Amp recommendation for tube preamp

[Sokel]

SENGTERBELLE replied to the output impedance question: 50K

That must be way-way wrong.
They either didn't understand your question or some random person there got a multimeter and measured one while it was off

 

[Sokel]

To give you an example of a tube pre I'm very familiar with (Audio Research) has 600/300 Ohm (bal/SE) output impedance.
Still on the high side but not the astronomical number they gave you.

 

[Rotel75]

 

[Sokel]

View attachment 409704

That's input impedance and it's about right.
Thought we were talking about pre's output impedance,same seller

 

[Rotel75]

no, it's a coincidence
slp-90 clone impedance out = 50k (Ali seller)
audiolab 8000sx impedance in = 50k (manual)
so, perfect match?

 

[raindance]

It probably is 50K. A few of these so-called clones take the output from the volume pot in order to reduce noise and to try to get around the excessive gain problems that these ancient designs have. I've seen a few that have a 100K pot at the output.

 

[Rotel75]

So what do these 50k out mean for pairing? Any Amp ok?

 

[raindance]

If it is correct it means no modern amp is a match.

 

[MaxwellsEq]

So what do these 50k out mean for pairing? Any Amp ok?

View attachment 409714

50 kOhm output impedance from a preamplifier is simply stupid. You are in trouble.

You might be lucky, and all that's affected is signal strength (which, given an unnecessary gain of 10, may be a blessing). More likely, you will have weird impacts at high and low frequencies. Google "impedance bridging".

 

[Blumlein 88]

It is likely bad information. If someone did build it with 50 K output impedance, they really had no idea. Seller probably gave input impedance for both. I'd ask for a clarification.

 

[Rotel75]

Currently it's connected to Onkyo CR-L5 (TV/LINE input), as far as I can tell it's working fine.

 

[Rotel75]

Why? Do you hate all DSP, or just treble/bass controls?

What if your music is well recorded and it's your room that sucks? Do you just suffer through it, or adjust some settings?

you're right, I never thought of it as room correction

 

[Rotel75]

I lost the Audiolab 8000sx auction (50K imp.) but won the Fosi V3 monos (25K imp.)
Will try the Fosi's next week. I'm very sure I'll have to keep the RCA gain switch on low

Thanks again for all you help! I enjoyed it.
I had absolutely no idea that matching audio devices was so tricky (wattage, gain, voltage, impedance, rolloff, power on/off procedure).

 

[gwing]

I lost the Audiolab 8000sx auction (50K imp.) but won the Fosi V3 monos (25K imp.)
Will try the Fosi's next week. I'm very sure I'll have to keep the RCA gain switch on low

That was perhaps fortunate Enjoy the V3s.

Thanks again for all you help! I enjoyed it.
I had absolutely no idea that matching audio devices was so tricky (wattage, gain, voltage, impedance, rolloff, power on/off procedure).

It isn't usually complicated, generally things just work together although mixing old and new gear might run into gain issues as line level voltages have increased since pre-CD days. The power on/off sequence suggested is *always* good practice - but with tubes you just have the additional step of allowing them to warm up and stabilise. Some old well behaved tube amps were solid and not too finicky - but modern cheapies warrant a bit of babying