Something stirs in the Undergrowth

Dedicated to those large boxes at one end of the room
User avatar
Mike H
Amstrad Tower of Power
Posts: 20157
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#271

Post by Mike H »

Ah I see gotcha.
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#272 Phew !

Post by IslandPink »

Phew !
The second piece of bendy MDF was easier .
I feel quite righteous now :sunny:
Attachments
KIF_0125.JPG
KIF_0126.JPG
"Once you find out ... the Circumstances ; then you can go out"
User avatar
Toppsy
Shed dweller
Posts: 2400
Joined: Mon Jul 23, 2007 12:10 pm
Location: red rose country

#273

Post by Toppsy »

Keep up the good work.

I bet you're really looking forward to filling all those grooves in in the bendy mdf, hey :wink: :roll: :roll:
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#274

Post by IslandPink »

Actually Colin I'm not too bothered about that job . Might be quite relaxing , I'll pick a nice sunny day on the back porch .

The fitting of those MDF sides was a stressful job . With the glue going off in about 15mins , banging in little veneer pins every 2-3 inches and trying to get the piece from veering off ( I cut it a bit too close to the min size ) - was getting quite a sweat on there . You have to keep checking it's fitting tightly along the ply all the way ; and wipe off drips of glue running down ; and avoid standing on the glue bottle ( thankfully not THIS time ! ) .
"Once you find out ... the Circumstances ; then you can go out"
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#275 Filler

Post by IslandPink »

Back on the job after a week in the Lakes.
Looks like 500g of filler doesn't go very far. Looks like I should have bought about 3kG !
Attachments
KIF_0127.JPG
"Once you find out ... the Circumstances ; then you can go out"
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#276 Flange

Post by IslandPink »

Slow progress ... dividing time between this and Pass F4 amp finishing .
Here is a 'simulation' picture before the rear flange is fitted ; with B&C speaker also plonked on top . I like it !
Plenty to do yet on the second layer of 9mm bendy and subsequent filling .
Attachments
KIF_0128.JPG
"Once you find out ... the Circumstances ; then you can go out"
User avatar
Paul Barker
Social Sevices have been notified
Posts: 8867
Joined: Mon May 21, 2007 9:42 pm

#277

Post by Paul Barker »

Excellent, looking forward to hearing it.
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#278 Fane & Bud

Post by IslandPink »

Not too far from getting one side going .
New batch of Fane Studio 8M nearly ready :

http://www.diyaudio.com/forums/group-bu ... run-9.html

I've also been e-mailing Bud Purvine and he's finalising the design of two pairs of 2A3/6B4G output transformers.
Probably level 1 construction and M3 lams for 120-700 Hz band ( with good performance eg. 2 octaves each side ).
The pair for the 288H's ( 700Hz-8k) are likely to be level 3 construction with litz secondaries and again M3 lams . Could be 48% nickel , not sure yet.

Shame these things are not going to be portable for Owston-type meets . Also the amps and speakers are going to be inseperable !

ILPS
"Once you find out ... the Circumstances ; then you can go out"
User avatar
Mike H
Amstrad Tower of Power
Posts: 20157
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#279

Post by Mike H »

The finish is certainly looking smoother! Must be a good sign :D
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#280 Interesting Calculation

Post by IslandPink »

It's a sign Mike ! -
A sign that I have a sore arm and the house fills with dust every time I open the door !
Colin was right, it's a chore doing that filling. I spent far too much time getting the first layer really nice - it'll only get covered up with the second layer . Won't be so picky on the second speaker .

Meanwhile...
James D did a calc for me today on e-mail :

Q : How much power do I need from each small SE amp ( there are three to power the three horns ) , to get 90dB average at the listening position ?

A : :!: 30mW :!:
"Once you find out ... the Circumstances ; then you can go out"
User avatar
Dave the bass
Amstrad Tower of Power
Posts: 12273
Joined: Tue May 22, 2007 4:36 pm
Location: NW Kent, Darn Sarf innit.

#281

Post by Dave the bass »

A 76 in SE should sort that. Job done :-)

DTB
"The fat bourgeois and his doppelganger"
chris661
Shed dweller
Posts: 2556
Joined: Mon Feb 22, 2010 7:29 am
Location: Sheffield

#282 Re: Interesting Calculation

Post by chris661 »

IslandPink wrote:...

Meanwhile...
James D did a calc for me today on e-mail :

Q : How much power do I need from each small SE amp ( there are three to power the three horns ) , to get 90dB average at the listening position ?

A : :!: 30mW :!:
Um. Having heard the effect SE amps can have on bass (high output impedance interacting with speaker impedance peaks), I'd consider trying them with a SS amplifier too. You might find you prefer the sound with the SE amps, but horn resp only considers a voltage source driving the speakers. A non-zero output impedance may not give the same results as the sims.

Chris
User avatar
Mike H
Amstrad Tower of Power
Posts: 20157
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#283

Post by Mike H »

That is certainly something that needs to be taken into account.
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#284 Amps ( or lack of )

Post by IslandPink »

Come on guys ...
Why the ...'k would I want to run highly efficient horn speakers from SS amps ? I mean the whole point of doing this thing was to be able to run 2A3 or 45 type amps to get the lowest distortion and highest audio quality !!
The only SS option I might ever consider is driving low bass and bass/mid from the Passlabs F4 . With any other SS amps you are literally 'down in the noise' at this sort of output .

As regards the driving impedance, you'll see if you look at the Hornresp data for the bass/mid horn I've used about 1.8R on all the sims . The bass/mid horn is not as picky about driving impedance as the Tapped horn , in that case as Chris pointed out, you need the lower impedance, and 0.3R from Pass F4 + cables should be ideal .

Anyway, what about the 'optimum' driving impedance for critical damping ? - it does not have to be as low as possible . I refer you to a recent post on JJ's blog for a reminder on that one :
http://hifiheroin.blogspot.com/2011/03/ ... dance.html

Rant over, I think :o
MJ
"Once you find out ... the Circumstances ; then you can go out"
User avatar
ed
retired
Posts: 5384
Joined: Thu Jun 21, 2007 4:01 pm
Location: yorkshire
Contact:

#285

Post by ed »

chill bro...the young one has more time to learn than the rest of us...and at the moment he dances to a different tune.....

from an audio point of view I wish I'd known what he knows when I was that age.....however, on reflection I wouldn't jeopardise any of the experiences I have had since then..so maybe I'll leave well alone

snigger
There's nowhere you can be that isn't where you're meant to be
Post Reply