Speaker re-wire and re-cap

[Macca]

If they didn't use fancy capacitors in the studio equipment that made the recording, how can you possibly get back what is already lost by inserting fancy capacitors into the playback equipment?

[chartz]

Correct: the fancy Studer and Neve mixing boards use tons of 5534’s and electrolytic caps on the audio signal. Nothing fancy.
There are loads of myths and placebos in hi-fi circles. Do try the switch test and be amazed. I’d put my money on the result.
That said, there are truly awful components too, most of them coming from China, whose entire economy is based on fake or counterfeit products. Big factories that employ thousands to make that s…t.
But I digress!

[Macca]

I suppose if you allow for the theory that caps can sound different then you can at least flavour the sound by changing them, and if you prefer the change in the sound it's an 'improvement.'

[chartz]

I have my doubts Paul. It’s a theory as you say.

[sailor]

@macca, sure once the sound is finalised in the studio then that is it, however, we are not trying to get back what is lost but simply attempting to minimise any damage. This applies to everything, not just caps!

@chartz, "I for one have never, ever been able to discern the sound of good caps. Unless you listen with a switch for instant comparison at the same level, any judgement has to be biased"

Therein lies your problem perhaps. Rather listen to the different caps for maybe a week or longer to get a true feel for what they are doing. Rapid switching just confuses the comparison.

You also state that the Solens are fast and dynamic. How do you know? By your own disclosure you can't hear the difference.

[chartz]

I didn’t say that Charles. I said that my speakers which have loads of them sound that way!
Differences should be heard instantly.
Waiting for a week doesn’t make any sense.
I don’t have any problems by the way, I’m happy to steer clear of all that audiophile nonsense, that’s all.

[Qwin]

I got a bit bored this morning so read the whole of this thread.

My 2 cents.

Ali hit the nail on the head, a 1.5uF cap will give a crossover frequency of around 13kHz for an 8 ohm tweeter and 26kHz for 4 ohm.
So we are presuming its an 8 ohm tweeter with a corner frequency (-3dB) of 13kHz for the XO and -9dB at 6.5Khz.
I read two reviews that suggested the full range driver started to roll off above 10kHz. It's a fair assumption that it would be -3dB at 13kHz to marry with the tweeter XO slope.
The tweeters contribution will be small, but still well within the audible range of most of us old farts.

Interesting as all of this is, its not really addressing the question that was asked, about cap choice.

To me, you wont really hear the tweeter output on its own, within the audible range of most of us, as the caps attenuation curve doesn't level till well above 20kHz. It will only be present at a reduced level, adding a little sparkle to the combined output with the full range driver - Which makes sense.
Because of this, the series cap choice is not going to make a big difference to the sound, compared to say a tweeter cap in a three way design, crossing at 5 or 6kHz.

Some of the OP's suggestions for caps are quite large and expensive, which I would stay clear of in this application, as I don't feel the audible difference, if any, warrants that amount of expenditure.
I've always found the basic Solen to sound a little grainy at the top.
A Mundorf Supreme would do fine, as would the Jantzen Superior Z-Cap.
I use the Jantzen in a three way design with a Yamaha Beryllium dome tweeter and in that application it sounds to me, just slightly better than the Mundorf at the very top frequencies, but not by much. In the OP's application I doubt anyone would hear a difference between them.

I wouldn't go any further up the price range than either of these two, due to the parts limited contribution to the overall sound of the speakers.

[florin]

Hello everyone.

I'm working on upgrading a pair of Radford Monitor speakers crossovers.
In the process I'm adding a super-tweeter to the setup and turn them into Radford Auditorium model (they share the same FN7/5 crossover schematic, they just need an inductor and a 0.47uf cap aded to the existing crossover in order to enable the HF2 terminal).
I bought the following replacement capacitors from willys-hifi.com:

8x Mundorf ECap AC 8uf 70V Bipolar Electrolytic Capacitor - PLAIN
https://willys-hifi.com/products/mun...42037499265279

4 x Mundorf ECap AC 4uf 70V Bipolar Electrolytic Capacitor - PLAIN
https://willys-hifi.com/products/mun...42037209596159

4 x Mundorf MCap EVO Oil 0.47uf 450V Capacitor
https://willys-hifi.com/products/mun...nt=51344326867

I bought the 4 "Mundorf EVO Oil" only because I couldn't find the "Mundorf E Cap" in 0.47uf.
I'm no expert but I presumed that splashing more money on caps for such old drivers won't make much of a difference.

Now I got a few questions regarding these capacitors:

1. I've measured all of them with the multimeter.
The 8uf Mundorf ECap measure in the region of 9.2uf (15%)
The 4uf Mundorf ECap read around 4.92uf (23%)
The 0.47uf Mundorf MCap Evo Oil measured 0.465 (>1%)

I wonder if this is normal given that the tolerance on the Mundorf ECap is stated -/+5% and they measure between 15% respectively 20%.

2. I was wondering if someone could have a look at the diagram and let me know if I got the A - Z ends of the Evo Oil caps right as I've read somone saying that "even though film caps are non polarised, the outside of the foil should be connected to the low Z side of the circuit." I get that the A stands for the entrance point of the electrical current (binding posts / amplifier signal) whereas Z stands for the exit point and lower power meaning towards the speaker drivers?

Many thanks!

FN7:5 3 Radford Monitor Crossover (Solderboard)_8.jpgFN7:5 3 Radford Monitor Crossover (Solderboard).jpg

[walpurgis]

How did you establish that a supertweeter is required? Many Radford speakers employed the Goodmans DT3 tweeter that responds up to 22kHz.

[florin]

There is no Goodmans DT3 in this configuration and the stated frequency range is 45Hz-15,5kHz ±3dB
https://www.radiomuseum.org/r/radford_monitor.html

Radford Monitor has the following drivers:

Kef B139 6171
Goodmans mids driver (also used in Goodmans Maxim "M range" speaker)
Celestion HF1300

Auditorium and Studio models also have a super-tweeter either Telephones or Coles 4001G

https://www.radiomuseum.org/r/radford_monitor.html