Willsenton R8: Replacing the Front End Components

In this video I am replacing the resistors and the tail cap on the driver and phase splitter tubes. No real mods or changes to the circuitry being done in this video, just installing higher quality parts!
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.
Edit: Thanks to "CohibaJoe" for pointing out I got confused installing the film cap and yes when used as a normal coupling cap they are installed "the direction of the signal", when used on the tail of this phase splitter, the short lead (outer foil) goes to ground.
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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[@VintageStereoCollectorChannel]

Excellent vid! We really appreciate your dedication to this R8 project. Your research, analysis and approach to what needs to be done at each phase. Lots of effort on top including recording, editing and interaction with your subscribers. Two thumbs up👍👍

[@SkunkieDesignsElectronics]

Much appreciated!

[@crimsonghost6454]

These videos are great. I'm curious to see how this upgrade in parts will change the sound or performance . It's awesome that you measured it first so there can be a comparison. Either way I can't see a negative with using better quality parts. Thank you for doing this series.

[@bootstrapjesse]

Fantastic! Watching all the R8 vids on your playlist in one sitting. So amazing, so much to learn!

[@claretlover1]

I have no idea what you are doing but it is just wonderful to experience your knowledge and watch your skills in practice. Thank you! I have a modest system with a Chinese matisse preamp and it sounds great to me.

[@joesapereira5539]

Another Great video. Thanks Stephe, really enjoying how this is coming together. Looking forward to the testing to see how these changes are affecting the performance. Keep up the good work.

[@johnkimpton5100]

Discovered your channel a few weeks ago, am now hooked! Linked it to a good friend that was in the audio business and he was impressed as well. So much of this community is drawn into the hype of marketing. Particulary enjoyed the 'rant' on speaker cables and interconnects, agree whole heartedly. My significant other was immediatly impressed on many accounts, she almost wept with understanding the dilemma facing women as a whole. We see that every day unfortunately. Continued success!

[@SkunkieDesignsElectronics]

Welcome aboard!

[@ja8020]

Great content Stephe. Keep the videos coming and let’s us know the sonic difference your hearing.

[@toddhupp]

the phase splitter is really the heart of the amp.last stop before the power tubes.I noticed a difference using better GL tubes in detail resolution.

[@richardbradley6229]

Brilliant video series, great pace, filming and explanations.

[@dtg474]

Another great video Stephe. I'm very curious to see what the audio analyzer suite shows.

[@cobar5342]

Thank you for yet another great video. You are becoming a national treasure!

[@SkunkieDesignsElectronics]

Wow, thank you!

[@cobar5342]

@@SkunkieDesignsElectronics and I am in Australia. Soon you will be a world star! He he

[@anhdangduc1061]

I can see the big caps bag on your right haha. Looking forward to how you would split the channels.

[@igormoh6888]

The time flew by)

[@brycejeannotte7699]

I am really enjoying this series and trying for follow along the best I can. I had a question about the 22K 3 watt shared cathode resistor on the 6SN7. The vendor has said this should be a 5 watt unit. Is that overkill for this resistor? What sort of voltage is on pin 3 and pin 6 of the 6SN7?

[@SkunkieDesignsElectronics]

5W is way overkill IMHO as it has 1W going through it. Pin 3 and 6 is 145V, across a 22000 ohm resistor is just under 1W at .955W. 3X over is more than enough using a quality film cap.

[@brycejeannotte7699]

@@SkunkieDesignsElectronics Much easier to find 3W film resistors too!

[@boborman5537]

Really great job❤

[@kevinmonceaux2101]

With the circuit board they used in place of a tag strip, in the video it looked like the trace was on the bottom side. If so, after the components that were sticking through the board to the trace were removed, without inserting the new components through the board and soldering them from the bottom side to the trace, how does one know they have a good connection to the trace? A better question would be, why didn't the folks who built the amp turn the board over so the trace would be easy to get to when replacing components?

[@UptownReef]

Anyone else waiting PATIENTLY for the next video in the series!?

[@richardbradley6229]

Love my R8. Would you be able to explain how the headphone output operates, is it taken from the preamp stage ? Are there any mods that would improve it as i beleive its the weakest part of the amp.

[@SkunkieDesignsElectronics]

I will when I get to that part of the mods.

[@radicalaudiodesign]

Many thx again 😍

[@dennisjames7611]

Thank you Great video!

[@johnkal8403]

Another question, why change the cap to a 450 volts when the original one is 630 volts? I thought we should always increase voltage instead of decreasing it.

[@SkunkieDesignsElectronics]

There is less than 300V on any of the film caps. 630 is over kill by 2X. if we are talking about that .33uf one, it only has 133V on it.

[@huntercoleman460]

How long did this take to do?

[@SkunkieDesignsElectronics]

Had to say given it takes so much longer trying to keep everything on camera etc.

[@pguttad]

Hello increasing the capacity of the capacitors 0.22 and 0.33 with 0.33 and 0.47 can be a good idea to increase the low tones...or not? thank you

[@SkunkieDesignsElectronics]

Possibly? But looking at the frequency response curves, that doesn't appear to be a problem.

[@pguttad]

@@SkunkieDesignsElectronics OK thank you

[@pguttad]

maybe even more...

[@PGHJR002]

How do you know the difference in quality between resistors, by reputation or price or something else?

[@SkunkieDesignsElectronics]

It's hard to go wrong with those Vishay "pro" metal film resistors for audio work. There is a point where some of those high price ones are just snake oil

[@toddhupp]

yes Skunkie those resistors look like real junk.This amp will sing when you get done-and last!

[@SkunkieDesignsElectronics]

One of my main goals is reliability. I'm actually considering replacing that bridge rectifier too. I've read a few people saying theirs went out.

[@MrGleb1966]

Hello. I have the Mc2 model. Is it necessary to do this work on my amp?

[@SkunkieDesignsElectronics]

No need to do a lot of this, but I do thing doing the "dual channel" thing to the 6SN7 makes sense.

[@earlgreen1720]

I would be interested to know how the old resistors measured, were they in spec and how old is this amplifier?

[@SkunkieDesignsElectronics]

I didn't measure all of them, but a few were clearly off by 5-8%. This amp is only a few months old.

[@trevordoeseverything219]

This lady is impressive af

[@adriang.4604]

Hi. Nice videos! I did not get the resistors on both video time first at 8:30 to 9:20. And 2nd at 11:48-12:40. Pls let me know. Im new here. Very interesting. Thanks

[@SkunkieDesignsElectronics]

At the end of the series I will be posting a BOM. in the meantime I posted a schematic at my site.

[@stephencosta6814]

I❤you lol the best

[@wowyummyyy]

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