Right on. I plan on starting my A10 mods this weekend. Then the preamp project is another im very interested in and the spud amp too. Love your content. You are a machine...
Very good! I like the way your thinkin. Minimal. Maybe, speakers wired directly to the output transformers right inside the box/speaker enclosure. Or better yet, open baffle speakers.
I use a marantz PM7001 Int amp in power amp only mode with my tube pre-amp. Sounds fantastic. Only just found your channel. Learning a lot from you. Thanks for making these videos
I like the concept especially as I've found I no longer need a preamp. My LCR phone amp has so much gain and l'm now using an auto transformer for gain control.
I acquired a pair of 1959 Lafayette LA-70 monoblocks that I fixed up recently. Both have a pair of KT88's (6550's). They aren't integrated, so I built a single 12A_7 preamp w/the 6CA4 power supply (the 4S preamp found on the DIY Audio website and I found the 12AU7 to sound best), and the whole thing sounds decent. I actually built this on a small Hammond chassis with techniques I learned from watching your 6SQ7 build! I should post some photos on your forum. :) I also robbed a 6BQ5 amp out of an old Dumont stereo and built the same preamp for it, but I use a pigtail from the amp to the preamp for the required voltages. That also sounds surprisingly good! I love this stuff!! lol
Like I said I'm in no hurry. It'll all be worth it in the end I'm sure. Besides I'm happy that it's helping you produce more content that I can watch 😉
Seriously, this sounds like a great project. I wonder if this type of driver amp could be be adapted to use other output tubes like KT66, KT88 or 300B.
The problem with those other tubes as a "spud" is the voltage peak to peak they need to drive them. A 300B for example need 140-160Vpp. What is possible: is for the amp itself to provide the gain from the 15Vpp (or whatever the preamp makes) to the tube requirement and not need to make the whole drive voltage from the 3Vpp it normally would. This would be designing them to work with each other. The more I think about this, the more sense it makes to build a system this way.
They also have a western electric 211 amp. I could get that one as a kit or finished and send it to you to build or modify. At least that would be something different. it would be down the road a bit. have to save some money for it.
hi on the schematic is nice what is missing is the black dot on the connections, example 0.15uF is connected to 470K and 1K it needs the dot connection ( • ), and yes we already know that, but for the new builders might be a bit confused 😊
If there is no connection the circuit does a bump over it. Look at the feedback circuit. It takes two little bumps over the B+ circuit. Not always necessary to use black dots.
@@markmckelvey6515 I like to see good sized black dots for joins AND 'speed humps' for crossing connections, just for clarity & elimination of any doubt. - Especially when I forget my glasses!
I may be wrong, but that schematic looks odd. The cathode only has a ground path through the secondary of the the o/p transformer, so it will have dc idle current running through it, as will the speaker?
You are correct, it is odd :) "This connection will cause there to be (no more than) about 40 mV of DC produced across the speaker terminals. But in actual practice however, this is insignificant, with the benefit of the closed loop response then being entirely based on the characteristic of the OPT outweighing the slight DC bias impressed on the speaker." There is an alternate schematic the grounds the cathode but requires a much larger cap (1000uf). I will likely explore and measure both!
Stephe the centre preamp of the 3 I see here looks like the same basic chassis as the 6P3P/6N1 INTEGRATED amp I'm building! But you got more tubes in that one & it's just a preamp! What's goin on with that?
@@@SkunkieDesignsElectronics Yeah Stephe, I know you did. Nevertheless, I'm not real confident I'm gunna get great performance from my amp, let alone 7 'useable' watts (as the online ad stated) from the small o.p.t's. that would fit in your hand. If they were misleading with the output power specs I'm already suspicious!
"This connection will cause there to be (no more than) about 40 mV of DC produced across the speaker terminals. But in actual practice however, this is insignificant, with the benefit of the closed loop response then being entirely based on the characteristic of the OPT outweighing the slight DC bias impressed on the speaker." The majority of the voltage/current is going through the OT, and the current is ma.
@@SkunkieDesignsElectronics Thanks. That makes sense. The air gapped SE transformer can obviously cope with it and the DC resistance will be very low so not much hits the speaker. I guess I should do as Richard Feynman suggested, with respect to quantum mechanics, and "shut up and calculate".
Hey I sent you an email with a 300b kit link in it. Take a look at it and let me know if it looks good. It looks pretty good by the weight alone. 44lbs. 40lbs without the chassis. It's supposed to be a clone of the Western Electric 91B.
@@SkunkieDesignsElectronics for $600 shipped it looks like a good one. They said in the description that they can do it that cheap because they make their own transformers. Looks like the driver tubes can be replaced with ECL 805's and 5y3 rectifiers. It's supposed to be a western electric 91b clone.
The Spud is a one tuber, that is, one tube per side. Fun Project!
Congrats on the 2K subs Steph. Great series on the A12. Keep up the good work.
Can't wait to see how this project turn out, like the A12 project, I have a feeling it's going to sound good. You go Skunkie 🙂
Right on. I plan on starting my A10 mods this weekend. Then the preamp project is another im very interested in and the spud amp too. Love your content. You are a machine...
Very good! I like the way your thinkin. Minimal. Maybe, speakers wired directly to the output transformers right inside the box/speaker enclosure. Or better yet, open baffle speakers.
enjoying your videos! I think this spud amp is going to be a fun project!
I use a marantz PM7001 Int amp in power amp only mode with my tube pre-amp. Sounds fantastic. Only just found your channel. Learning a lot from you. Thanks for making these videos
Looking very much forward to you starting that power amp build series. Perhaps it will indeed seem easy/simplye enough as a first build for a newbie.
I like the way you think! Could you say out of the box. This is gonna be a winner for sure 🌹
Great video Stephe
Love the channel by the way I do solid state amplifiers studies but valve amps always going to be a solid foundation for Hifi Audio
I like the concept especially as I've found I no longer need a preamp. My LCR phone amp has so much gain and l'm now using an auto transformer for gain control.
I acquired a pair of 1959 Lafayette LA-70 monoblocks that I fixed up recently. Both have a pair of KT88's (6550's). They aren't integrated, so I built a single 12A_7 preamp w/the 6CA4 power supply (the 4S preamp found on the DIY Audio website and I found the 12AU7 to sound best), and the whole thing sounds decent. I actually built this on a small Hammond chassis with techniques I learned from watching your 6SQ7 build! I should post some photos on your forum. :) I also robbed a 6BQ5 amp out of an old Dumont stereo and built the same preamp for it, but I use a pigtail from the amp to the preamp for the required voltages. That also sounds surprisingly good! I love this stuff!! lol
That sounds like fun! :)
Anticipating your "spud" build & which pre-amp sounds best!
Like I said I'm in no hurry. It'll all be worth it in the end I'm sure. Besides I'm happy that it's helping you produce more content that I can watch 😉
Awesome!!!! Thanks again for you generosity.
Seriously, this sounds like a great project. I wonder if this type of driver amp could be be adapted to use other output tubes like KT66, KT88 or 300B.
The problem with those other tubes as a "spud" is the voltage peak to peak they need to drive them. A 300B for example need 140-160Vpp. What is possible: is for the amp itself to provide the gain from the 15Vpp (or whatever the preamp makes) to the tube requirement and not need to make the whole drive voltage from the 3Vpp it normally would. This would be designing them to work with each other.
The more I think about this, the more sense it makes to build a system this way.
The 6sn7 was $195 shipped I believe and the m7 was $318 with tax on Amazon.
They also have a western electric 211 amp. I could get that one as a kit or finished and send it to you to build or modify. At least that would be something different. it would be down the road a bit. have to save some money for it.
I have zero interest in working on an amp with 1000V+ of B+ lol
@@SkunkieDesignsElectronics omg! I found your weakness! Haha
hi on the schematic is nice what is missing is the black dot on the connections, example 0.15uF is connected to 470K and 1K it needs the dot connection ( • ), and yes we already know that, but for the new builders might be a bit confused 😊
Ill take a look at it. It isn't my schematic, I just updated some values to the parts I plan to use.
If there is no connection the circuit does a bump over it. Look at the feedback circuit. It takes two little bumps over the B+ circuit. Not always necessary to use black dots.
@@markmckelvey6515 I like to see good sized black dots for joins AND 'speed humps' for crossing connections, just for clarity & elimination of any doubt. - Especially when I forget my glasses!
I may be wrong, but that schematic looks odd. The cathode only has a ground path through the secondary of the the o/p transformer, so it will have dc idle current running through it, as will the speaker?
You are correct, it is odd :)
"This connection will cause there to be (no more than) about 40 mV of DC produced across the speaker terminals. But in actual practice however, this is insignificant, with the benefit of the closed loop response then being entirely based on the characteristic of the OPT outweighing the slight DC bias impressed on the speaker." There is an alternate schematic the grounds the cathode but requires a much larger cap (1000uf). I will likely explore and measure both!
@@SkunkieDesignsElectronics Thanks. I look forward to seeing how you get on with this circuit.
Stephe the centre preamp of the 3 I see here looks like the same basic chassis as the 6P3P/6N1 INTEGRATED amp I'm building! But you got more tubes in that one & it's just a preamp! What's goin on with that?
Tofu Dreg
@@@SkunkieDesignsElectronics Chinese JUNK huh? Great.😒 At least I've only wasted 300 bucks or so dangit! 😠😡🤬🤬
I meant the pre-amp in the center is tofu dreg.
@@@SkunkieDesignsElectronics Yeah Stephe, I know you did. Nevertheless, I'm not real confident I'm gunna get great performance from my amp, let alone 7 'useable' watts (as the online ad stated) from the small o.p.t's. that would fit in your hand. If they were misleading with the output power specs I'm already suspicious!
Yeah, highly unlikely to get 7W from that
That spud amp. Is it really ok to put that much dc through the secondary of tho opt. And your speakers?
"This connection will cause there to be (no more than) about 40 mV of DC produced across the speaker terminals. But in actual practice however, this is insignificant, with the benefit of the closed loop response then being entirely based on the characteristic of the OPT outweighing the slight DC bias impressed on the speaker."
The majority of the voltage/current is going through the OT, and the current is ma.
@@SkunkieDesignsElectronics Thanks. That makes sense. The air gapped SE transformer can obviously cope with it and the DC resistance will be very low so not much hits the speaker. I guess I should do as Richard Feynman suggested, with respect to quantum mechanics, and "shut up and calculate".
hi skunkie i llike your vidéos ,i make tube project but id like to measure output impedance of tube preamp can you help me thanks
Dolly sighting 03:29
O Wow Stephi Sweetie 💖🙏 This Spud Amp Build Is Going To Be Awesome, I Really Want To Make One, Would Suite My System Perfectly 😘🎶🎵🎧
> 2k subscribers! 👍
Hey I sent you an email with a 300b kit link in it. Take a look at it and let me know if it looks good. It looks pretty good by the weight alone. 44lbs. 40lbs without the chassis. It's supposed to be a clone of the Western Electric 91B.
Hmm didn't see this.
@@SkunkieDesignsElectronics for $600 shipped it looks like a good one. They said in the description that they can do it that cheap because they make their own transformers. Looks like the driver tubes can be replaced with ECL 805's and 5y3 rectifiers. It's supposed to be a western electric 91b clone.
It's a spud amp because it is a one tuber.