Upgrading drivers of an existing old cabinet (pics)

Hi all,

I got this vintage Japanese speaker set sometime back, it's a 50w speaker and some drivers are blown/damaged. Now I'm thinking if I could upgrade it to a better speaker meaning I'll replace drivers and crossover but keep the same cabinet.

It's external dimensions are (made of 20mm plywood)
H 62cm
W 36cm
D 31cm.

Has a 10in woofer. Would be great if I could convert this to something like Scanspeak Discovery 3w classic. Is it a worthwhile project? I have attached some pics .
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It sounds like a plan. The older cabinet may be resonant, either naturally or due to deterioration of the wood or adhesive. You can either work with that or brace it. It's usually a good opportunity to add some wadding inside. The new drivers and crossover will present it's own challenge but why not :)
 
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A crossover is typically unique to drivers and cabinets, so anything you can buy pre-made that isn't designed for them specifically may not give satisfactory results. It may be possible to find a kit for similarly sized units, or for two at least and you can add the third.. or maybe someone here might help you with the crossover.
 
Since I haven't seen any replies aside from Allen's, I should probably offer my own $0.000586 in AUD ;)
We're looking at a 70s-80s ish speaker with really vague specs and design parameters.
Put it simply, that speaker is unique. How many drivers are there and that the drivers xover at a certain frequency point is because it's what the designers had originally intended. Similarly for the cabinet material, tone controls, etc...
By gutting it and put new, modern speakers instead, you kinda run the risk of it not sounding good, leading to aggressive tuning with xover...and this may prove to be far too time-consuming in the end.
Given the current situation, I'd suggest you build the Scanspeak speaker from scratch, if possible.
A restoration of the existing speaker can be an interesting project by itself.
 
I've repaired old speakers with a blown driver by just buying something the right size and impedance and installing it. Results weren't science but it made decent music. I don't like building cabinets, the sawdust makes me sneeze. Sawdust dirties up a garage I rebuild engines in. I can't do both carpentry and mechanics without 2 shops. Most apartment dwellers cannot operate one dirty shop. Besides the 1976 cabinets were beautiful walnut veneer, which is a process I could not possibly replicate.
Watch nominal diameter versus actual diameter. I wasted $140 buying a pair of "10"" woofers that wouldn't fill a 10" hole. They were 9.5". I can't fill in a hole that is too big. I should have downloaded the datasheet and read it first.
Science involves buying a microphone compatible with some test software. Setting up a test zone and loading the software on a PC or smart phone. Testing the result. Changing the result with stuffing, ports, crossover parts, graphic equalizer, or whatever. A source of free software is room e wizard. I forget what the e stands for.
The crossover in the 1976 speaker was one polyester cap blocking the tweeter. Polyester caps do not deteriorate. Your crossover has two non polar electrolytic caps. These do deteriorate based on time, the rubber sealant dries up and can crack and let the water out. If my 1976 speaker had a low frequency blocker, a large capacitor series the woofer, perhaps my footsteps on the wood floor might not have torn the ribbon in the woofer. However that big capacitor would perhaps have cost $20, and the 1976 speaker cost $99 new.
 
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The box size and shape are close enough to the Troels 3way classics.
Just start with the correct tweeter/edge spacing,, and let the mid and woofer follow.

Put the port in a similar place as Troels.
A simple butt joint for the mid box, some bracing, and you'll be good to go.
 
Science involves buying a microphone compatible with some test software. Setting up a test zone and loading the software on a PC or smart phone. Testing the result. Changing the result with stuffing, ports, crossover parts, graphic equalizer, or whatever. A source of free software is room e wizard. I forget what the e stands for.
The crossover in the 1976 speaker was one polyester cap blocking the tweeter. Polyester caps do not deteriorate. Your crossover has two non polar electrolytic caps. These do deteriorate based on time
Application of FFT in a non-LTI environment with signals ...
The persistence of wood in applications where sound-proof Is wanted...
Talking about deteriorated capacitors when the speakers are Rotten Is funny.
And...I guess the E in REW stands for equalization
Maybe it's empty!
 
diyAudio Member
Joined 2007
Those Coral mid-range are great drivers, very efficient. They are worth rebuilding if you have the skills or the money. I have a pair waiting on a rebuild due to hungry rats.
TBH those old boxes are garage speaker quality but these can be fun projects, just don't spend too much money.
If you were local I could find some cheap drivers would suit those boxes
 
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This kind of junk is probably best left alone, otherwise when you start improving things about it, you will end up building a new set of cabinets, eventually. So, I advise to replace the parts with similar quality ones and leave the x/o philosophy intact, adding a couple of resistors to maintain "even" spl of all the drivers (midrange and tweeter padded down to woofer spl). Woofer should be of the high inductance type, which will make it perform as if it had a separate LP filter. It's meant to be the kind of a loudspeaker that would pass for not too demanding an audience. A simulation is considered a necessary tool to pull it off.
 
diyAudio Member
Joined 2007
Well Davor the problem being geographical location.
If the OP wants to keep the crossover that is there already; and seeing how bad that box is the cost of new drivers shouldn't exceed ~$50-
If you really want something like the Scanspeak Discovery 3w classic Sscov you'll need to start from scratch with the Troels design or something close and a couple of thousand dollars, the midrange alone costing $130-each, the woofers $160- etc.
 
Most cheap speakers are very shallow to save $$$ on shipping. Your corals are 34 cm deep, if 2 cm walls the volume without driver deductions is 59.1 liters. Could get some decent fairly deep bass with this with the right woofer. Mid-range & tweeter don't depend so much on the cabinet.
 
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