Nobsound 6P1 Revisited: Fixing the Power Supply

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Nobsound 6P1 Revisited: Fixing the Power Supply

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Күн бұрын

We are going to revisit this popular made in China vacuum tube amplifier. I want to show in detail how to do some minor changes that transform the sound and performance. I also will show the testing that proves they work.
This second video is showing you how replace one of the filtering capacitors in the power supply and adding a bleeder resistor, as well as explaining why.
The very first video on this channel was on this amp, and since that time I've learned a lot about not only tube amplifiers, but also about video production and how best to show how to do mods on tube amps. I now have better test equipment and some new ideas on how to possibly get even more performance out of this fun, cheap little amp so stay tuned!

Пікірлер: 53

@joemartin6439 Жыл бұрын

As usual you are marvellous in explaining what to do

@SkunkieDesignsElectronics Жыл бұрын

Thank you so much 😀

@rickg8015 2 жыл бұрын

Some Cary amps from the past have this issue.. Very high value (uF) input cap for a tube rectifier..

@randywells5477 Жыл бұрын

Nice job. Not understanding why a large value input capacitor is a problem. The inherent nature of the tube rectifier makes it a soft start. I would think the large value capacitor would help the overall bass and transient response.

@SkunkieDesignsElectronics Жыл бұрын

It's because of the way a tube rectifier works. It's not the startup that is an issue, a large first cap reduces the window of time for current to be drawn through the tube, which spikes the load and kills the tube. This is the reason the tube data sheet specifies the max value of this first cap and not the others. Also the second large cap will provide any current storage needed.

@randywells5477 Жыл бұрын

@@SkunkieDesignsElectronics I apologize for asking before I watched the whole video. Are you saying if I were to put a milliamps meter on the output of the rectifier tube, I would say much higher current drain With a much larger capacitor? I’ve never had a reason to try this.

@SkunkieDesignsElectronics Жыл бұрын

No, and honestly this is too hard to explain in a comment, I'll make a video about this as people don't seem to understand what is happening.

@hyperion8008 2 жыл бұрын

I did this mod today. I used a 47uf because that's all I had (nice Nippon one sourced from an old server PSU). I guess it's better than what was there before. I also replaced the horrid blue LED with a more fitting yellow one.

@SkunkieDesignsElectronics 2 жыл бұрын

That blue LED is HORRIBLE! lol

@KRAFTWERK2K6 2 жыл бұрын

swapping blue LEDs to amber / yellow ones is basically self defense at this point. Definitely just as important as the power mod.

@AndrewBPowers 2 жыл бұрын

Thank you very much... very well and understandably explained!

@cau8365 2 жыл бұрын

Thank you, very well explained and executed.

@ofiroman123 Жыл бұрын

Thanks for this video!

@joemartin6439 2 жыл бұрын

You think with great knowledge thank you so much

@quad1000 2 жыл бұрын

Great explanation. You should teach.

@NuttySwiss Жыл бұрын

Does it make sense to use a 4.7uF cap after the rectifier, followed by a dropping resistor, and then another 47uF cap? To drop the high voltage from the 110v TX a bit and further smooth out the B+?

@SkunkieDesignsElectronics Жыл бұрын

That's not a bad plan.

@JohnScheppler 2 жыл бұрын

Great job

@joemartin6439 Жыл бұрын

Sure like to buy the amp but do no soldering could you please in a KZfaq all the changes need to mak this a perfect class a tube amp

@zefrog7482 Жыл бұрын

Can I ask what those silver thing's to your right are? The aluminium looking thing's with the angled ends?

@SkunkieDesignsElectronics Жыл бұрын

Those are 8 ohm dummy loads for testing.

@zefrog7482 Жыл бұрын

@@SkunkieDesignsElectronics nice, looking at them they seem well engineered, another of your creations I'm guessing.🙂

@SkunkieDesignsElectronics Жыл бұрын

Nope, amazon. My only addition was some banana plugs with a copper lead for attaching test leads. amzn.to/45iXYjL

@Iam-mad Жыл бұрын

Dear Skunkie, I have the Nobsound "Mona" EL34 tubeamp, which is identical to the 6P1, but it uses each channel 1x EL34 instead 2x 6P1. Inside everything is wired similar, but the two big blue caps are even bigger, they are 450uF..! I wonder if I should try to replace the first with a bit higher value, or should I go for 22 uF as well? Thank You for Your great explanations, and best regards from another Leica User!

@SkunkieDesignsElectronics Жыл бұрын

I would use a 22uf with this rectifier.

@Iam-mad Жыл бұрын

@@SkunkieDesignsElectronics Thank You! I will try and share my experience then later!

@frankgeeraerts6243 2 жыл бұрын

Even well respected brands make this mistake , .....!!!!! And audiophiles love BIG capacitors !......but the principle of correct filering primes on the value of these capacitors ! And there even other reasons with have an important impact on the " musicality " of amplifiers !

@SkunkieDesignsElectronics 2 жыл бұрын

But you can't fudge like this on the first cap after a tube rectifier and expect them to live. And these regularly eat rectifier tubes!

@califmike2003 2 жыл бұрын

Liking your channel and im new to tube amps. Is there a amp you have come across that sounds good and needs next to no work for $600 and under ?

@SkunkieDesignsElectronics 2 жыл бұрын

Not that I know of.

@randywells5477 Жыл бұрын

Find a used Dynaco Stereo 70 Or one of the clones that are being offered today. Far superior.

@jefflouey6318 Жыл бұрын

What size bleeder resistor should I use?

@SkunkieDesignsElectronics Жыл бұрын

470K 2W is a good size to use.

@jefflouey6318 Жыл бұрын

Thanks Skunkie. ❤ your videos.

@Warclock07 2 жыл бұрын

How hot do you think it's not good? I have 110v PT too that runs at 120v, the temperature is around 95F where I can touch with my hand without problem. It's kinda warm. The reason I run at 120v is giving filament for 300B at 4.8v instead 4.5v at 110v.

@SkunkieDesignsElectronics 2 жыл бұрын

I think you are talking about a different amp, this one doesn't use 300B tubes. If the heater voltage on the tubes is correct, then everything is OK.

@Warclock07 2 жыл бұрын

@@SkunkieDesignsElectronics Yeah it's my used 300B with 110v PT. And I think it has been used with 120v for a long time since this amp probably 12 years old. We are in US so it's a standard 120v and I don't want to use variac. I wonder how hot of that amp you're working on.

@hyperion8008 2 жыл бұрын

You could use a cheap and effective bucking transformer. We have the same issue in the UK. These come from China wired for 220v, but ours is 240v! So a bucking transformer is a must. I actually used an old 24v output Christmas light transformer. 240v in, about 215v out when wired in buck mode. So slightly under voltage but better than 20v over voltage. Amp works fine.

@frankfrank9711 Жыл бұрын

How does this thing sound?

@SkunkieDesignsElectronics Жыл бұрын

If you only need 1W of power, they sound good. Otherwise, look elsewhere.

@raiderxx Жыл бұрын

Where do you source your capacitors?

@SkunkieDesignsElectronics Жыл бұрын

www.mouser.com/ for most of the larger power caps and www.partsconnexion.com/ for the specialty audio note and mundorf ones.

@raiderxx Жыл бұрын

@@SkunkieDesignsElectronics thanks so much!!

@raiderxx Жыл бұрын

@@SkunkieDesignsElectronics Thanks!!

@ranbymonkeys2384 2 жыл бұрын

How do you feel about replacing all of them caps with Nichicon or something along those lines?

@SkunkieDesignsElectronics 2 жыл бұрын

I replaced all of them in my personal amp.

@ranbymonkeys2384 2 жыл бұрын

@@SkunkieDesignsElectronics Nichicon, Elna, what are you fan of I bet you used a film cap for that 22uF too didn't ya?

@SkunkieDesignsElectronics 2 жыл бұрын

@@ranbymonkeys2384 Nichicon lytics are fine. But used audio grade ones for the cathode bypass ones.

@ranbymonkeys2384 2 жыл бұрын

@@SkunkieDesignsElectronics I'm thinking a big whopping 22uF film cap there.

@ranbymonkeys2384 2 жыл бұрын

@@SkunkieDesignsElectronics Hey let me ask you something. Have you ever sat down to do a fairly simple cap upgrade on something, you put it all back together and whaa whaa whaa, NOTHING!!! It won't work and you can't figure out for the life of ya what the hell is wrong with it so you take it and smash it in the driveway, haha. I made the last part up but, you get the idea.

@christopherwest5840 2 жыл бұрын

Does the directionality of the resistor matter?

@SkunkieDesignsElectronics 2 жыл бұрын

No, never.

@Bleats_Sinodai 2 жыл бұрын

Resistors are not polarized. They're essentially the equivalent of adding a wire to the circuit. a wire that's made for reducing the current flow and dropping voltage thru itself.