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Old 17th May 2009, 10:08 AM   #11
jemraid is offline jemraid  United Kingdom
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Dear Denis,

Here in the UK MDF is either 12mm or 18mm, well the stuff I can get is and it would be a lot for me to cut to a taper only having a handsaw.

I can get the rest of the MDF for the cabinets cut into parallel strips by B&Q (a DIY shed) and they can easily cut me some 2" wide strips as well.

I thought of making one side and the front and glueing in the first two internal baffles and then attaching the tapers (hatched lines) and proceed from there, as you say it will be 'interesting' at the bends, but a bit of packing will soon sort it out :-)

Click the image to open in full size.

Looking at the design as I do quite often it looks to be the most elegant I've ever seen.

Kind regards - Jem
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Old 17th May 2009, 11:36 AM   #12
dhenryp is offline dhenryp  United States
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I can see where a handsaw would limit your options. I plan to use a band saw, although a jigsaw with a longish blade would also work.

This may be a dumb idea but, what about making the wedge out of 2" rigid foam insulation? It really isn't very compressible and it's certainly easy to cut.

Veteran horn builders; what do you think?
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Old 17th May 2009, 04:44 PM   #13
jemraid is offline jemraid  United Kingdom
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Dear Denis,

It occured to me whilst digging at the allotment this afternoon that I'd done that taper thing entirely wrong, there's not enough volume in it.

It should be as you suggested, just the one 'wedge' I will still make it from 2" x 1/2" MDF.

As per this drawing;



I've no idea about the foam stuff I've never used it.

Regards - Jem
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Old 17th May 2009, 07:43 PM   #14
dhenryp is offline dhenryp  United States
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Jem - I think the two tapers are equivalent area. The advantage to the second is that you only have to fit one board instead of two.

In the interest of saving a thousand words, I've attached a picture of a mockup of the wedge done with scrap wood and Styrofoam.
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File Type: jpg img_0210.jpg (41.5 KB, 1142 views)
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Old 17th May 2009, 07:58 PM   #15
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Default Re: Bigger Frugel horn (Bugelhorn?)

Quote:
Originally posted by dhenryp
I'm planning a horn derived from the Frugel horn but taller ... internal width is the same as the frugel
These dimensions will actually make it a tiny bit smaller than Frugel-Horn MkII.

dave
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Old 17th May 2009, 09:00 PM   #16
dhenryp is offline dhenryp  United States
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Dave - any thoughts on a Styrofoam wedge? It would seem that if Styrofoam is OK to reduce the size of a CC that it should also be OK in the throat - or am I all wrong on this?
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Old 17th May 2009, 09:40 PM   #17
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The really heavy duty styrofoam they use for building insulation might work, but i'd be more comfortable with solid. This is a place where MDF is probably OK. When we built the wedgies, the wedge was a real pain to do.

dave
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Old 18th May 2009, 10:57 AM   #18
dhenryp is offline dhenryp  United States
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The wedge in the mockup went together really quickly; no more than 20 minutes. Granted it's Styrofoam, but I cut it with the same power tools I would use for a solid; a miter saw for the short angles and a bandsaw for the major slope. The bandsaw is a luxury but as I mentioned before,a jigsaw should work nicely too

I think this wedge has some advantages over the original frugel "wedgie"; The short angles are 30 and 15 degrees - easy to set up and the the major slope is only on one side which is easier to cut and fit.

WRT to FH2; it look like it will be an interesting comparison. I can't wait to see it. Have you refolded it or kept basically the old design? Do you have an ETA?

It occurs to me that the Bugelhorn name might be seen as an attempt to "horn in" (irresistible pun) on the fugel-horn lineage, especially now that I know the the legitimate heir is in the works. If this is the case I apologize - it wasn't my intention. I've been fiddling with this basic design since the original fugel came out years ago. If anyone sees this as a cause for confusion, please comment or send a PM and I will happily change the name of the horn and thread.

Denis
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Old 19th May 2009, 07:53 PM   #19
dhenryp is offline dhenryp  United States
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Can somebody help me with a hornresp question? I'm trying to simulate the bugelhorn and have a problem with CMS for a Fostex FE126E.

The data sheet lists CMS at 0.0017mm/Newton while hornresp is looking for meter Newton. That is 1.7E-06 meter Newton (I think).

When hornresp calculates CMS based on an SD of 6.5 square cm and a VAS of 9.95 liter it gives me 1.65E-01 meter Newton.

Which is correct?

The 1.7E-06 meter Newton causes RMS to calculate out to 400+ while the 1.65E-01 meter Newton causes RMS to be calculated at less than .01 (fs = 70, QMS = 2.96).

Thanks!

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Old 20th May 2009, 07:23 AM   #20
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Quote:
Originally posted by dhenryp
The data sheet lists CMS at 0.0017mm/Newton while hornresp is looking for meter Newton.

When hornresp calculates CMS based on an SD of 6.5 square cm and a VAS of 9.95 liter it gives me 1.65E-01 meter Newton.

The 1.7E-06 meter Newton causes RMS to calculate out to 400+ while the 1.65E-01 meter Newton causes RMS to be calculated at less than .01 (fs = 70, QMS = 2.96).
Hi dhenryp,

The Fostex FE126E specification sheet contains a typograhical error. The units shown for Cms should read m/N not mm/N. Also, your value of Sd should be 65cm^2 not 6.5cm^2.

Cms = 0.0017m/N = 1.70E-03m/N

Sd = 0.0065m^2 = 65cm^2

For Sd = 65cm^2 and Vas = 9.95 litres, Hornresp calculates Cms to be 1.65E-03, which is close to the 1.70E-03 value specified by Fostex.

Using the Fostex value of 1.70E-03 for Cms, Hornresp calculates Mmd to be 2.74 and Rms to be 0.45. Mmd seems about right given that Mms (which includes the air load) is quoted by Fostex as having a value of 2.9grams.

Hope this helps.

Kind regards,

David
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