Crazy affordable Reisong A50 300B tube integrated amp Review done at Thomas & Stereo I sent Him to your channel. Whole series of mods & testing on this Boyuurange / Reisong A50 300B Tube Amp Basic Mods Part One about half dosen vids @ Skunkie Designs Electronics on youtube. . You deserve the views all the hard work you did.
I don't own this amp, a viewer had this drop shipped to me to modify and make a video series about, and now I plan to box up this modified amp and mail it back to them. But these two "screen shots" show how drastically it changed. As delivered, making 3W at right at 3% distortion. th-cam.com/video/b2T_b91yI0Q/w-d-xo.html Final mod is making 7W at right at 3% distortion. th-cam.com/video/7tEv6Bfvd8c/w-d-xo.html At the same 3W output, the distortion was reduced from 3% to well under 1% th-cam.com/video/7tEv6Bfvd8c/w-d-xo.html
@@flemdoghd Thank You for the links she deserves the views all the hard work she did . But I don't know if she can send the amp for review #1 its not Hers #2 She lives in Georgia USA He lives in Canada shipping be expensive.
Glad it was helpful! I really think this is the right approach. So many great 300B amps use a pentode to drive them, so creating a virtual pentode from 2 triodes made a lot of sense to me.
Thanks for sharing all your hard work on this project with us! I am trying to follow all your steps for reconfiguring the driver tubes. You showed the steps in detail on the first driver tube, and the second driver tube is pretty much the same as the first - However, I noticed a couple of resistors you added to a black wire (heater?) on the second tube. Looks like they split off the wire like a Y and you put heat shrink tubing on them. Can you clarify what that's for, what the values are for the resistors, and which pins they connect with? Thanks!
Those are two 100 ohm resistors, one end of each connected to the 6.3V heaters. This creates a virtual center tap that in connected to the voltage divider that lifts the heater reference DC voltage. See: www.skunkiedesigns.com/boyuurange-a50-mods?pgid=ktb1lluh-3f3ec5c7-d5e9-4b4d-aa40-dfb7adaae7b7
Are you planning to release an instruction/manual document with all featured upgrades, parts specs? This will make it much easy to overview the options you offer. Thank you.
This "upgrade" or mods to this amp is just a video showing what I did. I do plan to publish a schematic and a BOM of the parts needed but I'm don't plan at least at this time to offer anything beyond just sharing what I learned. I'm sure there are probably other mods that could be done past what I did. Hope it was helpful!
A great series of videos. Thank you so much. Before I start implementing them I was wondering, if there are any changes to the mods needed, if you operate the amp in Europe with 230V? Are you going to have a final video on your listening experience with the mods compared to the other 300B amps you have? Is it now a really decent amp and is it worth the effort? Have all the mods any impact on the v-meters on the front?
Hold on until I spend a little time with this amp. And no, the mods shouldn't have any issues working with a 230V version, but the key word is "shouldn't" as I don't have any way to check what the internal voltages are in one of those models. When I am finished, I'll have a schematic with all the "after" voltages and I highly recommend folks check the voltages. Do understand these are LETHAL voltages, and watch my safety video before you start probing around inside one of these!! On the VU meters, I'm not sure people understand their purpose. They shouldn't get into the red until the amp is turned up high enough to be into distortion. From my testing, they seem to be doing their job, but I think some people want them adjusted so they dance full scale at normal listening levels. So no, my mods don't effect how they work. And yes, I plan to do a final wrap up video with pros and cons along with comparing it to the other DIY 300B amp I did a video series on. I expect to have that done in a day or two :)
Looking great.. I would personally just replace the Dale heatsink bodied R’s with a parallel pair of Mills MRA12 12W resistors - “floating away” on the board.. Oh, I find that the (Solen) decoupling cap in the cascode is also crtical to SQ, I would personally at least use an Auricap or Sonicap in that position.. The Solen would be a bottleneck IMHO.
To find the center of the holes rather than guess where the centers are just set the calibers to the left side of the each hole and you will be a lot closer to the distance between the holes.
Hello there, I was wondering why you chose the cathode bypass res/cap on the cascode instead of the LED/res like your other design? Also, I am a bit confused because consumer products have a stated output of -10dbv, which is just under 1 vpp. You use a max 3 vpp input (1 vrms). Is this to give the amp more headroom or/and is it possible that some manufactures have outputs that are not really -10dbv? I'm learning a ton from you and I am super interested. thanks for doing all this!
I did end up using an LED/resistor on the cathode of the cascode. The resistor/cap is on the cathode of the 300B. And most devices made today output 1-2V RMS, at least that is my understanding.
Thanks for your series, it is so great. May you explain about input circuit? I saw that the audio inputs have aux, cd, and tape. Do you have a schematic for this one?
The aluminum plates look to be anodized which makes them conduct heat much better than bare aluminum. The 300B cathode resistors have found a better home.
Lots of folks have praised it. I don't think they actually measured the THD or the output... I can only assume they have never listened to a tube amp before?
Hi - great series of video's, im still very much at a learning stage but building with safe results - i have considered buying this amp but prefer kit builds or my own builds - i was wondering if you have considered building the Boyuurange A9 el34 kit thats available on 'bay - diyaudio have thousands of comments about it but its a minefield of opinions , i do hear its a well liked little kit but i would love to know your thoughts and would be fantastic to see your improvements to it -- much thanks for all your time and efforts to help learners -- like me ! kind regards --- Chris
@@SkunkieDesignsElectronics ahh - ok its selling with Douk audio as the el34 - black chassis with gold front panel, ive always known it as the A9 - best wishes chris
Very good job!!! but I think you need a better Soldering Iron if you are dealing with Tube Amps. A least 60-Watt Iron with medium size tip will do better job if you handle it properly.
Crazy affordable Reisong A50 300B tube integrated amp
Review done at Thomas & Stereo
I sent Him to your channel. Whole series of mods & testing on this Boyuurange / Reisong A50 300B Tube Amp Basic Mods Part One about half dosen vids @
Skunkie Designs Electronics on youtube. . You deserve the views all the hard work you did.
Stephe, maybe Thomas can test your modded amp and compare it to the base model - th-cam.com/video/bzTMjSqQ-Zk/w-d-xo.html
I don't own this amp, a viewer had this drop shipped to me to modify and make a video series about, and now I plan to box up this modified amp and mail it back to them. But these two "screen shots" show how drastically it changed.
As delivered, making 3W at right at 3% distortion.
th-cam.com/video/b2T_b91yI0Q/w-d-xo.html
Final mod is making 7W at right at 3% distortion.
th-cam.com/video/7tEv6Bfvd8c/w-d-xo.html
At the same 3W output, the distortion was reduced from 3% to well under 1%
th-cam.com/video/7tEv6Bfvd8c/w-d-xo.html
@@flemdoghd Thank You for the links she deserves the views all the hard work she did . But I don't know if she can send the amp for review #1 its not Hers #2 She lives in Georgia USA He lives in Canada shipping be expensive.
@@SkunkieDesignsElectronics thanks. I agree that getting someone else’s amp to Canada and back would be a mission 😳
Thanks for a superb series on this and your own build 300b amp. Super informative and helpful. I am going to do the cascode mod on my 300b.
Glad it was helpful! I really think this is the right approach. So many great 300B amps use a pentode to drive them, so creating a virtual pentode from 2 triodes made a lot of sense to me.
That power reading to thd is amazing wow. Great job!!!
Thank you! It sounds really sweet now.
Thanks for sharing all your hard work on this project with us! I am trying to follow all your steps for reconfiguring the driver tubes. You showed the steps in detail on the first driver tube, and the second driver tube is pretty much the same as the first - However, I noticed a couple of resistors you added to a black wire (heater?) on the second tube. Looks like they split off the wire like a Y and you put heat shrink tubing on them. Can you clarify what that's for, what the values are for the resistors, and which pins they connect with? Thanks!
Those are two 100 ohm resistors, one end of each connected to the 6.3V heaters. This creates a virtual center tap that in connected to the voltage divider that lifts the heater reference DC voltage. See:
www.skunkiedesigns.com/boyuurange-a50-mods?pgid=ktb1lluh-3f3ec5c7-d5e9-4b4d-aa40-dfb7adaae7b7
WoW..very nice job!👌👍👍
Are you planning to release an instruction/manual document with all featured upgrades, parts specs? This will make it much easy to overview the options you offer. Thank you.
This "upgrade" or mods to this amp is just a video showing what I did. I do plan to publish a schematic and a BOM of the parts needed but I'm don't plan at least at this time to offer anything beyond just sharing what I learned. I'm sure there are probably other mods that could be done past what I did. Hope it was helpful!
A great series of videos. Thank you so much. Before I start implementing them I was wondering, if there are any changes to the mods needed, if you operate the amp in Europe with 230V? Are you going to have a final video on your listening experience with the mods compared to the other 300B amps you have? Is it now a really decent amp and is it worth the effort? Have all the mods any impact on the v-meters on the front?
Hold on until I spend a little time with this amp. And no, the mods shouldn't have any issues working with a 230V version, but the key word is "shouldn't" as I don't have any way to check what the internal voltages are in one of those models. When I am finished, I'll have a schematic with all the "after" voltages and I highly recommend folks check the voltages.
Do understand these are LETHAL voltages, and watch my safety video before you start probing around inside one of these!!
On the VU meters, I'm not sure people understand their purpose. They shouldn't get into the red until the amp is turned up high enough to be into distortion. From my testing, they seem to be doing their job, but I think some people want them adjusted so they dance full scale at normal listening levels. So no, my mods don't effect how they work.
And yes, I plan to do a final wrap up video with pros and cons along with comparing it to the other DIY 300B amp I did a video series on. I expect to have that done in a day or two :)
amazing series of videos...thank you!!
Looking great.. I would personally just replace the Dale heatsink bodied R’s with a parallel pair of Mills MRA12 12W resistors - “floating away” on the board.. Oh, I find that the (Solen) decoupling cap in the cascode is also crtical to SQ, I would personally at least use an Auricap or Sonicap in that position.. The Solen would be a bottleneck IMHO.
To find the center of the holes rather than guess where the centers are just set the calibers to the left side of the each hole and you will be a lot closer to the distance between the holes.
Good tip :)
Hello there, I was wondering why you chose the cathode bypass res/cap on the cascode instead of the LED/res like your other design? Also, I am a bit confused because consumer products have a stated output of -10dbv, which is just under 1 vpp. You use a max 3 vpp input (1 vrms). Is this to give the amp more headroom or/and is it possible that some manufactures have outputs that are not really -10dbv? I'm learning a ton from you and I am super interested. thanks for doing all this!
I did end up using an LED/resistor on the cathode of the cascode. The resistor/cap is on the cathode of the 300B. And most devices made today output 1-2V RMS, at least that is my understanding.
Thanks for your series, it is so great. May you explain about input circuit? I saw that the audio inputs have aux, cd, and tape. Do you have a schematic for this one?
I plan on going over BUT I do not plan to dive deep into the relay boards or the remote control etc.
@@SkunkieDesignsElectronics yeap~I see. Do you have a link to buy it?
Have you tried copper foil audio capacitors? I know they’re expensive … but they sound terrific for some applications.
I tried some Miflex caps and wasn't super impressed. They sound OK and do take a LONG time to settle down.
The aluminum plates look to be anodized which makes them conduct heat much better than bare aluminum. The 300B cathode resistors have found a better home.
I believe so too!
Hi, Is it possible to use bypass caps in an amplifier to increase the sound quality?
I've not found them to sound good personally, some people say they like the sound? Sounds too shrill to me.
Is this the same amp that Steven reviewed with so much praise?
Lots of folks have praised it. I don't think they actually measured the THD or the output... I can only assume they have never listened to a tube amp before?
Hi - great series of video's, im still very much at a learning stage but building with safe results - i have considered buying this amp but prefer kit builds or my own builds - i was wondering if you have considered building the Boyuurange A9 el34 kit thats available on 'bay - diyaudio have thousands of comments about it but its a minefield of opinions , i do hear its a well liked little kit but i would love to know your thoughts and would be fantastic to see your improvements to it -- much thanks for all your time and efforts to help learners -- like me !
kind regards --- Chris
I haven't seen an A9 kit?
@@SkunkieDesignsElectronics ahh - ok its selling with Douk audio as the el34 - black chassis with gold front panel, ive always known it as the A9 - best wishes chris
Very good job!!! but I think you need a better Soldering Iron if you are dealing with Tube Amps. A least 60-Watt Iron with medium size tip will do better job if you handle it properly.
This Hakko FX888D I now use is a 70W iron and you can change the tip. I do agree you need more than something like a 25W pencil for this work.
I see you use Mundorf caps, does the Mundorf silver Oil better than this one?
Not really. There is a point of diminishing returns IMHO. I can't hear any improvement.
@@SkunkieDesignsElectronics Thank you, I will stay at a reasonable one under $20
Also the hotter the resistor.. the more noise..
putting PCB on tube amp creates a tons of problems
I didn't put those in there, it comes this way + hundreds of tube amps are built with PCB.