Stephe is spot on! 2 days ago, one of my 274B tubes arced and put on a purple light show of biblical proportion. learned a lot from these videos. Thank you for sharing your knowledge.
Thank you so much for the series on this amp. I bit hard and bought one of these amps. So I'm very interested in your mod results. I've tube rolled using the Western Electric 300B tubes but funny, I too didn't trust how close to the rectifiers they sat so I put the stock tubes back in. BTW, the Western Electric tubes did improve the sound quality quite a bit. Now I need to open the amp to figure out what version I have. I have fallen in love with your channel. Straight, no BS content that is really easy to understand. Thanks again!
Really do appreciate your series on this particular amp. I was surprised at your assessment of the amps inner electronics considering the rave reviews this amp has received. That all being said I am fairly interested in purchasing one of these units but I'll wait until you finish up your exploration of "fix" potentials. I am not an electrician but I do follow your explanations with interest and intrigue. I love your down to earth "the-way-it-is" assessments ... no BS, no hype.... just the facts. Keep up the good work. 🇨🇦
What a coincidence! I am dealing with a situation where 5AR4 are arc’ing due to a lack of resistance between the PT secondary and the rectifier plates. So, do yourself a favor and check that you have ~150 ohm before each plate if you plan to run them at 425V.
Interesting. I'm still learning about how to keep rectifier tubes happy at higher voltages and currents. I am curious what brand of rectifier you are having issues with? I've had JJ tubes do this but not higher quality ones.
@@SkunkieDesignsElectronics I have had it happen with Sovtek, Linlai and Psvane. They are made to the same specs with varying levels of care. But the NOS datasheets all have something called “minimum limiting resistor per plate”. Transformer secondaries used to provide enough resistance to satisfy that requirement because they were wound with higher-gauge wire. Modern transformers are wound with “very efficient” wire, which gives much less DCR on any of the secondaries. Hence arc’ing rectifiers. It’s quite sneaky too. Depending on the quality of the rectifier, it could arc on the first power on or 3-6 months down the line.
I got mine in November of 2022. It came with 5U4G tubes. It developed a hum about 3 months later. China HiFi said there was a bad batch of those tubes and within a week sent me some 274B tubes. In the interim I bought NOS JAN Phillips 5U4G tubes from my local Tube Depot. To date, I haven't had any issues with the amp. I never even tried the 274B tubes. Hopefully I won't need to. I love this amp and it has more than enough power for my old Klipsch Forte II speakers. I'm retired and I listen to this amp more than 4 hours every day. For me, it sounds fantastic and has proven to be very reliable so far. I let it warm up at least 30 minutes before use.
Glad it's working for ya. That doesn't change the fact that cap is hugely oversized and is hard on rectifier tubes. Please do not ever put those 274B tubes in it!
Many thanks for this next episode in the Willsenton R300 serie Stephe! I have a version without the delay board, with 274B rectifiers. I just checked the PSU board, only 100uF 450V caps. Really looking forward to your upcoming content, and to modify along 👌
Really appreciate your channel, I bought one of the preamps from your recommendations in another vid... sorry you'd been getting the negativity about this amp. One question if you may help, I actually have this version too as marklabee and came with 274b with no delay board and 100uf 450V cap, I am actually in Hong Kong and have had this amp since April and haven't had any problems with the 274b yet, but I did try your vid suggestion with swapping 5ar4s, but I honestly like the 274b sound more, is it possible that my version being in Asia which is 220v has a different way of affecting the amp? Sorry I know nothing about electronics and tube amps design and its also my first 300b tube amp that I actually really like after I tubed rolled and feel I found magic with it.. (with cv181-tii and a nos slvania 6sl7 and shuguang 300b -98 brown base plus stock willsenton 274b, so far is the magic combo)... May I ask, if I want to stay with 274b and not worry since I haven't had any problems so far, is it okay or is it still better for the amp and all inner components inside to use 5ar4 tubes and bias to the left 1 click as you suggested in your later video? thank you very much for your informative channel 🙏🙏🙏
Thanks for the wonderful demo. Seems that the 5AR4 + delay board might give the filaments an extra margin of warmup time, before the softer B+ rise....Thanks again!
Stephe, I'm not sure the designers at Willsenton in Zhuhai aren't avidly watching your videos and your mods wouldn't be adopted in their newer releases of R300s !
Sorry, my dear, didn't mean to offend you. Of course you understand the economics of your unit and you're entitled to charge whatever you choose for your time and skill; however, I was just sharing my thoughts on making an irresistible offering, like the Wilsenton people. Maybe that's why they can afford to produce such bargain pricing on their offerings, because they take short cuts with the components and the craftsmenship inside their amps...but they SELL a lot of them.
Those Gold Lion 300B’s work fine in my Elekit TU-8900 amp. I’ve heard a lot of different things about Wilsenton amp. I think you’re onto something when you mentioned the different manufacture of the same model.
Maybe the first 100uf cap is the large one and has a higher ripple current rating .....If I had one of these, I'd do your 47uf/choke mod and I'd measure the idle current with a multi-meter. I wonder how much the idle changes with line voltage?
Thanks Ms. Stephe again for doing these videos. My R300 has Willsenton brand 5U4G rectifier tubes. I thought about replacing them with NOS RCA 5U4G’s but maybe I should go with the 5AR4 you recommend but I have to admit I’m confused about these nomenclatures. 😢
Hi ! I have this amp and I'm using Rca nos 5u4g in it and the sound quality is even better than stock 5u4g but after to watching this videos I definitely gonna make this mods
@@cdpepe1000 Thanks for that info. If I can get good prices on both NOS RCA 5U4G’s and on some 5AR4’s I might try both as long as we’re not talking about the same tube with just another name/nomenclature.
I only buy tubes from a trusted source. Yes you pay more but I know what I'm getting!!! worth it.... I could not agree more on your choice of Rectifier tube for this amp and yes, looks better to me too... The reason for the two caps, I'll assume in parallel, is for better drain...
try some WE 422A's, I use them in a Geartz Hybrid (Shotky Diode) configuration for my self built WE 437A / WE 300B in a Lofton-White (stacked power supplies) topology. A recitfier for each tube. 4 total for my dual monos.
The original WE274B rectifier was the standard choice for a 300 WE tube amplifier........ Input capacitor max was 4µF ! With choke input .........min value = 3H Usefull current as indicated by WE was equal or below 70 ma........ This amplifier was certainly NOT designed for use with 274B rectiifiers ! The 274B can be replaced by the 5U4G rectifier... In this amplifier the GZ34 may be indeed the problem solver ...... No copy of a WE 300B ever comes close to the quality standards and lifetime expectancy of the original....... Best way to use a 300b or any other tube amplifier is to build one amplifier yourself as does Steph in his videos.
That's another option, downside is the heat they generate inside the chassis and don't think the voltage ramp up is as soft as a 5AR4 or another indirectly heated rectifier is.
love this 🙏 i'm not sure which version i have but would you recommend swapping out the 274B regardless? and which 5ar4 tubes should i pick up - are those the genalex ? thank you !
Thank You! Content I learn from. Does the rectifier tube clear up the entire sinus wave or only half of it? I remember at least one tube amp manufacturer to use 4 rectifier tubes in a bridge circuit, but seems like I cannot affort them.
A full wave rectifier clean up the AC just as well as a bridge does. And a single rectifier tube can do full wave, not sure why this amp uses two with the sections in parallel.
Hi Steph. I will be following along and will implement your mods in my R300, which I've had for about 3 months. I did all your mods on my A10 and still sounds great! Thank you for that! Back to the R300, I upgraded all the tubes except the two 274b stock rectifiers. I recently noticed one of them burns bright orange while the other does not. When I swapped them I discovered it is the tube itself. Not sure if it was always a bad tube or a result of what you diagnosed. Either way I now have one bad tube for certain. I cannot detect any audible change in the amps performance. I have some 5AR4s that I installed and adjusted the bias accordingly. I will open the amp to see if there is any obvious damage to the circuitry. Unless I find some obvious burnt components inside do you think it is ok to run it as-is until your complete modification/parts list is available?
@@SkunkieDesignsElectronics Thank you so much. I upgraded the coupling caps recently, so I've already voided the warranty, which is fine as I enjoy tinkering and I'm reasonably proficient with basic electronics and soldering. Also I learned a lot following your instructions on the A10. While I had the bottom off looking for any burned components (didn't find any btw) I realized apparently my unit does not have the delay board. Also no resistors on the rectifier tubes and the silicone diode is only on one side. Interesting. Looking forward to your videos on all this. Thanks for all you do!!!!!!
Can I ask if I just need to remove the 274b and replace it with the 5AR4, do I need to edit anything further? sorry I'm not very good at amp tube, thanks a lot
See the next video. While just replacing the 274b tubes with 5AR4 tubes helps, a lot depended on the version of this amp you have if this will resolve the issues. There are at least 3 different version of this power supply that I have seen, some are worse than others.
