Willsenton R8: Power Supply Mod and Upgrade
ฝัง
- เผยแพร่เมื่อ 18 ก.ย. 2024
- In this video I am replacing the resistors and caps under the power transformer, as well as eliminating the 115/230 switch and installing 18ga solid core twisted pair power wiring.
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.
A great book for DIY amp building info!
Morgan Jones: Building Valve Amplifiers.
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You can buy this amplifier here
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The tools I use in this video include:
Hakko FX888D-23BY Digital Soldering Station
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Hakko-CHP-170 Micro Cutter - Red
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Hakko CHP CSP-30-7 Wire Stripper
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Long needle nose pliers
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Thank you for the content. I almost think I could tackle these projects thanks to your detail and filming. You should consider selling a kit with all the caps, resisters etc... I would happily pay a premium for such kit. I am more concerned I get the wrong parts then I am doing the soldering.
I am seriously considering that.
I would buy that.
I would also buy that.
The two Morgan Jones valve amplifier books are the best investment I ever made!
Dan
And so you can see why this wiring is so cringy lol.
I am so glad you women take over on electronic repairs. Men can change and do cat care videos now!
Watching these vids on the R8 really got me interested in getting one and doing all these mods.
Very glad to see you do it step by step and take the time to explain everything.
Hope you will be doing a recap when it is all done and mention all the parts that were exchanged (values and quality and such).
Love your channel , well done 👍
Glad you like them!
Man that’s a great skill you have. Had two years electronics in high school ( 36 years ago) and did a bunch of soldering with solder sucker bulbs. I would be terrified today to try this. Great channel
I've been following this series of videos closely. Congratulations for the wonderful job. 😍
Congratulations with this improvement.
Nice job, beautifully filmed, Al mist meditative way of you talking while soldering.
Glad you enjoyed it!
Amazing how much better things are looking already. I especially agree with your comment about the switch and the fuse in the same wire. It is often not done that way. You are making this project more desirable all the time. Looking forward to your schematic. I was able to work out the voltage regulator...it was much easier to figure out what was going on when I realized the tube was in parallel. Keep up the great work.
Yeah, the online schematics I have seen are wrong!
Another great video! I really enjoy the way you explain what your doing. Top-notch communicator. Love the vids!
Bonjour je vous remercie et vous regarde de France il est vrai que je ne peux pas écrire en anglais mais je vous comprends très bien parceque vous parlez très lentement et vous ne Mangez pas les mots vos conseils éclairés sont très cool et très complets ne changez rien je vous remercie et vous aimes Thierry Caudron de Rouen en France
Great video! I was hoping someone knowledgeable would take on this amp!
Hoping for more info on the resistors you used. Like wattage, tolerance, even brand.
Can't wait for the next vid.
I plan to post a complete parts list when I am finished.
Excellent and informative video. I was getting really OCD until 13:10 when those two wire cuttings vanished. 😀 I know you mention the difference in the video but is there any chance of a short visual explanation of how to wire the transformer for 230/240V countries?
Yeah I will do that in the next video.
Yes this would be helpful - I could work it out but it's always good to get confirmation.
@@SkunkieDesignsElectronics Awesome!
Wow, I'm really surprised at the factory soldering and layout. They are using leads from resistors as "tag strips". The old magnavoxes that I modify and rebuild at least terminate at tag strips and not piggy back on top of leads. Again, great job and thanks for doing this!
Yeah, leads soldered on top of leads...
Excellent video as always. Merci infiniment :)
Going well Stephe. I am really enjoying this project
Great video! Could you please guide us who use this amp on 230v ac on how to get rid of the switch?
Sure, I will do that in a future video.
@@SkunkieDesignsElectronics very appreciated 👍 I pulled the trigger on the R8 yesterday thanks to your videos. Hopefully it arrives next month so I can start working on it.
At the end of the upgrades video serie It would be very helpful if you could supply a parts list Thanks a lot !
Noted!
This is interesting and I have no idea about any of it. Keep up the work *thumbsup*
Wouldn't mind learning about whats going on with these electronics inside the audio equipment.
Subscribed
Another interesting video just love wacthing your videos.
Well done!
hi stephe .. great videos, im about to purchase R8 , along with parts for modding, so going thru your mod series - albeit noting that the “new” unit should have some of the mods already (per yr recent vid) .. however in trying to reconcile the parts list BOM (yr web site) and yr circuit diagrams… i coildnt find the 0.33uF caps (i was looking for red boxes :)
infound them of course on diagram .. but not shown as a’modded” .. this is just an FYI …
if i find anything concerning when “new” stock arrives - will let ya’all know.
Vid's 8 minutes old ! First Post.. What's Skunkie up to ???
Oh yeah I was told only use metal oxides in filter stage, not signal .. OK in 'decoupled' roles.. Lets see :)
Oh yeah Morgan Jones .. And ol Norman Crowhust's worth reading too, 'back in the day'
Oh Seperate L/R HT (B+) rails ? O-Kayyy :)
Oh Seperate L/R HT (B+) rails --- What do you mean by this? ill be doing this upgrade to my R8 soon
Hi @@mike212916 - that was a mod she referred to in this build but didn't quite go there - strictly speaking, separate Left and Right High Voltage FILTERING. I hadn't really thought of that and thought I might use it too ;)
Its a bit of a luxury, doubt if you'd notice anything much .. and it'd require a few extra terminal points R's and C's...
Skunkie might bring it out as a mod later ;) ?
Thank you for sharing these informative videos! At about 19 minutes, you placed the positive supply capacitor right on top of a resistor. Does this resistor get hot?
No, those are super low current resistors in that part of the amp.
It would be very helpful if you could supply a parts list with each upgrade Thanks
Not doing this because in the past I ended up going back and changing things. Will post at the end!
Thanks
As always really enjoyed your video. Was wondering if any of the modifications you are planning will make such that something like a KT120 or even a KT150 could be used. If I understand correctly in its present use of parts that permit installation of el34 tubes, this is not possible.
I doubt this amp would ever support KT120 tubes, there just isn't enough power supply and I have no idea if the output transformers could deal with them either.
Really admired the wiring clean up part. Can you show how to connect that transformer in series for 220V country?
Yeah, I will cover that in the next video.
Stephe, that schematic on SNA forums was supplied to a buyer from the Chinese seller of the amp, and yes, it is not very accurate. Can I ask if you were feeding full mains voltage to the R8 when you measured the plate voltages in the other vid? As some of the guys down under have measured around 435v and you were getting 390v? some things are not adding up with different R8 amps. Thanks for these vids, they will help owners no doubt about it.
In one of the earlier initial videos I was running this through a isolation transformer/variac, which I later discovered wasn't supplying full line voltage. It is closer to that 430V you mention.
@@SkunkieDesignsElectronics Thank you, Stephe :)
I became less confident with this video because towards the end your camera died and we missed you install 2 or 3 things.
#1. Mainly you didnt show us a zoomed-in image of the twisted wire soldered to the fuse and how to make sure you're soldering the correct wire to the fuse 20:10 .
#2. when you bridged that 18guage wire to the transformer how did you make that bridge? Did you just cut the wire and use a piece of it to solder back to the wire which turned it into two leads?
#3 moving that rectifier to a different location. Did you just unscrew it then screw it into the terminal above it? Any tricks or tips or was it straight forward?
#1The top lug of the IEC connector is the fused one, if you study the connector that becomes clear. As far as which wire is going to the switch, it's the wire going to the switch. not the wire going straight to the transformer.
#2You can make that bridge how ever you want, I showed how I bent the power wires to make up that bridge, but it could be a separate piece of jumper wire. Never use solder as a wire.
#3Yeah, it has a screw, you unscrew it and move it.
Honestly if not seeing this in total detail confuses you, I would suggest you probably shouldn't be doing this more detailed "rebuild", replacing the wiring, and just stick to replacing components.
You are awesome!
Good work! I wonder with the ht feed to the front end if separating the decoupling is possible as the front end has a voltage regulator which presumably feeds both channels? Also I don't like the power choke being so close to the input section....but there's only so much you can do without rebuilding the whole thing.....
Just wait till you see what I end up doing to power the input tubes :)
@@SkunkieDesignsElectronics Look forward to it!
@@SkunkieDesignsElectronics whatever you do, I’m following suite. Been upgrading a each of your videos come out. Call me dumb but, Mouser has certainly taken some unnecessary shipping charges because I can’t seem to get it all in one swoop. Haha
Nice job! Any chance to make a list of parts to upgrade for people living in 230v (Europe)? Thx!
The parts list is exactly the same, the only difference is how the transformer primary is wired to the power IEC socket.
@@SkunkieDesignsElectronics can you briefly explain how should be the wired to the IEC performed for 230v? Thank you very much for your dedication and work!
For 120V the two primary winding are in parallel, for 230/240 they are in series.
L I K E 👍👍👍👍👍 💯🧡💯💛💯 🤩🤩🤩🤩🤩
is there any nice Tube pre-amps out there made well out of the box, that don't need any tweaking ? that do deliver that tube sound ? I have a B&K EX-442 Amp (Solid State).. thanks!
Not that I know of right off the top of my head.
Hey! If possible, tell us about how the anode current control circuit is implemented and its features.
I plan to do that in the next video.
Do the resistor wires have to be long enough to reach the bottom of the transformer or is it enough that they are soldered to the top silver boiling point of the transformer?
Just reaching the contact point at the top is fine.
@@SkunkieDesignsElectronics many tnx , maybe in future you will do video that you replace the transformer for something high quality, i will keep follow
would it be possible to include a list of the component's changed along with their values for each episode you do?
No, I don't want people following along, as I may go back and change things. You are watching the "development" of this in real time.
dear please sos, can i use on power supply 220uf 160v.. i dont have 100uf 160v.. it can be work normal?
No, use the correct caps.
Hi Skunkie, didn't you solder 220ohm resistors instead of 22 ohm at 10:00 ?
These are 220ohm. Also, I always measure every resistor with an ohm meter before installing just to make sure a bad one didn't get through production.
What qualifies you do do up grades on tube amps? why is it necessary anyway?
Mainly it's necessary because most of them have some fairly serious design flaws that anyone who know ANYTHING about electronics can see, like having capacitors rated below the voltage they operate at. Other flaws like the lack of a backup bias supply resistor cause the tubes to red plate if the potentiometer fails, which is tube amp 101 design . Finally Willsenton ended up implementing the majority of these upgrades to their own amps after these videos were published.
Have you tried any of the preamps you have on hand using PRE-IN input in the Willsenton R8? I would be curious to see if you see in improvement in sound quality.
Not yet, I'm still working my way through this.
BTW where do you buy your solid core 18g wiring ?
I've just been using this Amazon wire. When the wire gauge is so overkill for the application, cheap wire is fine.
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@@SkunkieDesignsElectronics Hopefully when you create a upgrade kit you can include the twisted wire with the cutout. I dont feel like spending $15 on a spool of wire I will only use once.
I have a question about the twisted pair power wire going to the front panel switch. Usually you twist pairs that have out of phase signals on them so they effectively cancel out . In this case the two wires actually have the same (I assume hot) side of the AC signal going to the switch and then back again. Is twisting needed here? Could it actually be worse? Just curious as i was always taught to twist signa/ground or signal/opposite single (opposite in terms of phase).
Hi what good resistors quality vs price you suggest to have a very good stuff. thanks
Vishay "Pro" series. I use 2W for everything unless there is a need to use something different wattage.
sorry for bother ,please the watt resistors you use in transformer all of them 2w or 3w?
2W vishay PRO2
I figure this amp was made in the same place as prima luna and vincent.The Chinese make knock offs with some different tubes and lower quality parts @ maybe 50% of the retail price or less.
Hi, what wattage are the resistors please?
So far all 2W 5% except the cathode 10ohm, that is a 1W 0.5%
Since this is an amp made in China why wasn't it used and/or tested with your 110 volt power supplies?
Because it has a power transformer rated for 115-120V use.
Hi hun always great to see you. P.S. love the show