Hi,
Anyone familiar with Radford speakers? I have a pair of monitor 180 but all components on the crossover except the inductors has been removed by a previous owner.
Wouldn't be a problem if my x-over were a match to the original wich seemed to have the designation FN.11
My board says FN8(.31)
does anyone have a clue?
Best,
Phil
Anyone familiar with Radford speakers? I have a pair of monitor 180 but all components on the crossover except the inductors has been removed by a previous owner.
Wouldn't be a problem if my x-over were a match to the original wich seemed to have the designation FN.11
My board says FN8(.31)
does anyone have a clue?
Best,
Phil
Last edited by a moderator:
Hi Phil!
I found the attached schematic in this thread: https://www.diyaudio.com/community/threads/radford-m180-50-speakers.318401/
I found the attached schematic in this thread: https://www.diyaudio.com/community/threads/radford-m180-50-speakers.318401/
Attachments
Got a pair of Radford Monitor speakers a few weeks back - https://www.radiomuseum.org/r/radford_monitor.html
It's a 3 way sealed box design:
- Kef B139 most probably the MKII - 6171 version (rated 40W in closed box),
- Goodmans mid rage driver,
- Celestion HF 1300 tweeter.
Frequency range is quite limited at 45Hz - 15.5kHz
1. Has anyone attempted to modify the crossover and add a Coles 4001G super-tweeter in order to extend the high range beyond 20kHz? Would it be a complicated procedure for a novice?
2. Would it be a good idea to upgrade the KEF - B139 6171 (40w) to one of their more recent 1044SP versions (100W)
Apart from wattage the only other differences other than the size (6171 > 1044) seems to be the Fundamental Resonance (FS) which is 20 for the 6171 and 25 for the 1044SP. Does it matter, would it affect the overall sound signature?!?
I've calculated the enclosure volume and it's about 50L. The 1044SP radiomuseum.com page here says 1044SP is recommended for cabinets 40 - 60L in volume.
3. And lastly, I've checked the capacitors inside. There are 4 caps labeled 8uf that score between 13.5 - 16uf, and 2 caps labeled 4uf that score aruond 12uf on the multimeter. There is another one of 0.47 uf that measures 0.49. I'm guessing the last one is fine but the rest of them are way out of their range. Where do I buy replacements if I'm in the UK?
It's a 3 way sealed box design:
- Kef B139 most probably the MKII - 6171 version (rated 40W in closed box),
- Goodmans mid rage driver,
- Celestion HF 1300 tweeter.
Frequency range is quite limited at 45Hz - 15.5kHz
1. Has anyone attempted to modify the crossover and add a Coles 4001G super-tweeter in order to extend the high range beyond 20kHz? Would it be a complicated procedure for a novice?
2. Would it be a good idea to upgrade the KEF - B139 6171 (40w) to one of their more recent 1044SP versions (100W)
Apart from wattage the only other differences other than the size (6171 > 1044) seems to be the Fundamental Resonance (FS) which is 20 for the 6171 and 25 for the 1044SP. Does it matter, would it affect the overall sound signature?!?
I've calculated the enclosure volume and it's about 50L. The 1044SP radiomuseum.com page here says 1044SP is recommended for cabinets 40 - 60L in volume.
3. And lastly, I've checked the capacitors inside. There are 4 caps labeled 8uf that score between 13.5 - 16uf, and 2 caps labeled 4uf that score aruond 12uf on the multimeter. There is another one of 0.47 uf that measures 0.49. I'm guessing the last one is fine but the rest of them are way out of their range. Where do I buy replacements if I'm in the UK?
1. Adding the super-tweeter can be as simple as wiring it up with a 1.5 uF capacitor in series.
2. I don't know, other than to say if the original B139s are in good working order I'd stick with them!
3. The capacitors will be bipolar electrolytic types that have aged badly by now. I would replace them all with modern equivalents as a matter of course. Suitable repacements are available from: https://wilmslowaudio.co.uk/mundorf-electrolytic-ecap-capacitors or from https://willys-hifi.com/collections/electrolytic-capacitors-non-polarised
2. I don't know, other than to say if the original B139s are in good working order I'd stick with them!
3. The capacitors will be bipolar electrolytic types that have aged badly by now. I would replace them all with modern equivalents as a matter of course. Suitable repacements are available from: https://wilmslowaudio.co.uk/mundorf-electrolytic-ecap-capacitors or from https://willys-hifi.com/collections/electrolytic-capacitors-non-polarised
https://www.t-linespeakers.org/classics/TLS80/index.html
https://www.t-linespeakers.org/projects/jakob/index.html
Neither of the links has XO plans. The link to the original Atkinson is MIA, i found these on my HD…
dave
https://www.t-linespeakers.org/projects/jakob/index.html
Neither of the links has XO plans. The link to the original Atkinson is MIA, i found these on my HD…
dave
Attachments
Thank you everyone for your input.
My initial thought was to use the existing crossover making minimal adjustments to it to cover the top end by adding a Coles into the mix. Don't know if I'd be that proficient to build crossovers from scratch or complicate things by changing the crossover all together.
I do have a B&W DM2 crossovers available that I could use. Obviously the DM2 uses the DW200 bextrene as a bass driver which has different from B139 and it also doesn't have a mids driver. Again I would rather operate a modification on the existing crossover rather than complicate things.
Either way adding a Coles to the mix would complicate things from a space pov as it would not fit in between the existing tweeter and mids driver.
Another option would be to do away with the Celestion HF 1300 for something with a higher range provided that the higher range is not limited from the crossover. I got a pair of Acoustic Research AR18LS (50w two way 48Hz to 25kHz crossed at 2000Hz). I could use those tweeters in the Radford Monitors however they are only 5.4 ohm. A 16ohm upgrade seems impossible to find. The only one I could find was this Beyma CP22.
Ultimately the safest bet would be to build a crossover identical to Radford Auditorium which has the same configuration + supertweeter or take a clue from there in order to modify the FN7/5 crossover that's in them.
I could not find a schematic of the FN7/5 Radford Monitor Crossover so I've added some pictures of the board here. Don't know how to draw a diagram / schematic. Probably something I'll look into.
My initial thought was to use the existing crossover making minimal adjustments to it to cover the top end by adding a Coles into the mix. Don't know if I'd be that proficient to build crossovers from scratch or complicate things by changing the crossover all together.
I do have a B&W DM2 crossovers available that I could use. Obviously the DM2 uses the DW200 bextrene as a bass driver which has different from B139 and it also doesn't have a mids driver. Again I would rather operate a modification on the existing crossover rather than complicate things.
Either way adding a Coles to the mix would complicate things from a space pov as it would not fit in between the existing tweeter and mids driver.
Another option would be to do away with the Celestion HF 1300 for something with a higher range provided that the higher range is not limited from the crossover. I got a pair of Acoustic Research AR18LS (50w two way 48Hz to 25kHz crossed at 2000Hz). I could use those tweeters in the Radford Monitors however they are only 5.4 ohm. A 16ohm upgrade seems impossible to find. The only one I could find was this Beyma CP22.
Ultimately the safest bet would be to build a crossover identical to Radford Auditorium which has the same configuration + supertweeter or take a clue from there in order to modify the FN7/5 crossover that's in them.
I could not find a schematic of the FN7/5 Radford Monitor Crossover so I've added some pictures of the board here. Don't know how to draw a diagram / schematic. Probably something I'll look into.
Attachments
Does the mid have its own box?
If you are going as far as tweeter swapping, what i would do is sun in an A;pair 5.2/3 (or CHN50) for botht he tweeter and the mid. And biamp (a paaive is doable, B139 has to be completely out of the picture by 1kHz. They could well end up giving you more money than you started with given what some people will pay for vinatge parts to fix up their old speakers.
dave
If you are going as far as tweeter swapping, what i would do is sun in an A;pair 5.2/3 (or CHN50) for botht he tweeter and the mid. And biamp (a paaive is doable, B139 has to be completely out of the picture by 1kHz. They could well end up giving you more money than you started with given what some people will pay for vinatge parts to fix up their old speakers.
dave
You don't have to disturb the existing crossover, or build a new one from scratch, in order to add a supertweeter.
The supertweeter can simply be connected straight to the loudspeaker input terminals via a 1.5 uF bipolar capacitor.
Or, alternatively, connected to the terminals via the series C7 & parallel L5 combination shown at the top of my attachment in post #9.
P.S. It looks like there's room for the Coles directly above the HF 1300.
The mid doesn't have its own box. I was thinking of doing that I have some plumbing pipe in the garden left that would fit around the mids driver but I would say it's rather tight as it only leaves around barely 5mm for the air to move so I guess that would be too tight of a fit?
See picture with the mids driver and the vernier measuring 102.94(that's the inside of the pipe). It gets in the way a bit on the terminals but they can be bended straight and the whole assembly can be anchored with elastic cords to the front baffle and some 5mm window seal would close the gap on the speaker side whereas the bottom will be hot glued with a flat bottom patch. Still the question remains as to whether there is enough space around it for the air to move without affecting the sound.
Having a closer look at the FN7/5 Radford crossover I noticed that there are two terminals labeled HF2+ HF2-. Bingo! The crossover has terminals for a supertweeter however is missing parts. Luckily I managed to find a picture of the "Radford Studio" online which is the bigger brother of the "Monitor" model. I've put them side by side and draw some lines showing the differences in the HF2 section. All it needs is an inductor to which I don't know the value of and a 0.47μF capacitor. Two soldering spots seem to be connected with a piece of wire. Any idea of what μH the inductor should be? I've had a look at some B&W DM2 crossover schematics and it they have a 300μH inductor connected there before the Coles 4001G.
Last but not least and here I'm going to touch on Galu's question, there is very little space to squeeze in the supertweeter. Galu pointed out that there is room above the HF1300 however this would be out of the cutout of the speaker grills so my best bet would be to move the mids driver to the right and fit the Coles inbetween the mids driver and the HF1300. Is there any impediment to placing speakers to close to each other?
It would be sticking out about 4 inches but I'll drill a hole and seal it tight to the box 🤣🤣🤣
From what I've read online a mids speaker of 4 inches wide would need between 1L - 2L of room. Did some math via online calculators and at that ø I'd need about 20cm so quite a stretch lol. Forgot to look inside if there is enough room and is not hitting the cab braces. But seriously what do you think? I should look for some wider pipes 🤣🤣🤣
Made a mistake in regards to the inductor value on B&W DM4 and DM2 crossover. The DM4 crossover uses a 0.2 mH before the Coles 4001G whereas the DM2 uses 0.3mH. I'd be grateful if someone would come up with an ideal value I should be looking for.