Impedance Matching Question

Impedance Matching Question

Most know that the input impedance of an amp needs to be ~10X the output impedance of the preamp for proper matching. Is there an inexpensive device that can be placed between a higher impedance preamp and lower impedance amp to help solve the issue? This is not for critical listening, but I do want it to sound good.
tls49

"Most know that the input impedance of an amp needs to be ~10X the output impedance of the preamp for proper matching."

This is correct 10x is fine some even say 5 x is ok. If you can't do this ratio a unity gain low output impedance buffer will do the trick. Like this.            http://www.6moons.com/audioreviews/burson/buffer.html

Or a tube one, but some have a high output impedance as this one at 1kohm you may not be better off, and it could even be worse than 1kohm in the low bass because of the dc coupling capacitor that's needed on their outputs if it's not large enough.
http://www.decware.com/newsite/zbox.htm

Cheers George

The Burson Buffer has not been made for quite a while now, and are hard to find. However Burson has this ingenious RCA cable with a small solid state buffer built into it. It is powered by 5 Volts DC. It will help with most any impedance mismatches.

Specifics of the gear being connected, cable type and length would help. It may be possible to simply change an output or input resistor.
It is also possible that with short cable runs, worry is not warranted.

atmasphere - thanks for your additional info, made an inquiry to Rolls about the bandwidth, but have not heard back. The box, RCA's, solder, and assemble would be no problem, however getting the proper transformer is beyond my expertise.

George - the preamp is an old VTL Maximal with a 5K ohm output impedance. I have tried a few amps with it. One was a 75 watt Belles with a 25K ohm input impedance. The result was poor, soft, rolled off, and no dynamics. That amp sounded great with a SS preamp. Surprisingly, the best sound with the VTL has been with the 18 watt power amp section of an Advent 300 receiver, quite a bit better than the Belles on the same speakers. It's input impedance is 100K ohms, so that proved to me that proper impedance matching is important. Thanks for the links to the buffers, however as I said previously, more than I want to spend in the location.

koestner - thanks for the info, that Burson RCA cable looks intriguing. Appears that it would solve the problem and it might be entertaining trying it on some other systems I have. I sold some cables in the past year, so it's easy to justify spending some of that money on new cables. :-)

VTL Maximal with a 5K ohm output impedance.

Wow that’s hi, I can understand it would be a no go (1:5) with the 25kohm of the Belles. But with an amp of 50kohms or higher (>1:10 ratio) as you found out with the Advent it was fine.

Remember back in those days the "industry standard" for input impedance of amps and preamp’s was 47kohm and that VTL would have been happy then as it was made then, and sources were very low in output volts phono ect and also high in output impedance, and you needed preamp’s for the extra gain they gave. But today gain is not the issue, as Nelson Pass says "we have too much."

Where today source have output stages that are the equal sometimes better than preamps, with high output voltage more than >2v, with low output impedance less than <100 ohms output impeance, and many amps today only need 0.5v to 1v for them to give their full wattage before clipping, and we have >2v available from our sources, do the math.

Cheers George