This is the final schematic, cathode grounded through LED + 200ohm resistor. www.skunkiedesigns.com/boyuurange-a50-mods?pgid=ktb1lluh-4ad9aad6-de55-4454-b972-3f9bdc405f0b
I am the owner of the MK III version of this amp. I am not sure if the one in your video series is a MK III or an earlier version, since you never (to the best of my knowledge) clarified this issue. I have not heard, or had an earlier version in my system, so I cannot comment on whether there is a noticeable difference between the versions. So I guess what I am going to say below may not completely be relevant if in fact you were using an earlier version. I have had this amp for over a year, and find it one of the most enjoyable amps I have had in my system. The only change I made to the stock amp was to replace the 6SN7 tubes with some vintage tubes. There was a slight but noticeable change, which I felt was an improvement. Others may prefer the sound of the original tubes. I have been an audio hobbyist for many years and have heard and used a very wide variety of gear. So, for me to keep this amp in my system for this long is rather unusual, and speaks to the satisfaction I derive from it. In addition, I have noted that several other You Tube channels (Thomas and Stereo, A British Audiophile, The Audiophiliac, etc.) have found this amp to be quite enjoyable, an audio bargain, and in a league of its own. And I believe that the gentlemen of these channels have had a great deal of experience in reviewing gear, and base there judgements on comparison with a lot of amps. I am therefore quite confused by your evaluation of the functioning of this amp to be sub-par (a general impression I get from your various comments about its design and sound). I, and others that review gear for a living find the opposite. I don't know what to make of this. I have only a vague idea of what you use to evaluate the sound of an amp. In this case of the A-50, you only, I think, describe your not liking the amp because of your impressions of the bass output, calling it 'bad' or 'weak'. I don't recall that you judged or evaluated the mid and upper range of the sound. And to the best of my knowledge you said little about the sound staging presented by this amp, or its handling of transients, its overall timbre, its naturalness (or not) , etc., etc., the usual "universals" or commonly held categories of amp sound we tend to use to decide if we like a piece of gear or not. So I am at a loss as to how to benefit from your information presented in the case of the A-50. Perhaps, if you have time, you could respond to this note and help me out. I thank you in advance for any consideration of these comments. Regards, Rich
It's the latest MKII version. I can't help what other reviewers say nor do I understand why they would rave about a product this defective, and I also can't help this amp fails miserably to produce anywhere near it's advertised specs. Another friend of mine on audiokarma tested a MKII out of the box and got the same results I did. Numbers don't lie but if you are happy with your amp, great. I know better and so do many other folks who have listened to this thing. And I have to LOL at the "original tubes" comment, those things are horrible! Even the original 300B tubes it comes with are bad. I just have to assume here that these people have just never listened to a good tube amp before or were being paid to promote it. I'm going to be nice and assume the former. Multiple people have done my mods to this amp and universally say things like "wow, I now see how bad this thing really was." It's like taking a blanket out from in front of your speakers. And if an amp has over 10% distortion as it goes into heavy clipping, I'm not sure how folks evaluate "sound staging" and "handling of transients"? All I heard was weak bass, muddy midrange and distorted highs from this amp as it came out of the box. I agree this amp is in "A league of it's own" but not in the same way you are thinking.
@@SkunkieDesignsElectronics The latest version is the Mk III (3) not II (2). And the Mk III appeared over a year ago. So perhaps there is significant differences between the II and III. Again, I ask you to please define or clarify the ways that you judge an amp's sound. You have offered a few additional terms in your reply that I had not heard in the videos. "...weak bass...": does this mean low volume, not going to low cps, what? Please clarify. And "...muddy mid-range...": does this mean many overtones, distorted signal, what. Please elaborate. And I still see no information in your reply that would indicate the kind of sound that you want from an amp: e.g. clear, accurate, articulate sound with a mid-range/treble/midbass forward, or warm balanced presentation with a less forward sound, etc. Please elaborate so that I can have some sense of what you hear and like. Then we will be using a common vocabulary. If you say the sound "stinks" I do not get much information. And, by the way, the others nearly always evaluate things such as transients and soundstage. I suppose there is no particular measuring procedure for these terms, but they do go on to describe the unit's performance in these areas using words that have definitions that most of us know, so that we can get a pretty good idea of what they heard. They're evaluations are subjective for sure, and convey more information than "stinks" does (that is subjective too, unless you have a multimeter that reveals odor). I would suggest you re-consider your assumption that the reviewers I mentioned have "never heard a good tube amp". They have ample experience, both owning, and reviewing, a great variety of good, industry leading tube amps. If your testing, etc., was of the Mk II, then I could see how there could be differences in your view and theirs. They all reviewed the Mk III. Putting the possible differences between the II and III, I still find it hard the differences heard by you and them would be as great. Thanks for your response to my initial post.
@@richardcarroll4495 Mine was the "latest version" as sold by Amazon a few months ago and after some reviewing: the schematic supplied has "MKIII" written on it, the parts inside match this schematic, so I assume it must be that version. They also state the MKIII has "an inductance transformer" which means they added a choke to the power supply, which my version had. I'll admit I'm not an expert on Boyuuange A50 revision history.. The "weak bass" can not only be heard (or not heard because it's just not there), but is easily seen in the frequency response curves as at 100hz the frequency rolls off. Likewise the "muddy midrange" is due to the measurable distortion which does exactly what the term says, it distorts the signal into something different, smearing any details that were previously there. It's clearly audible listening to this and a "good" tube amp. If all you listen to is alto jazz type music with little to no bass track, it probably sounds OK. And if someone A-B listens to this and a SS amp, I could see liking the tube amp sound better, even as distorted as this one is. Just as you have a right to like the way this amp sounds, I have to right to say I think it sounds like crap, especially comparing it A-B to the other 300B amp (and other tube amps) I own, and to this amp after the mods have been done. The difference is not subtle or nuanced. I want to clarify too, even after the mods, the low quality output transformers hold this amp back from what it could be with good iron. As far as these other reviewers, again I can only speculate why they would give an amp, that is this defectively engineered and pumping this much distortion, rave reviews. I want to shy away from claiming they were paid to give these rave reviews, but that does happen. Did they A-B listen to the A50 back to back with another know good tube amp? It's still baffling to me anyone would think this is good if they did that. The numbers don't lie and there is no such thing as "alternate facts" here. This is not what the manufacturer advertises it as: a 7.6W @ 1% distortion amplifier. It doesn't come close to meeting even 1/2 of those. All that said, it's clear you just want to argue here, make excuses for and defend your purchase choice. Very common for people to get their ego tied into their ownership of material things, clouding their perceptions, and I've learned people doing this are rarely rational or interested in actually learning anything. My advice is to ignore my videos, go watch the ones that match your beliefs, defend your purchase choice and enjoy your amp. Have a nice day!
I had a Boyuurange / Reisong A50 300B came with a bad 300b. So I never really got to listen to it.I asked Amazon to send new tubes and they said the only thing I could do was return it and get another one. I said never mind give me my money back.I figured if I am having trouble out of the box not a good sign.
I'm going to purchase this amp for vinyl listening (I've not decided on a preamp yet, but am open for legitimate suggestions that would go with this amp...), and I like the mods, but I'm wondering if I only replace the tubes, will that make a worthwhile difference. I am out of my depth on modifying electronics, and don't want to ruin a "good" amp. I plan on running it into a 75W / 95dB set of Klipsch floor speakers.
@@SkunkieDesignsElectronics Thanks. It gives me something to think about... Watching the videos (I've not seen them all yet), I feel confident I could do the jumper wire and the one you ran to ground, at least, but for sure I was going to replace the driver tubes anyway. Doing that, I'll hear how it sounds, and if it's not what I need, then your videos and the soldering iron it is! Again, thanks.
At the end of the day, it didn't make sense as A) there really isn't room on this chassis for larger ones + the chrome plated stainless is so hard to deal with and B) spending $500+ on transformers for a $1000 amp just doesn't make a lot of sense to get some extra bass out of it. A powered sub will do that better and is cheaper.
I am a journetman machinist of more than 20 years. On drilling stainless sheetmetal I have a few suggestions. First off stainless sheetmetal becomes work hardened when it is rolled. It is NASTY to drill. Esp with small diameter drills. First off if you have access to a drill press USE IT. Take the extra time and set it up right. Clamp everything you can. Another thing is WATCH YOUR SPINDLE SPEED. You need to run the drills much slower than you think you should, Look at your chips. If they are dark brown or black ( SS sheetmetal makes these nasty looking chips. but watch the color) SLOW IT DOWN. Slow it down if they are blue as well but you rarely get blue color drilling this crap but blue is too hot as well. DRILL SELECTION.. If you have a drill press buy solid carbide drills. They are not cheap but if you have several holes to drill it will make it childs play compared to HSS drills. If you do not have a grill press then buy COBALT drills. You will break carbide in a hand drill no matter how careful you think you are. Start off slow and let the drill cut. Do not crowd it. Now you may get to a point where the drill starts to squeek. This means you have seriously work hardened the metal. My trick for this require 2 drills the same size or at least close. Also you need a pedastal grinder to grinad the tip of the drill. What you do is sharp one drill with a narromer included angle and the other a flatter angle.. Not extreme just 10 degrees maximum. You then use one drill until it squeeks. then switch drills until it squeeks or breaks thru. You go back and forth keeping the drills sharp in between until you are thru. This lates you focus the cutting force in a smaller area. Take your time it works, Now lastly cutting fluid is your friend. If you can find it (as its not made anymore) anything with 1.1.1. thriclorethylene in it BUY IT. That is the best stuff for this job. Just dont bathe in it. Somethin about causing cancer. Next best is MOLY cutting oil. Messy but it rocks. If neither of these then but some super safe and eco friendly crap from McMaster carr. Tap Magic is best.. If you take only one thing away from this WATCH YOUR SPEED... Hope this helps.
Cool tip about the safety pin.. Thanks!
You bet!
great video like watching others build valve gear blue nail polish blue resistors great match
Haha, Thank you!
So did you try with some more expensive caps? I just ordered 0.33uf Mundorf 1400VDC caps for my amp.
I've tried others, I like the sound of the alum/oil ones.
My respect! It is great Chanel.
Thanks!
I'm only partially through the video but your schematic didn't have led in series to ground. Am I missing something?
This is the final schematic, cathode grounded through LED + 200ohm resistor.
www.skunkiedesigns.com/boyuurange-a50-mods?pgid=ktb1lluh-4ad9aad6-de55-4454-b972-3f9bdc405f0b
I am the owner of the MK III version of this amp. I am not sure if the one in your video series is a MK III or an earlier version, since you never (to the best of my knowledge) clarified this issue. I have not heard, or had an earlier version in my system, so I cannot comment on whether there is a noticeable difference between the versions.
So I guess what I am going to say below may not completely be relevant if in fact you were using an earlier version.
I have had this amp for over a year, and find it one of the most enjoyable amps I have had in my system. The only change I made to the stock amp was to replace the 6SN7 tubes with some vintage tubes. There was a slight but noticeable change, which I felt was an improvement. Others may prefer the sound of the original tubes.
I have been an audio hobbyist for many years and have heard and used a very wide variety of gear. So, for me to keep this amp in my system for this long is rather unusual, and speaks to the satisfaction I derive from it. In addition, I have noted that several other You Tube channels (Thomas and Stereo, A British Audiophile, The Audiophiliac, etc.) have found this amp to be quite enjoyable, an audio bargain, and in a league of its own. And I believe that the gentlemen of these channels have had a great deal of experience in reviewing gear, and base there judgements on comparison with a lot of amps.
I am therefore quite confused by your evaluation of the functioning of this amp to be sub-par (a general impression I get from your various comments about its design and sound). I, and others that review gear for a living find the opposite. I don't know what to make of this.
I have only a vague idea of what you use to evaluate the sound of an amp. In this case of the A-50, you only, I think, describe your not liking the amp because of your impressions of the bass output, calling it 'bad' or 'weak'. I don't recall that you judged or evaluated the mid and upper range of the sound. And to the best of my knowledge you said little about the sound staging presented by this amp, or its handling of transients, its overall timbre, its naturalness (or not) , etc., etc., the usual "universals" or commonly held categories of amp sound we tend to use to decide if we like a piece of gear or not.
So I am at a loss as to how to benefit from your information presented in the case of the A-50. Perhaps, if you have time, you could respond to this note and help me out.
I thank you in advance for any consideration of these comments.
Regards, Rich
It's the latest MKII version. I can't help what other reviewers say nor do I understand why they would rave about a product this defective, and I also can't help this amp fails miserably to produce anywhere near it's advertised specs. Another friend of mine on audiokarma tested a MKII out of the box and got the same results I did. Numbers don't lie but if you are happy with your amp, great. I know better and so do many other folks who have listened to this thing. And I have to LOL at the "original tubes" comment, those things are horrible! Even the original 300B tubes it comes with are bad. I just have to assume here that these people have just never listened to a good tube amp before or were being paid to promote it. I'm going to be nice and assume the former.
Multiple people have done my mods to this amp and universally say things like "wow, I now see how bad this thing really was." It's like taking a blanket out from in front of your speakers. And if an amp has over 10% distortion as it goes into heavy clipping, I'm not sure how folks evaluate "sound staging" and "handling of transients"? All I heard was weak bass, muddy midrange and distorted highs from this amp as it came out of the box. I agree this amp is in "A league of it's own" but not in the same way you are thinking.
@@SkunkieDesignsElectronics The latest version is the Mk III (3) not II (2). And the Mk III appeared over a year ago. So perhaps there is significant differences between the II and III.
Again, I ask you to please define or clarify the ways that you judge an amp's sound. You have offered a few additional terms in your reply that I had not heard in the videos. "...weak bass...": does this mean low volume, not going to low cps, what? Please clarify. And "...muddy mid-range...": does this mean many overtones, distorted signal, what. Please elaborate. And I still see no information in your reply that would indicate the kind of sound that you want from an amp: e.g. clear, accurate, articulate sound with a mid-range/treble/midbass forward, or warm balanced presentation with a less forward sound, etc. Please elaborate so that I can have some sense of what you hear and like. Then we will be using a common vocabulary. If you say the sound "stinks" I do not get much information.
And, by the way, the others nearly always evaluate things such as transients and soundstage. I suppose there is no particular measuring procedure for these terms, but they do go on to describe the unit's performance in these areas using words that have definitions that most of us know, so that we can get a pretty good idea of what they heard. They're evaluations are subjective for sure, and convey more information than "stinks" does (that is subjective too, unless you have a multimeter that reveals odor).
I would suggest you re-consider your assumption that the reviewers I mentioned have "never heard a good tube amp". They have ample experience, both owning, and reviewing, a great variety of good, industry leading tube amps. If your testing, etc., was of the Mk II, then I could see how there could be differences in your view and theirs. They all reviewed the Mk III. Putting the possible differences between the II and III, I still find it hard the differences heard by you and them would be as great.
Thanks for your response to my initial post.
@@richardcarroll4495 Mine was the "latest version" as sold by Amazon a few months ago and after some reviewing: the schematic supplied has "MKIII" written on it, the parts inside match this schematic, so I assume it must be that version. They also state the MKIII has "an inductance transformer" which means they added a choke to the power supply, which my version had. I'll admit I'm not an expert on Boyuuange A50 revision history..
The "weak bass" can not only be heard (or not heard because it's just not there), but is easily seen in the frequency response curves as at 100hz the frequency rolls off. Likewise the "muddy midrange" is due to the measurable distortion which does exactly what the term says, it distorts the signal into something different, smearing any details that were previously there. It's clearly audible listening to this and a "good" tube amp. If all you listen to is alto jazz type music with little to no bass track, it probably sounds OK. And if someone A-B listens to this and a SS amp, I could see liking the tube amp sound better, even as distorted as this one is.
Just as you have a right to like the way this amp sounds, I have to right to say I think it sounds like crap, especially comparing it A-B to the other 300B amp (and other tube amps) I own, and to this amp after the mods have been done. The difference is not subtle or nuanced. I want to clarify too, even after the mods, the low quality output transformers hold this amp back from what it could be with good iron.
As far as these other reviewers, again I can only speculate why they would give an amp, that is this defectively engineered and pumping this much distortion, rave reviews. I want to shy away from claiming they were paid to give these rave reviews, but that does happen. Did they A-B listen to the A50 back to back with another know good tube amp? It's still baffling to me anyone would think this is good if they did that. The numbers don't lie and there is no such thing as "alternate facts" here. This is not what the manufacturer advertises it as: a 7.6W @ 1% distortion amplifier. It doesn't come close to meeting even 1/2 of those.
All that said, it's clear you just want to argue here, make excuses for and defend your purchase choice. Very common for people to get their ego tied into their ownership of material things, clouding their perceptions, and I've learned people doing this are rarely rational or interested in actually learning anything. My advice is to ignore my videos, go watch the ones that match your beliefs, defend your purchase choice and enjoy your amp. Have a nice day!
@@SkunkieDesignsElectronics Thanks again for your time and energy taken to respond to my questions. I appreciate it. Regards, Rich
I had a Boyuurange / Reisong A50 300B came with a bad 300b. So I never really got to listen to it.I asked Amazon to send new tubes and they said the only thing I could do was return it and get another one. I said never mind give me my money back.I figured if I am having trouble out of the box not a good sign.
I'm going to purchase this amp for vinyl listening (I've not decided on a preamp yet, but am open for legitimate suggestions that would go with this amp...), and I like the mods, but I'm wondering if I only replace the tubes, will that make a worthwhile difference. I am out of my depth on modifying electronics, and don't want to ruin a "good" amp. I plan on running it into a 75W / 95dB set of Klipsch floor speakers.
Absolutely, the stock driver tubes are really bad, but honestly without at least the basic mods, replacing the 300B tubes probably isn't worth it.
@@SkunkieDesignsElectronics Thanks. It gives me something to think about... Watching the videos (I've not seen them all yet), I feel confident I could do the jumper wire and the one you ran to ground, at least, but for sure I was going to replace the driver tubes anyway. Doing that, I'll hear how it sounds, and if it's not what I need, then your videos and the soldering iron it is! Again, thanks.
Did you upgrade the output transformers or not ?
At the end of the day, it didn't make sense as A) there really isn't room on this chassis for larger ones + the chrome plated stainless is so hard to deal with and B) spending $500+ on transformers for a $1000 amp just doesn't make a lot of sense to get some extra bass out of it. A powered sub will do that better and is cheaper.
@@SkunkieDesignsElectronics fair enough.
@@SkunkieDesignsElectronics one more question did you ever measure to see if this amp was true class A ? If so how does one measure it ?
@@skularatna8136 By design, Single Ended (SE) amps have to operate as class A
@@SkunkieDesignsElectronics yes but how does one measure it?
I am a journetman machinist of more than 20 years. On drilling stainless sheetmetal I have a few suggestions. First off stainless sheetmetal becomes work hardened when it is rolled. It is NASTY to drill. Esp with small diameter drills. First off if you have access to a drill press USE IT. Take the extra time and set it up right. Clamp everything you can. Another thing is WATCH YOUR SPINDLE SPEED. You need to run the drills much slower than you think you should, Look at your chips. If they are dark brown or black ( SS sheetmetal makes these nasty looking chips. but watch the color) SLOW IT DOWN. Slow it down if they are blue as well but you rarely get blue color drilling this crap but blue is too hot as well. DRILL SELECTION.. If you have a drill press buy solid carbide drills. They are not cheap but if you have several holes to drill it will make it childs play compared to HSS drills. If you do not have a grill press then buy COBALT drills. You will break carbide in a hand drill no matter how careful you think you are. Start off slow and let the drill cut. Do not crowd it. Now you may get to a point where the drill starts to squeek. This means you have seriously work hardened the metal. My trick for this require 2 drills the same size or at least close. Also you need a pedastal grinder to grinad the tip of the drill. What you do is sharp one drill with a narromer included angle and the other a flatter angle.. Not extreme just 10 degrees maximum. You then use one drill until it squeeks. then switch drills until it squeeks or breaks thru. You go back and forth keeping the drills sharp in between until you are thru. This lates you focus the cutting force in a smaller area. Take your time it works, Now lastly cutting fluid is your friend. If you can find it (as its not made anymore) anything with 1.1.1. thriclorethylene in it BUY IT. That is the best stuff for this job. Just dont bathe in it. Somethin about causing cancer. Next best is MOLY cutting oil. Messy but it rocks. If neither of these then but some super safe and eco friendly crap from McMaster carr. Tap Magic is best.. If you take only one thing away from this WATCH YOUR SPEED... Hope this helps.
Thanks for this reply. I'm really glad this amp isn't made from stainless and is very easy to drill.