Willsenton R8: Repair and Testing!
ฝัง
- เผยแพร่เมื่อ 16 ก.ย. 2024
- This is a video series about the popular Willsenton R8 KT88 EL34 Push Pull tube audio amplifier. We will go through the repair this amp needs, testing and reviews of the amp as delivered, and then work on modifications to improve the sound quality and durability.
I also want to note something a viewer pointed out, when doing some of these initial voltage tests after the repair, I was using a variac/isolation transformer for safety, which wasn't supplying full line voltage to the amp.
The voltages on this amp are 430V on the plate, 427V on the screen in triode and 428V on the plate with 430.5V on the screen in UL, which I may want to play with the value of the screen stopper to lower the screen voltage a touch. Sorry for any confusion that may have caused.
This first video is about repairing the amp that was brought to me and the initial testing done to benchmark it's performance.
You can buy this amplifier here
amzn.to/3Q3Ynjr
The test gear I use in this video includes:
Analog Discovery 2 Kit
amzn.to/3Z1F4LF
BNC to RCA cable
amzn.to/3Cct9AZ
RCA Y cable
amzn.to/3Q8PwNC
A pair of 8 Ohm non-inductive dummy loads
amzn.to/3GoRSoe
The freeware Audio Analyzer Suite
• Audio Analyzer Suite v...
Hey there! Along with many I've been waiting for this. Thank you!!!
More to come!
What a great video. I don’t know anything about cathodes, resistors, and the like, but you made it very relatable and I felt like I understood a fair amount. Looking forward to seeing what impact the mods make.
Glad it was helpful!
The most detailed and professional explanation I've seen. You go all the way explaining possible problems. Thank you. On my r8, one channel went completely silent. unfortunately, I live in Croatia and there are no services that would go into the problem of matter in such detail. Hope will found someone who will understand this video. I'm actually sad because it sounded so nice. I wish you all the best and I greet you. Grateful, Davor - Croatia
Your channel is everything a tubie could ask for. You explain so much and in a methodical way. I wish I knew more so that I could understand more of what you talk about, But that's my problem to solve unless you want to make a series of remedial tube amp engineering posts. So grateful. Love the channel. Have a great new year.
Some of these might help?
th-cam.com/play/PLtEhh3UpOsiDdHABS0q5byT2gAQ5z31Hk.html
I had an R8 and did a few mods on it. By far the best mod was to replace the 4 coupling caps to the output tubes with U-Cap copper foil Teflon caps. Very expensive mod but the dynamics of the amp improved out of sight. I've now moved on and have 805 monoblocks but fondly remember the R8.
I am saving up for an R8 so I'm watching every video I can find. I loved this. I'll be ready when I finally have the $.
Excellent video, you really made my day and confirmed for me that I made a good purchasing decision on my first tube amp after watching reviews by Thomas Stereo, Jay’s Iyagi and the British Audiophile.
You really caught my eye with your video about red plating as one of my brand new GL KT88s lit up like a candle on the left channel. Shut it down and noticed the bias meter pegged for V2. Luckily the warranty for the tubes was still good and Upscale Audio swapped me a new matched tube.
I subscribed to your channel for future R8 vids and to see your other presentations. Thanks for the heads-up on those power caps and link in the comments section! I’ll have a tech I use to swap them out. Bless you & Happy New Year!
Clear, concise and informative! Perfect!
As far as I know, the Wilsenton's are made by one of the more reputable companies. I can't be 100% sure, but I am 90% confident that the caps are genuine in these. Really great video. Wonderful to see this amp is as good as they claim, and can be improved on by adding some nice tubes to it. They do sell this with two options. KT88's or EL34's I'd be interested, if you have a set, to see the performance with the EL34's. It's rated at 40Watts in the EL34 configuration (UL) and 25Watts (Triode).
I do have some EL34, 6CA7 and KT77 I plan to try in it.
Like a kid sitting up all night waiting for Santa...I've been awaiting this video for days. I have Svetlana EL34s in mine and a pair of old RCAs up front. Sound awesome. I am not a techie, but tend to impulse buy tubes and caps based on things I read but don't understand.
Just bought a Pair (not a quad!) of 1940s British VT60 (807) tubes online (EL37?). I'm not even sure they will fit this R8 amp. I just believed the description by the seller. An Indian tube seller, but he has some unusual stuff.
Trying to cancel the order.....he doesn't have another pair.
You watchers are brain surgeons......and I can apply a band aid.
But I do love the tube amp music reproduction.!!
And love these Skunkie vids!
Thanks SKunkie!
Yeah, those aren't even close to what this amp uses.
Love to see more of these and Love what you do. I just purchased WILLSENTON R300 SINGLE-ENDED INTEGRATED 300B Amp. A few reviews have positive results with the R300 and will be upgrading the Films also. Happy New Year!!!
Very cool!
I have the R800i 845 and love it! But I wonder what solid core silver hookup and upgraded caps would sound like… Thank you for these videos!!
I'm more into just using "overkill" gauge copper wire, especially for short hookup wires, but agree on the upgraded caps. I really like these alum/oil Mundorf caps for sound quality vs price point. Now I can see silver wire in like the output transformer windings being a good idea.
Loved the video!!! You definitely proved that one to be a win. Looking forward to more testing Skunkie. Happy New Year!!!
the GLs make a big difference on my similar prima luna.much clearer.worth the $$
purtroppo ho già fatto conoscenza con i resistori di questo tipo: è veramente robaccia inaffidabile! Grazie, dell'impegno.
Despite all the positive reviews this amp gets, and I have no reason to doubt them, I get the impression its not something that will last a good long while.
I can’t wait until you out your improvements. Loving this.
Just loving this amp!! Using my Freya+ as a pre amp, sending to some DynAudio Emit 50!!! Glorious. 🎉❤😊
Great work on fixing the amp, the R8 really is a nice piece of kit, I have had 2 now and the build quality has alway been good.
Great! I have this amp with NOS EL34 tubes and it sounds very good. Looking forward for your next videos on it.
I really wanna try it with some budget friendly JJ EL34L. I've used those in single ended amps and they sound really good.
@@SkunkieDesignsElectronics I've tried those with this and they have a very pure sound.
Great video. Please do more about the R8. Thank you
Oh I plan on it :)
So glad you did this. As a proud owner of a Willsenton R8, you are a fantastic source of information. : )
Glad you enjoyed it!
Glad to see your thorough and detailed videos on the R8 repair. Mine just did the same exact thing on V2. Both the 10 ohm and 1kohm show they got hot and burnt but when removed the resistance is correct. I only had it on for a few minutes and heard static and saw sparks around the tube for a few seconds then the sound came back on. I am not sure if one channel went out as I turned it off quickly. This Willsenton R8 was purchased Jan 2022 and had Gold Lion KT88 repops.
Now a question did you use the same tube and what caused this ? Thanks and keep up the great work.
Once they arc/die, they are dead. and likely the bias was set way too high or the bias pot is faulty/has no safety resistor in the circuit.
Love your channel!!!
Any chance upgrade kits for the Willsenton R8 coming soon?
Sure many of R8 owners will purchase and help to grow your channel.
Keep up the great work!
I'm looking into a basic kit to sell.
I have for the last couple years plugged every amp I have into a voltage regulator to try to avoid any issues. The old house Im in is just a rental. I can’t repair the Elec myself, even if I know there is faults in the wiring. I just make sure my fire alrams are working, and the exits are clear. I am moving out asap btw.
Good plan!
Hello, first of all I would like to congratulate you on what you do. Secondly, I would like to specify that I made the recommendations recommended as a hobby, not as a professional. Partly they succeeded. I followed all the episodes of countless times and I managed to order the pieces just America. I changed them as you recommended. But in the final test, that is, at the audition, one channel is heard perfectly (right) and the other (left) is very weak. In conclusion, not having the electrical scheme of this amplifier I can't find the problem. I would be grateful if you can help me in this regard.
You must have missed where I said "Do not do this all in one big change and test along the way". All the schematics are on my website.
www.skunkiedesigns.com/r8-mods
Another great video!
I have NOS Svetlanas running mine, plus NOS 80's Russian valves on the preamp stage. I must say I prefer it with EL34s (I got both KT88 and EL34 Svetlanas). The increase in sweetness and coherence over the stock tubes is not subtle.
Plus the sound keeps getting better (after over a year)
Excellent video, very informative, thanks
Really great job, great info😊 and great skill
Great video. Keep up the good work, and I hope you have a great New Year!!!
Enjoying your videos. I did notice in this testing that the gain of the channels you were comparing wasn't closely matched. This could skew the distortion measurements between the channels.
I bought a Gold Lion ECC88 for my Schiit Vali 2 and never looked back. They are a bit bright compared to the mellow NOS Brimar's and Mullard's but they're so clear.
It'd be super interesting if you could get your hands on some Line Magnetic gear 😊
That would be cool!
I heard this amplifier really has balls.
It should have PLENTY of power for most any home audio use.
😂
Hello, thank you for the great video. I have had a similar problem. i replaced all the 10 ohm 1 watt and another resistor with a metal film (1%). Unfortunately, the bias meter does not work now. I found this out after i noticed one channel that is lower volume. I am using different tubes and have swapped left to right. The one channel remains lower volume? Any suggestions? I fear the worst. Thank you, looking forward for more videos.
Oh, I made an error. Be careful of small solid conductors on preamp tube sockets. They break easily. So I have equal volume in both speakers now. I still have a pegged bias meter that was related to a similar issue you are sharing with everyone! Thanks!
I have completed the capacitor upgrades and the electrolytics as well. A noticeable improvement, especially with controlled bass. I think tube rolling gives a bit more improvement but it can be very expensive. If you have an idea about why the bias meter is pegged all the time. I will be watching.
i wish some day you do video how can replace the outpot with hammond 1650s please!!
I will probably be replacing mine at some point with something different.
@@SkunkieDesignsElectronics update us how you do it...tnx
Be great if you get a Willsenton R300 on the bench.
As soon as someone sends me one to test and mod :)
Wow. Red China Amp is going to leave you very happy when you're finished.
I have an intergraded tube amp that's limping around broken. made in Spain Think about it.
My baby would be in good loving hands with you
Let's get that right
Hi Skunkie,
I set my up my R8 today.
Running quality cables with Heresy speakers. Source is hi-res files Bluetooth from my phone. (I know, but a streamer is in the near future).
Almost NO bass. I expected punch and got foam.
QUESTION, please and thank you! :)
On the INPUT selector, both the CD and AUX 1 light up simultaneously. Doesn't matter which of those two I select; both come on, although the "selected" LED is a tiny bit brighter than the other.
AND, my Bluetooth device, connected to AUX 1, will work even if the CD source is selected.
Should the amp go back?
Thank you a million times for your input.
Sounds like there is something wrong with it for sure.
Hello! I need your help! Today I replaced resistors on an output tubes an power transformer, checked the amp and it worked fine. After that I replaced 4 electrolytic caps on bias boards (clipping caps I did earlier) and added resistors to a signal wires. on the check one of the tubes went red plated and 10 Ohms resistor burned out. I replaced that resistor and set of tubes. On the check that same tube bias shows max and can"t be regulated by potentiometer. What can it be? what I did non correct?
Send me a direct message. www.skunkiedesigns.com/contact
Excellent video,as always. Where can u buy the Mundorf caps that you mentioned?
I buy those and the audio note electrolytic caps at:
www.partsconnexion.com/
After watching your video, I couldn't resist so I opened the amplifier cleanly to see visually if anything could be detected. As I said, one channel (left) stopped working. Everything looked normal, but I still decided to remove the small black square cover in the middle of the bottom, which I think is the transformer (sorry for my ignorance, I hardly know what + and - are). And I found a small green, I think ceramic resistor cracked. This could probably be the cause. But I don't know which resistors they are and which value. Is there a schematic of the Willsenton r8 somewhere? I would be very grateful for an answer. But anyway, you helped me a lot in terms of giving me the courage to open it, because I was afraid of screwing something up. Thank you very much !

Povratne informacije
Web-rezultati
There is a schematic but those resistors aren't going to kill just one channel.
www.skunkiedesigns.com/r8-mods
@@SkunkieDesignsElectronics Thanks Skunkie ! You are the One ! I'm going forward to resolve problem. You were of great, great help. Thanks again.
Thank you so much for the video. So much valuable information.
Do you think I should buy this amp as my first tube amp within this 1.4k range?
It seems like a well made amp so far.
Where can you. get one of your amps already built to buy?
Hello. Can you write a list of caps and resistors to replace. This will help a lot to order them all and a shipment will be cheaper. Thanks for help.
Was done months ago. www.skunkiedesigns.com/r8-mods
Not long been subbed! But I can say I love all your vids and your format is great. Keep up the excellent work!! Big Hi from Newb well learning my passion again due to kids finally leaving the nest Hooray!!! From rainy Liverpool U.K
I just got mine delivered today and guess what? The volume control is busted! Yay! Now I have to ship this back! Yay! Not great first impression tbh.
Oh no! That's not good :(
Thank, can you leave the description for the two
550volts capacitors please, Thanks
330uf 550V Cornell Dubilier 380LX331M550A052
www.mouser.com/ProductDetail/598-380LX331M550A052
Hi, thanks for your videos which I enjoy. The AudioAnalyser shoftware shows four lines in scope more: two are the sine wave of the channels but what are the none sine wave lines ? Secondly do you know a way to use the software to chart a phaseshift plot from input to output ?
I would go ask the person who wrote the software. :)
Hi, I got the anser: @TheStuffMade
@TheStuffMade
15 hours ago
Hi Alex, thanks, the extra plots in the scope view is the signal with the fundamental tone notched out, so basically showing the distortion plus noise waveform. I haven't added a phase plot, but I probably should. You can do a phase plot using the Digilent Waveforms software, it's under the Network tab and it's a bit fiddly to configure but it will do the job.
Cheers,
Jake
What was done to keep this problem from occurring again? Power conditioner of some type?
Yes, an APC voltage regulator.
I have this same amp. It's not even a year old and I have what I would call static at certain high frequencies. I know it's the amp as I swapped it with a solid state and get no static. It comes out both channels but is more prominent on the R channel. Could changing the tubes out help this problem?
Are you using it in triode or ultralinear? The triode mode sounds bad to me.
@@SkunkieDesignsElectronics Actually watching this video made me think to try it on the opposite of what I have been which is default (not sure which one tho). Still don't think I should be hearing it. Thanks for the reply!
@@SkunkieDesignsElectronics The static happens on either mode. It is volume related. If I have the volume about the 10 o'clock position the static kicks in, turn it down just a hair and its gone. I don't this this is your standard distortion, but I could be wrong. Just never heard distortion come through as static and this amp should be able to pump out much more power before distorting. Do you think this could be from the tubes?
Hello, I just subscribed to your channel! Can you please do a demo about the Audio Analyzer kit ?
Thanks!
Already did one :) th-cam.com/video/vZdL6jmCJvE/w-d-xo.html
I wonder how much it costs Willsenton to make these amps given the small additional expense better quality components would have added?
They probably won't use better components like those Mundorf caps for this model. R800 have some mundorfs but I dont know witch. I dont know about quality those Willsenton caps but they are easy to replace, and probably change sound a lot. Often much more than tubes.
Am I requesting too much to get a list of each part you bought with a link to buy them and quantities of each we’ll need to do all these upgrades?
I plan on this once I am done.
@@SkunkieDesignsElectronics lovely!
I was wondering, cAN you reverse ingeneer it so we can replicate it and upgrade it in future builds ? It would be nice if we can do one of these kt88 PP
It mostly has been done. And who knows, a future project may be a DIY version of this amp, this isn't something unique.
Add it, writte it down in your schedule :)
Maybe you should design amps
I have :) See the 47 globe tube amp, the 6SQ7-EL34 amp, my "budget 300B" etc. at my website.
Could the r8 be mono blocked
Not really IMHO, not to good effect.
HEY LADY! I might be drunk! But you need a YOITUBE THANKS BUTTON! Now get HOT! ALso loved the video! 😀 BE COOL!
Hello analog traveller. My third try due to disability., ? Apc regulator Italy or Phillo
pines? Need safe power Radio Craftsman C 400- ground plug only mod due to history of company and the engineers. I am determined to use voice on laptop rather than exit the web. I do wish to share war stories, poor stage wiring nand primitive guitar wiring. Strings to ground... Really? Death cap ., really? Warm wishes, adams, ma, 15 min from old sprague factory. Bose tour after hours, and more. I'm 70 and musician 55 years. References available. keepin it 1200ft/sec!