Back in the 70s I played bass in a band with a guitarist with a 100 watt Hiwatt. It was ridiculously loud in our basement rehearsal space! No one played them clean since there wasn’t a lot of distortion pedals back them. So you had to crank it. It was painful! Lol
Hi. Is the 540V that you measured goes into the center tapped of the OT? I am currently building a guitar amp the marshall silver jubilee. My concern is that my available PT (from old hi fi system) output around 580V DC. In the amp where I took it that is where the CT of OT is connected. The HT winding has a CT which where they take the low voltage for 6l6 grid and for PI and the negative output from the bridge rec goes to ground. Will it nnot gonna destroy the tube? Is my voltage too high? Im also thinking of using lower voltage around 300V by using half bridge rectification. Is it still ok to run that low coz I see in all marshall amp they use around 450V. Thank you.
I assume I grounded the high voltage center tap, so yes that would be 540 to ground and the center tap. You'd want to check the output tubes you're using to make sure you're not exceeding the max plate voltage. I don't recall what that is for 6L6GC, but the datasheet would say under maximum ratings. You also want to make sure you're not exceeding the voltage rating for filter caps. The higher voltage will change the bias point, so the bias circuit/cathode resistor value may have to be tweaked for the higher voltage operation. I would recommend reading up on tube amps at valvewizard.co.uk. Merlin will fill in a lot of blanks. Good luck!
I think closer to 500VDC, but that was at 1970's wall voltages. Good chance vintage Hiwatts used today are around 530VDC. High voltage alone will not cause excessive wear to output tubes as long as your bias is still acceptable. EL34 are rated for max 800VDC.
Swap 1 output lamp from one arm to equalize the load of the output, the lamps are specially matched in pairs. 18 24 in one shoulder and the same parameters 18 24 for the other shoulder. All in all a good job, but as I said earlier in video 1, you unfortunately failed to achieve the original sound of this amplifier because the output transformer does not have the complex winding sectioning of the Partrigue transformer.
Firstly, I am building my first amp, and it is a Mojotone DR103 kit, so your video series is a tremendous help. So thank you. Secondly, how did you connect the power meter to your variac? I have one built into my current limiter, but it would be nice to have that on my variac for those times I run without it.
I don't have it handy, but there are install guides out there. The meters are essentially just DMMs. The voltmeter goes across the variac output. You want to get one with the current sense transformer: www.amazon.com/HiLetgo-Multimeter-PZEM-061-Voltmeter-Transformer/dp/B079JNY5VD/ref=sr_1_51?crid=2GUW214QTK7FM&keywords=multimeter+current+sense+transformer+panel+mount&qid=1679172486&sprefix=multimeter+current+sense+transformer+panel+moun%2Caps%2C56&sr=8-51
The artist at work...brilliant build really enjoyed watching.
Even though the o/p tubes are mismatched the sound quality is great-which begs the question how critical is quad matching? Well done Joe!
I think you answered your own question :)
Excellent clean build and it sounds really good. I look forward to seeing it in it's new head shell.
Thanks, me too :)
Cool Clean Sound!
Back in the 70s I played bass in a band with a guitarist with a 100 watt Hiwatt.
It was ridiculously loud in our basement rehearsal space! No one played them clean since there wasn’t a lot of distortion pedals back them. So you had to crank it.
It was painful! Lol
Sounds great, awesome clean too
Thanks!
Can you do a tear down of the hamstead odyssey pedal? For me that my desert island do it all drive preamp sounding pedal!!!
Чудово зібраний підсилювач! Лайк і підписка з мене! І звісно повага! 👍🙂
Do a video on the Muffuletta or the Pack Rat.
Hi. Is the 540V that you measured goes into the center tapped of the OT? I am currently building a guitar amp the marshall silver jubilee. My concern is that my available PT (from old hi fi system) output around 580V DC. In the amp where I took it that is where the CT of OT is connected. The HT winding has a CT which where they take the low voltage for 6l6 grid and for PI and the negative output from the bridge rec goes to ground. Will it nnot gonna destroy the tube? Is my voltage too high? Im also thinking of using lower voltage around 300V by using half bridge rectification. Is it still ok to run that low coz I see in all marshall amp they use around 450V. Thank you.
I assume I grounded the high voltage center tap, so yes that would be 540 to ground and the center tap.
You'd want to check the output tubes you're using to make sure you're not exceeding the max plate voltage. I don't recall what that is for 6L6GC, but the datasheet would say under maximum ratings.
You also want to make sure you're not exceeding the voltage rating for filter caps.
The higher voltage will change the bias point, so the bias circuit/cathode resistor value may have to be tweaked for the higher voltage operation.
I would recommend reading up on tube amps at valvewizard.co.uk. Merlin will fill in a lot of blanks. Good luck!
@@graybenchelec thanks for the info. This is what info I am lookings for.
Hi, thank you for the video! Do you know if original Hiwatts ran at 530v DC? I guess you will swap quads of tubes rather quickly at this voltage..
I think closer to 500VDC, but that was at 1970's wall voltages. Good chance vintage Hiwatts used today are around 530VDC.
High voltage alone will not cause excessive wear to output tubes as long as your bias is still acceptable. EL34 are rated for max 800VDC.
@@graybenchelec 800V is rating was prob. max for vintage tubes that were durable.
@@Stu66orn I haven't heard of any issues with high plate voltage and JJ tubes, guess we'll see 👍
It's the EL34's screens that take the hit with higher voltages, they over dissipate. Original Hiwatts ran their tubes at 460 vdc.
So awesome.. 😊
Swap 1 output lamp from one arm to equalize the load of the output, the lamps are specially matched in pairs. 18 24 in one shoulder and the same parameters 18 24 for the other shoulder. All in all a good job, but as I said earlier in video 1, you unfortunately failed to achieve the original sound of this amplifier because the output transformer does not have the complex winding sectioning of the Partrigue transformer.
Firstly, I am building my first amp, and it is a Mojotone DR103 kit, so your video series is a tremendous help. So thank you.
Secondly, how did you connect the power meter to your variac? I have one built into my current limiter, but it would be nice to have that on my variac for those times I run without it.
I don't have it handy, but there are install guides out there. The meters are essentially just DMMs. The voltmeter goes across the variac output. You want to get one with the current sense transformer: www.amazon.com/HiLetgo-Multimeter-PZEM-061-Voltmeter-Transformer/dp/B079JNY5VD/ref=sr_1_51?crid=2GUW214QTK7FM&keywords=multimeter+current+sense+transformer+panel+mount&qid=1679172486&sprefix=multimeter+current+sense+transformer+panel+moun%2Caps%2C56&sr=8-51