Need Advise - Radford Crossover Inductors

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I'll take a shot at it. I see Erse has got all the inductor measures online, for Dayton I'm not sure I see any. Would you measure Length and diameter for I would draw these as 2 dimensional objects on a board in a pcb making software so you can solder all the conections on the bottom side of it and the upper side would be clear from it, with -IN+ ; -W+; -M+ ; and -Tw+ only. I think I'll need a day or two for it.


Thankyou for your offer to help me.

Did you mean you will draw up a PCB for the Radford xovers I'm making or would it be easier to draw up a board where I can put a centre strip and mount all components on a timer board? Where do I get the PCB made once it's drawn up? I can measure all the caps for you?


I've attached a rough picture of how I would wire up using all components on a timber board. All the negatives will be linked together. Is there any issues with my drawing? Anything I should change?
 

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HaHa! This looks like a car-wreck to me! :eek:

Radford-FN10-XO.gif


I just simmed it with any old drivers. It is a horror! What is that impedance -wrecking 12kHz notch for?

The original KEF filter looks much better, albeit has some other impedance issues.

But really a complete redesign might be in order. I see considerable evidence that the people who drew up both schematics wouldn't know correct polarity from a hole in the ground. :cool:
 

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Well, I can tell, by your silence, you are in a state of shock. I am telling you this project of yours is RUBBISH! :eek:

AFAIK, it is some sort of "one size fits all" idea. You just adjust resistors to get it to work. Except that the designer was clueless. :D

To rescue it, we must understand the doyen of loudspeaker design, Steen Duelund. This is the guy who designed the ideal 3-way. In simple terms, he realised that the perfect 3-way is built around the mid. It's not hard to tack on a bass and a tweeter to get it all to work.

This is what Troels Gravesen did with his classic 3-way: SEAS-3-Way-Classic

644710d1510200536-advise-radford-crossover-inductors-3-classic-troels-gravesen-png


Where I have got to on your project is much better. But seriously, you must abandon this ancient 40-y-o Radford nonsense. It can be taken no more seriously than 95% of the inept projects at this forum. How do I explain this? If you want an opinion on your open-heart surgery, will you consult an experienced Surgeon or a West Ham football supporter? I rest my case. :D
 

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Thanks Steve for your kind words :D

These are my fathers and i'm trying to improve their sound for him. He doesn't have much money to go out and spend dollars on something new. I know these can sound much better than the original kef dn12 xover.

What i will do is i'm in the building stages upgrading the dn12. I will make the FN10 & your improved xover and i will come back and tell you what i think.
 
Thankyou for your offer to help me.

Did you mean you will draw up a PCB for the Radford xovers I'm making or would it be easier to draw up a board where I can put a centre strip...?


Originally I meant to draw up a Radford version as if it were on a pcb, meaning not that you should actually use a pcb, rather as a way of hiding wires underneath the board which could be anything ( timber, plexi...). Your idea is simpler and you should follow it through. Usually people advise to turn the inductors in such a way that by looking through the hole of a vertically mounted one, you would not spot another near by placed inductor. This would eliminate any possibility of inductance coupling from one to another.
 
I am actually pretty interested in loudspeakers. But, IMO, there is more to it than frequency response. :D

We have power response, dispersion, impedance and phase. All these things matter. Phase is actually one of the tougher parameters.

I am the World's Number One fan of 90 degree 18dB/octave BW3. This is the principle which creates a huge +3dB frequency response at crossover unless the phase works out. Sometimes it works nicely, sometimes it doesn't. :D

I had a serious look at the three-way Radford design tonight. It may be pure BW3. The theoretical two-way values are below. This makes for lovely flat impedance, but takes no account of bafflestep correction. IMO, bafflestep is one of those deeply confusing speaker cabinet or room-corrections.

What I can tell you, is I respected KEF's ideas of what to do with the midrange 5" polycone driver.

644709d1510200387-advise-radford-crossover-inductors-kef_concerto_crossover-jpg


I just left it alone, apart from the minor change from 4mH to 1.8mH and 1.5R. I assume KEF knew what they were doing. As it goes, I have worked on the KEF Concerto which a friend of mine used to own. A good speaker.

644727d1510213186-advise-radford-crossover-inductors-radford-improved-circuit-png


Where my tweeter filter is clever, is that it is a much flatter impedance than the original KEF 5uF/0.25mH/5uf filter. Of course, KEF eventually moved to the theoretically better 3:1 ratio 3.3uF/0.18mH/10uF idea. It makes for flatter impedance. I like flat impedance. It works well with any amplifier.
 

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frugal-phile™
Joined 2001
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What's that Radford improved xo he has drawn up then?

That is the one he is dissing. It is the XO i drew up from Zaphod’s sketch and the one i assume you have parts for.

Attached are KEF’s drawings for DN12 SP0004 & DN12 SP1002 for T27/B110/B139.

dave
 

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That is the one he is dissing. It is the XO i drew up from Zaphod’s sketch and the one i assume you have parts for.

Attached are KEF’s drawings for DN12 SP0004 & DN12 SP1002 for T27/B110/B139.

dave



Dave,


There are other members from different sites currently doing the Radford upgrade. Why would Zaphod say to do this upgrade and now others are stating its not better than the original DN12?? When Bailey released his drawing on the transmission line, he recommended to upgrade to the Radford FN10 for better results. Has Zaphod reverse engineering xo drawings not the correct original values used from Radford??

I've attached the Bailey drawings stating it is recommended for better results to use the Radford xo.
 

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frugal-phile™
Joined 2001
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Steve (aka system7) is saying it is not good, he has not explained why or offered an alternative. Zaphod (as far as i understand) reversed the FN10 XO which i drew up into a nice format, i have no experience with it or anything to say about its veracity. I have with the DN12 which is very much a weak point of the system (as in many cases the XO is harest to do).

With many doing the updrade we will likely get real world modern feedback soon enuff about the merits of this XO.

I do think that it is likely that some XO guru with modern equipment & modelers could likely com eup with an even better XO. Steve, with his speculations is not that.

dave
 
Here's the thing. Radford are famous for building great valve amplifiers. I have a still lasting interest in the Radford STA-25, below. A fab amp.

But, IMO, Radford knew ZIP about loudspeakers. :D

The best Radford sound I ever heard was a Goodmans 12" bass with a 3" tweeter. In huge closed box in a huge room. We are talking Decca London vinyl cartridges too. Ah, memory lane. :eek:

What do I know about 3-ways?

644711d1510200656-advise-radford-crossover-inductors-kef_concerto-jpg


The KEF Concerto was a very fine classical music speaker. My neighbour used to own a pair. I tuned them up for him, just by cleaning the contacts. Not rocket-science. :eek:

TBH, the plastic bextrene era didn't make for the liveliest speakers. My BBC monitor Chartwell PM400 speakers were inoffensive, but hardly lively:

486371d1433293422-rogers-studio-1-crossover-circuit-boards-chartwell-pm400-monitor-jpg


Here's another way of doing things with paper bass and mid drivers and Celestion HF2000 mylar tweeters:

323189d1357929498-celestion-ditton-44-sounding-muddy-celestion_ditton_44-loudspeakers-speaker-002.jpg


This is a Celestion Ditton 44, which I still own. It's a party speaker. It goes hugely loud without too much distortion. But not perfect, because I always hear the cone-breakup from the 6" mid.

I might be completely wrong on my suggested crossover improvements to what is essentially a KEF Concerto, albeit I have heard the very dull IMF transmission line version with the Coles 4001 supertweeter.
644727d1510213186-advise-radford-crossover-inductors-radford-improved-circuit-png


But I am feeling confident here. :)
 

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frugal-phile™
Joined 2001
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Here's the thing. Radford are famous for building great valve amplifiers. I have a still lasting interest in the Radford STA-25, below. A fab amp.

My 1st exposure to Radford was their S90 TL. It really left an impression on me and lead to my metting with one of my hifi gurus. It wasn’t till some 30 year slater that i learned they ever made a tube amp. I have heard the original STA-25, a rather nice amp.

dave
 
frugal-phile™
Joined 2001
Paid Member
Which model IMF are we talking about with the coles?

The IMF TLS80 MkII at least had the Coles 4001. In the late 70s a very impressive loudspeaker. A friend had a set, which i spent much time listening too. One had to be careful with the amp used or they could be kinda hard/shrill on the top. Steve must have heard another or with a poor amp/speaker pairing.

cutawayTLS80.gif


The pair i had turned out to have mismatched bass drivers, i was able to part it out for more than they cost me. I’d still love to get my hands on TLS80s or TLS50s and swap out the mid/tweeter/supertweeter with a nice 3 or 3.5” FR (FF85wKen, Alpair 5.2/6.2eN) and biamp with a lower XO point.

dave
 
Looks like the scan off my website: Radford Studio S.90

These XOs were for Goodman’s sourced Bass & mid & Peerless (?) tweeter. Not likely to work well with T27/B110/B139.

dave

I have just emailed Zaphod regarding the FN10 and this is his response;

Yes, I did reverse engineer it. Yes, I ran it with those drivers for more than a decade. Sounded great.

Will wait and see how good they sound. Might need a bit a tweaking.
 
The IMF TLS80 MkII at least had the Coles 4001. In the late 70s a very impressive loudspeaker. A friend had a set, which i spent much time listening too. One had to be careful with the amp used or they could be kinda hard/shrill on the top. Steve must have heard another or with a poor amp/speaker pairing.

cutawayTLS80.gif


The pair i had turned out to have mismatched bass drivers, i was able to part it out for more than they cost me. I’d still love to get my hands on TLS80s or TLS50s and swap out the mid/tweeter/supertweeter with a nice 3 or 3.5” FR (FF85wKen, Alpair 5.2/6.2eN) and biamp with a lower XO point.

dave



I have the 80'sII & the 50'sII plus others and they sound fabulous. Steve's probably hearing 20 - 30 year old caps or as you said, not a great match for the amp he was using at the time.
 
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