Something stirs in the Undergrowth

IslandPink · Post by **IslandPink** » Fri Aug 07, 2015 2:08 pm

I love the smell of baltic birch in the morning ...
Might make some progress on the left OB unit now.

IslandPink · Post by **IslandPink** » Tue Sep 15, 2015 10:30 pm

Just about done on OB unit No.2 now .

andrew Ivimey · Post by **andrew Ivimey** » Wed Sep 16, 2015 6:10 am

I love the smell of burning baltic ply. .. ek ek ek

IslandPink · Post by **IslandPink** » Wed Sep 16, 2015 10:01 pm

I have supplied my friend Mark at work some of the finest quality offcuts you could ever wish for, to burn in his woodburning stove.

Meanwhile .... Phwoaar ! - RMS = 0.39

http://www.enviee.de/en/files/data%20sh ... 20cone.pdf

Joachim Gerhard is a very interesting and clever guy :
http://www.diyaudio.com/forums/full-ran ... 7-mpl.html

IslandPink · Post by **IslandPink** » Wed Sep 16, 2015 10:20 pm

Cripes, there's always MORE out there isn't there ?
http://www.diyaudio.com/forums/vendors- ... lx521.html

vinylnvalves · Post by **vinylnvalves** » Thu Sep 17, 2015 9:04 am

What happened to the perspex baffles?

pre65 · Post by **pre65** » Thu Sep 17, 2015 9:26 am

vinylnvalves wrote:What happened to the perspex baffles?

Still there ?

Ali Tait · Post by **Ali Tait** » Thu Sep 17, 2015 1:15 pm

They're transparent so you can't see them Phil.

IslandPink · Post by **IslandPink** » Thu Sep 17, 2015 7:03 pm

"What happened to the perspex baffles ? "
Did you not notice the thing lying on the floor, in the middle of the picture ?

IslandPink · Post by **IslandPink** » Thu Sep 17, 2015 7:28 pm

OK, now with improved transparency :

andrew Ivimey · Post by **andrew Ivimey** » Thu Sep 17, 2015 9:17 pm

Ssssssrubbish as eni fule no you need some louspeakers. That wont make a sound, I mean even jzzzzz will sound awfully er quiet.

IslandPink · Post by **IslandPink** » Thu Sep 17, 2015 9:49 pm

What ?

Now too transparent ??

andrew Ivimey · Post by **andrew Ivimey** » Thu Sep 17, 2015 10:04 pm

There's no pleasin' some people, I mean, really!

Onwards! ;------------------)

IslandPink · Post by **IslandPink** » Fri Sep 18, 2015 12:35 pm

Need to do some mods to the crossover for 8PE21 - been thinking about this and trying to find any useful articles on series crossovers , as I can't manage to get James at the moment. Drawn a blank though ! ( all the search results lead to dead or useless webpages ) .
However after a bit of thinking, I reckon ( see picture of approx crossover below - mine uses 138uF and 8.2mH btw ) that I'll need to increase the value of the capacitor . The problem is that with its higher Fs and lower Q, the 8PE21 naturally rolls off at a higher frequency than the Fostex . I need to decrease the roll-off effect from the crossover to this unit , which I think means increasing the cap, so reducing its resistance at 200Hz or so where both drivers are blending, and hence feeding more signal to the B&C . Whether I can get an acceptable combination in the context of an 8.2mH choke ( which sets the Supravox -3dB point around 180Hz I believe ) is a good question. I could probably do with a crossover at more like 220Hz or 250Hz

I'll see if I can find another PP/oil cap and clip-lead it in some time today, aim for 200uF total .

IslandPink · Post by **IslandPink** » Fri Sep 18, 2015 6:22 pm

I added an extra 40uF and it sounds a fair bit better . Getting the low mid tone back and a better connection between the drivers.

audio-talk

Something stirs in the Undergrowth

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