Hammond 166 and 266 series are a good solution, with dual (split) bobbin across the range.
Hammond Mfg. - Power Transformer - Dual Primary / Dual Secondary (266 Series)
Or use the 166 for 115V-only and lower cost.
Hammond Mfg. - Power Transformer - Dual Primary / Dual Secondary (266 Series)
Or use the 166 for 115V-only and lower cost.
Regal,
I use a couple of Rod's regulators each feeding 4x 4p1l ( parallel push pull) filaments at 4.2 V total 1.3A. Each channel has its own raw supply and regulator. I know that 4p1l acts more linear at 2.1V filament, i tried but didnt like the sound. For the raw supply i bought some propower( made in England dual metric bobbins) transformers from Newark. The 75W was only $25. For the push pull i am working on now there is no issue to have a separate chassis for power supply. My next project will be a quad 4p1l PSE with filament bias. I bought two more regulators from Rod and intent to use them at 2.1V and 4x0.55-.6A(2.2-2.4A). It is going to be more challenging, bigger iron, more amps ripple for the filtering capacitors, bigger heatsink...hope for a better sound too...🙂
I use a couple of Rod's regulators each feeding 4x 4p1l ( parallel push pull) filaments at 4.2 V total 1.3A. Each channel has its own raw supply and regulator. I know that 4p1l acts more linear at 2.1V filament, i tried but didnt like the sound. For the raw supply i bought some propower( made in England dual metric bobbins) transformers from Newark. The 75W was only $25. For the push pull i am working on now there is no issue to have a separate chassis for power supply. My next project will be a quad 4p1l PSE with filament bias. I bought two more regulators from Rod and intent to use them at 2.1V and 4x0.55-.6A(2.2-2.4A). It is going to be more challenging, bigger iron, more amps ripple for the filtering capacitors, bigger heatsink...hope for a better sound too...🙂
Thing I am concerned about is heatsinking, the two SSHV's are going to take up most of the back of the amp for a heatsink, so I'm going to have to find a wide case to sink two SSHV's + two coleman regs, it will be worth it though
Abszero.
Can you post the schematic of your 4x 4p1l parallel push pull amp, please?
What output transformers you use?
Can you post the schematic of your 4x 4p1l parallel push pull amp, please?
What output transformers you use?
I don't have the schematics ready, but I can describe it for you.
Paralleled 4P1l triode mode at 240V and 35mA ( 93% PDmax) push pull, filament bias, OT is LL1663. Filaments of 4P1L at 4.2V with Rod Coleman's regulators. IT is LL1660/10mA, driver 6N30P at 25mA and 90V cathode bias. Power supply with LL1649, LL1638 choke, clarity caps, and SSHV for driver. Raw supply for Rod's regulators uses SPC ProPower 75W, 2x9V,4A. No global NFB.
The amp needs 2V from CD player for full power. I have it built and under testing now. Sounds sweet and transparent🙂. I am listening it with Klipsch Sinergy B3. Excellent playing classical, jazz, voice. I intent to have it for sale by this summer at simplepleasuretubeamp.com.
Best,
Radu
The Filament Regulators are DIY kits for self-assembly. I can send you some email/PM with details, manuals and cost.
opt
I'm looking at the Sowter TRANSFORMERS FOR HEADPHONE AMPLIFIERS to get the appropiate opt for the attached schematic? also I need to know the appropiate power spec for B+ 300V for 4p1l & 440V for 307A (I want to use SSHV2 so I need extra 20V for the reg)?
TIA
Felipe
I'm looking at the Sowter TRANSFORMERS FOR HEADPHONE AMPLIFIERS to get the appropiate opt for the attached schematic? also I need to know the appropiate power spec for B+ 300V for 4p1l & 440V for 307A (I want to use SSHV2 so I need extra 20V for the reg)?
TIA
Felipe
Attachments
hi Felipe,
The 9351 will work with a 307A, if your load is somewhere around 600/300/150/40 ohms specified for Sowter 9351.
The 9351 offers around 5W - if that is enough. I assume you are not working with the 'Difficult' headphones, that Regal is aiming for.
Beware of running the 307A at 400V+. Ale's curves seem to suggest it will have lower distortion at nearer to 300V.
You could try to plot a 5K load line on 307A curves and see how they look. Or you could just build, since you have the 307As already!
If it doesn't work out, the transformers can be used with many other triodes, including 300Bs: 325V to 350V will work with these, also - but 45mA max dc though.
The 9351 will work with a 307A, if your load is somewhere around 600/300/150/40 ohms specified for Sowter 9351.
The 9351 offers around 5W - if that is enough. I assume you are not working with the 'Difficult' headphones, that Regal is aiming for.
Beware of running the 307A at 400V+. Ale's curves seem to suggest it will have lower distortion at nearer to 300V.
You could try to plot a 5K load line on 307A curves and see how they look. Or you could just build, since you have the 307As already!
If it doesn't work out, the transformers can be used with many other triodes, including 300Bs: 325V to 350V will work with these, also - but 45mA max dc though.
Hi Rod,
Thank you for opt advice.
I don't know how I can plot a 5K load line on 307A curves.
About power transformer how much power? how many secondaries one for 4p1l and one for 307a or only one for both tubes?
What about the power transformer & psu necessary for your heaters reg for 4p1l, wich transformer: voltage/power necessary for 307a heaters?
A big thanks for your support Rod.
Thank you for opt advice.
I don't know how I can plot a 5K load line on 307A curves.
About power transformer how much power? how many secondaries one for 4p1l and one for 307a or only one for both tubes?
What about the power transformer & psu necessary for your heaters reg for 4p1l, wich transformer: voltage/power necessary for 307a heaters?
A big thanks for your support Rod.
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Wow, total cost for 2 Sowter opt incl. shipping 450€ near the 500€ Bartolucci asked, now I doubt wich one to purchase having in mind that Bartolucci are custom made and Sowter not.
Hi Felipe,
If you are sure that the 307A wll meet your Power demands, you can just build it, but I recommend 300-325V dc for this tube, unless you can get better information. Many other triodes work with 5K loads, even EL84 in triode mode - so you can use the OT with confidence.
For PT, you can achieve 325V dc with this trafospec.:
0-350V 75 to 100VA
EI-structure of core, with split bobbin (= dual bobbin)
choke-input filter
choke 5H 100mA
If using SSHV, then trafo is 370V rms 100VA-rated.
Please use a private transformer for the filament heating (important!)
Have you considered the Tribute versions of OT, also?
If you are sure that the 307A wll meet your Power demands, you can just build it, but I recommend 300-325V dc for this tube, unless you can get better information. Many other triodes work with 5K loads, even EL84 in triode mode - so you can use the OT with confidence.
For PT, you can achieve 325V dc with this trafospec.:
0-350V 75 to 100VA
EI-structure of core, with split bobbin (= dual bobbin)
choke-input filter
choke 5H 100mA
If using SSHV, then trafo is 370V rms 100VA-rated.
Please use a private transformer for the filament heating (important!)
Have you considered the Tribute versions of OT, also?
Please model the PSU with PSUD2, to fine-tune the transformer specification!
use choke-input filter.
You can see the demand on the trafo by looking at the rms-current column in the PSUD2 output.
use choke-input filter.
You can see the demand on the trafo by looking at the rms-current column in the PSUD2 output.
The Tribute I ordered one is of nano-tech non-amorphous core (finemet), its fairly experimental for this application although has been done with the Japanese Feastex Takatsuki 300B commercial amp.
I would recommend contacting Tribute thru email for pricing, but he has a lot of business, so since this is a developmental OPT you may want to wait till it is a standard product.
I will be building my DHT SET headphone amp with 2A3 output tubes after Ale's not so good measurements of the 307A. I think the new JJ-2A3-40 and Chinese 2A3-C's which are basically 300B's with 2.5V filaments are ideal (the sims show much better linearity with 300B than an other DHT short of the HV transmiters.) Would be interesting to see Ale's measurements of these modern 2A3's-300Bs.
I plan on IDHT drivers in order to keep it 2 stage, just not enough gain from small signal DHT's for 2-stage.
Hi Regal,
I don't have any JJ-2A3-40 or Cs unfortunately. I do have 6C4C and classic 2A3 and recently someone gave me an EH 300B which I will trace as soon as get some time
Cheers,
Ale
I don't have any JJ-2A3-40 or Cs unfortunately. I do have 6C4C and classic 2A3 and recently someone gave me an EH 300B which I will trace as soon as get some time
Cheers,
Ale
The JJ 2A3-40 does not inspire confidence, for working above the usual 2A3 voltages.
compare the published curves:
http://www.jj-electronic.com/pdf/2A3.pdf
And, to keep the comparison fair - intramural, even - please see their 300B:
http://www.jj-electronic.com/pdf/300 B.pdf
And see how the 2A3's behaviour goes bad, much above 400V.
The 40W thermal rating is deceptive. It's the internal geometry that makes the 300B the beauty it is (when well fed, and watered).
.
compare the published curves:
http://www.jj-electronic.com/pdf/2A3.pdf
And, to keep the comparison fair - intramural, even - please see their 300B:
http://www.jj-electronic.com/pdf/300 B.pdf
And see how the 2A3's behaviour goes bad, much above 400V.
The 40W thermal rating is deceptive. It's the internal geometry that makes the 300B the beauty it is (when well fed, and watered).
.