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AUDIO FORUMS >> Replacement Tubes >> 6N23P-MS humming
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Message started by JHC on 07/24/25 at 23:15:12

Title: 6N23P-MS humming
Post by JHC on 07/24/25 at 23:15:12

Hi, I looked through the forums but didn't see much about the 6N23P and hum, so if there is some info, please let me know.

I swapped the stock 6N6P in my SE84UFO for Russian 6N23P-MS. It has a significant amount of hum, especially when the bias is pointed forward (towards the tubes) which is how I prefer it. When switched the other way, it is significantly reduced, but still present.

According to Decware, the 6N23P-MS is a drop in replacement for "6922, 6N1P, 6DJ8" which is what the input tube is spec'd at. So, wondering if I got a bad tube, of if they are not all that compatible.

Secondarily, wondering if anyone knows has a very quiet input tube recommendation compatible with the SE84UFO.

On the up side, I have always wondered where the hum in my system is coming from, so it's nice to know it is from the input tube and bias setting—at least from what I can tell.

Title: Re: 6N23P-MS humming
Post by CAJames on 07/24/25 at 23:51:36

Quote:

Posted by: JHC Posted on: Today at 15:15:12

...I swapped the stock 6N6P in my SE84UFO for Russian 6N23P-MS. It has a significant amount of hum, especially when the bias is pointed forward (towards the tubes) which is how I prefer it. When switched the other way, it is significantly reduced, but still present...

You have what we in the business call a bad tube. Sorry.

Quote:

...wondering if anyone knows has a very quiet input tube recommendation compatible with the SE84UFO...

The 6N23P is an excellent tube, usually. Unfortunately any tube can hum, starting at any point in it's life, or go bad in other ways. Another common failure mode is the staticky "frying egg" sound, often when adjusting the volume. Really the only "solution" is to buy from a seller who will let you return it if there is problem, or to find them cheap enough that you're willing to take the risk. Buying bad tubes has always been a thing, but as the supply of NOS, or NNOS (nearly new old stock) tubes dries up the odds of getting tubes with dubious life histories is continually getting higher. You can always get current production, but they have issues as well.

Title: Re: 6N23P-MS humming
Post by JHC on 07/25/25 at 01:52:02

Thanks for your quick reply. I will reach out to Decware and see if they can do an exchange. Bummer.

Title: Re: 6N23P-MS humming
Post by CAJames on 07/25/25 at 18:18:08

No place is more reliable than Decware to buy tubes. The fact you got a bad tube from them just illustrates the truism: if you buy vacuum tubes sometimes you get a bad one.