[crossroadazn]

Just check the manual for ouput impedance of the RM-5 and it's 1.6K @ 19db gain but my amp input Z's 10K could this make a problem with compatibility ? Any input will be greatly appreciated.

[Roger A. Modjeski]

No problem with that. You are good down to 1.6 Hz ( -3dB). I'm curious what amplifier has this low input impedance?

I appreciate that you used the word "compatibility". A very good choice. Too many people use the word "match" and that is not a good choice.

For those interested we never "match" (as in seek the same input and output impedance) the mating of the preamp to the amp. What we look for is a preamp whose output impedance is several times lower than the input impedance of the power amp it is driving.

The word match has taken a new, and unclear position in audiospeak. A few years ago I never heard it (except for tubes) and now it is applied at every interface. Very few things match in those situations. To me the term match implies making two things equal and in many cases we want just the opposite.

There is a lot more to say on this topic if anyone is interested.

[crossroadazn]

Thanks for the input the amp I'm using is McIntosh MC202.

[Roger A. Modjeski]

Thanks for the input the amp I'm using is McIntosh MC202.

I looked it up in the McIntosh museum. Thats quite an amplifier. The 50 amps output caught my eye. Good for  electrostatic speakers. How much do they go for used?

[crossroadazn]

For used they're ~$1750 on A'gon and ~$2000 on eBuy. This amp can put out a very deep soundstage  aa

[richidoo]

There is a lot more to say on this topic if anyone is interested.

Thanks for offering! I hope you don't mind a specific question about impedance compatibility? Maybe you can segue into a more appropriately general explanation.

Is a separate active preamp with 20dB gain really required in this world of sources with high output voltage and low output impedance, and tube power amps with high gain and high input impedence?

A lot of people are using their Squeezebox or CD players connected directly to power amps, using built in volume control on the sources, or using a stepped resistor or TVC to attenuate. The sound is good with such a configuration, but I wonder if I'm missing something. Guest preamps (Mac, AR, CJ) in my system affect the sound quite noticeably. Are they just coloring the sound as they pass it? Without a preamp installed the sound is ultra detailed, pure natural and realistic tone, great dynamics, extended freqs in both extremes. I can't fault the sound except that with a preamp it sounds a little fuller, but I don't know if that is really just sweet distortion to make all sources sound "good." I could get the same result with a parametric EQ.

My SB3 source has 220 ohm outputZ (lower than many tube preamps' output) and 2Vpp output from 5V/2A linear PS (more than amps' input sensitivity.) The tube power amp has 450kohm inputZ and 26dB gain. 1 meter silver wires of neglible resistance and capacitance. Into 95dB speakers this is perfect amount of gain for me, I rarely play above 80/100 volume setting, except for occasional uncompressed 1812 overture with lots of headroom for the guns.  How does a 20dB gain active preamp inserted in the system improve things electrically, besides source switching and other features. I see 20dB added in gain and 25dB attenuated back out to get where I am now with a straight wire. But I have an open mind, I want to understand, and I know many experienced audiophiles who swear by their preamp. Any insight or wisdom is appreciated. If I don't need a pre, Id rather get a better source instead.   Thanks Roger!
Rich

[Roger A. Modjeski]

Rich,

I wrote a Witty reply to your post and it disappeared. The dog ate my homework! Maybe it will apprear in another dimension. If not I will try to re-create it.

[richidoo]

That has happened to me plenty of times due to my fat thumbs and these stupid hidden keyboard "shortcuts" to make our lives so much easier.    I usually scream first, then chalk it up to "probably for the best" but it's frustrating! I will look for it in the other dimensions you mentioned.
Thanks
Rich

[Roger A. Modjeski]

That has happened to me plenty of times due to my fat thumbs and these stupid hidden keyboard "shortcuts" to make our lives so much easier.    I usually scream first, then chalk it up to "probably for the best" but it's frustrating! I will look for it in the other dimensions you mentioned.
Thanks
Rich

Yes those shortcut keys are a hole waiting to fall into. I disabled the control key on the left side of my keyboard by putting a match stick under it. There must be a better way. I would also like to disable the all caps key. Any tips out there?

[richidoo]

Roger, you are crafty. The matchstick is funny! Whatever works. As you said from your previous post about EQ for cellos, 'I prefer not to suffer when a simple solution is at hand. '

Here is how to null keys. Make sure you create a system restore point before editing registry.   At the bottom of the page are links to CAPS key nulling procedure and scan codes for other keys like your Control.  Of course this only works on PC, because Macs' CTRL Keys function perfectly all the time!    The real challenge is to keep smiling while you do it.
Rich

[Roger A. Modjeski]

thanks for the tip. Have a look at my posting on the Welcome thread for the EQ.