Put both speakers back together. Tested them. One sounds pretty good. In fact much better than I expected. The other the 8" is distorting which makes me think despite the frequency spectrum test i did the driver is shot. I have a dilemma: Should I replace the driver with a modern one, replace both cabs drivers with modern new ones or try to salvage the Richard Allen driver? Another problem I have is when I tried them in one of the rooms my wife didn't warm to the look of the speakers ...Can't really swap out the wife so is anybody on here interested in taking these speakers off my hands?
I'd be interested in which Richard Allan 8" is distorting - the Golden 8 or the Type CB8?
"Salvaging" the faulty driver would likely involve a complete replacement of the cone and voice coil assembly which is an outside job that I don't see as a cost-effective option in this case.
It would be hit or miss determining which "modern" driver would suit this enclosure, the mode of functioning of which is rather a mystery.
I don't regard these speakers as historically significant, so I'd be inclined to put the working RA 8" up for auction, keep the new tweeters and capacitors for a future project and reluctantly submit the enclosures to the recycling centre.
Alternatively, you can offer them up for sale in the Market Place: Swap Meet section of the forum.
"Salvaging" the faulty driver would likely involve a complete replacement of the cone and voice coil assembly which is an outside job that I don't see as a cost-effective option in this case.
It would be hit or miss determining which "modern" driver would suit this enclosure, the mode of functioning of which is rather a mystery.
I don't regard these speakers as historically significant, so I'd be inclined to put the working RA 8" up for auction, keep the new tweeters and capacitors for a future project and reluctantly submit the enclosures to the recycling centre.
Alternatively, you can offer them up for sale in the Market Place: Swap Meet section of the forum.
Sagging could lead the voice coil being off-centre which could cause distortion. Perhaps rotating it would see a difference.
I presume you mean that, due to the horizontal cone sagging downwards, the voice coil assembly could have been damaged by bottoming out on the back plate of the magnet assembly.
Its the golden 8" that's distorting. I will closely examine and look for sagging.
I'm a little saddened that you suggest the possibility of land fill : ( I'm hoping with a new 8" I can find a caring home for these artifacts. I was quite impressed by the sound of the working one and would keep the speakers, but as I mentioned The Boss says 'NO' !
I'm a little saddened that you suggest the possibility of land fill : ( I'm hoping with a new 8" I can find a caring home for these artifacts. I was quite impressed by the sound of the working one and would keep the speakers, but as I mentioned The Boss says 'NO' !
I was just being realistic as these enclosures are an unknown quantity. Insufficient information has been made available to define their operating principle.
Because of this, it would be pure guesswork on my part as to which modern 8" speaker would work well in this column enclosure.
Perhaps someone with the necessary measuring equipment would rise to the challenge of matching drivers to these enclosures so, as I said, you could put them up on the Swap Meet section of the forum to see if they evince any interest.
Because of this, it would be pure guesswork on my part as to which modern 8" speaker would work well in this column enclosure.
Perhaps someone with the necessary measuring equipment would rise to the challenge of matching drivers to these enclosures so, as I said, you could put them up on the Swap Meet section of the forum to see if they evince any interest.
The mid/bass driver in the working column enclosure is a Richard Allan CB8. Here's a reminder of its specifications:
Impedance = 15 ohm
Resonance frequency = 55 Hz
Frequency range = 45 Hz - 10 kHz
Power handling = 30 W RMS
Cambric surround
Weight = 0.9 kg
Crucially we don't know the sensitivity, but I assume it to be very high.
Dr Smith, you can supply the overall frame diameter and the mounting hole diameter.
Here's the first thing that popped up on ebay when I searched for 8" 8 ohm speaker driver chassis (scroll down for specs):
https://www.ebay.co.uk/itm/16685927...ZFmST04G2W/9Pb4EBgwiXfA0HQc=|tkp:BFBMms24mttk
The EBP figure is 91 which means the driver is suited to a vented enclosure. At its low price it would provide a low risk starting point for experimentation.
Other suggestions from members would be welcome!
P.S. A replacement driver must fit your mounting board.
In my example above:
Frame diameter: 210 mm
Mounting cut-out diameter:182 mm
In my example above:
Frame diameter: 210 mm
Mounting cut-out diameter:182 mm
Yes, sensitivity would be one of the more important things to watch since it would affect the tonal balance requiring the upper crossovers to be changed. This would be easier if the woofer sensitivity is not greater than previously.
You might also find the need to adjust the woofer cross to trim it's upper response, and sticking with paper as a cone material may be a safer choice in that regard.
You might also find the need to adjust the woofer cross to trim it's upper response, and sticking with paper as a cone material may be a safer choice in that regard.
The only crossover in this 'child of the sixties' speaker is a small value capacitor on the tweeter.
The sound was allowed to issue freely from this omnidirectional speaker untrammeled by a full crossover network.
Note that both tweeters are not original, and neither is the one working mid/bass driver. There's lots to experiment with here!
The sound was allowed to issue freely from this omnidirectional speaker untrammeled by a full crossover network.
Note that both tweeters are not original, and neither is the one working mid/bass driver. There's lots to experiment with here!
Indeed. Components or not though, it's still a cross between ranges.. with needs like any.
It's interesting to consider it's beginnings. Manufacturing a capacitor like that would probably have been labour intensive and expensive. These days we have a better understanding of when using components in a crossover amounts to a correction and when it can only be called a compensation. In other words, a minimalist crossover which is all about component count isn't as easy to justify as it once was.
It's interesting to consider it's beginnings. Manufacturing a capacitor like that would probably have been labour intensive and expensive. These days we have a better understanding of when using components in a crossover amounts to a correction and when it can only be called a compensation. In other words, a minimalist crossover which is all about component count isn't as easy to justify as it once was.
I wish we knew more about the enclosure design. That remains a bit of a mystery.
Is it simply an absorbent filled cylinder with a large tuned/untuned opening at the top?
Or is there more to its internal construction than meets the eye?
Is it simply an absorbent filled cylinder with a large tuned/untuned opening at the top?
Or is there more to its internal construction than meets the eye?
Hi, Apologies for delay, I've been struck down by some tedious and debilitating bug...feeling very ill.
So I took the 8" golden out and ran some audio through it from a Mission cyrus amp and there was sound, but it was rather 'tinny' with little bass. I examined the driver for 'sagging' but none was evident. Neiter did the cone look damaged. I tested the coil for continuity and yes of course it has continuity. I measured the resistance - 16.1ohm. Does the fact that this driver is nominally 15ohm and the other driver is 8 ohm have any implications? The inexpensive driver you linked to Galu would fit perfectly. The chamber below the driver mount is as follows: 38cm high x28cm diameter. Three quarters is lined with 'acoustic material' The bottom of the cylinder is constructed from the same material. I'm leaning to getting replacement drivers and 'experimenting'. Infact, I'd welcome your input regarding the experimental design : )
So I took the 8" golden out and ran some audio through it from a Mission cyrus amp and there was sound, but it was rather 'tinny' with little bass. I examined the driver for 'sagging' but none was evident. Neiter did the cone look damaged. I tested the coil for continuity and yes of course it has continuity. I measured the resistance - 16.1ohm. Does the fact that this driver is nominally 15ohm and the other driver is 8 ohm have any implications? The inexpensive driver you linked to Galu would fit perfectly. The chamber below the driver mount is as follows: 38cm high x28cm diameter. Three quarters is lined with 'acoustic material' The bottom of the cylinder is constructed from the same material. I'm leaning to getting replacement drivers and 'experimenting'. Infact, I'd welcome your input regarding the experimental design : )
The Golden 8 is a 15 ohm nominal impedance driver so I would expect a DC resistance reading of between 10 and 12 ohm. Consequently your reading of 16 ohm seems unusually high.
Try pushing the Golden 8 cone gently and symmetrically inwards. If the cone has sagged down, you may feel the voice coil former coming into contact with the magnet assembly.
The fact that the suggested experimental replacement driver is of 8 ohm nominal impedance is of no consequence, as we are effectively re-inventing this column loudspeaker.
If the experiment is successful, you would go on to replace the CB8 in the other enclosure and end up with a DSS (Dr Smith Special) speaker system!
P.S. I hope you feel better soon. Do you know a good doctor? 😉
Try pushing the Golden 8 cone gently and symmetrically inwards. If the cone has sagged down, you may feel the voice coil former coming into contact with the magnet assembly.
The fact that the suggested experimental replacement driver is of 8 ohm nominal impedance is of no consequence, as we are effectively re-inventing this column loudspeaker.
If the experiment is successful, you would go on to replace the CB8 in the other enclosure and end up with a DSS (Dr Smith Special) speaker system!
P.S. I hope you feel better soon. Do you know a good doctor? 😉
Good afternoon, plenty of snow today up here on the Moors. I went to order the 8" driver as suggested by Galu but they are on back order until 20/12. Maybe I'll have to wait. In the meantime does anybody have any other reasonable suggestions. I think I'll follow what Galu has suggested and replace both 8" drivers and sell the Richard Allen's with the necessary caveats.
A reminder that the 8" driver I suggested was intended as a low cost experimental unit. If it had proved not to be compatible then at least the financial outlay would have been low.
There are other inexpensive 8" drivers you could experiment with - buy only one till you've established its effectiveness.
Like this one: https://www.ebay.co.uk/itm/35496753...5Mg5kN99DnX7b68FcaHN6YySE=|tkp:Bk9SR9TNsNDoZA
(Outside diameter: 205 mm; Cut-out diameter: 184.6 mm.)
There are other inexpensive 8" drivers you could experiment with - buy only one till you've established its effectiveness.
Like this one: https://www.ebay.co.uk/itm/35496753...5Mg5kN99DnX7b68FcaHN6YySE=|tkp:Bk9SR9TNsNDoZA
(Outside diameter: 205 mm; Cut-out diameter: 184.6 mm.)