Hi there,
I bought the PS-2A in April 2025. Recently I have started to hear a pronounced rustling/crackling when turning the unit on, then it goes away, but reappears at times when playing. I removed the tubes and reinstalled them, and this seemed to help a little, but then the noise reappeared. I then swapped out the preamp tube, and the issue was still there. Based on advice I see given to another user, it may be the power tubes (I don’t have extra 6L6 tubes on hand to try). When replacing power tubes, do you suggest these be matched and the same value/rating as in my unit? Would you recommend a parts request for new power tubes? Thank you!
Hi Throwback,
Sometimes this type of problem can come from a heater or cathode issue in the triodes, so it’s worth adding that to your checklist. Before you go out and buy a new set of tubes, do you have a spare pair of 6L6s you could try, even if they’re unmatched? You don’t need to play through them to confirm the noise — just swap in any set to test.
Hi Dan,
I attached a 3 second video of the noise (but it goes on for up to a minute when starting up), and then reappears. And no, unfortunately I do not have extra 6L6 tubes to test.
Dale
Hi Throwback,
Ok, that helps.
What about an extra 12AX7?
Are we hearing the power station in operate? What happens when in bypass?
Hi Dan. In bypass, there are no rustling noises. I have extra 12AX7 tubes. I just tried swapping in two different 12AX7 tubes and the noise was still there. So, that’s three 12AX7 tubes, so maybe the issue is with the power tubes?
Hi
Yes sounds like it. Note the Ia rating of the tubes (it’s written on an internal label) and aim to get something close.
Ok. I’ll do that and report back. The number is 50. How far from the mark can I be off? I’ll order from The Tube Store, so I’m sure they will steer me right 
Sounds good. Matched pair will prevent any nasty crossover distortion. If the anode current value is a little more or less, it will bias the tube hotter or colder, so it will affect things like total output power and when it starts to break up. Get as close as you can. I don’t actually have a good idea of how far off you can be. Tube circuits seem to be quite forgiving in general.
Hi Dan.
I reached out to The Tube Store and I shared a pic showing the reading of 50 for the tubes in my SP-2A. Here is the response I received - "*The problem here is that their 50 rated tube does not relate to our ratings due to differences in equipment and the settings they used to achieve that 50 number. You tweak even one test parameter, and you can get wildly different numbers. To give you a quick hypothetical example, a 6L6 we measure here at iP 24, may appear to be iP 47 at Fryette’s lab because of this difference in equipment. So we have no point of reference. You can tell there is a difference in how we measure things by the simple fact that we do not have any 6L6’s from any brand that measure iP50 in our equipment. You had asked about JJ for example, and the very highest number we ever see those come in at is about 23. *
You can ask them if they use Maxi Matchers, and if so what test settings they use. If they happen to have used that tester it’s likely the only way we can be sure we are getting something close. "
Dan, does Fryette use Maxi Matchers, and if so, what test settings do you use?
Checking on this for you…
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Thanks Dan. Keep me posted!
So that figure is really just an internal number used at the shop during QA/QC process. And yes, it’s a number you can use to place a tube order with Fryette if you want. The advice Fryette gives (and this is also in the user manual) is to simply replace the tubes in the Power Station with any matched pair, this is due the way the Power Station is designed.
Thanks for checking Dan! This is important info, and different from some of what I’ve been reading in the forum threads. Much appreciated
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