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Fully agree with you!

Hi, Is it possible to use bypass caps in an amplifier to increase the sound quality?

Me again, for the iec connector, are you wiring the line and neutral reversed intentionally, because it seems the neutral is wired for the fused terminal. I'm just about done!!

335 / 5.000 Hello everyone! I also bought this clone. I have to clearly disagree with your description. The clone is, I emphasize, the best in terms of sound that I have ever heard. Unfortunately, however, the power is only enough for a little more than room volume. I can only recommend this clone for sound fanatics (like me)! 🙂

IMO if you want to really test the OPT alone and not the amp, you should use a low distortion Cl. AB amp and connect it to OPT's secondary through a power resistor equal to nominal secondary load, and then load the primary with resistance equal to the tube's plate resistance.

I went with worlds best cables and so happy. Mainly to have good RCA connectors that lock. And hey they look good also. They are kind of like garnishing.

what a difference

Just got in a R8. Which sound signature would you prefer between EL34 and KT88 for it? I usually like detailed sound with strong bass so not sure if the EL34 would be strong enough. Thanks.

Thanks to this video, I was finally able to fix my ringing problem. Even though the frequency response isn't flat to 30KHz, it's only 1.2dB different from 20Hz to 20KHz.

@Skunkie. Happy to see you got back on this amplifier and shared the mods and testing! I had come on a bit late and I actually viewed the video with the transformer upgrade first and it did seem that is probably just best to stick with the original transformers. So then I came here and looked at the mods. Great video! After watching both videos, I would say that if I could get the amp for around $350 to $375, then I would go for it myself and do the mods here. But lately I have seen it between $425 and $550 and that is a bit much. Also, I am curious that if there is an alternative preamp to use as I prefer a glass tube over a metal one.

@Skunkie VERY interesting results with your testing! It did go inline with my thoughts and I had figured that with the enclosed transformer from Edcor that you would get a jump in performance. I was very curious about the open core transformer, but when you mentioned that transformer was more for guitar amplifiers, my hopes were a bit dashed and your tests confirmed that. Further, I am lead to believe that the original transformers in the amp were probably meant for guitar amps given that the performance between those and the open core Edcors were similar. So, yeah, I agree that it would be best to stick with the original transformers and just do the mods to the amp. I would say that if I could get the amp for around $350 to $375, then I would go for it myself. But lately I have seen it between $425 and $550 and that is a bit much. Great video and thanks for sharing the test results!

@Skunkie. Very interesting testing around the 12AU7. I didn't know that this tube had issues with microphonics. But then again, I mostly see it lower gain applications, such as follower stage or splitter. Nice to see that your testing revealed the new PSVANE Horizon 12AU7 to be a good tube to compete with the NOS tubes. Now, I have a question for you. What are your thoughts if one was to build your color preamp, but to use 6SN7's instead? I have a boatload of these and would be curious to how they would perform in the role of the color preamp. I also like octal tubes better :).

In my experience SS amps with high negative feedback also do not sound right.And they also tend to mask the good quality of a tube preamp.I used a Supratek 6SN7/ 300B preamp for 14 years that could sound gloriously tubey with some SS amps but less so with others .Anything designed by Nelson Pass let the good stuff through.A Musical Fidelity A5 and Rotel Michi did not so much. I also had an Almarro 318B SET which used 6C33C tubes .I got a friend to install a variable negative feedback selector in it that gave 5 different settings .I think all tube amps should have those.On most speakers just a hint of negative feedback sounded best .The factory setting actually had too much for my taste and speakers and zero was too euphonic and bloomy .If you apply too much the soundstage noticeably shrinks.I think you get that same effect with SS amps although the differences are less obvious.Nelson Pass has spoken about that.

I had no doubt 🎉💪

Taking about component skimping. I have seen a review that showed the only difference between an entry level Prima Luna pre amp and the next model up is a capacitor upgrade. That's one big reason why I think my entry level Prima Luna amp has a less than ideal output transformer, besides the muddy sound and mushy rolled off base. My "12 watt???" Cheap Chinese amp is staggeringly more punchy and much louder base than the 40 watt Prima Luna. And that is using the same output tubes. I must say though despite the mushy sound. I still prefer to listen to the Prima Luna than any transistor based amp I own. Even though I know details are missing. it is still more pleasant to listen to music and closer to real life sounding. When I get around to upgrading those transformers, I will have to do a video about it. I wasn't sure to sell the amp or try upgrading the transformers, but this video convinced me to investigate a transformer upgrade further. Thank you 🙏

Love your channel ❤ Hoping you might consider making a small 2a3 amp with a passive volume control making about 2_ 3 watts per channel. Kind of similar to that Don Fi 2a3 amp from the early 2000s.

I have to get the Analogue discovery now. I have a bottom of the range Prima Luna and I am certain the transformers are rubbish. It's the only explanation why this amp sounds so wishy washy. Inside the circuit design looks very good. It even has direct coupled input to driver stage with no capacitor. I also have a cheap Chinese SE amp that sounds best in triode mode but probably only getting 2 watts in triode mode so that will be getting examined and upgraded. Basically I have two amps that don't sound quite right. Thank you for your inspiration to dig into these amplifiers.💜

At the very least consumers should be informed enough to know that there is such a thing as an FTC rating and that if the product doesn’t have one, they might have second thoughts.

On the Muzishare x7 amp. do you have any idea on the main transformer temperature should be when using a Digital IR Temp.gun after a few hours of playing music? my Muzishare x7 middle transformer was very hot to the touch after playing music at very low volumes for 4 hours. the bias was checking good. thank you...

I built a EAR834p clone. I scratched my head about loading of the MM cartridge. That required 47k and a capacitance of 200pF to 300pF. The phono lead could account for 125pF, but what did the phono input contribute? Studying how to calculate the Miller capacitance for a stage with a gain of about 50x gave a figure around 100pF. For a circuit with passive equalisation that would be it. Simulation of the circuit showed the gain of the first stage was only about 5x. This is because the feedback is summed at the point between the anode of valve 1 and the grid of valve 2. This reduces the voltage gain of the first stage. This in turn reduces the Miller effect by the same proportion. So the input capacitance is of the order of 15-25pF. Clever that! So strapping a 100pF across the 47k load gives me a cartridge loading of approximately 250pF. At last I can close the box.

You may be able to form a class against U.S. resellers of the product, but good luck suing anyone who is in China.

Have you already closed your auction question? Thinking about that. R8

Great advice 👍

Boss Audio: 4x inflated power. Chinese no name? 3x easy. Car audio? 2-3x on avg less than MAXX PowA!!! u know what this reminds me of? Mr. Beeny from New Zealand. I miss him.

It's about time they took action on this. I've been complaining about this forever with tube amps. Some manufacturers can only meet their power specifications at 10% THD. I do know that John Atkinson at Stereophile measures tube amps at 1% THD and consistently finds tube amps that aren't even close to their power out claims. The other problem are speaker manufacturers that are fudging numbers on their sensitivity claims. This nonsense has to stop! Manufacturers have to stop being deceptive!

Current runs along the outside of the wire not through it.

Glad to see some kind of regulation on power ratings. I wonder if this will apply to pro PA amps. We have the same BS ratings to deal with in the live audio world.

Question - if I were to switch the volume pot to the input with no pot on the output are there any changes to the components on the schematic? Thanks.

Hi there, Stephe. Quick question for you, if that’s ok. Why do you stick with the Alps stereo (I assume 100K) volume pots? Are they just the best sounding to you? When I built my Elekit 300B amp, the pot that came with it was awful. I tried a few others like TKD, EIZZ, Audio Note, and Alps. The TKD sounds best to me, but that was also years ago. There’s a couple I can’t recall off the top of my head, but because a volume pot in a SE class A amp is basically attenuating the signal rather than increasing gain, it’s obviously an important part. Thanks ahead of time, Stephe. 🔊😊🎶

Your`e a wizard Steph ! Very impressive .

I got one of the "clone" EAR834's from China. The one that comes with the power supply separate from the the preamp board. It wasn't overly expensive, but I found it to be virtually silent even at idle. So much so that I have forgotten to turn it off a couple of times.... About the only thing I found with it that I needed to change was just some of the capacitors in the audio chain. Like a lot of clones, the components chosen were not the best quality

Any reason not to use shielded cable with drain wire at the phono input side as well?

I have sx52b in my ao7max, deeper soundstage, more separation.

Reminds me of when I was a kid in the 70’s going into department stores and seeing Lloyd and Electrophonic all in one stereos rated at 100 watts per channel.

For the last 10 years there has been the AD-1 Amp Dyno. Mostly used to test car audio as that is where it originated. It measures Certified= 1% distortion, to Clipping and Dynamic Burst= simulates music with a burst at 40hz or 1000hz. People still get confused because this is testing the amplifiers maximum potential, not what an amp puts out while playing music. The AD-1 amp dyno has set a new standard for testing.

Looking at the pictures and dimensions, the GXSE 15-8-5k might just fit.

why don;t they just have a B version with the op amp already installed

I am building this amp now and I never cease to be amazed at you knowledge and skill

Really like and have learned from your channel!

How about addressing the power ratings of HT receivers. Claiming, for example, 70 watts per channel. However, it can only do that with one channel driven. If you drove all five or seven channels simultaneously you’d get half that power out of each one channel. The power supply has the voltage to drive one channel to the rated output but, not the current to drive all channels to that rating. The supply voltage sags and you get a lot less than one channel.

Hi stephe on your shematic circuit you have 12au7 and the supply shematic you have 12ax7 which you use cause its not the same amplification factor( the u ) 12au7 has 20 and 12ax7 100 its not the same ,so why put a pot on the ouput to rise impedance ,normally we create a desigh to lower impedance ,i think its not logical.

I just wanted to thank you for making these videos. Obviously a lot of time and effort is involved in making these quality videos.

Hi Stephe.. I know your feelings about Parafeed (band-aid..), but in this case it might be worth a try, if you are ever you get curious.. If you could measure the stock OPT inductance the parafeed film cap value ballpark calc usually gives good results.. Regards.

Really interesting. Thanks!

WHAT? How the h*ll can anyone design an amplifier so badly that it only delivers 1.5 watts with a mains transformer that big and output transformers that look capable of 10 watts?

Interesting comparisons. I would have loved to see how the ISO iron would compare. The ones I have provide excellent bass response.

curious about the app, where do you find it?

Hi, im trying to watch almost all your vids since i want to get to a point where i can build my own tube amps. I found it quite funny how much u think power cables are snake oil, they are defintely overpriced very often. I with my own ears hear a clear difference between power cables and they can be diyed way cheaper aswell.

Any plans for 6L6 amps..?

Yet the same Tube Brand..... made in Russia.. I have found various tubes made in Russia 30-40 years ago, which I have many of... work far better than Russian tubes made today, especially tubes that never existed even 10 years ago...like KT120's...