Well I finally got the TL SEII 300B biased up and running. First difference I noticed was deeper bass than with my 45 version, using 3k One Electrons. One question I'm showing about 360 B+ Volts from the Edcor 131, is this too much? I haven't wired in the 80 mf run cap yet. Can I solder the run cap into the holes for the choke, on the board?
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Congrats!
360V B+ seems spot on..which tap did you use?
With the 260V seems barely possible, but if its with the 330V then you must have burned off a ton of voltage?
How much did you set the bias?
Regarding the run cap, it should not connect to both choke inputs (that would put it in series).
You need to use one of the choke connectors (the one closer to the star ground), and the second to the star ground).
360V B+ seems spot on..which tap did you use?
With the 260V seems barely possible, but if its with the 330V then you must have burned off a ton of voltage?
How much did you set the bias?
Regarding the run cap, it should not connect to both choke inputs (that would put it in series).
You need to use one of the choke connectors (the one closer to the star ground), and the second to the star ground).
Mains - 330-0-330@220mA | Edcor CXSE25-8 | Choke - 7H@200mA . The mains and choke are local build.
With a Matsushita GZ34 I get ~377 and the tubes are biased at 71mA. The 300b are EH Gold. One of them took a really long time to settle as the bias kept drifting. With about 400hrs of playing, they seem stable now.
Hope that helps.
With a Matsushita GZ34 I get ~377 and the tubes are biased at 71mA. The 300b are EH Gold. One of them took a really long time to settle as the bias kept drifting. With about 400hrs of playing, they seem stable now.
Hope that helps.
Sanity check here, please? I've been monitoring driver voltage (175VDC) and 300B bias (62Ma) and although the bias jumps around a bit, it's starting to settle down. My B+ across R30 is 380VDC and across R6 it's -190 VDC. Actually it's +190 VDC, but I assume it's because I have the wire's reversed? This is with a 5AR4 rectifier. With a 5U4 rectifier I get 345 VDC across R30 and the same -190 VDC across R6. Should I change some values on the board, or is that 380 V fine? IIRC a 300B is good for up to 400V, but it shortens tube life.
Thanks. I've settled on the 5AR4, which gives me 380V. Bias at 70mA. From searching around the web I found that for 380V the bias should be 90% or 94.7 mA for class A....and best sound. Supposed to shorten the life of the 300B, tho. Also suggested to back it down from that point, but not to the point you can hear the quality of sound go down. Maybe 5 to 10%. I installed a pair of Hashimoto H-20-3.5U...these also have a 2.5 tap on them, which I much prefer.
Oh interesting....I'm trying to decide on an opt for a "premium" build.. my shortlist is Hashimoto H-20-3.5U, ElectraPrint and Monolith Magnetics.
Attaching the WE300B list of operating points, you seem to be fairly close. Maybe experiment with 80mA too.
What are the differences you found on the Hashimoto vs. the UBT-3?
Attaching the WE300B list of operating points, you seem to be fairly close. Maybe experiment with 80mA too.
What are the differences you found on the Hashimoto vs. the UBT-3?
Attachments
My setup is VTA SP-14 preamp, VTA PH-16 phono amp, Marantz turntable (can't remember the model #), it's the one built by Clear Audio. Speakers are DIY Sound Group Tempests (12 inch driver, horn on top, 98 db efficiency). Sorry to say this kit is no longer available My wifes setup is identical, except she has TLSE 1 version with Electraprints and her speakers are AN kit speakers. Her speakers and the Electraprints go lower than my Tempests. I know this because I tried my amp (TLSE2), with the Hashimotos, on her speakers and we got the same deep bass. The One Electrons won't go this low. Her setup sounds fantastic, with a maybe more relaxed sound, but still great and she loves it. Mine with the Hashimotos through the Tempests sounds more revealing, but still smooth, on the 2.5 tap. Plainer but tighter on the 3.5. I like the 2.5 better. It's the kind of sound that makes me want to try more albums. I haven't heard Monolith Magnetics. If I had to leave them on the 3.5, I might just prefer the Electra Prints and save some dough. But on the 2.5 they are well worth the extra cost. I hope this helps. I will try upping the bias.
The EH300b I'm using would keep drifting when set around 80mA. I changed from a 310-0-310 (350 B+) to 330-0-330 (377 B+) and reduced current to 70mA. Mains supply is 230v with a power conditioner.
Its been running a few months without problems and no longer drifts by more than 1mA now.
Its been running a few months without problems and no longer drifts by more than 1mA now.
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Chassis for the TSE-II is almost ready. Need help with a question.
I would like to add test points on the rear of the chassis for simple testing without opening it up. At a minimum, would the 300b bias be sufficient to keep track of tube life ?
Any other points a better indicator of tube drift /life (B+ | -ve V | 5842 V etc...)
Thanks.
I would like to add test points on the rear of the chassis for simple testing without opening it up. At a minimum, would the 300b bias be sufficient to keep track of tube life ?
Any other points a better indicator of tube drift /life (B+ | -ve V | 5842 V etc...)
Thanks.
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Bias test points
I’ve built three TSE-IIs; two 300B monoblocks and a 45 stereo.
I agree that it’s a good idea to use test ports, at least on the power tube bias, particularly if you roll tubes regularly, as I do with the 45 version.
I put two test receptacles (for banana plugs) at the rear of the chassis for each channel, each testport wired to one side of the 10-ohm bias resistor. Note that I bought a handful of 1% 10 ohm resistors and picked the best, usually about 9.99 ohms on the fancy LCR meter.
I put a Bourns 10-turn pot next to the test jacks and wired it in place of the bias trimmer pot. I did not install a knob so as to discourage random bias twiddling.
Voltage across the test ports x 100 represents bias amps, for those tuning-in late.
Also used an upside-down machine screw at the Star ground (one of the PST feet) so that I could easily double check Vp (as TSE-II is grounded cathode, I remind myself…) by measuring voltage between plate and ground.
Note that I’m running the 300Bs quite cold here. Can’t really notice any difference, which might be related to the big 5K EDCOR OPT…
I’ve built three TSE-IIs; two 300B monoblocks and a 45 stereo.
I agree that it’s a good idea to use test ports, at least on the power tube bias, particularly if you roll tubes regularly, as I do with the 45 version.
I put two test receptacles (for banana plugs) at the rear of the chassis for each channel, each testport wired to one side of the 10-ohm bias resistor. Note that I bought a handful of 1% 10 ohm resistors and picked the best, usually about 9.99 ohms on the fancy LCR meter.
I put a Bourns 10-turn pot next to the test jacks and wired it in place of the bias trimmer pot. I did not install a knob so as to discourage random bias twiddling.
Voltage across the test ports x 100 represents bias amps, for those tuning-in late.
Also used an upside-down machine screw at the Star ground (one of the PST feet) so that I could easily double check Vp (as TSE-II is grounded cathode, I remind myself…) by measuring voltage between plate and ground.
Note that I’m running the 300Bs quite cold here. Can’t really notice any difference, which might be related to the big 5K EDCOR OPT…
