The amount of power needed should tell you which tube to use. The 45 will do 0.5W to 1W. 2A3 will do 3-4W. And 300B can do more like 8W. All approximate numbers. You need 100 db/W speakers to really take advantage of a 45.
I tend not to be nearly as concerned about power as the average user, but I appreciate your point. Currently, my SSE amp can push about 3.5 W (RMS):
My speakers are about 91dB 1W/1m, and the 3.5 W is plenty. I can play the system loud enough (clean) that people cannot have a conversation in the room. That is typically much too loud for my needs. I am guessing that I am typically running a couple hundred mW (for BGM), and maybe 1-2 watts for active listening.
Having said that, I do think the 45s might leave me wanting more efficient speakers, for those odd times when I want to really lose myself in the music.
2A3 seem to be the right fit, but they get slagged by everyone around here, so I hesitate. The filament draw is just another reason to dislike them without really knowing why and I realize that a dedicated 6.3v transformer is an easy solution.
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I mulled it over and I think I will start with 2a3 and then shift to 45 down the road if/when the spirit moves me and I feel like building some new speakers. If I go with 45 from the start, then I'll need to add more filament power to go to 2a3, and if I start with 300B, then it will be a considerable effort to shift to 2a3 or 45.
In other words, it seems a TSE-II amp built for 2a3 with 5Kohm OPTs, a dedicated 8A 6.3v transformer and a chunky heat-sink on the filament regulator can easily handle 45 tubes with a simple bias adjustment. When I am running 2a3, I can put 4ohm speakers on the 8ohm taps (or 8ohm speakers on the 16ohm taps), for a tube load of 2.5Kohm if I really need the power. For both setups, I'll use a choke and the recommended low value C4 to tame the B+.
Am I forgetting anything else in this plan?
In other words, it seems a TSE-II amp built for 2a3 with 5Kohm OPTs, a dedicated 8A 6.3v transformer and a chunky heat-sink on the filament regulator can easily handle 45 tubes with a simple bias adjustment. When I am running 2a3, I can put 4ohm speakers on the 8ohm taps (or 8ohm speakers on the 16ohm taps), for a tube load of 2.5Kohm if I really need the power. For both setups, I'll use a choke and the recommended low value C4 to tame the B+.
Am I forgetting anything else in this plan?
Hello All,
Newbie on the tube lab tse ii with 300b output tubes.
I have an issue on checkout.
At the beginning i got to section of setting the bias pots to raise the output tube current... then it went down hill. The rectifier tube begun arching. I immediately turned it off and powered down, and removed all tubes.
Now whilst the B+ begins climb in volts the Psvane 5ar4 tube begins arching/sparking and R5 is smoking. I'm unsure if the 5ar4 needs replacement... the. filament still glows (I do not have a tube tester) or whether its another issue. the R36 resistor 10kohms/7w has always got very hot... 100 degrees celsius. D6 is the 200v for over 350v as per Georges notes.
D 2 & 3 are working correctly, i've replaced the 270ohm resistor, the 650vac HV from power transformer is working fine.
Help is much appreciated.
Thank you
Newbie on the tube lab tse ii with 300b output tubes.
I have an issue on checkout.
At the beginning i got to section of setting the bias pots to raise the output tube current... then it went down hill. The rectifier tube begun arching. I immediately turned it off and powered down, and removed all tubes.
Now whilst the B+ begins climb in volts the Psvane 5ar4 tube begins arching/sparking and R5 is smoking. I'm unsure if the 5ar4 needs replacement... the. filament still glows (I do not have a tube tester) or whether its another issue. the R36 resistor 10kohms/7w has always got very hot... 100 degrees celsius. D6 is the 200v for over 350v as per Georges notes.
D 2 & 3 are working correctly, i've replaced the 270ohm resistor, the 650vac HV from power transformer is working fine.
Help is much appreciated.
Thank you
Not enough information here to really understand what happened. Could you elaborate?
Hello Francois, Thanks for the reply.
The issue is resolved. The grounding wire had come out of the T1-red_yellow-1 terminal. Fixed that and also replaced the 5a slow blo fuse to 3a
All the specs look right i think.
B+ 350vdc / Bias @ 60mA
B- 181vdc
L & R 5842 plate @ 175vdc
Feeling relieved that is sorted out.
Now to setting the Bias.
Thanks again
The issue is resolved. The grounding wire had come out of the T1-red_yellow-1 terminal. Fixed that and also replaced the 5a slow blo fuse to 3a
All the specs look right i think.
B+ 350vdc / Bias @ 60mA
B- 181vdc
L & R 5842 plate @ 175vdc
Feeling relieved that is sorted out.
Now to setting the Bias.
Thanks again
Hi,
Can I ask please for some advice re transformers for a 300b TSE2 build in the UK.
Am I right in saying the 372hx would be a suitable pt, is there an edcor equivalent?
Which rating choke?
And the biggie, which opt? I used Edcors on by tse and sse builds (now sold) but I'm unsure of the ratings. Naturally I want to go big.
Can I ask please for some advice re transformers for a 300b TSE2 build in the UK.
Am I right in saying the 372hx would be a suitable pt, is there an edcor equivalent?
Which rating choke?
And the biggie, which opt? I used Edcors on by tse and sse builds (now sold) but I'm unsure of the ratings. Naturally I want to go big.
As George states on his website, for TSE 300B "The power transformer needs to provide about 640 or 650 volts center tapped at 150 mA or more, 5 volts at 2 amps, and 6.3 volts at 4 amps. A center tap on the 6.3 volt winding is NOT required."
You could use the 372HX, but your B+ will end up on the low side. I suggest the 376X or 373EX.
The Triad C-14x is a popular choice for choke. 150ohm, 200mA.
Re: OPTs more from Greorge ... "use a 2.5 K, 3 K or 3.6 K ohm load" ... "Most users go for a 3K ohm OPT and about 360 volts of B+. Some also use a 5K ohm OPT and a B+ nearing 400 volts, this is my preference."
IMO, you don't need to go too big on the OPT. You'll be pushing maybe 7-9 watts, so a (true) 10-15 watt OPT will do. This means at least 4 lbs (1.8kg). Not a 2-3 pound "15 watt" Edcor. 🙂
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As far as I know, yes. The TSE-II is a fairly minor change from TSE. Initially motivated by a shortage of one of the critical components (regulator?). George needed to redesign the circuit a bit and incorporated some feedback from others, made the board a bit bigger for better heat management, etc.
The latest BOM and important BOM notes are in the first post of this thread.
@mudchute,
Being in the UK there are several good options. I don’t know you budget, but I hear good things about Primary Windings - https://primarywindings.com/product/300b_20w_se/
At lower cost (although I don’t know the import taxation) is Toroidy in Poland. I have used several of their output transformers with great satisfaction and currently have a pair of TTG-EL84SE with 5k primaries that I reserved for my Tubelab TSE-II build. I purchased them from www.tde.com because they ship to the US for $9.99 per transformer. Toroidy also makes TTG-KT88 (3k primary) and TTG-EL34 (3.2k) that you could consider.
Best wishes!
Being in the UK there are several good options. I don’t know you budget, but I hear good things about Primary Windings - https://primarywindings.com/product/300b_20w_se/
At lower cost (although I don’t know the import taxation) is Toroidy in Poland. I have used several of their output transformers with great satisfaction and currently have a pair of TTG-EL84SE with 5k primaries that I reserved for my Tubelab TSE-II build. I purchased them from www.tde.com because they ship to the US for $9.99 per transformer. Toroidy also makes TTG-KT88 (3k primary) and TTG-EL34 (3.2k) that you could consider.
Best wishes!
Thank you again.
Thank you for the suggestions re opt. Looks like Edcor is completely off the table as they no longer ship to the UK. PrimaryWindings is tempting, the price is good and they're here. I also found the Majestic Transformer Co who are only an hour away.
My speakers use Alpair 10p drivers with an 89.6db sensitivity. Knowing that, would this steer you towards any particular opt?
Thank you for the suggestions re opt. Looks like Edcor is completely off the table as they no longer ship to the UK. PrimaryWindings is tempting, the price is good and they're here. I also found the Majestic Transformer Co who are only an hour away.
My speakers use Alpair 10p drivers with an 89.6db sensitivity. Knowing that, would this steer you towards any particular opt?
mudchute,
Have you tried looking at Don Audio - they are listing Edcor in stock:
https://www.don-audio.com/Audio-transformers
If you prefer to go with a 5K OPT then the Edcor GXSE10-8-5K should work (10 watts, 8 Ohms secondaries, 5k impedance for the output transformer primaries).
If you prefer to use an OPT with lower output impedance of 2.5K, then the GXSE15-6-2.5K (15 watts, 6 Ohms secondaries, 2.5k impedance for the output transformer primaries) is also a choice; with a transformer with 2.5k primaries vs a 5k one, the tradeoff is a little bit more output power vs slight rise in distortion.
You speaker will work with both 8 ohms and 6 ohm secondaries.
Also check out the local suppliers if possible. 🙂
Have you tried looking at Don Audio - they are listing Edcor in stock:
https://www.don-audio.com/Audio-transformers
If you prefer to go with a 5K OPT then the Edcor GXSE10-8-5K should work (10 watts, 8 Ohms secondaries, 5k impedance for the output transformer primaries).
If you prefer to use an OPT with lower output impedance of 2.5K, then the GXSE15-6-2.5K (15 watts, 6 Ohms secondaries, 2.5k impedance for the output transformer primaries) is also a choice; with a transformer with 2.5k primaries vs a 5k one, the tradeoff is a little bit more output power vs slight rise in distortion.
You speaker will work with both 8 ohms and 6 ohm secondaries.
Also check out the local suppliers if possible. 🙂
I’m not an expert in the TSE-II since I have not built mine yet. I see your loudspeakers feature relatively high impedance (on the 8 ohm tap) and somewhat low sensitivity. The latter to me indicates the desirability of (slightly) more power and therefore I would choose a transformer with primary impedance around 3k. (5k will give slightly lower power and lower distortion, depending on the operating conditions you end up with.)
I agree with @cogitech that you will be better of with a substantial output transformer, rather than a 2-3 lbs Edcor, such as the 15 watt GXSE15-6-2.5K that weighs 2.75 lbs. Looking at the offering from Primary Windings it weighs 4.3 kg! Really in a different class. If the budget will allow those are the transformers I’ll investigate further.
I agree with @cogitech that you will be better of with a substantial output transformer, rather than a 2-3 lbs Edcor, such as the 15 watt GXSE15-6-2.5K that weighs 2.75 lbs. Looking at the offering from Primary Windings it weighs 4.3 kg! Really in a different class. If the budget will allow those are the transformers I’ll investigate further.
Hi, that's reassuring as from the readily available options I was beginning to lean in their direction!
Hi, I had used them in some stand mount enclosures designed by planet10. I can remember the name now, demarken? I'm now building a replacement, the same design but full height.
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Here is another option in the UK - Majestic Transformer Company.
They are cited by Keith Snook as the recommended supplier of Quad II transformers. I am hoping to try one of their offerings at some point since the factory is close to the places I visit in the UK, in Poole.
They are cited by Keith Snook as the recommended supplier of Quad II transformers. I am hoping to try one of their offerings at some point since the factory is close to the places I visit in the UK, in Poole.