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Impedance Question: Tube Preamp with SS Power Amp

Having researched this issue with the archived threads, I am still having difficulties understanding the problems of impedance mismatch between Pre and Power amps. As a budding audiophile moving onto my first separates Pre/Power, I want to know more about impedance matching. I have several questions that I hope veterian audiophiles can help me out with.

1)Is the 10:100 ratio between the output impedance of preamp and input impedance of the power amp an absolute rule?

2)What would happen if impedance mismatch do occur? Will the sound be any less satisfying?

3)I understand that Tube preamps generally have higher output impedance values compared to SS, so does that make it problematic to use it with a SS power amp even though tubed preamps are often priased over their SS counterparts?

I ask these questions because I recently purchased a tubed Preamp (Musical Design SP-2B)that has an impedance of 2K Ohms. I want to match that with a SS power amp with an impedance value of 20K Ohms. Am I cutting it too close? (exactlly 10:100 ratio) Or are all of these issues irrevalent and I should just listen to that setup and hear for myself if it would work or not? Thanks in advance for the answers.
speedracerucr
johncusick
10 posts
 
Just to follow up - I spoke to Leonard at ARC and he clarified for me the fact that the Ref One has DC capacitors in it's output to filter DC from the Amp. So unless a tub blows or some such crisis the Krell's should be ok. He thought it to be a reasonable gamble to leave the jumpers in the Krell so as to keep the capacitors out of the signal path.

Thanks all
John
vladimir
346 posts
 
Impedance mismatches in this way affect (diminishes) the very low bass; some of those who say they don't have any problems may be due to the fact that they don't own really full range speakers.
johncusick
10 posts
 
Vladimir you're piqued my curiosity.
Can someone walk me through how to assess the impedance charactreristics of both my Krell 350mc's and the ARC Ref One Mk2. I'm sure I can go to the owner's manuals but I just don't have a clue as to what I'm looking at.

Thanks
John
morbius396c
134 posts
 
John,

On page 26 of the current FPB-series manual; under the
column labeled FPB 350Mc - the input impedance is
specified as 100 kOhms.

In fact, all the amplifiers, both stereo and mono; and all
powers have an input impedance of 100 kOhms.

Dr. Gregory Greenman
Physicist
johncusick
10 posts
 
Ok. Thaks for that. And if I go to my ARC manual, in the Spec section under Output Impedance it states:
400 ohms Balances, 200 ohms SE main(2),
20K ohms minimum load and 2000pF maximum capacitance.

In the Rated output section it states:
4V RMS (2V RMS SE) into 100K ohms balanced load.

My proplem is I don't know how to make sense in comparing the two.

AGH!!!!, so you wanted to be a carpenter...grasshopper

Thanks

John
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