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Multi-Way Conventional loudspeakers with crossovers

Building a big two way system, a homage to the KEF BBC LS5/1A
Building a big two way system, a homage to the KEF BBC LS5/1A
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Old 22nd February 2014, 09:16 PM   #11
mayhem13 is offline mayhem13  United States
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With such a large enclosure, the Eminence kappalite 3015 would be my choice to 2khz. It will need a notch filter between 1-2khz but the OEM crossover count at 15 pcs indicates there's a notch in there somewhere as well. The low pass after the notch could be as simple as a 2nd order electric to work well with the natural acoustic rolloff.

IMO, the tweeter limitations of the day indicated the need for two tweeters......and given what we know now about combing, I think a single modern day 1 1/8" dome would be better served. It won't be a clone, but I believe the system would perform better overall.
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Old 22nd February 2014, 09:32 PM   #12
sreten is offline sreten  United Kingdom
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Hi,

Just a very bad idea to attempt to clone nowadays, speaker
design has moved on leaps and bounds since that very self
serving description of the speakers merits was written *.

FR : 40Hz –13 KHz +/- 5dB : is poor by any standards.

This will utterly slaughter it in all respects :
http://www.zaphaudio.com/SB12.3/
your looking at 40Hz to > 30KHz +/- 2dB.

As will this :
https://sites.google.com/site/undefinition/tarkus
and this :
http://www.zaphaudio.com/ZDT3.5.html

rgds, sreten.

* No doubt it was efficient and didn't need much power to
go loud, but its no better than modern good PA speakers.

Last edited by sreten; 22nd February 2014 at 09:54 PM.
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Old 27th February 2014, 01:12 AM   #13
Inductor is offline Inductor  Portugal
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By the way, (and I agree with the previous comments) I was only giving links in the UK for the OP. To design a speaker you need to know what you are doing. To clone... well chose your poison: 1. you use the same drivers (xover/alignment/net.vol/speakers) or 2. you are building a new one (speaker)! Bet "all" are happy now (more food for thought).

I don't disregard the original idea but I have serious doubts that OP wants to take it further...

To clone a problematic design is not a good idea unless you want to listen to the same obvious mistakes reproducing the sound and building the speaker. And it has a longer learning curve, reproducing/diy the bad (mistakes) first, as in a learning curve.

Look at the good examples of speakers instead (like the Kef's Concertos) for vintage, try to understand why they were good. Or to the good designs of this late years like Troels-DK for one good example (various), if not just build a kit.
Loudspeaker Kits: Stand Mounted Loudspeakers, Floorstanding Loudspeakers, Sub Woofer Kits
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Old 27th February 2014, 06:26 AM   #14
DrBoar is offline DrBoar  Sweden
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I have cloned the Spendor BC1 the "Dorspen" and kind of cloned the Decca Corner Horn. But all designs are set in their time and context. The BC1 is a unusal 3 way design in that it is a classical two way design crossed at about 3 kHz and then have a third driver above 10 kHz. At the time they could find tweeters they were happy with all the way from 3 kHz to 20 kHz, but later designs scrapped the supertweeter as it was no longer needed when better domes was avaible.

It is my understanding of the BC1 that the main "magic" component is the bass/midrange driver and crossover. The second thing is damped thin wall cabinet. The fact that the system happen to be a 3 way system with a supertweeter is not critical. Nor that it is a bass reflex box. Nor that the bass is rearmounted. Nor that the panels are detatchable.

The Decca Corner Horn claims that the cabinet flexing is critical for the damping of the system and that the addition of damping material spoil the system. My finding was that flexing was not the reason why a totaly empty cabinet fared quite well, it rather had to do with geometry of the nonparallel walls and various tapers. Adding damping material both sounded and measured better.

So to clone you have to have both experience and measurement tools and a good understanding of the different interacting factors. When I started building speakers a 20 Hz highpass filter was allways needed in the amp as all records has some warp and rumble and the fashion at the time was to have pickups with very soft suspensions so the tonearm resonanse was too low and too undamped. This was to protect the loudspeaker especially open systems like bass reflex or pipes. With the arrival of the CD in the 1980s the need for a rumble filter was gone. There is no way that I could properly clone the Spendor BC1. I can take some elements of the design and incorporate it in a new design but then I need to understand what I should try to pick and also understand the limitations of what I also can pick as opposed to what I wish (like the 8" driver).
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Old 9th March 2014, 01:18 PM   #15
darkmatter is offline darkmatter  United Kingdom
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To 'clone' per-se means that identical drivers would need to be used as part of the project
If not ones that very closely match the properties of the so called cloned speaker.

I like the challenge but as a paper exercise to see if it is possible to replicate a particular design. I achieved this in part with my X-1 project which was featured in Hi-Fi news in April 2002 page 58~

It is interesting that since I have looked at the LS5/1a design I have found a couple of drivers that come close nothing that can be used to clone so that design has morphed into something different.

My X1 took the original in a different direction so cannot be classed as a clone.
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Old 9th March 2014, 01:24 PM   #16
darkmatter is offline darkmatter  United Kingdom
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Quote:
Originally Posted by DrBoar View Post
I have cloned the Spendor BC1 the "Dorspen" and kind of cloned the Decca Corner Horn. <snip>
Interesting project, found it

http://www.diyaudio.com/forums/multi...ge-design.html
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Old 14th July 2014, 08:23 PM   #17
hallc is offline hallc  England
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Hi - just joined!

I am about to embark on a similar project, but maybe from the other way round. I have the baffle from an LS5/1, complete with Plessey (I assume) 15" bass unit, 2 GEC tweeters, and an FL6/2 crossover network. What I lack is the box. The bits I have work and I am listening to it now. I have scaled the box from photos online, and the dimensions given in the KEF data for the LS5/1a, and they match the dimensions of the baffle.

The sad thing is that I had a complete working LS5/1 some years ago, from a skip at work, but after a couple of years sold it to someone who had another one because I assumed I wouldn't be able to get another.

What I don't remember from the complete one I had was whether the box was chipboard or plywood - the LS3/1s I have are plywood, and whether the panels were damped and braced?

I am about to buy several sheets of 18mm OSPB to make cupboards for the workshop and could knock up a box from this to try out.

I don't really need another large speaker but since the bits were a bargain from ebay, and close to home too, it seems bad mannered not to!
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Old 15th July 2014, 07:20 AM   #18
Charles Darwin is offline Charles Darwin  United Kingdom
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Not sure that the Volt R3813 is suitable as it shows massive cone break up at 1.5k.
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Old 15th July 2014, 08:30 AM   #19
DrBoar is offline DrBoar  Sweden
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There are tons of arguments for MDF or plywood and plenty of heated arguments around. As far as published measuremnets goes, the difference soundwise is small. Bracing, damping and laminations plays a greater role than the acutal box material. Plywood is vastly superior in taking abuse in field, mobile use but for sitting still in a dry room...

Why not make a box in the OSB leftovers and take it from there.
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Old 15th July 2014, 10:00 AM   #20
speaker dave is offline speaker dave  United States
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Quote:
Originally Posted by hallc View Post
Hi - just joined!.

What I don't remember from the complete one I had was whether the box was chipboard or plywood - the LS3/1s I have are plywood, and whether the panels were damped and braced?
Plywood. I had a pair I got from KEF and they were plywood. Fairly thin and heavily damped by a thick and heavy felt layer, if I recall. There might have been a pair of side braces vertical on the left and right sides.
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