Impedance Matching Question

This maybe interesting for those with impedance matching questions, that I posted on another theard, I'll copy to here as well.

I’ve dealt with impedance matching for many years now, having the product that I have.

With impedance matching if one stays with the 1:10 or higher ratio you’ll have things covered. This goes for source to pre and from pre to amp/s

All you have to worry about then is if the "1" (source or pre) has an output coupling cap, (if they’re dc coupled no problems) and that cap is large enough to maintain that impedance 1:10 ratio flat from 20hz to 20khz you’ll have no problems

If not and it’s too small you may get a change in that ratio in the bass maybe down to 1:2, if this happens because of that coupling cap being too small then you’ll get a "voltage divider" scenario happening in the bass rolling it off too early, maybe at 50 or 100hz and giving a thinner sound with lack of perceived level in the bass.

Cheers George

Polk Audio RTi A3 is on closeout for $240/pr, so not much more than the cable.

Yeah definitely the money shot is for the speakers, how come we don’t get those kind of deal down here in Oz, it really ****** me off. Enjoy!


Cheers George

Nice find, now that looks good I think, seems to be tube input with ss output great combo to get low output impedance and high input impedance.
100k input impedance and 1ohm!!!! output impedance, can be used as a unity gain buffer, or preamp with gain and volume control.

" 8 DIP switches that allow us to select the gain (0dB/6dB) and whether using it as a pre-amp or as a buffer with the help of a flat screwdriver (like the one included)."

https://www.head-fi.org/showcase/ifi-audio-itube.16539/reviews

https://www.audiostream.com/content/ifi-itube-active-tube-bufferpreamplifier

Cheers George

koestner
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.

Don’t know how good that would be, as it runs off the +5v usb supply, and from what I’ve seen it looks to be an opamp based buffer, and for audio these +5v single ended supply buffers are not too good, and I think they also would have to be capacitor coupled as they have dc offset with switch on/off thumps. 
Cheers George

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

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