Відео

I saw your scope probe was still set to 1x. Set it to 10x! The 10x mode has much lower capacitance and is safer to use for these applications. If your Darlington pairs transistors aren't low enough Vbe you could build a discrete Sziklai pair.

Hi Andy, having had my fair share of delay start demons to deal with as you know, I’m glad you managed to sort it in the end. Looking forward to the sound test through your big speakers ! : ) Your bike sounds great as well! : )

fun stuff building valve amps and goodies

Another good video. Cheers! Liked the bike and tank artwork too. ATB Adam

Can't wait until you get the bike fully going. It's been a long haul on it. Odd that the amp was working fine them the diode failed. Chineseium part? I've been had by counterfeit parts off one site by a certain seller.

what a strange thumbnail… 🫢

Hi , Thanks for the review of this Sanyo Music Center , appreciate the time you take to explain things and showing so much inside the unit. I have just purchased a G2612N, which is very simular in New Zealand . Look forward to any undates of this unit , Great video 👍🏻.

Great video. I love your approach and the 'fat lass on a trampoline' analogy

I recently built a small valve amp, mostly as a fun little project and also for something I can use to connect a pair of headphones to my 43-inch Blaupunkt HDTV, the amp itself is what's called an OTL (Output Transformerless) Headphone Amplifier that uses three Svetlana 6N1P twin-triode valves, one of the 6N1P valves has its two triodes wired as standard common-cathode voltage-amplifier stages, the other two 6N1P valves are wired in a configuration known as a White Cathode-Follower which acts like a push-pull output stage, very simple circuit, but it sounds wonderful, it is able to easily drive my Audio Technica ATH-M50X headphones, rated at 38 Ohms impedance, plenty loud enough, the sound is crystal clear, and from what I read in the original webpage articles I built it from, frequency response is ruler-flat from 10Hz to 100kHz where it gently rolls off, I had a lot of fun building it.

big green boy

I'm so happy to see you back! I hope you'll feel fully back on your feet soon! ❤ And a interesting fault, I know how it is with forgetting to change a pot for example when you redesign something. That has happened hundreds of times for me it feels like, heh. Neat little buffer you made! Simple but effective! I love the big green amp a lot, it's such a beauty and I love all your little features on it! I'd love to buy it from you if you do want to sell it like you mentioned, I just fear what the shipping price would be... But we could look it up :) I'd use it every day for my main speakers, having a piece made by you would also feel very special to me since you are one of my biggest inspirations and also have taught me so much thanks to your calm and very well done explanations of things :) You were the person who gave me the confidence to actually start building my own valve amps and do testing and all that and I am forever grateful for that! This hobby is the most fun I've ever had :) See you next time! I'm excited!

Beautiful work.

Nicely demonstrated ,hats off sir !

Hi Andy, just revisiting this monster you built way back, what was the pri of those outputs please? I can see they are Hammond 1650 series but curious to know the Z? Cheers Ian

Thank you father 😁 although don’t appreciate the slander at the start…

The U.S. Military often had 50 or 100 hour burn in on certain tubes to stabilize them. Any tube is going to have characteristics changes as it ages. Yes, correct, you will run in circles trying to match tubes and still never really succeed. There was quite a discussion on "Matching" tubes I read. Some sellers only match brands, some match date codes, and some match who knows what. I remember rebuilding an old Minschel organ as a Mothers Day surprise gift to my mother. My friend was an organ repairman and he saw my pile of new tubes for it. He told me don't put new tubes in, but put used ones in. If I had put new tubes in, he told me it was very likely he would have to retune it a couple of times, due to characteristics changing as they age. I installed used tubes, and the tuning stayed pretty accurate until she passed away, when I sold it.

My all "matched" tubes after few hour of playing are now not matched:)

Cheers for doing that video Andy, that subject has been on my mind a lot regarding “matched” pairs and how important it is. Your experiments / tests have proved it seems not? Looking forward to the sound tests, bung a bit of dub on! : ))

Andy- Many of my tube testers have ferrite beads on the wires to prevent any oscillation. Hickok and Seco use them on just about every wire, IIRC. Please keep in mind that it was very common for tube companies to buy from each other, then put their own brand name on them, but the mfg. codes WILL be different, no matter which brand is stamped on the tube. Please keep in mind that a tube which shows a bit of gas, if run for several hours at about max current, can sometimes heat up enough to cause getter material to activate again. Good progress on the project.

A really interesting and informative video. Cheers! Any old valve with a 'flying saucer' getter came from the USSR (in fact current Russian production still has them I think?).

Excellent video mate

nice

Really interesting and cool piece.. ✌️

Funny thing that I couldn’t find a station to listen to on my radio either all I got was a load of hiss 🤷🏻‍♂️

Hi Andy, I’m glad you had a look at the briefcase music centre. My brother often goes to boot sales looking for records and picked it up for a few quid years ago. It was knocking about in my shed then van for ages and I couldn’t bring myself to throw it away. As you say it’s what a lot of people listened to back in the day and was part of the pop culture of its time and amazing it still works after 50 odd years eh, even though it sounds a bit iffy! : ) Thanks for making the video 👍

beast

I too like repairing my pots instead of replacing them - that also applies to all my other projects, no matter if it is a valve amp, flourescent lamp, electrical project, vehicle, solar power, you name it! I repair and reuse everything I possibly can. I have a VERY limited budget, so yeah, I make do with what I have and can find! I also reuse parts from old projects whenever I get tired of them! So nothing goes to waste, ever! Many of my things are trash picked, and repaired/restored to useful shape - my flourescent lights in my off grid solar power shed is a great example! I like them a lot, and they came right out from the dump! I recently aquired a generator set that I am repairing, the connecting rod bearing is bad, it knocked like hell! So instead of trashing it, I am going to replace the connecting rod. Just gotta wait for it to arrive from ebay! was not that expensive either, so soon I'll have a good little generator to use whenever it gets dark and cold, and the solar panels arent doing anything :D

Hi andy! Been a while since I have been able to spend lots of time watching videos :) Thats why you havewnt heard from me in the comments for so long! Im so happy to see more valve amp vids from ya! Been really missing you! I love these monoblocks, I am excited for the day you pull out the big speakers and crank em up :D I want to do that with my tube amps I have built and restored aswell, bring out some of my big PA speakers and crank em up, I have some folded horn subwoofers that can be used with them and together with some good midrange and tweeters, it's gonna pound really good! Anyways I hope you are doing well, I love your work, never ever give up! You are one of my biggest inspirations. If you feel down, please know that I'm thinking about ya :) I go on vacation on friday, and I am so excited to finally be able to relax and watch many of your videos, work on my own valve amp projects (recently started a new one!), continue with my flourescent lamp installation in my solar powered shed, replace my worn out batteries with some new ones, and maybe go on a bit of a trip with my car somewhere too! best wishes from your swedish viewer, Lennon! <3

Nice. Are you going to add any ventilation for the chassis? That should lengthen the life of the components & transformer.

Hi Andy, great progress on those beasts! Inspiring stuff , looking forward to the next inststallment : )

Those Cannon type connectors, at least the ones used in aircraft take a special what I call a 360 deg crimping tool. I have the ones needed, fortunately. Glad to know I am not the only one who forgets to put covers and fastening rings on harnesses. I forgot one on a 40+ connector., then had to disassemble and re-do. I finally taped paper notes to any cable that had a multi part connector, and that really helped.

I'm with you on wiring stuff up and finding the part of the connector that I should have threaded the cable through sat on the bench! Arrrrggggghhhhhhhhh!!!! I bet everyone has done that at some time or another too🙄

had you thought of using a 100 ohm 1/4 watt resistor as a fuse in the anode supply

I like the feature to test the split filament tubes. Some tube testers just put voltage across the fil and not the tap. The tap is crucial in any radio that uses a pilot lamp across the rectifier filament. I really appreciate your explanation of how your circuits work. I still learn a bit on every one of your videos. I am wondering if a MOV circuit or an SCR crowbar might be able to damp the surge that blows the PS parts. That was one big arc in the 807. Maybe one of the varistors. I know Zenith used them in their TV sets for a long time. Take Care.

Thanks :) Sorry for the delay in replying. I have been a bit busy myself. 5:07 to 7:14 The MPSA92 and diodes are a constant current source(approx 0.5mA) to feed the Zener diode. Zener's provide the best voltage regulation when they are fed from a constant current source. When the circuit is switched on the MPSA42 is not conducting. Providing a high voltage to the gate of the MOSFET. Which conducts feeding a voltage to the 330k, pot and 20k voltage divider. This is the voltage regulation feedback. As soon as the voltage on the base of the MPSA42 exceeds the Zener voltage + 0.65V the MPSA42 starts conducting to provide voltage regulation. 7:15 to 9:30 I agree that the there is a problem with the placement of the 100 ohm resistor in the emitter leg of the MPSA42 in this circuit. I would move it to the base leg of the MPSA42. As used in many bipolar power amplifiers for the short circuit protection of the output transistors In the first circuit with its 22ohm resistor limits the current to 14.3 mA. If you are using the first circuit then that would explain why you were having problems with the 6V6GTA valve. You were hitting the buffers so to speak. 9:30 to 11:15 Steve Benches circuit: 10:09 It is an IRF820 not 320 I agree that the there is a problem with the placement of the 100 ohm resistor in the emitter leg of the MPSA42 in this circuit. I would move it to the base leg of the MPSA42. As used in many bipolar power amplifiers for the short circuit protection of the output transistors The Anode supply with the 10 ohm resistor limits the Anode current to 65ma. If you have an anode to cathode short that would be between 23 and 33 watts of heat across the IRF820 So heat sink for 50 Watts which is their maximum heat dissipation. The Screen grid supply uses a 22 ohm which limits the current to 14.3ma. If you have a screen grid to cathode short that would be between 5 and 7.5 watts of heat across the IRF820 So heat sink for 10 Watts which is their maximum heat dissipation. BTW I provided you with a straight unmodified version of Steve Bench's RAT tester circuit and a LTSpice 'build' of circuit. ok it was a low res gif of the circuit. I would make some serious modifications myself. But here is a link to all the design and all the build details for Steve Bench's RAT Tube tester. diyaudioprojects.com/mirror/members.aol.com/sbench101/#TubeTest

Poor design, there are a lot better ones around, keep searching on google. Don’t build this.

what kind of valve are you testing?

Pretty good start for a man under the influence....

So far, looking good.

Great video, love the sound effects.

Good progress. I am really interested in seeing this completed. I am still working on the tube tester for transmitting tubes, but have made little progress since the medical problems cropped up.

Excellent stuff Andy! Looking forward to your next one

Cracking on nicely......

Great progress Andy and lots of useful tips and advice. Looking forward to the next video! : )

If you use neon bulbs, you may not be aware that they are not consistent from one bulb to another for regulating voltage, and that the operating voltage will change between being in the dark vs in the light. One can put them in black heat shrink to make a more stable operation. They make "locking" hinges that are used on stereo cabinets that will lock open when fully lifted, so no need for propping the panel up when open.

Good stuff again. BTW your mention of Mother Earth reminded of an obscure Krautrock album which is worth a listen if you have the time - Gaea (Gaia) Auf Der Bahm Zum Uranus. ✌

Fine fettling!

Interesting stuff Andy! Looking forward to part 2 (which I am going to watch next).

Well done Andy, it’s taking shape now eh? I have a 10 tonne hydraulic hole punch, they are great when they work, but the holes can look a bit iffy on the smaller punches. Looking forward to the next instalment. : ))

New subscriber here. I cannot find the data sheet for my BBC TQ 2/3 Thyratron. I was hoping I could switch 2,000 volts at 60 to 120 times a second. Would you know how I would wire the Thyratron to do this? Thank you in advance my friend. You do some awesome stuff. I am sharing your videos with my friends. I hope you can help. Thanks again