I would be inclined to swap the tubes around between both channels to see if the symptom follows a particular tube. To me initial impressions suggest a microphonic tube.

4 hours ago, Eduardope said:

First I had the scratchy volume knob but some Deoxit seems to have fixed that.

The noisy volume control is indicative of noisy front-end tubes (most likely the higher gain 6SN7)... Other than replacing the tubes, there's not much you can do about it... DeOxit won;t fix it. You can spin the volume knob a couple of times when you power on the amplifier to eliminate the noise but you will have to repeat the process every time you turn it on... I have swapped the tubes numerous times and noticed some tubes are dead quiet and others are noisy as heck. I also have a Muzishare X7 and it also has issues with noisy front-end tubes. In fact, the Muzishare has more issues with noisy tubes than the Willsenton. The 12AX7 tubes have a lot higher gain the the 6SN7 so it is more susceptible with noisy tubes.

You probably going to roll some tubes. You can't go wrong with Sylvanias but they can be expensive. GEs are pretty cheap but make sure you get the GE 6SN7-GTBs, not the GTAs as the are less reliable. For power tubes, the EL34 gives a smoother, warmer sound but the KT88s deliver a more dynamic sound but are not as smooth. Go with the Mullard EL34 or Psvane EL34-PH. For KT88s, opt for the Gold Lions. Be aware that Chinese tubes are generally not as reliable as the current New Sensor Russian (Electro Harmonix, Tung-Sol, Gold Lions, Mullard, Svetlana, Sovtek (~$200-300/quad)) tubes. The best EL34s are the vintage Mullard El34 XF2s, Matsushita 6CA7 but they are getting pricey now, easily topping several hundred dollars.

It's definitely not the tubes as I have tried three different sets of preamp and power tubes with no effect on the wierd sound. Strangely, my NOS GE 6sl7 and re-issue Tung-Sol 6sl7 tubes are definitely a little microphonic based on the pencil tap test. However, even when I swap them, the microphonic behavior only occurs when I tap the right channel 6sl7 (correction to my original post- the noise is in the right channel, not the left). I thought this was a clear sign that something was wrong with the amp but when I put in the lower quality stock tubes they did not exhibit any microphonic responses to the pencil tap yet the odd whishing sound was still present when I feed a signal! I will try switching the left and right channel source cables and see what that does because I am at a loss. For reference, I am feeding a digital high-res signal via a Wiim Ultra, then through a Cambridge Audio DacMagic 200M, and ultimately into my CSS Typhon speakers. I know these speakers (rated at 87 db sensitivty and 4 ohm impedence) are pushing the limits of this amp but they seem to be okay up to about 100db before they start to noticeably clip and distort, plus the noise is only in the right channel so that doesn't seem to support a theory that its just the speakers taxing the amp. I hope I can get it figured out because, as much as I love this amp, this is way more drama that I bargained for after only 3 weeks of ownership.

4 minutes ago, jon96789 said:

The noisy volume control is indicative of noisy front-end tubes (most likely the higher gain 6SN7)... Other than replacing the tubes, there's not much you can do about it... DeOxit won;t fix it.

That has not been my experience, albeit limited, thus far. I had a pretty bad static sound within a week of using it and I eventually pulled out the pot and spent a significant amount of time figuring out how to clean it since it is sealed. I was able to pry it open ever so slightly--just enough to get some Deoxit D5 in it and followed it with F5 and it has stayed completely silent for over 2 weeks now. Prior to doing that it would come back daily. I guess time will tell.

14 minutes ago, jon96789 said:

You probably going to roll some tubes.

Understatement of the year right there. LOL! I have only had this amp for less than a month and I already have the GE NOS 6sl7 and 6sn7 (GTA's unfortunately), Tung-Sol reissue 6sn7 and 6sl7, Gold Lion KT88 and EH EL34. I don't even use the stock tubes any more because, as Steph observed, they were way too shouty for my old ears to handle. Perhaps they would get better with time but, as a wise woman once said, "ain't nobody got time for that!". I really like the Gold Lions with the GE preamp tubes as it's nicely balanced. The Tung-sols with the Gold Lions was also nice --very detailed and analytical--but almost sounded too solid state to me and the amp lost its tube charm. The EH EL34s sound sumptuous with the GE 6sn7 and the Tung-Sol 6sl7 tubes on the front end--just the right amount of detail with that lovely tube warmth. I listen to a lot of small combo jazz and chamber classical music so it really works for me. When I want to go big with some rock or orchestral music, I break out the Gold Lions and strap in. I really want to get my hands on the Sylvanias but they are too cost prohibitive. I'm sure I could do better, but I plan to not know what I am missing for a while because I can see how this tube life can get out of hand pretty quickly...

Edited March 20Mar 20 by Eduardope

32 minutes ago, Eduardope said:

It's definitely not the tubes as I have tried three different sets of preamp and power tubes with no effect on the wierd sound. Strangely, my NOS GE 6sl7 and re-issue Tung-Sol 6sl7 tubes are definitely a little microphonic based on the pencil tap test. However, even when I swap them, the microphonic behavior only occurs when I tap the right channel 6sl7 (correction to my original post- the noise is in the right channel, not the left). I thought this was a clear sign that something was wrong with the amp but when I put in the lower quality stock tubes they did not exhibit any microphonic responses to the pencil tap yet the odd whishing sound was still present when I feed a signal! I will try switching the left and right channel source cables and see what that does because I am at a loss. For reference, I am feeding a digital high-res signal via a Wiim Ultra, then through a Cambridge Audio DacMagic 200M, and ultimately into my CSS Typhon speakers. I know these speakers (rated at 87 db sensitivty and 4 ohm impedence) are pushing the limits of this amp but they seem to be okay up to about 100db before they start to noticeably clip and distort, plus the noise is only in the right channel so that doesn't seem to support a theory that its just the speakers taxing the amp. I hope I can get it figured out because, as much as I love this amp, this is way more drama that I bargained for after only 3 weeks of ownership.

You will have to look inside at the wiring to see if there are any loose

connections for that specific channel that is noisy. Use a DMM in continuity mode to specifically check tube socket connections, ground connections and also speaker output and RCA input terminal connections. Try using the different inputs at the rear of the R8 to see if there is a miss there in one specific channel.

Edited March 20Mar 20 by xlr8or

4 minutes ago, xlr8or said:

You will have to look inside at the wiring to see if there any loose

connections for that specific channel that is noisy. Use a DMM in continuity mode to specifically check tube socket connections, ground connections and also speaker output and RCA input terminal connections. Try using the different inputs at the rear of the R8 to see if there is a miss there in one specific channel.

That's great advice. I knew you guys would have some ideas that I could not come up with. I will give these suggestions a try this weekend and circle back with my results so others can reference it. Thank you!

On 17/03/2026 at 3:06 PM, jon96789 said:

How do you like the Psvanes? IMHO. they sound best with Sylvania or other vintage tubes... They sound mediocre with new production tubes.

Does the EL34PH sound even better after the 50-100 hour burn-in period? Did you notice any changes after a longer listening session? I have to admit, they sound great even after 15 hours.

Edited Saturday at 05:57 AM5 days by xinvisiblex

Actually, i did not think they sounded that good initially... It was when I paired them with the Sylvania VT229/VT231s when I noticed the great sound and that was after I put about a hundred hours on them...

The only tubes I liked better are the Matsushita 6CA7s and the Mullard EL34 XF2s. The Mullards are too expensive now, ~$2000/quad for NOS or ~$500-1000/quad for used. A lot of the Mullards on eBay are useless. The tubes are way past their useful lifespan. You can tell because the getters are pretty thin. Good Mullards have heavy getters on the top of the tubes.

At least you can buy the Matsushitas at reasonable prices but generally they are pretty worn out, at least the ones I bought. The only decent Matsushitas I have were the sealed NOS tubes. All the others measured on the weaker side. I bought about 16 Matsushitas. Four were really weak, eight was barely acceptable and the last quad was NOS so they measured strong.

Edited Saturday at 07:20 AM5 days by jon96789

25 minutes ago, jon96789 said:

Actually, i did not think they sounded that good initially... It was when I paired them with the Sylvania VT229/VT231s when I noticed the great sound and that was after I put about a hundred hours on them...

The only tubes I liked better are the Matsushita 6CA7s and the Mullard EL34 XF2s. The Mullards are too expensive now, ~$2000/quad for NOS or ~$500-1000/quad for used. A lot of the Mullards on eBay are useless. The tubes are way past their useful lifespan. You can tell because the getters are pretty thin. Good Mullards have heavy getters on the top of the tubes.

At least you can buy the Matsushitas at reasonable prices but generally they are pretty worn out, at least the ones I bought. The only decent Matsushitas I have were the sealed NOS tubes. All the others measured on the weaker side. I bought about 16 Matsushitas. Four were really weak, eight was barely acceptable and the last quad was NOS so they measured strong.

Unfortunately, I don't have any other tubes to compare them to, as the only ones I've listened to are standard Willsenton EL34s, but the difference is significant in favor of the EL34PH. The bass extends lower and is better controlled. There's better layering, and I can hear more fine detail. The sound seems to be cleaner. There's better dynamics, and the presentation is more "alive." They're more neutral compared to the Willsentons, which were too warm for my liking. The EL34PHs seem more hi-fi, but they represent an interesting blend where resolution, detail, and control intertwine with musicality and a typical tube sound. Everything is very well balanced for my taste, so thanks for the recommendation. I think we have similar tastes 😀 I just hope they will work for about 1000 hours. Now I'll be on the hunt for the VT229/231.

Edited Saturday at 07:55 AM5 days by xinvisiblex

40 minutes ago, jon96789 said:

Actually, i did not think they sounded that good initially... It was when I paired them with the Sylvania VT229/VT231s when I noticed the great sound and that was after I put about a hundred hours on them...

The only tubes I liked better are the Matsushita 6CA7s and the Mullard EL34 XF2s. The Mullards are too expensive now, ~$2000/quad for NOS or ~$500-1000/quad for used. A lot of the Mullards on eBay are useless. The tubes are way past their useful lifespan. You can tell because the getters are pretty thin. Good Mullards have heavy getters on the top of the tubes.

At least you can buy the Matsushitas at reasonable prices but generally they are pretty worn out, at least the ones I bought. The only decent Matsushitas I have were the sealed NOS tubes. All the others measured on the weaker side. I bought about 16 Matsushitas. Four were really weak, eight was barely acceptable and the last quad was NOS so they measured strong.

There are many other auction sites located around the world where really good tubes can be snapped up at bargain prices. Unfortunately eBay is no longer a desirable place to buy tubes due to significant mark up in pricing. Tubes that were worth $100 a decade ago are now priced at least 10x or more in value.

My advice is to invest in tube amp designs that utilise tubes that are uncommon and yet to be mass produced by today's manufacturers. Take the 807 for example - modify the R8 to take that and you're set for at least 5+ years or more for acquiring vintage stock that is ubiquitous.

6 hours ago, xinvisiblex said:

Unfortunately, I don't have any other tubes to compare them to, as the only ones I've listened to are standard Willsenton EL34s, but the difference is significant in favor of the EL34PH. The bass extends lower and is better controlled. There's better layering, and I can hear more fine detail. The sound seems to be cleaner. There's better dynamics, and the presentation is more "alive." They're more neutral compared to the Willsentons, which were too warm for my liking. The EL34PHs seem more hi-fi, but they represent an interesting blend where resolution, detail, and control intertwine with musicality and a typical tube sound. Everything is very well balanced for my taste, so thanks for the recommendation. I think we have similar tastes 😀 I just hope they will work for about 1000 hours. Now I'll be on the hunt for the VT229/231.

What tubes are you using in the front? You can also try the Sylvania 6SN7GT/6SL7GTs... The tall bottles with the getter on the bottom sides, aka "bad boy" types. The Sylvania 6SL7WGTs are pretty good too... These are the short bottle tubes with the getter on top with the brown micanol bases. The Sylvania 6SN7-GTA/GTB are okay but I feel the older tubes are better. The only issue I have with the older "bad boy" tubes is that they tend to be noisy. You may find that adjusting the volume control will make a scratchy noise... Spinning the knob while the amp warms up while in mute mode usually negates that.

The RCA 6SN7/6SL7 with the gray glass tubes are also pretty good. They are a tad warmer than the Sylvanias but the Sylvanias are bit more musical with a smidgen bigger soundstage. I find that the Psvane EL34PH sounds mediocre with any new production tubes.

You might want to try the Tung-Sol 6SL7 smoked glass tube with the clear tops. They are a bit more detailed but loses warmth, making the amp sound a bit more solid state like.

MELZ tubes are somewhat nice. Decent soundstage but all the tubes I bought seem to go bad or noisy.

3 hours ago, jon96789 said:

What tubes are you using in the front? You can also try the Sylvania 6SN7GT/6SL7GTs... The tall bottles with the getter on the bottom sides, aka "bad boy" types. The Sylvania 6SL7WGTs are pretty good too... These are the short bottle tubes with the getter on top with the brown micanol bases. The Sylvania 6SN7-GTA/GTB are okay but I feel the older tubes are better. The only issue I have with the older "bad boy" tubes is that they tend to be noisy. You may find that adjusting the volume control will make a scratchy noise... Spinning the knob while the amp warms up while in mute mode usually negates that.

The RCA 6SN7/6SL7 with the gray glass tubes are also pretty good. They are a tad warmer than the Sylvanias but the Sylvanias are bit more musical with a smidgen bigger soundstage. I find that the Psvane EL34PH sounds mediocre with any new production tubes.

You might want to try the Tung-Sol 6SL7 smoked glass tube with the clear tops. They are a bit more detailed but loses warmth, making the amp sound a bit more solid state like.

MELZ tubes are somewhat nice. Decent soundstage but all the tubes I bought seem to go bad or noisy.

The middle 6SN7 is a Tung-sol 6SN7GTB. 2x Melz metal base 6SL7 (6N9S) and 2x GE 6SN7 GTA. My Melz is quiet, but only has 300-350 hours of playtime. We'll see in a while.

So i bought a R8 back in December and its a almost a complete upgrade over the douk audio F5. So as of writing down my experience with the R8 it currently has the stock KT88 in them and only the front end has been changed. For the 3 6sn7 slots the two on the sides are Linlai Elite 6sn7-E and the middle is Radeon 6n7G and for the 6sl7 I've replaced those with some RCA 6C8G. I find this combo to be pretty well rounded it doesn't bring out the most detail in a song but this combo manages to still bring out micro detail effortlessly. I think I'll stick with the KT88 as I like how they sound in triode mode.

I also have a quad of JJ Kt88 ruby red glass that i wanna test this weekend since I don't see much talk about them unlike the blue glass ones

4 minutes ago, Sullivan said:

So i bought a R8 back in December and its a almost a complete upgrade over the douk audio F5. So as of writing down my experience with the R8 it currently has the stock KT88 in them and only the front end has been changed. For the 3 6sn7 slots the two on the sides are Linlai Elite 6sn7-E and the middle is Ken-Rad 6n7G and for the 6sl7 I've replaced those with some RCA 6C8G. I find this combo to be pretty well rounded it doesn't bring out the most detail in a song but this combo manages to still bring out micro detail effortlessly. I think I'll stick with the KT88 as I like how they sound in triode mode.

I also have a quad of JJ Kt88 ruby red glass that i wanna test this weekend since I don't see much talk about them unlike the blue glass ones