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Partial tear down of Willsenton R8


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15 minutes ago, chinook9 said:

 

I would have to go with the R-300B model due to the weight.  Its 32Kg and I'm too old for heavy amps.  I have Tekton Electrons which are 92db efficient but at 4 ohms the 8 watts of the 300b might not do it so I'm thinking about the R8.  Everyone reports great success with the R8 and I think  I could  enjoy tube rolling the R8 and trying the KT88 and maybe 6550 tubes.  I have new production Mullard EL34s in R-35i.  It sounds great

 

Electrons!!! Man, I almost bought a used pair of those in August, but they were a very early pair that didn't have the tweeter array updates. Those or some DI's are on my list for 2021. The R8 and Electrons should pair VERY well. How do you like your Electrons?

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I am not an expert on tube amp like many on this forum however writing this blog to help those who are thinking of buying Willsenton R8 or those who owns it and want to know bit more about it. I am no

It came!!     😲😲😲😲😲😲   Ordered November 22nd.  Arrived January 26th, by ocean.  (I was too cheap to pay the airfreight)    Off we go!  

It's not in its final resting place yet, but couldn't wait to test it.   I'm running all standard Willsenton tubes currently with KT88s   I let it warm up for about 20 minutes, che

2 hours ago, echorec said:

Thanks for the reco! A pair of ECC35's is one the short list. Either Mullards or Phillips Holland, though they are getting really pricey. Currently using TS black glass 6SU7GTY, which are my favorite so far. But I still feel like I want to relax those highs a tad more, hence the RCA Red Base for the next round.

 

Just confirming that the ECC35 was only made in the UK at the Mullard Blackburn plant. Philips and Adzam (Mazda backwards) are all relabelled from Blackburn.

 

The RCA 5691 red bases you are getting are quite analytical sounding in comparison. They are in a sense over militarised around achieving minimal microphonics and noise, and complement a very warm sounding system nicely.

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15 minutes ago, xlr8or said:

The RCA 5691 red bases you are getting are quite analytical sounding in comparison. They are in a sense over militarised around achieving minimal microphonics and noise, and compliment a very warm sounding system nicely.

 

hmmm. It's interesting because I've heard so many opposite or conflicting descriptors of the Red Base 5691 from people with lots of experience. Everything from "laid back, rolled off highs" to "forward, with great treble extension", but more so the former. I guess it is impossible to know for sure until I try it in this circuit with my own speakers.

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1 hour ago, echorec said:

 

Electrons!!! Man, I almost bought a used pair of those in August, but they were a very early pair that didn't have the tweeter array updates. Those or some DI's are on my list for 2021. The R8 and Electrons should pair VERY well. How do you like your Electrons?

 

I had high expectations given the reviews and they easily met my expectations.  I was lucky enough that when I called Tekton they had this one upgraded pair on sale.  I'm not too far from them so they were delivered  3 days later.  That was nice.  I had to wait a month for the R-35i to be built but then shipping was just 4 days.  the wait was worth it.

 

I like the Tektons so much I made some acoustic panels to try and get the most out of them.

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On 20/11/2020 at 11:37 AM, chinook9 said:

Been following this thread with interest. 

 

I have the Willsenton R-35i  and had been considering one of their 300B models.  The cost of 300B tubes has slowed me down however and I am now thinking about getting an R8 to play with.  Yong said in an e-mail yesterday that he can have a unit shipped 7 business days after I order it.  That sounded too good to me so I asked him for confirmation.  If he confirms, I will probably order a unit with the Willsenton KT88 tubes.  I'll then try some tube rolling with the 6SL7s and two of the 6SN7s.

If I were you, I would hold off on the R8 purchase. Moving from the R35i to the R8 is a sideway move, not an upgrade since the difference between those two is $100 (R8 with EL34 is $708, R35i w/o Bluetooth is $600). The coupling capacitors and transformers are probably the same quality. People told me that you only tell a (big) difference in sound if your upgrade is at least one step above, preferable 2 steps.

Wait for Thomas's review of the Doge 10. He already mentioned that it's one of his rare rave reviews, he likes it even better than the Cayin CS-55a. Their preamp, Doge 8, is well-received (google it), and the Doge 10 preamp stage is a variation of it (12ax7 and 12at7). The cost is about $1850 without tariff.

 

 

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2 hours ago, lotoboy21 said:

If I were you, I would hold off on the R8 purchase. Moving from the R35i to the R8 is a sideway move, not an upgrade since the difference between those two is $100 (R8 with EL34 is $708, R35i w/o Bluetooth is $600). The coupling capacitors and transformers are probably the same quality. People told me that you only tell a (big) difference in sound if your upgrade is at least one step above, preferable 2 steps.

Wait for Thomas's review of the Doge 10. He already mentioned that it's one of his rare rave reviews, he likes it even better than the Cayin CS-55a. Their preamp, Doge 8, is well-received (google it), and the Doge 10 preamp stage is a variation of it (12ax7 and 12at7). The cost is about $1850 without tariff.

 

 

 

Thank you lotoboy21.  I haven't pulled the trigger yet and I would prefer something more likely to be an upgrade. Haven't heard of the Doge 10, but I will be reading up on it later today.  Thank you.

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As a tinkerer I'm not keen on the PCB style of the Doge 10, looks like the board would need to be lifted to do part changes to get at the other side.

I'm sure it sound nice though, and if a buyer has no inclination to make changes apart from tube rolling I guess all good.

 

DOGE_10_INSIDE_CARRE.thumb.jpg.fcd68dc0a5b5bfdb0fbf0f318a03631c.jpg

 

 

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That Doge 10  looks really nice, especially the ClarityCaps.  I have opened another thread for the Doge 10 so that this R8 thread does not get hijacked.

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17 hours ago, muon* said:

As a tinkerer I'm not keen on the PCB style of the Doge 10, looks like the board would need to be lifted to do part changes to get at the other side.

I'm sure it sound nice though, and if a buyer has no inclination to make changes apart from tube rolling I guess all good.

 

DOGE_10_INSIDE_CARRE.thumb.jpg.fcd68dc0a5b5bfdb0fbf0f318a03631c.jpg

 

 

Very true. It is a 2 sided pcb (PTH) hence will be more difficult to work with.  All the cables are soldered on the pcb rather than having connectors. It will be a risky task of upgrading caps on this for sure.

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30 minutes ago, Atmaj said:

Very true. It is a 2 sided pcb (PTH) hence will be more difficult to work with.  All the cables are soldered on the pcb rather than having connectors. It will be a risky task of upgrading caps on this for sure.

PCBs .like this are definitely more difficult t work with but I doubt that replacing ClarityCaps would be a high priority for me.

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No idea what series those Clarity caps are, but they make from ordinary to good caps, no idea where those sit.

 

I prefer point to point construction personally, but that thing does have some interesting features if they appeal to the buyer.

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7 minutes ago, muon* said:

No idea what series those Clarity caps are, but they make from ordinary to good caps, no idea where those sit.

 

I prefer point to point construction personally, but that thing does have some interesting features if they appeal to the buyer.

 

The writeup on their website mentions that they are the coupling capacitors and are ClarityCap Esa.  They may be decent but not at all expensive as caps go. Not a big selling point but better than no name chinese caps.  Reviews of this amp use the old name, Prima Donna.

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45 minutes ago, chinook9 said:

 

The writeup on their website mentions that they are the coupling capacitors and are ClarityCap Esa.  They may be decent but not at all expensive as caps go. Not a big selling point but better than no name chinese caps.  Reviews of this amp use the old name, Prima Donna.

I checked the website and this amp has everything "auto", lots of microprocessor controlled stuff, can switch between Class A and Class AB (which is a nice feature though). Complex PCB and layout where turing around the PCB  itself will be tricky task. Runs only on KT88 family so you loose all the mids magic of EL34 family.

 

If something goes wrong with this amp, it will be difficult to repair or may have to replace the whole pcb if control circuit has a fault. Lots of SMD components are there.

 

Sorry but not for me. I would love point to point wired amp and some flexibility to experiment. 

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MIFLIEX caps arrived today with UPS express post. Gosh... they are big and heavy. Won't be able to fit on pcb for sure, will have to do some inventions for installing these.

 

Caps.jpg.611f004a63e6d48f9b6f9e07e7626f55.jpg

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3 hours ago, chinook9 said:

 

The writeup on their website mentions that they are the coupling capacitors and are ClarityCap Esa.  They may be decent but not at all expensive as caps go. Not a big selling point but better than no name chinese caps.  Reviews of this amp use the old name, Prima Donna.

Ah...ESA, I used these in a A400, a decent cap and better than no name caps, I was replacing electrolytic caps..

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57 minutes ago, Atmaj said:

MIFLIEX caps arrived today with UPS express post. Gosh... they are big and heavy. Won't be able to fit on pcb for sure, will have to do some inventions for installing these.

 

Caps.jpg.611f004a63e6d48f9b6f9e07e7626f55.jpg

Yes, 50mm x 30mm

 

Depending on how you mount them you might be able to connect them direct instead of using the fly wires like they do with the stock application.

Make sure those twists stay as they are as I have heard that it can alter the sound slightly if they are separated anywhere.

 

I think the leads are enameled?

Of course the end with the line is the outer foil end.

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The NOS Red Base 5691s arrived today. I was shocked at how heavy they are compared to other 6SL7s. They are definitely "overbuilt". Some first impressions after a couple hours using them with modern Tung Sol EL34Bs:

 

The first thing I immediately noticed was how much wider and taller the soundstage was. Holy cow! The stage extends ~10 inches beyond were it did before on my test tracks and feels taller. The highs are much softer compared to the TS 6SU7GTYs and the GE 6SL7GTs. They are so mellow that I feel like these may not be a good match for the TS EL34B, since that tube already has some softer highs, but we'll wait and see how things change over the next week. Everything sounds very big and lush, but I'm missing the extension of the higher frequencies with this combo. I'm thinking the 6CA7 and these Red Base could be a really good pairing for my speakers since the 6CA7 don't have rolled highs like the EL34Bs. The soundstage expansion is no joke though. I was really surprised in this regard. These might also be really nice with KT88s. I'll try that combo after I've had some more time using them with these EL34Bs. More in a week or so...

 

 

RCA-5691.jpg

Edited by echorec
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3 hours ago, echorec said:

The NOS Red Base 5691s arrived today. I was shocked at how heavy they are compared to other 6SL7s. They are definitely "overbuilt". Some first impressions after a couple hours using them with modern Tung Sol EL34Bs:

 

The first thing I immediately noticed was how much wider and taller the soundstage was. Holy cow! The stage extends ~10 inches beyond were it did before on my test tracks and feels taller. The highs are much softer compared to the TS 6SU7GTYs and the GE 6SL7GTs. They are so mellow that I feel like these may not be a good match for the TS EL34B, since that tube already has some softer highs, but we'll wait and see how things change over the next week. Everything sounds very big and lush, but I'm missing the extension of the higher frequencies with this combo. I'm thinking the 6CA7 and these Red Base could be a really good pairing for my speakers since the 6CA7 don't have rolled highs like the EL34Bs. The soundstage expansion is no joke though. I was really surprised in this regard. These might also be really nice with KT88s. I'll try that combo after I've had some more time using them with these EL34Bs. More in a week or so...

 

 

 

 

Nice write up, I am keen to get your thoughts how they pair up with KT88's once you try that configuration out!

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Ok, now that I've spent about 50 hours with the RCAs, here's my assessment of the Tung Sol 6SU7GTY Black Glass compared to RCA Red Base 5691 when used in the R8 with Tung Sol EL34B power tubes. Keep in mind everything is relative and YMMV:

 

It really comes down to preference - If you like a bigger soundstage, with a more laid-back sound, then you'd probably like the RCAs. If you prefer a more-balanced, fuller sound, that has more soul, then you'd probably like the Tung Sols.

 

In this combination, I really liked the RCAs at first, but feel like their bigger soundstage comes at the expense of being a bit too thin and soft for me. The RCAs also have a bit less bass.

 

The Tung Sols just get everything right for me and sound more natural and balanced. Though the soundstage is smaller than the RCAs, it is not by any means small.

 

Next up is switching back to the KT88s. I haven't listened to them in months, so that will be interesting to see how all these NOS tubes interact with the KT88.

 

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I have replaced Miflex caps in my amp. Currently breaking in and still need to add some resistors and shielding for the protection.

 

Million thanks to @muon* for his great and thorough support in doing this. Will post pictures and review once it is completely done.

 

Watch this space 😉

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@Atmaj I'm really excited to hear your impressions of these caps!

 

I popped the KT88s back in last night. My first thought was - dang, I miss the EL34Bs... KT88s have nice oomph and energy, but sound too dry for me and remind me more of what I think as solid state sound. I really miss the 3D midrange of the EL34B. IMO, the KT88s don't sound great in triode mode vs. the EL34Bs which sound incredible in triode mode. In triode the soundstage loses depth with the KT88 and becomes very flat. Perhaps, all a matter of preference and system synergy though. But it's nice to confirm that I do prefer the EL34 sound in the R8 and that it was not my imagination when I first installed them months ago. I'll still roll the NOS preamps with the KT88s this week and see what happens.

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1 hour ago, echorec said:

@Atmaj I'm really excited to hear your impressions of these caps!

 

I popped the KT88s back in last night. My first thought was - dang, I miss the EL34Bs... KT88s have nice oomph and energy, but sound too dry for me and remind me more of what I think as solid state sound. I really miss the 3D midrange of the EL34B. IMO, the KT88s don't sound great in triode mode vs. the EL34Bs which sound incredible in triode mode. In triode the soundstage loses depth with the KT88 and becomes very flat. Perhaps, all a matter of preference and system synergy though. But it's nice to confirm that I do prefer the EL34 sound in the R8 and that it was not my imagination when I first installed them months ago. I'll still roll the NOS preamps with the KT88s this week and see what happens.

Yeah, same experience with me. After listening to 6CA7 for few weeks I installed KT88 to see how different it sounds and felt the same thing. Put back 6CA7 within half an hour.

 

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Morning / Evening all.  

 

Totally new to the forum and joined as well as purchased the Willsenton R8, as my first tube amp, because of this thread.  So it's on you lot if it doesn't work out for me!  😉

 

I'm quite confused about the advice for tube rolling, and which to roll.  

 

For the 6SN7 in the V5 middle front position.  Preamp Power supply filtering tube.  Some say it doesn't need to be rolled, others say it's the most important.  Which is it?

 

Should I then be rolling the other 2 6SN7 tubes in driver stage, or the 2 6SL7 tubes in the voltage amp stage?

 

I don't mind doing all of them, but I'd like a starting point.  

 

I'll be ordering more tubes before I receive my unit ordered with stock tubes.

 

Thanks ☺️

 

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39 minutes ago, Candan said:

For the 6SN7 in the V5 middle front position.  Preamp Power supply filtering tube.  Some say it doesn't need to be rolled, others say it's the most important.  Which is it?

 

Should I then be rolling the other 2 6SN7 tubes in driver stage, or the 2 6SL7 tubes in the voltage amp stage?

 

Congrats on becoming an R8 enthusiast!

 

The two 6SL7s are the tubes to focus on with the R8, as they will have the biggest impact on sound. The middle tube will have no impact on sound, IMO (I could hear no change). Changing the outer 6SN7s was a VERY subtle for me, but I found myself questioning if I was hearing truly a difference. So, focus on the two 6SL7s and, if you're feeling adventurous, you can try the others. It can be very subjective and system dependent too. In general, the more revealing your system is, the more likely you are to hear the nuances and reap the benefits of different tubes.

 

Down the rabbit hole!

 

Edit: also forgot to say - Listen to your R8 with stocks tubes for several weeks first! There is a break in period with the amp where things smooth out. Then you will have an idea of the R8's "stock" sound.

 

Edited by echorec
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36 minutes ago, echorec said:

 

Congrats on becoming an R8 enthusiast!

 

The two 6SL7s are the tubes to focus on with the R8, as they will have the biggest impact on sound. The middle tube will have no impact on sound, IMO (I could hear no change). Changing the outer 6SN7s was a VERY subtle for me, but I found myself questioning if I was hearing truly a difference. So, focus on the two 6SL7s and, if you're feeling adventurous, you can try the others. It can be very subjective and system dependent too. In general, the more revealing your system is, the more likely you are to hear the nuances and reap the benefits of different tubes.

 

Down the rabbit hole!

 

Edit: also forgot to say - Listen to your R8 with stocks tubes for several weeks first! There is a break in period with the amp where things smooth out. Then you will have an idea of the R8's "stock" sound.

 

Thanks a ton Echorec!  Very helpful info to get me started.  Just the answers I needed!  

 

Once I get the amp (still about 30 days away I guess) I'll report my findings from stock after a hundred hours of burn in or so.  Then I'll look to start rolling the 6SL7s.  

 

It is interesting that when I look at the China Hifi site where I bought it, it's suggesting the purchase upgrades on the preamp side are the 6SN7s upgrades, and keeps the Willsenton 6SL7s.  Which about-faces what you and just about everyone else is saying LOL.   Yong Lee at China Hifi emailed me to say to switch the 6SN7s, but also admitted "he thinks"    

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51 minutes ago, Candan said:

Thanks a ton Echorec!  Very helpful info to get me started.  Just the answers I needed!  

 

Once I get the amp (still about 30 days away I guess) I'll report my findings from stock after a hundred hours of burn in or so.  Then I'll look to start rolling the 6SL7s.  

 

It is interesting that when I look at the China Hifi site where I bought it, it's suggesting the purchase upgrades on the preamp side are the 6SN7s upgrades, and keeps the Willsenton 6SL7s.  Which about-faces what you and just about everyone else is saying LOL.   Yong Lee at China Hifi emailed me to say to switch the 6SN7s, but also admitted "he thinks"    

 

Looking forward to hear your experiences!

 

You'll definitely want to keep your expectations in check when it comes to preamp rolling. The differences between even the 6SL7s are going to be fairly subtle to many ears; mostly small refinements in top end, midrange, or separation. For me, anyway, it requires deep listening. Personally, I've found it is better to listen to one tube for a week or two before switching it to another. My memory of the previous tube's sound seemed to last longer this way and the differences were much clearer at the swap. Also, many tube's sound can change subtly over that first week, so best to just leave them in and enjoy them for at least a week before you swap.

 

Also, where you will notice bigger changes is when you switch between the two power tube classes. If you are getting the KT88s, definitely buy a quad of EL34 so you know what they sound like in this amp, and vice versa. I thought I was a KT88 kind of guy until I tried EL34. I did not expect that. And I'm sure there are some EL34 people that could prefer the KT88. All preference, of course, but you won't know unless you try.

 

More important - Have fun with it! Rolling tubes in this amp has kept me happy during the pandemic. That, in itself, is worth the money.

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2 hours ago, Candan said:

For the 6SN7 in the V5 middle front position.  Preamp Power supply filtering tube.  Some say it doesn't need to be rolled, others say it's the most important.  Which is it?

 

 

Welcome! I'm sure we take full responsibility for your choice=)

 

I hear you and I got confused too. Not too long ago I came across the Prima Luna website on tube rolling and website said that the gain preamp tubes have more effect than the driver preamp tubes. https://www.primaluna-usa.com/tube-rolling

 

Anyway.. I changed it as part of a set from China Hifi. Maybe I should try rolling the middle tube. Previously I always rolled all. 

 

Do try it.. if it works for you. Why not?

 

Edited by 2Dculture
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Thought I'd post up the numerous reviews of this amp in here too. 

It can serve as a good reference for anyone choosing between this and the other talked about and  regarded Tube Amps ...

 

 

 

 

 

 

 

 

 

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I might chime in here and share my experiences on tube rolling power toobs over 12 years now. If in triode mode look no further than EL34's. In UL mode, it's a neck to neck contest between 6550's and KT88's. The 6550's win hands down when it comes to fullness. The KT88 is more extended and vertical in tonal character. As Thomas mentions, once the 3 hole grey perforated plate Tung-Sol 6550's from the 1960's go in there you're in heaven. His quad set is from 1968. There are variants to this vintage 6550 tube including black solid plates with 4 revisions all with different getter configurations, solid grey plates and then the 3-hole perforated plates. These sound nothing like Russian or Chinese tubes.

 

Now something separate to share. The realm of going backwards with tube rolling to get more bass slam is restricted as this is primarily controlled by the design of the circuit topology. I would seriously get the R8 if this feature is inherent in the tonal character of the circuit design by default. You can always work forward with tube rolling and fine tune it if it's too overwhelming to start with.

Edited by xlr8or
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Just pulled the trigger on a quad of Mullard EL34 tubes and a pair of Brimar CV1985 6SL7s.   

 

Guess I'm now on double burn-in duty.

 

Wishing I'd paid for faster shipping now 🤣

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10 hours ago, xlr8or said:

If in triode mode look no further than EL34's. In UL mode, it's a neck to neck contest between 6550's and KT88's. The 6550's win hands down when it comes to fullness. The KT88 is more extended and vertical in tonal character.

 

While I'm not using NOS power tubes (yet!), I've found the same to be true with new production power tubes in the R8 - EL34 = Triode Wins. KT88 = UL Wins.

 

Definitely keen on getting a quartet of NOS power tubes for my collection. Just waiting for the right one to pop up...

 

40 minutes ago, Candan said:

Just pulled the trigger on a quad of Mullard EL34 tubes and a pair of Brimar CV1985 6SL7s.  

 

Nice! Russian "Mullards"?

 

I bought a couple more new production quartets to try in the R8 - Both Russian "Tung Sol" 6550s and "Mullard" EL34s. I've been using the Russian "Mullards" for a few days. I think they sound good and are very balanced in the R8. Compared to the TS EL34B, they are more more neutral sounding, with a tad smaller soundstage. They don't have the richness in midrange that the EL34Bs have, but will match better with a wider range of speakers, IMO (EL34Bs really pair better with metal dome tweeters due to their darker highs in this circuit). While these are nothing like real Mullards, I was honestly surprised at how good they sound. For the R8, I think they are a great starter tube because of their more neutral character in this circuit. Very affordable too.

 

The 6550s should be here next week.

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22 minutes ago, echorec said:

 

Nice! Russian "Mullards"?

 

I bought a couple more new production quartets to try in the R8 - Both Russian "Tung Sol" 6550s and "Mullard" EL34s. I've been using the Russian "Mullards" for a few days. I think they sound good and are very balanced in the R8. Compared to the TS EL34B, they are more more neutral sounding, with a tad smaller soundstage. They don't have the richness in midrange that the EL34Bs have, but will match better with a wider range of speakers, IMO (EL34Bs really pair better with metal dome tweeters due to their darker highs in this circuit). While these are nothing like real Mullards, I was honestly surprised at how good they sound. For the R8, I think they are a great starter tube because of their more neutral character in this circuit. Very affordable too.

 

The 6550s should be here next week.

 

Yes, Russian reissue ones.   I figured for the price, it is was definitely worth grabbing some to get an idea of comparison against the stock Willsenton KT88.   Then I know if I get NOS later, it'll likely be better still.  But at least I'd have heard the characteristic differences.  

 

I'm a bit concerned the EL34s might drive the speakers a bit too bright.  I have Focal Kanta #2 speakers.  The beryllium tweeters are already very forward in mids and highs.  Perfect now with my Rega Ellicit-R, but don't want to add much more.  We'll see!

 

The Brimars are NOS.  Looking forward to those as a pre upgrade to the stock Willsentons too.

 

Let us know on the 6550s. if there's a solid diff between them and the KT88 !

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21 hours ago, Candan said:

I'm a bit concerned the EL34s might drive the speakers a bit too bright.  I have Focal Kanta #2 speakers.  The beryllium tweeters are already very forward in mids and highs.  Perfect now with my Rega Ellicit-R, but don't want to add much more.  We'll see!

 

I think they'll be fine. They seem pretty neutral, so I don't think you'll be doubling down on any aspects, plus you will be "taming" the R8 with the Brimars, which are often described as a being a bit smoother on top. IMO, anything is better than the stock 6SL7s, which by the way, are actually rebranded Sovtek (Reflector) Russian 6H9Cs.

 

Just wait to judge the R8 until it's been run for a few weeks. I did not like it at first because it was too edgy sounding. It smoothed out quite a bit over that period and the soundstage opened up. Some say the caps are being burned in during this time, or perhaps it was the stock tubes settling in, but there was definitely a big change for me. The R8 is now my main amp.

Edited by echorec
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On 14/09/2020 at 9:24 AM, Atmaj said:

I am not an expert on tube amp like many on this forum however writing this blog to help those who are thinking of buying Willsenton R8 or those who owns it and want to know bit more about it. I am not good with ears as Audiophile guys but can provide some technical insight.

 

Initially I was thinking of building my own tube amp as I am a keen DIYer but then looked on the net and saw hype about R8. Pulled the trigger in the hope that it is Point to Point wired amp so if not good, I will enjoy modifying it rather than building from the scratch.

 

Received my amp 5 days ago and first thing I did is that I opened up back cover before even trying it out. I was curious to know the quality of soldering, and the internal voltage switch is correctly set to run on 240V. To my surprise, it was great. I did not have to re-solder any point, all the components used are of good quality, relays and electrolyte caps are of reputed Japanese brands. Coupling caps and Grid bypass cap in driver stage are own ‘Willsenton’ branded but looks good (and looking at the way it sounds, I don’t think there is a need of replacing those with better branded caps or PIO caps). All the components and cables are laid out properly and tied together. The only flaw I found was that the outside sticker displays 240V but the inside voltage selector switch shows 230V. Also, I could not see Capacitor discharge resistor on main filter caps.

 

After satisfied with the build quality, I connected the amp to my system and wow… it sounds amazing and better than my other tube and SS amps. It is dead quiet when no signal and the sound is just clean, open and excellent coverage at both bottom and upper end. While it was sounding great, I found that the outer casing of power transformer was warming up a bit. The casing felt like a thick sheet of metal hence was bit concerned about the actual temperature of the transformer itself. Also, the bias was bit on the higher side when I checked first time which created the doubt that they have actually used 230V trannie and just put the sticker of 240V.

 

However, with these concerns in the mind, I decided to partially tear down the amp over the weekend to check the Power transformer rating, measure all voltages, trace down Schematic and install a discharge resistor on the filter cap. Supplier sent me the Schematic but it was too basic and wanted to confirm that it is accurate.

 

Below are my findings.

 

  1. About 30% of resistor values in amp are different to actual schematic. The capacitance multiplier circuit is also different and there are some typo errors as well. I ended up drawing my own.
  2. Transformers are potted in the casing (which is a great thing) hence did not remove those  as it would require de-soldering of too many connections. However, when measured the heater voltage, it was precisely 6.33V at my home supply voltage of 245V which indicates that it is a 240V transformer and switch labelling is not correct. The potting of transformer also explains that the heat on the casing is a conduction from transformer and not the radiation (which would be in case of hollow casing), so nothing to worry about it. Potted transformers also explain why this unit is so heavy and outer casings feel like made of a thick metal sheet.
  3. KT88/EL34 switch changes the negative Grid voltage to power tubes and calibrates front Bias meter. I was expecting this switch to change the B+ voltage for different tubes but that’s ok, you can’t get everything at such a low price. B+ measures about 440V. This is optimum for EL34 but KT88 would have performed better with bit more voltage of about 500V or more.
  4. The soft start delay circuit does not delay B+ supply voltage to tubes but rather mutes input signals for 30 seconds after turning it on. At least something is better than nothing.
  5. I am not 100% sure about the Pre-IN input but I think it is not directly fed to driver stage bypassing pre-amp section. It still goes through pre-amp and volume control is bypassed to mimic the Power amp only condition. I do not use this input so didn’t bother going into further details.
  6. The designer has taken great efforts to minimise noise in the amp by adopting Capacitance Multiplier using tubes to remove ripples from the supply voltage before it is fed to Pre-amp tubes. An elevated heater supply using virtual ground is also used to heat preamp tubes to prevent humming. 6SL7 are great tubes for audio application but at the same time they are high gain tubes and hence prone to noise and humming. With implementation of these 2 measures, amp is extremely quiet and noise free.
  7. The elevated heater supply circuit also works as a capacitor discharge and no need to add additional resistor on the cap. I measured that after turning off the amp, there is hardly any voltage on power caps within 3 seconds, so it is very safe from that point of view.
  8. One drawback of this amp is that it uses digital circuit for input and TR/UL selection but there is no memory function. If you are using CD as an input source and TR mode, then you do not have to do anything. For anything else, each time you turn on amp, you will have to select the source and the mode. A simple rotary selector switch would have been a better option here.

 

In conclusion, this is a great amp as a value for money. I am not an audiophile and do not own too many amps so I would leave those reviews and comparison for Youtubers but from the technical point of view, you will not get anything better sounding and better-quality product in this price. Looking at how it performs in bottom and top end, I am sure that the output transformers are also of great quality which is heart and soul of any tube amplifier.

 

I don’t’ think spending thousands of $ and buying Prima Luna or something like that will give any kind of added benefits. Just roll few tubes on this and it will shine like those branded amps costing multi-folds. This is my personal opinion considering my own circumstances and others may have different opinion and I respect that as well.

 

As a summary, it is nicely designed for flexibility of tube rolling, manufactured with quality components, built with care and professionalism, very reasonably priced and most important, it also sounds great.

 

Waiting for lock down in Melbourne to open so that I can try some tube rolling 🙂.

 

Cheers,

Atmaj hi. Great job! The R8 feels, looks and sounds quality indeed. I have a question in mind though. When the R8 arrived I immediately enjoyed it and after 3 1/2 hours of listening I noticed something. I'm not familiar with how tube amps work but is the middle transformer at the back of the tubes really that hot? I mean a lot hotter than the two on the sides. It is even slow to cool down. My previous amp had only two transformers and did not heat up that much.

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6 hours ago, Phrangko said:

I'm not familiar with how tube amps work but is the middle transformer at the back of the tubes really that hot? I mean a lot hotter than the two on the sides. It is even slow to cool down. My previous amp had only two transformers and did not heat up that much.

 

The middle transformer is the power transformer for the unit and it's typical for it to get hot. The outer ones are the output transformers; one for the left channel and the other for the right channel. Now you maybe asking yourself how hot is hot. You'd be able to touch it and not burn yourself. If it's any hotter than this then a few things need to be checked including the input AC voltage matching the rated line voltage of the power transformer and the bias points of the power tubes.

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4 hours ago, xlr8or said:

 

The middle transformer is the power transformer for the unit and it's typical for it to get hot. The outer ones are the output transformers; one for the left channel and the other for the right channel. Now you maybe asking yourself how hot is hot. You'd be able to touch it and not burn yourself. If it's any hotter than this then a few things need to be checked including the input AC voltage matching the rated line voltage of the power transformer and the bias points of the power tubes.

What a relief to know. Thanks a lot friend. I'll enjoy the R8 now more freely.

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On 07/12/2020 at 4:34 AM, Candan said:

 

Yes, Russian reissue ones.   I figured for the price, it is was definitely worth grabbing some to get an idea of comparison against the stock Willsenton KT88.   Then I know if I get NOS later, it'll likely be better still.  But at least I'd have heard the characteristic differences.  

 

I'm a bit concerned the EL34s might drive the speakers a bit too bright.  I have Focal Kanta #2 speakers.  The beryllium tweeters are already very forward in mids and highs.  Perfect now with my Rega Ellicit-R, but don't want to add much more.  We'll see!

 

The Brimars are NOS.  Looking forward to those as a pre upgrade to the stock Willsentons too.

 

Let us know on the 6550s. if there's a solid diff between them and the KT88 !

Think you will find that the new production Mullards are nothing like the NOS production ones, the only similarity is the name.

New sensor purchased the names of most of the legendary tube brands around 2000 or 2001.

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12 hours ago, xlr8or said:

 

The middle transformer is the power transformer for the unit and it's typical for it to get hot. The outer ones are the output transformers; one for the left channel and the other for the right channel. Now you maybe asking yourself how hot is hot. You'd be able to touch it and not burn yourself. If it's any hotter than this then a few things need to be checked including the input AC voltage matching the rated line voltage of the power transformer and the bias points of the power tubes.

Another one for you or Atmaj. My R8 is fairly new. It is true my hand does not burn when I touch it for a period of time. After switching it off how long should I expect it to cool off? The smell like paint coming from the R8. Is that normal? I noticed it out of the box as well.

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