Quad II and Quad Associated bits, decision time...

[Radio Wrangler]

Modern loud speakers have improved in a number of ways since the 1950s. Frequency response variations have been somewhat ironed out and transient responses have been improved. They still have significant impedance variation over their frequency range, but their crossovers were designed under the assumption that they would be driven from an amplifier with a very low output impedance. The biggest price paid for all this is in efficiency.

As a result the amount of power needed for a given level of perceived loudness has gone up substantially.

The amount of power a hifi speaker can handle falls at higher frequencies and a speaker which may need a hundred watts to drive it as loud as it can go at its low frequency end might hav its tweeter destroyed by a tenth of that above the tweeter crossover frequency. (This is one reason why using hifi speakers for guitar or synthesiser amps can end in tears) So you will find that a pair of KT66 will likely not be able to drive your speakers to the loudness levels they are capable of in the bass register.

If you listen to fairly quiet stuff or bass-light stuff then you will have a more favourable opinion than the Quad II should be fine. If you're a Deep Purple fan, then you'll probably find them limiting (bad pun) and not able to drive the speakers to the bass levels they could have handled.

(An amplifier driven hard into its end stops creates more energy at harmonic frequencies than there was in the original music. It's why amplifiers made to work too hard at parties result in burned out tweeters - though this is more of a problem with too-small semiconductor amplifiers. Valve amplifiers have a gentler clipping characteristic and resolt in less at higher harmonic ratios.)

Some years ago I replaced my speakers. The old ones were sealed-box infinite baffle types. The new ones were large floor standing ones using transmission line loading on the bass driver. My taste in music covers classical orchestra, vocal and hard rock. Did I mention I'm a pipe organ nut? I found my old 50w/channel amplifier had become a problem and had to set out and design a new amplifier for them, one capable of much more output current and at low frequencies so I could make use of the extended low frequency response and survive the reduced efficiency.

The '8 Ohm' spec of your speakers is not a guaranteed parameter. It will vary a lot across the frequency range with bumps and dips above and below that number. These will interact with the amplifier driving it and will reduce the amount of power it can give at the frequencies where it deviates from 8 Ohms.

This means that you have to listen to the amplifier/speaker combination with your kind of music and at your kind of loudness level so you can form your own opinion whether it's sufficient.

Have a look at the amplifier power rating B&W recommend for your speakers, then look at the QuadII's rating. It'll give you a rough idea to begin with.

David

EDIT: Just seen your latest post, I'm a slow typist.

The Quad 22 preamp and tuner have their own fans, and some people would like a full, matching set, but on the whole, the preamp and tuner do not have quite the fan club the power amp does. There is no easy answer to the selling question. It depends who is looking to buy. If you advertise them as individual items for simple sale, there is a fair chance someone will come along and say "I'll take the lot". If you sell by auction then it's not possible for someone to do that. Even seeling the power amps as a pair could possible miss out people already having one and desperate to find another to complete a stereo pair. It's not possible to predict how things will turn out.

If the serial numbers on your QuadIIs are close together, then that boosts their price sold as a pair. If the serial numbers were very close, some people could get quite excited.

For advertising, good photographs help. Describe what types and makes of valves are fitted. These sorts of things can boost prices.

The hifi market is strange. people sometimes pay a lot of money for things which could be described as imaginary.

David

[Marty Wild]

All interesting stuff, thanks.

The 603 have a recommended 30-200w power requirement. Currently getting circa 150w from the receiver.

I’ll look at the serial numbers now.

[Marty Wild]

Numbers are not close enough to be worthy of mention.

Have the stereo box for the radio too. I’ll get them appraised and go from there. Guess with all my personal considerations, they’re probably not best suited to joining my household.

My Dad was a staunch classical man, so have all of his vinyl. Whilst I do like classical, it’s not my go to. So my taste ranges from Classical to Reggae all they way to proper underground Techno. I’m guessing the Quads probably wouldn’t be best suited to the heavier ends of my tastes.

[GrimJosef]

I'm currently listening to this https://www.youtube.com/watch?v=1YpUffH9atY through mine. North London's finest sound good to me.

Cheers,

GJ

[Marty Wild]

Graeme, that’s right up me street. Going to listen to that in the office tomorrow morning.

Which speakers you running?

Crazy how heavy the Radfords are, real wood (in places) I suppose.

[GrimJosef]

Yamaha NS1000s. Nice and sensitive - around 91dB/W @ 1m - but sealed-box and engineered in their 'M' version for studio monitoring back in the 70's, so there's really no bass emphasis. My room helps them a bit there, but not much to be honest. They are extraordinarily heavy. Each 100 litre box weighs 39kg !

Cheers,

GJ

[Marty Wild]

Sound interesting. I feel like I know less than nothing when I frequent this board.

Could spend all day googling the responses.

[Marty Wild]

Testing my first photo upload.