some polyester batting instead, recognizing that it wouldn't perform the required duty, but maybe better than nothing.
My room is such that the left speaker is 3 feet from the side wall, and the right speaker 6 feet from its' side wall. Both baffles are 2 - 3 feet from the front wall.
There seemed to be quite a disparity in the bass performance of the Tabaq(in the corner) to the FH on the right.
So, this morning, I got my Radio Shack SPL meter out and ran through the Stereophile test CD2 warble tones.
Using the C scale, I set my reference level(6ft from the speaker) to 60db at 200Hz(the first tone in the bass seqence) and determined the following:
In the corner(left), the Tabaq sound pressure level was +/- 3db from 200Hz to 40Hz(63db), whereas the FH suffered a bump between 100Hz and 50Hz peaking at 74db(80Hz) dipped to 61db at 50Hz and finished 63db at 40Hz. Nothing audible below 40Hz.
Comparing each speaker in the right channel(non-corner) location, they performed within 2db of each other, albeit, with much reduced low bass output(53db@40Hz).
This is the first horn type enclosure I have built - since both the Tabaq and the FH apparently benefited(?) from room corner loading, is there something peculiar about the FH that would cause the bump in the 50-100Hz octave when in the corner, or possibly lack of felt damping?
Completing the warble tone tests, both speakers played within 2db all the way up to 10kHz(limit of my hearing).
Looking forward to completing the other - thanks guys for a beautiful design.
Peter
I have planed the oak, cut, assembled and sanded the first of my FHs - the second will be finished similarly this week.
The CHP-70s have been playing 10 hours+ a day for a week in some lashed up BR boxes. I transferred one of the drivers to a folded Tabaq that I finished last month, and, with it playing the left channel, and the FH the right, I had a quiet session while indulging in a bottle of merlot.
The only known construction deficiency in the FH is a lack of felt lining behind the driver. I live very close to the carpet capital of the world, but unable to find felt locally, except under the carpet of my F-150. I used some polyester batting instead, recognizing that it wouldn't perform the required duty, but maybe better than nothing.
My room is such that the left speaker is 3 feet from the side wall, and the right speaker 6 feet from its' side wall. Both baffles are 2 - 3 feet from the front wall.
There seemed to be quite a disparity in the bass performance of the Tabaq(in the corner) to the FH on the right.
So, this morning, I got my Radio Shack SPL meter out and ran through the Stereophile test CD2 warble tones.
Using the C scale, I set my reference level(6ft from the speaker) to 60db at 200Hz(the first tone in the bass seqence) and determined the following:
In the corner(left), the Tabaq sound pressure level was +/- 3db from 200Hz to 40Hz(63db), whereas the FH suffered a bump between 100Hz and 50Hz peaking at 74db(80Hz) dipped to 61db at 50Hz and finished 63db at 40Hz. Nothing audible below 40Hz.
Comparing each speaker in the right channel(non-corner) location, they performed within 2db of each other, albeit, with much reduced low bass output(53db@40Hz).
This is the first horn type enclosure I have built - since both the Tabaq and the FH apparently benefited(?) from room corner loading, is there something peculiar about the FH that would cause the bump in the 50-100Hz octave when in the corner, or possibly lack of felt damping?
Completing the warble tone tests, both speakers played within 2db all the way up to 10kHz(limit of my hearing).
Looking forward to completing the other - thanks guys for a beautiful design.
Peter
Attachments
The MA units don't really require corner loading in FH3 (as you've just discovered), and are mostly content with just a front wall and floor for boundary conditions. What you describe is almost exactly what I'd expect them to do in such conditions, i.e. produce substantially more gain. You'll need to add more damping to that channel to bring it back into line. Avoid too much near the driver or you'll mass-load the cone.
Very nice looking build BTW.
Very nice looking build BTW.
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