I completed my first power tube swap (Mullard EL34s to replace stock KT88s) thanks to your excellent instructions!! I checked the bias after 20 minutes. So far I am enjoying the new matched EL34s with a greater sound stage. I’ll be checking the bias over the next few days as you recommended👍👍
Ahhh success well done! When you first start out in tubes you're always worried - will these things explode, send out lightening bolts etc,but if you follow standard safe tube changing practices of course everything works just fine.
Hi Jim, Excellent video! I recently bought the R8 to use as a power amp and watched this video and your other one on the build quality👍👍 As a person new to tubes I feel more comfortable about tube replacement and biasing process. My only other piece of tube gear is my Luxman CL-35MkIII preamp. Time to check out your website. Thanks again!
I am new to tube amps. What is a socket saver? Why does the socket need saving? What are we saving the socket from? Do I need socket savers on my new amp? Thanks for the videos.
All good questions! First, traditionally a socket saver was used for high use sockets, such as in tube testers, basically it saved wear and tear. Also older equipment with iffy sockets would have an adapter dropped in to help save replacing the socket. These days they're used as lifters, a lot of modern amps have sunken sockets (R8, schiit preamps etc) once the tube is plugged down and in, the only way to remove it is to partly pull on the glass, and this can loosen the glass to base glue bond, ruining your tube. The lifters solve this problem by getting the tube high enough you can now remove by pulling on the plastic base. Note if you aren't into tube rolling (trying different tubes), you won't need socket saver/lifters. Just plug your tubes in and forget about them!
I was wondering what was your toughs on the Muzishare x7 tube amp from China.(I own a Marantz solid state amp) It’s seems people love the sound and the cost of the unit. Before I buy a tube amp, and after looking at this video, I was hoping to get your point of view on this matter , thanks , love your videos and they are well explained for a newbie 🍻
I took a quick look at the Muzishare x7. It looks like it only takes the KT88 power tube and the R8, can also take the EL34 giving more flexibility. Interestingly the one thing these modern tube amps don't talk about in their specifications is the tubes! Internal build quality of the R8 is superior based on what I can see from a picture. I've been inside my R8 on several occasions and am always impressed at how well layed out and built the amp is, especially when you consider that it's a budget amp. All that said, IF you can find quality affordable tubes to run, and after you check if the reviewers like the sound, the amp may be a good choice - I say MAY. Remember the tubes ARE THE AMPLIFIERS, so plan on replacing the stock Chinese tubes with something of quality. This can increase the cost of these inexpensive amps significantly, but if you want good sound it's gotta be done. Note it's not just inexpensive Chinese amps that come supplied with mediocre tubes, almost every tube amp made comes that way, even very expensive high end gear.
Yup, because you won't ever need to roll tubes into the centre socket (v5), I don't bother with a socket saver/lifter. The pair of 6sn7 (V6&9) and pair of 6sl7 (v7&8), they can be rolled as you try and find your perfect combo.
Sir. I await delivery of my very first tube amp, the Willsenton R8, and am entirely clueless about tube amps. Are there any recommended videos (of yours or others), or readings (Tube Amps for Dummies) that you would recommend that canvass the topic of tube amps? Thanking you in advance for any advice you are in a position to offer.
Well we do a Tube Lab every Friday and it covers subjects related to tubes and audio, so subscribe and join the Fun. We also have two years of back episodes, so feel free to go back in time. The very first episodes (Episode 1,2,3...) were meant for total beginners, so I would start with those.
Caution! Just swapping one good resistor for another good resistor may not necessarily improve the sound. Some of what she does looks like a good idea, but other things I'm not convinced. Remember the r8 in stock form with quality vintage tubes already sounds great. And watch the last episode First she got a bunch of resistor values wrong.
@@tubelab194 Yes, true. One good thing, though, was upping the voltage on the two electrolytic caps from 450 VDC to be able to handle the surge. Also, changing out the choke.
@@danielthomas3057 we've used our r8 commercially (it's a great test amp for quads of power tubes) for over 2 years and other than some minor problems due to the heavy use, it's worked perfectly and still sounds amazing - completely stock.
You probably have the rear bias switch (beside iec power cord inlet) in the wrong position. With the amp off, set the switch up for EL34/KT77 and down for KT88/6550. Now rebias the amp. Other possibilities include using the wrong type of power tube or defective power tubes, but I'm pretty sure it's the rear switch.
I can see you use the socket savers and only certain tubes is there a reason why you did not use them for the power tubes as well as the center rectifier tube just a question I’m new to this thank you
The socket savers are being used as lifters, the most common use by far for them these days. In the R8 the front preamp tubes don't have much finger room in the top plate hole to grip the base for removal (especially the standard shallow base), but the rear power tubes have huge cutouts to aid in ventilation, so you can grip the entire base for installation and removal. Basically if you push or remove your tubes by the glass instead of the base you will break the glue bond between base and glass, wrecking the tube. Some can be saved by a careful glue job - but who wants that if you can avoid it easily! Back in the Day this was never a problem because all tubes were surface mounted, it's only recently that tube amp manufacturers started using PCB's with sunken tubes. In my Kit Amp designs I avoid this poor design, even when I use a PCB, by carefully setting the boards at the right height so that the tube socket sits flush.
Modern gear generally doesn't include tone controls, the thinking being they will degrade the signal path and they're mostly not needed anymore. If you have quality source material and a good well balanced system you shouldn't really need to adjust the EQ. Back in the day, when I was a wanna be audiophile (1970's), many people ran graphic equalizers, our equipment just wasn't that great sounding - in particular our speakers sucked. But today if you play digital files, you can easily bring up a graphic equalizer in your software. If you play vinyl, then you are limited to adding a physical unit in the signal path. Simply upgrading your existing system may completely eliminate your need to apply EQ.
Great video Jim and demo on bias on the output tubes and the test for microphonics just great !!!! I have a pair of military 6sl7 dated I believe 1948 or 44.....Im enjoying the 6sn7 and 6sl7 tubes I bought from you....love the Marconi 6sn7....nice !!!!....Ed in New York 😎☕🗽🏙🎶🎵🎶
Great to hear from you Ed! Yes 1940's mil spec tubes rock! It's one of the main reasons I designed the Yuri monoblock Kit Amp - to take advantage of the much neglected cv6 / 7193 wwII radar tube (derived from 6J5), which as you might suspect, sound amazing! Dead quiet, zero microphonics and great little driver tubes for a small amp like the Yuri (2wrms).
Hi Jim, Love your Video! I was looking at the Willsenton R8 or the Cary CAD-120S MKII VACUUM TUBE POWER AMPLIFIER. I herd the Cary at a NY audio show with some Kef R900 about 2017 and it was amazing! Your thoughts vs Price Performance ect. The Cary is 4 g's. Expensive! Thank you.
I've only ever heard one cary amp and it was ok. I've had the R8 in for almost 2 years and for a larger 4 power tube (class AB) amp it has been great. Solid quality construction and i paid about $1,200 with the cheaper set of EL34 tubes (garbage). At that price it's a bargain! But remember with any tube amp the quality of the tubes makes a huge difference. Why? The tubes ARE the amplifiers! And unfortunately manufacturers - even good ones, often ship out amps with crap tubes. So plan on spending a significant amount to retube any amp you buy.
Hi, thank you for your excelent lessons.I learned a lot about tubes by your videos. I have a question for you.I own Willsenton R8 and a quad of 6p3s-e wich sounds wonderfull.I use them with the bias in the middle.I've read that they sound best at 500 mv but I don't know wich are the values in volts of the vu meter at the first line, in the middle and at third line.Maybe you can help me. Kind regards, Romeo
The 6P3S-E is not a good tube to substitute in the R8, it is basically a Soviet 6L6. Yes it will work sorta electrically, but not optimally. A lot more is involved when trying completely different tubes than just setting the bias. The tubes that will work well are the EL34, KT77, 6550 and KT88.
How do the socket savers work? Do they protect the female tube socket mounted on the amp? Or the male pins on the valve socket? Either way you still need to insert pins into the valve socket on the amp. The R8 is made in China right? Probably the best value valve amp that delivers quality performance in the world. Worth the $270 shipping costs I paid. (I have never forked out that much money for shipping and handling in my life. The highest amount i paid for shipping costs up to that point was about $25)
The socket savers are being used as lifters. The front preamp tubes are sunk below the chassis and there isn't enough room to get them in and out without grasping the glass, which is a very bad idea with vintage tubes as it is easy to break the old glue bond and end up with loose bases. Tubes with the shallow bases are the hardest to remove safely. The socket savers work perfectly at getting the tube up a wee bit.
Nope, on the left is my Yuri Monoblock Kit Amp and on the right is probably my Universal 6or12SN7 Kit Preamp. Have a look in the store www.valvesnmore.com if you're interested. Note in the shot are the pre-production builds.
I heard some lower hum or electrical noise coming from my SET 300B amp , not exactly sure if the noise is coming out from the 300B tube/5687 ,or is it because of biasing problem or failing tube ..noise only on one SET not the other Set amp.The 300B tubes has been 8 years old .Thanks for any opinion /help (wyetech claim to has auto bias)
If you want to know if it is a tube issue, just swap tubes, if the noise moved then it is the tube. If that doesn't catch it, check and see if ALL your power cords go to the same quality breaker bar.
I enjoy your video a lot and have a question to seek your advise. Recently I bought the wilsenton r800i 805 model, the rectifier tube is a 274b, if I have Ratheon 5U4G NOS, is it advisable to replace the 274b stock tube with the 5U4G ? Appreciate your advice ! Thanks
Your 274b is a Shuguang reissue of the famous tube made by Western Electric. And even my large rectifier cross reference doesn't give a direct equivalent. So I would suggest sticking with the stock tube. Other close rectifiers may well work just fine, But the circuit was designed for this particular tube and switching to a close compatible will at the least change the B+, probably nothing to worry about, but given how inexpensive the Shuguang probably is, I'd stay with it.
Have you had experience with the PSVANE tubes that can come with the r8 as a more expensive option to the standard Willsenton ones. I believe they may be a recent copy of philips types that are no longer in production but possibly are Chinese made, these are the ones I chose and sound nice but I have no clue on quality long term. Mine are the PSVANE EL34. Cheers
No I haven't tried the PSvane tubes, my specialty is vintage and frankly whenever I do come across a Chinese made tube I'm disappointed with the build quality, they just don't last. Now I'm sure the higher end tubes are an improvement, but when you look at the cost, wouldn't it make more sense to go vintage? I'm biased of course (get it biased haha)! I love the sound of vintage tubes!
@@tubelab194 I am biased as well to vintage Sansui ( non tube) but the r8 drew me to the other side. Hmmm vintage valves (tubes), could be a whole new ball game for me. Cheers for the advise
The tubes in the video are RFT EL34's, and along with the KT77, KT88 and 6550, are all tubes the R8 is designed to use. The 6L6 is a completely different tube and even if it can plug in safely electrically, it will sound aweful.
@@tubelab194 I have many guitar amplifiers and at the beginning we were using NOS tubes and found them to be less reliable but I have a nice stock of old tubes that I’m not using a bit more than happy to send them to you free of charge… email and I will send u pic of what I have, I’m sure u will find good use for them
Anyone here got interference on the left or right channel on there R8 amplifier, mine has produced a crackerling noise on the right channel. I have unplugged everything form the Amplifier and there is still interference happening? These amps do sound great, but I am not to sure about the build quality.
Build quality is excellent. A cracking noise on only one channel is almost always a tube issue and probably the 6SL7 v7&8 (high gain 70x voltage preamp) To trouble shoot, first unseat all the preamp tubes, clean the pins if dirty and reseat (in same order). Test. If still noisy, swap both v7&8, test, if the noise moved then you have a bad tube and now you know which one. Sub a spare and test. If quiet you have confirmation. Note I've had v5 get noisy and as a result recommend the rock solid Russian Foton 6sn7gtb, which I put even in my premium R8 tube sets. Also any and all tubes can get noisy - it's a tube thing and a pain, which is why I always recommend having spare tubes on hand and even a spare set. Lastly if these are the stock Chinese tubes, think of them as dollar store quality - disposable! Luckily vintage tubes were manufactured for many critical systems, and as a result are of superior construction and durability.
@@PINKFL0YD-s2h most tube amps can safely idle without a load with no (zero) input signal. What you don't want to do is apply a large signal to the input without a load on the output. But like everything, I'm sure there are exceptions! And your advice is a good precaution.
Jim's Videos are The BEST!!! With his help I just received a Set of The EL German Gold!!!
I completed my first power tube swap (Mullard EL34s to replace stock KT88s) thanks to your excellent instructions!! I checked the bias after 20 minutes. So far I am enjoying the new matched EL34s with a greater sound stage. I’ll be checking the bias over the next few days as you recommended👍👍
Ahhh success well done! When you first start out in tubes you're always worried - will these things explode, send out lightening bolts etc,but if you follow standard safe tube changing practices of course everything works just fine.
@@tubelab194 - Hey Jim, I just put an order to you for two Melz 6sl7 tubes for my Willsenton R8. Best 2 U
Hi Jim,
Excellent video! I recently bought the R8 to use as a power amp and watched this video and your other one on the build quality👍👍 As a person new to tubes I feel more comfortable about tube replacement and biasing process.
My only other piece of tube gear is my Luxman CL-35MkIII preamp.
Time to check out your website.
Thanks again!
The best videos on tube rolling, etc.
I am new to tube amps. What is a socket saver? Why does the socket need saving? What are we saving the socket from? Do I need socket savers on my new amp? Thanks for the videos.
All good questions!
First, traditionally a socket saver was used for high use sockets, such as in tube testers, basically it saved wear and tear. Also older equipment with iffy sockets would have an adapter dropped in to help save replacing the socket.
These days they're used as lifters, a lot of modern amps have sunken sockets (R8, schiit preamps etc) once the tube is plugged down and in, the only way to remove it is to partly pull on the glass, and this can loosen the glass to base glue bond, ruining your tube. The lifters solve this problem by getting the tube high enough you can now remove by pulling on the plastic base.
Note if you aren't into tube rolling (trying different tubes), you won't need socket saver/lifters. Just plug your tubes in and forget about them!
@@tubelab194 thank you for the great explanation.
I was wondering what was your toughs on the Muzishare x7 tube amp from China.(I own a Marantz solid state amp)
It’s seems people love the sound and the cost of the unit. Before I buy a tube amp, and after looking at this video, I was hoping to get your point of view on this matter , thanks , love your videos and they are well explained for a newbie 🍻
I took a quick look at the Muzishare x7.
It looks like it only takes the KT88 power tube and the R8, can also take the EL34 giving more flexibility. Interestingly the one thing these modern tube amps don't talk about in their specifications is the tubes!
Internal build quality of the R8 is superior based on what I can see from a picture. I've been inside my R8 on several occasions and am always impressed at how well layed out and built the amp is, especially when you consider that it's a budget amp.
All that said, IF you can find quality affordable tubes to run, and after you check if the reviewers like the sound, the amp may be a good choice - I say MAY.
Remember the tubes ARE THE AMPLIFIERS, so plan on replacing the stock Chinese tubes with something of quality. This can increase the cost of these inexpensive amps significantly, but if you want good sound it's gotta be done. Note it's not just inexpensive Chinese amps that come supplied with mediocre tubes, almost every tube amp made comes that way, even very expensive high end gear.
@@tubelab194 big thanks for these infos, I agree 100%, 🍻
Hi Jim,
Regarding the Socket Savers for use with the R8, would I use the for all 5 preamp tubes? I noticed in the video you had only four.
Yup, because you won't ever need to roll tubes into the centre socket (v5), I don't bother with a socket saver/lifter. The pair of 6sn7 (V6&9) and pair of 6sl7 (v7&8), they can be rolled as you try and find your perfect combo.
@@tubelab194 - thanks Jim👍👍
Sir. I await delivery of my very first tube amp, the Willsenton R8, and am entirely clueless about tube amps. Are there any recommended videos (of yours or others), or readings (Tube Amps for Dummies) that you would recommend that canvass the topic of tube amps? Thanking you in advance for any advice you are in a position to offer.
Well we do a Tube Lab every Friday and it covers subjects related to tubes and audio, so subscribe and join the Fun. We also have two years of back episodes, so feel free to go back in time. The very first episodes (Episode 1,2,3...) were meant for total beginners, so I would start with those.
@@tubelab194 Thanks very much. Very gracious of you.
Skunkie designs on you tube has some videos up on some important mods to perform on a Williston R8.
Caution! Just swapping one good resistor for another good resistor may not necessarily improve the sound. Some of what she does looks like a good idea, but other things I'm not convinced. Remember the r8 in stock form with quality vintage tubes already sounds great. And watch the last episode First she got a bunch of resistor values wrong.
@@tubelab194 Yes, true. One good thing, though, was upping the voltage on the two electrolytic caps from 450 VDC to be able to handle the surge. Also, changing out the choke.
@@danielthomas3057 we've used our r8 commercially (it's a great test amp for quads of power tubes) for over 2 years and other than some minor problems due to the heavy use, it's worked perfectly and still sounds amazing - completely stock.
Hi, the bias for the V1 and V4 on my R8, could not be adjusted and the needle is on the far right. May i seek your opinion on this please ? Thanks.
You probably have the rear bias switch (beside iec power cord inlet) in the wrong position. With the amp off, set the switch up for EL34/KT77 and down for KT88/6550. Now rebias the amp. Other possibilities include using the wrong type of power tube or defective power tubes, but I'm pretty sure it's the rear switch.
@@tubelab194 How do i fix this, please ?
@@alfa3421 did you read my instructions? If they didn't help, I need more information than "how do I fix this"
I can see you use the socket savers and only certain tubes is there a reason why you did not use them for the power tubes as well as the center rectifier tube just a question I’m new to this thank you
The socket savers are being used as lifters, the most common use by far for them these days. In the R8 the front preamp tubes don't have much finger room in the top plate hole to grip the base for removal (especially the standard shallow base), but the rear power tubes have huge cutouts to aid in ventilation, so you can grip the entire base for installation and removal. Basically if you push or remove your tubes by the glass instead of the base you will break the glue bond between base and glass, wrecking the tube. Some can be saved by a careful glue job - but who wants that if you can avoid it easily! Back in the Day this was never a problem because all tubes were surface mounted, it's only recently that tube amp manufacturers started using PCB's with sunken tubes. In my Kit Amp designs I avoid this poor design, even when I use a PCB, by carefully setting the boards at the right height so that the tube socket sits flush.
Why don't these amps have tone controls? What's the downside? It's a shame, is it not? I adjust my tone controls on each song.
Modern gear generally doesn't include tone controls, the thinking being they will degrade the signal path and they're mostly not needed anymore. If you have quality source material and a good well balanced system you shouldn't really need to adjust the EQ. Back in the day, when I was a wanna be audiophile (1970's), many people ran graphic equalizers, our equipment just wasn't that great sounding - in particular our speakers sucked. But today if you play digital files, you can easily bring up a graphic equalizer in your software. If you play vinyl, then you are limited to adding a physical unit in the signal path. Simply upgrading your existing system may completely eliminate your need to apply EQ.
@@tubelab194 Thanks much for that clear and informative explanation .
Great video Jim and demo on bias on the output tubes and the test for microphonics just great !!!! I have a pair of military 6sl7 dated I believe 1948 or 44.....Im enjoying the 6sn7 and 6sl7 tubes I bought from you....love the Marconi 6sn7....nice !!!!....Ed in New York 😎☕🗽🏙🎶🎵🎶
Great to hear from you Ed! Yes 1940's mil spec tubes rock! It's one of the main reasons I designed the Yuri monoblock Kit Amp - to take advantage of the much neglected cv6 / 7193 wwII radar tube (derived from 6J5), which as you might suspect, sound amazing! Dead quiet, zero microphonics and great little driver tubes for a small amp like the Yuri (2wrms).
Hi Jim, Love your Video! I was looking at the Willsenton R8 or the Cary CAD-120S MKII VACUUM TUBE POWER AMPLIFIER. I herd the Cary at a NY audio show with some Kef R900 about 2017 and it was amazing! Your thoughts vs Price Performance ect. The Cary is 4 g's. Expensive! Thank you.
I've only ever heard one cary amp and it was ok. I've had the R8 in for almost 2 years and for a larger 4 power tube (class AB) amp it has been great. Solid quality construction and i paid about $1,200 with the cheaper set of EL34 tubes (garbage). At that price it's a bargain! But remember with any tube amp the quality of the tubes makes a huge difference. Why? The tubes ARE the amplifiers! And unfortunately manufacturers - even good ones, often ship out amps with crap tubes. So plan on spending a significant amount to retube any amp you buy.
Hi, thank you for your excelent lessons.I learned a lot about tubes by your videos.
I have a question for you.I own Willsenton R8 and a quad of 6p3s-e wich sounds wonderfull.I use them with the bias in the middle.I've read that they sound best at 500 mv but I don't know wich are the values in volts of the vu meter at the first line, in the middle and at third line.Maybe you can help me.
Kind regards, Romeo
The 6P3S-E is not a good tube to substitute in the R8, it is basically a Soviet 6L6. Yes it will work sorta electrically, but not optimally. A lot more is involved when trying completely different tubes than just setting the bias. The tubes that will work well are the EL34, KT77, 6550 and KT88.
@@tubelab194 Thanks o lot for your answer
How do the socket savers work? Do they protect the female tube socket mounted on the amp? Or the male pins on the valve socket? Either way you still need to insert pins into the valve socket on the amp.
The R8 is made in China right?
Probably the best value valve amp that delivers quality performance in the world.
Worth the $270 shipping costs I paid. (I have never forked out that much money for shipping and handling in my life. The highest amount i paid for shipping costs up to that point was about $25)
The socket savers are being used as lifters. The front preamp tubes are sunk below the chassis and there isn't enough room to get them in and out without grasping the glass, which is a very bad idea with vintage tubes as it is easy to break the old glue bond and end up with loose bases. Tubes with the shallow bases are the hardest to remove safely. The socket savers work perfectly at getting the tube up a wee bit.
Is that some DecWare products next to the Willsenton R8?
Nope, on the left is my Yuri Monoblock Kit Amp and on the right is probably my Universal 6or12SN7 Kit Preamp. Have a look in the store www.valvesnmore.com if you're interested. Note in the shot are the pre-production builds.
I heard some lower hum or electrical noise coming from my SET 300B amp , not exactly sure if the noise is coming out from the 300B tube/5687 ,or is it because of biasing problem or failing tube ..noise only on one SET not the other Set amp.The 300B tubes has been 8 years old .Thanks for any opinion /help (wyetech claim to has auto bias)
If you want to know if it is a tube issue, just swap tubes, if the noise moved then it is the tube. If that doesn't catch it, check and see if ALL your power cords go to the same quality breaker bar.
I enjoy your video a lot and have a question to seek your advise. Recently I bought the wilsenton r800i 805 model, the rectifier tube is a 274b, if I have Ratheon 5U4G NOS, is it advisable to replace the 274b stock tube with the 5U4G ? Appreciate your advice ! Thanks
Your 274b is a Shuguang reissue of the famous tube made by Western Electric. And even my large rectifier cross reference doesn't give a direct equivalent. So I would suggest sticking with the stock tube. Other close rectifiers may well work just fine, But the circuit was designed for this particular tube and switching to a close compatible will at the least change the B+, probably nothing to worry about, but given how inexpensive the Shuguang probably is, I'd stay with it.
@@tubelab194 Thank you for your great advise !Appreciate it very much !
Have you had experience with the PSVANE tubes that can come with the r8 as a more expensive option to the standard Willsenton ones. I believe they may be a recent copy of philips types that are no longer in production but possibly are Chinese made, these are the ones I chose and sound nice but I have no clue on quality long term. Mine are the PSVANE EL34. Cheers
No I haven't tried the PSvane tubes, my specialty is vintage and frankly whenever I do come across a Chinese made tube I'm disappointed with the build quality, they just don't last. Now I'm sure the higher end tubes are an improvement, but when you look at the cost, wouldn't it make more sense to go vintage? I'm biased of course (get it biased haha)! I love the sound of vintage tubes!
@@tubelab194 I am biased as well to vintage Sansui ( non tube) but the r8 drew me to the other side. Hmmm vintage valves (tubes), could be a whole new ball game for me. Cheers for the advise
Can you use any of those 6L6 in the R8?
The tubes in the video are RFT EL34's, and along with the KT77, KT88 and 6550, are all tubes the R8 is designed to use. The 6L6 is a completely different tube and even if it can plug in safely electrically, it will sound aweful.
@@tubelab194 I have many guitar amplifiers and at the beginning we were using NOS tubes and found them to be less reliable but I have a nice stock of old tubes that I’m not using a bit more than happy to send them to you free of charge… email and I will send u pic of what I have, I’m sure u will find good use for them
@@stevenpaul3886 sounds good! Email: valvesnmore@protonmail.com
Anyone here got interference on the left or right channel on there R8 amplifier, mine has produced a crackerling noise on the right channel. I have unplugged everything form the Amplifier and there is still interference happening? These amps do sound great, but I am not to sure about the build quality.
Build quality is excellent. A cracking noise on only one channel is almost always a tube issue and probably the 6SL7 v7&8 (high gain 70x voltage preamp) To trouble shoot, first unseat all the preamp tubes, clean the pins if dirty and reseat (in same order). Test. If still noisy, swap both v7&8, test, if the noise moved then you have a bad tube and now you know which one. Sub a spare and test. If quiet you have confirmation. Note I've had v5 get noisy and as a result recommend the rock solid Russian Foton 6sn7gtb, which I put even in my premium R8 tube sets. Also any and all tubes can get noisy - it's a tube thing and a pain, which is why I always recommend having spare tubes on hand and even a spare set. Lastly if these are the stock Chinese tubes, think of them as dollar store quality - disposable! Luckily vintage tubes were manufactured for many critical systems, and as a result are of superior construction and durability.
You should tell people never switch them on without a load..
@@PINKFL0YD-s2h most tube amps can safely idle without a load with no (zero) input signal. What you don't want to do is apply a large signal to the input without a load on the output. But like everything, I'm sure there are exceptions! And your advice is a good precaution.