How to get a good sound out of JR 149s

[Mandryka]

My uncle left me to me in his will in 1992, they are circa 1977 from Laskys's I believe, have been offered various sums over the years, but will not part with them as just before I go, I am sure some e-bay collector will find a museum for 20th century audio that will pay a small fortune for them!

Not being a fan of the 1950's 'Hello and welcome to the BBC' style of plummy mid band sounds they do not flat my boat, however they are plenty of fan's out they that adore their presentation.

You have to find a way of making sure that the original ribbed foam doesn't corrupt. You can buy a reproduction ribbed foam from the USA but I notice that there's only one set remaining.

[spendorman]

It's likely that the reversible electrolytic capacitors need replacing if not already done. They can increase in capacitance a lot, and do other things as well.

[Mr. C]

Yes they can sound good with a quality class 'a' solid state

[Mandryka]

It's likely that the reversible electrolytic capacitors need replacing if not already done. They can increase in capacitance a lot, and do other things as well.

That's easy to act on, would you expect a sound improvement?

[spendorman]

That's easy to act on, would you expect a sound improvement?

A lot will depend upon the position in the circuit of the capacitors, if the ones across the bass unit have risen in value (likely) then the mid and whatever top that should come out of that unit will be reduced.

The ones in series with the tweeter, if they have increased (also likely) this will have the effect of putting lower frequencies through the tweeter.

The effects are more than this though, the capacitors also begin to act like resistors.

Falcon probably still do a capacitor replacement kit for the 149.

Just checked, still there;

https://www.falconacoustics.co.uk/ro...citor-set.html

[Alex_UK]

Always fancied a pair of these... But I'm supposed to be downsizing my collection...

[Wakefield Turntables]

1. Recap the X0 with the higher tolerance capacitor kit.t
2. Rewire them with decent purity copper.
3. Tighten the drivers and rotate them in case of sag.
4. Tighten the torsion bar in the speakers.

And a few other bits that you could do....

[graham67]

Your quad will work well with a sympathetic passive or buffer pre. As it has the adjustable gain switches it will help matching too. I have heard excellent sounds with a not dissimilar quad 405, so your 520 should be a good match with the 149.

[Light Dependant Resistor]

Hi
The 100k pot for each channel of your 520 should be wired out of circuit, to be the same as a power amplifier.

I also have JR149 and they sound great with a Quad 306 per channel.

My Quad 306 have been modified to establish 10ma of current at the base of T2 - I did a thread on this a bit earlier, it uses a LM329
https://www.analog.com/media/en/tech...s/129329fd.pdf
instead of the 6V8 zener at D12 ( d3 in a 306 ) ad hoc providing 100ma To get 10ma I am using a LM317 accessing its adjustment terminal as a current source.
I referenced HiFi engines schematic for a Quad 520F that is very close in design to the Quad 306

This forms my every day system to assess audio. The 149 and Quad amps with a few minor changes are a very good combination when used with
LDR attenuation.

Hope that helps.

[Mandryka]

Using an amplifier which has a power rating well in excess of the speakers requirement. But if you say Rogers recommend amplifiers up to 100W for the JR149s, than the 135W of the Quad 520 will make little difference. Where do you have the two input gain potentiometers set on the 520?

Adjusting the potentiometers made a big difference, I owe you one!