[jarthel]

as title. thank you

 

[dsavitsk]

Jarthel, this has been asked and answered as well as possible here http://headwize.com/ubb/showpage.php?fnum=3&tid=2152

Simply asking the same question on a different forum, without any more information, is not going to yield you a better answer. You either need to use the standard advice Amb gave you (that it will be fine, especially if this is a commercial cd player), try it yourself and see if it works, or provide some additional information such as what the tube/circuit on the output is.

Moreover, if you cannot determine what the tube/circuit is, and you are unwilling to simply try a 50K pot, then you can experimentally determine the output impedance. A technique to do so is outlined here: http://electra-print.com/techblog.php?blogid=1

Finally, the Y in DIY is important. Asking questions is fine, but at some point you need to do a little of the legwork yourself either through reading or experimentation or both.

 

[jarthel]

If you looked at amb's reply, he has no definite answer when it comes to tube sources as the output impedance can be high.

Also, my question is "Has anyone used a 50k pot when using a tubed source?"
how hard can that be? it's either you have not used a tubed-source or not with a 50K pot.

The question wasn't "Is it okay to use a 50K pot with a tubed-source?".

if someone has said yes, at least that would give me an idea that 50k pot is okay (at least for his source).

anyway, thank you for the link.

 

[dsavitsk]

What, are you a lawyer now? I fail to see the distinction. Amb said it would be fine if the source impedance was low enough. You can take this to mean that of course people use 50K pots with tube sources. But, this is of no help to you as a tube source could have an output impedance of a few ohms to many M ohms. Again, what matters is your source, but you won't give up the goods and say what it is.

Anyhow, for what it's worth, someone would need to be a moron to design a source with an output impedance over 5K. I am sure it has been done (i.e., a signal from the plate of a 12AX7, 12AU7, 6SN7, etc.), but it is unlikely that you will find it often.

Most "tube" sources use a tube as a buffer, which means it is a cathode follower, which means the output Z is low enough to use whatever pot your little heart desires. If they use a tube for gain, it is generally SRPP, which, for output Z purposes, you can think of as also being a cathode follower. In the rare case where the circuit is something different (I use a CCS loaded grounded cathode stage in one DAC and a transformer coupled differential parafeed circuit in another) the designer will usually consider that the stage needs to be connected to something like a preamp, and use a tube with a low rp, or a stepdown transformer. In any case, 50K is generally fine. Amb was giving you a worst case scenario, and was giving you enough information so you could work the problem through for yourself.

 

[d-cee]

WoW that thread was originally posted in 2002

I hope you haven't been looking for the answer for the same project since then

I mean, even if you did good on ya, but man that'd test anyone's patience