Tubelab Simple SE Project
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- Опубліковано 18 жов 2024
- Tube Amp Project: Tubelab Simple SE
My first single-ended tube amp. This video talks about the design and build process for this amp, which is built around the Tubelab Simple SE (now SSE) PCB.
Tube complement:
1 x GZ34 - full wave rectifier
2 x 12AT7 - input stage and driver
2 x EL34/6L6GC/KT66/6550/KT88 - output stage
Recorded on 04/08/2018.
Very nice work on the amp and excellent video !
Thanks!
Cool setup. I'd be thrilled to be able to build my own amp. That's some great knowledge you've got, Russ.
Jeff Kempin thanks Jeff. This is my favorite amp. It just works and sounds great, even if it's a bit utilitarian looking. I learned a lot of what I know about tube amps from a book called "Valve Amplifiers" by Morgan Jones.
Beautiful amp. I was thinking about building one but ended up constructing a M2 firstwatt amp. I'm itching for a new build.
Thanks! Tube amps are fun and rewarding to build.
You sure did neat work. Is it still in play for you?
Great looking build! Love the look and the all the configuration options. Any advice on specs or part numbers for the various switches (toggle and rotary)? I'm having trouble finding switches rated at 500+ V DC.
Hi Matt! You don't necessarily need 500VDC rated switches, depending on how you look at it. There are actually two voltage ratings for a typical switch. One is the maximum contact voltage; this is the max voltage that the contacts are rated to make and break a connection. This is the rating that you typically see. The other rating is the dielectric of the housing; in other words how well the insulation of the switch body and paddle can hold up against the voltages being handled. This is not often specified, but is obviously at least as high as the contact voltage.
If you think in terms of the voltage across any of these switch contacts, the voltages aren't actually that high. The local feedback switch and cathode resistor swapping switch sees the voltage between the cathode resistor and ground, which is less than 50VDC. The triode/ultralinear switch only sees the difference between B+ and the DC voltage coming out of the UL taps (or the screens if you go pentode). This is a few 10's of volts, even though they are elevated to 400+VDC relative to ground. The diode switch is the same...the voltage across the contacts is the difference between the tube and solid state rectifiers. A few 10's of volts elevated to B+ overall.
So the question isn't what the contact rating is so much as what the maximum working voltage is. Most switches don't specify this, but typical toggle switches seems to handle it OK. To make them safe, make sure they are mounted to a metal panel that is GROUNDED. Make sure there isn't any paint of other insulator between the switch body and the panel. That way if the switch does break down, it will short to ground and probably blow the fuse.
Good luck!
Nice build, brother. Great to have all the options enabled. I am planning a build and ordering parts right now (for an SSE) and I plan to have triode/UL switchable and NFB switchable but I am sticking with EL34s so will go with just the one set of cathode-bias resistors. Which EdCor OPTs are those? - the biggest ones? (CXSE ?) - I am thinking the medium-sized (GXSE) might be my best bet. BTW I know what you mean about building chassis - PITA!
Thanks for watching. Yes, these are the CXSE25-8-5K transformers. Good luck with the build!
Thank you for this video. I have had an SE board for some time and this has inspired me to finally complete it:) If you complete your SE could I invite you to make a video?
I will definitely post it. It's still my "bench amp", all mounted to a plank of wood. You'd think the current situation would free up more time, but it's been the opposite. :)
I'm thinking of upgrading my amp but I'm on the fence solid state or tube. The law of diminishing returns also has me paralyzed. All opinions welcome.
Yeah, that is a tough one. I have fun building and messing with tube amps as a hobby and there are arguments to be made for using them over certain solid state designs. I could go on and on about it. :) There are really good solid state amps out there too that address some of the shortcomings of your typical SS design.
The main drawbacks for tube amps are usually efficiency and heat. This amp is single-ended and can make between 8-14 watts, for example. It is enough power for most speakers of reasonable efficiency for listening in the sweet spot, but it won't fill a large room with sound unless you have more efficient speakers. My main system uses a pair of Klipsch KLF-10s, which are unusually efficient: 98dB. My other small SE amp is only about 1.5W and can drive these speakers quite well.
So one of the things to look at when choosing an amp would be to look at the efficiency of your speakers. You can also lurk around some audio forums to read about other people who own your speakers to see what kind of amps work well. There are some SS SE designs out there, too.
Nice!
Oh how I use to take those tubes out to a shooting range and shoot the hell out of those damn tubes!