What brand are the switches? They look like 19mm Bulgin switches, which are only available as momentary contact. Is your switch latching?
They are Bulgin switches. They're very good. I bought some of them from Newark Electronics. You'll need external current limiting resistors for the LEDs.
Even though the catalog indicates that the LEDs are rated for 24 volts, they are not.
I discovered this within milliseconds of applying 24 volts to the LED. Flash-Poof.
Even though the catalog indicates that the LEDs are rated for 24 volts, they are not.
I discovered this within milliseconds of applying 24 volts to the LED. Flash-Poof.
Is this the driver stage to your twin EL34 SE amp in an earlier post. I like the 6SN7 and understand they were developed for radar in the 1940s. I have a few different types. I have also never used them in the totem pole config. you show here. Though I know a few well known builds who do use them this way.
Other driver tubes that I have used and work well are the 6N1P and of course the 12AX7. I chose the 6SN7 for the 300B amp I'm currently building.
While it is more complicated than a simple latching switch, a D flip-flop, a few passives, and a relay with driver transistor turns the momentary switch into a latching one...
Only draw-back is that you'll need a control supply to keep the D flip-flop live when the amp is off.
~Tom
1. How does a parallel SE compare with a PP-triode mode (given that a PP would require a phase splitter stage too). I would assume the Parallel SE requires a much larger OPT. 6L6, What OPT did you use. (both the PP-triode and the Parallel SE deliver about 15W/rms).
2. Does the 6SN7 driver stage provide enough gain? If one needs more gain can a 6SL7 be used instead?
Yeah mine is Latching. I founded it on a dutch website Samenkopen.net.
But ebay has them too
vandal switch | eBay
Exactly why I'm looking for a latching switch.
I tried a flop flop thingy that I found on-line with a momentary, but could not get it working......
My first TubelabSE amp - complete
Here it is, not quite 100% DIY, because I had the aluminium machined, but I wanted it to look halfway decent...
Sides are poplar subjected to router and table saw and stained with some leftover mahogany stain.
Pictures: Stefan's TubeLab SimpleSE (They are all high-res, so I hope you have a decent internet link)
Learned a lot doing this and definitely wouldn't have gotten to this point without a lot of help and guidance from around here, so THANK YOU!
Stefan
Here it is, not quite 100% DIY, because I had the aluminium machined, but I wanted it to look halfway decent...
Sides are poplar subjected to router and table saw and stained with some leftover mahogany stain.
Pictures: Stefan's TubeLab SimpleSE (They are all high-res, so I hope you have a decent internet link)
Learned a lot doing this and definitely wouldn't have gotten to this point without a lot of help and guidance from around here, so THANK YOU!
Stefan
Sweep Tube SEP
So after getting the SEP bug with first of all the RH84, then a 13E1 monster, I've now built a SEP using the EL509 sweep tube.
At the moment it is a stereo chassis, using JJ EL509s, but plans are well underway to build a pair of monoblocks using NOS PL509 tubes
This amplifier uses a series regulated tube power supply, using a 6336A as the pass tube, controlled by a 6SJ7 metal tube pentode sitting on a 0B2 gas regulator tube.
It is supremely quiet and sounds absolutely fabulous, even with the JJ tubes.
Below are a few grainy glow shots, and interior view of the wiring
I'm expecting great things from the monoblocks
Steve
So after getting the SEP bug with first of all the RH84, then a 13E1 monster, I've now built a SEP using the EL509 sweep tube.
At the moment it is a stereo chassis, using JJ EL509s, but plans are well underway to build a pair of monoblocks using NOS PL509 tubes
This amplifier uses a series regulated tube power supply, using a 6336A as the pass tube, controlled by a 6SJ7 metal tube pentode sitting on a 0B2 gas regulator tube.
It is supremely quiet and sounds absolutely fabulous, even with the JJ tubes.
Below are a few grainy glow shots, and interior view of the wiring
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I'm expecting great things from the monoblocks
Steve
Last edited:
For those interested, here's the schematic:
An externally hosted image should be here but it was not working when we last tested it.
Thanks for posting that Steve. I still have a bunch of PL519 lying around which I tried to use for a 100W guitar amp about a decade ago. Ten years wiser, one of the things I thought of using them for would be a stereo SE amp, or a single-channel PP woofer amp.
What OPT's are you using for this amp? And did you try adding NFB to this design and eventually left it out because it didn't help any, or did you just leave it out to begin with and didn't add it because it wasn't necessary? I'm inquiring because I'm drilled by the experts around here that 'single ended pentode requires NFB'. I might have misunderstood that though, so I'm interested in your view on this topic.
Btw, did you experience any issues with oscillations at this plate voltage? For the guitar amp project I mentioned above, I tried running 4 PL519's in parallel PP at about 500V with fixed bias (somewhere around -45V), but all I managed to generate was RF The concept worked just fine at 170V plate voltage though, although I obviously didn't get the output power I was looking for at the time.
What OPT's are you using for this amp? And did you try adding NFB to this design and eventually left it out because it didn't help any, or did you just leave it out to begin with and didn't add it because it wasn't necessary? I'm inquiring because I'm drilled by the experts around here that 'single ended pentode requires NFB'. I might have misunderstood that though, so I'm interested in your view on this topic.
Btw, did you experience any issues with oscillations at this plate voltage? For the guitar amp project I mentioned above, I tried running 4 PL519's in parallel PP at about 500V with fixed bias (somewhere around -45V), but all I managed to generate was RF
The concept worked just fine at 170V plate voltage though, although I obviously didn't get the output power I was looking for at the time.