Wednesday, December 21, 2005

Vintage Hifi FAQ about ... ?

This FAQ about Vintage Hifi, audio Electronics, Quad, Revox and everything has to be filled by ... You!

Just post your Question as a comment below and I'll answer it myself, surf the Net or ask my friends what the answer is. Of course I count on all Hifi-freaks reading here as well to add your knowledge %)

Once the answer has been found the comment will make a promotion and become part of this post itself ;-)


PS. Please use English, French, Dutch or German otherwise I'll have have a hard time understanding what you mean.

You are lightning fast tonight ;-)
  • Jean-François (Belgium) asked:

Q: "Concernant les cables HP : quels genre de cables conviennent le mieux au Quad ? (HP Advent Legacy 8ohms) Ces cables sont des résistances..donc, il vaut mieux qu'ils soient de même longueur ? (mais pas de boucles ?)"

About the Loudspeaker cables: what kind of cables are best for the Quad amps? (I use HP Advent Legacy 8 ohm). Those cables are restistances... so they should be the same length for both channels ? (but not have any nods ?)

A: All cables are restistances indeed and at the same time they are capacitors. Some universities are experimenting with the "perfect" conductor so within 50 years we'll maybe have the perfect speaker-cable ?-)

The output of the Quad 405 at maximum undistorted output volume is around 4 Ampère @ 32 Volt into your 8 Ohm speakers.

This means the cables do not have to be excessively thick. To keep the resistance as low as possible they should be as short as possible of course and use a high-quality conductor inside (copper will do fine).

They don't have to be exactly the same length for both channels. The impedance of the cables is supposed to be very low compared to the impedance of the speakers. Except if the left channel cable is 1 meter and the right-channel cable 50 meters I would not care about it.

Nods are no big problem neither as the frequencies between the amp and the speakers are below 20 Khz. Just don't put 20 meters on a roll ;-)

I would say: Buy good quality Loudspeaker-cable but don't pay more than 2 Euro per meter. Keep them as short as possible. Don't believe the "High End" salesperson who tries to make you afraid of all kinds of problems you will have if you don't buy his 200 Euro leads.



Blogger Stefaan said...

The distortion can come from "dirty" power supply - if you arre connected to the same powerline as some large industry around - or from electro-magnetic fields - like when you have a GSM antenna or a radar next door.

Quads like the 404 or 606 are very insensitive to both. Being end-amps they treat voltages from 1V RMS on. And the 10.000 MF caps in the 405 flatten all freaky variations in te powerline.

Pre-amps are another story.

First of all I would check the "earth" lead in the 230V power supply. Is it connected? (often it is not) You might consider measuring the "earth-resistance" of the power-plug.

Connecting a scope to the DC-reels of the NAD might give some interesting information about spikes or distortion.

Are all cables between the pre and the power-amps connected as they should?


7:25 PM  
Blogger Stefaan said...

Hallo, Francis,

Please keep us posted on the solution you will find for the oscillation of the NAD caused by environmental electrical/magnetic fields.


5:39 PM  
Anonymous Anonymous said...

Hi Stefaan,

I like the Quad and I own a FM4, 34 and 303 : all revised with new capacitors.

I read on various forums that Quad 34 preamp sound is obscure, outdated, not up to today's standard etc....

Would replacing operational amplifiers and bilateral switch ICs in the 34 (about 13 components) greatly improve the sound quality, equivalent to modern preamp? Without compromising the reliability and create noises turning ON the power.

Regards, Rene

8:25 PM  

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