• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

EL84 Amp - Baby Huey

Tube Rectifier - that would be the Jessica Amp.

Here is the Power Supply I used for Jessica's BH.

Cheers,
Ian
 

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Tube Rectifier - that would be the Jessica Amp.

Here is the Power Supply I used for Jessica's BH.

Cheers,
Ian

That's interesting, I've been meaning to build a Baby Huey with tube rectification.

The obvious choice would be an EZ81 rectifier, however I will be using all-Russian (6P14P and 6N2P) tubes for my BH so ideally I want to use a Russian rectifier too. The Russians never seemed to have made a noval rectifier however, so I'm pretty much "stuck" with using a 5C4S, which is supposedly a 5Z4GT. I also have some nice 100uf film caps I want to use as a power supply reservoir cap.

Do you think I can run 4 EL84's and 2 6N2P's on one 5C4S? What would the total current draw be?

I'm using a 300-0-300 trans, 250mA
4,7uF behind the rectifier (this is a downside, because the ez81 can handle 50uF), a 10H choke with 100uF cap, then the EL84's.

I simulated this with PSUD (using 5Y3-GT as rectifier).
This gives me a B+ of about 285 volts. Is this sufficient? I think so?

Any other configuration that works better? Should I just ditch the valve rectification idea? (My trans does not have a 5v winding so I'll need a separate one anyway.)
 
Baby Huey Power.

For a simple but effective solid state high voltage (series not shunt) regulator see the pdf attached to dupyv (the other Yves) post #369

Cheers,
Ian

Hi Ian,

I have successfully built a phono stage and preamp from drawings but never a power amp. My tech knowledge is minimal. But with all the info here I am pretty sure I can do the Baby Huey.
I think, as I am a complete newbie, I will stick to your original schematic, keep it as simple as possible and use solid state in the PS. I can always have a go dupyv's regulated PS later.

Please can you tell me what voltage center tapped transformer is used in your original schematic? I can get a 240-0-240 @ 200mA transformer with 5V@2A and 6.3V@5A windings. I think this should give about 325v DC before smoothing. Is this correct?

Thanks.

Ian M.
 
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Sharkey22 (Ian M.),
Wioth 350-0-350 and Solid State Rectifier you will get a lot more than 315V DC (unless using a choke input power suppy).
For the original BH (schematic back on page 1) with a solid State Rectifier you want 240-0-240 typical, up to 285-0-285 would do but give you a higher B+ voltage.
I've also used a non centre tapped 240V AC secondary with a bridge rectifier successfully.
PSUD2 is your friend,
PSUD2 can be downloaded from here:
Duncan's Amp Pages
Cheers,
Ian (thats Ian M. as well).
 
Hi Ian, looks likeyou read my post before I edited it. If you look back you will see that I had sort of corrected my own error regarding voltages.

Just got PSUII and modelled a few variations. My original and way too high estimate was based on the Hammond rectification guide that suggests that DC output from HWCT Solid state is 0.45 x secondary AC output. (am I missing something here? think i was looking at choke input figures) Whereas in reality it is about 1.4 x secondary. I had tried using PSU11 a few times but have literally only just got the hang of it. Is there a dummies guide to psu11 anywhere?

I have already ordered a transformer with 280-240-0-240-280 @ 220mA. with 6.3 and 5 volt windings (future proof!)this should do for solid state or valve rectifier as I please with loads of current to play with. Custom built for about £60 UK. Bargain.

thanks for your help. Ian.
 
I also have a choke out of an old push pull el34 amp. Sure i can utilise this in some way but as yet i dont know its value. Should handle the current though. Is there a simple way of measuring the inductance without a LCR meter?

If i use a bridge rectifier i could use one of these? Dont know if i am allowed to post links but here goes.

http://www.ebay.co.uk/itm/BLOCK-UNI...al_Components_Supplies_ET&hash=item2a1af7e6fe
 
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All the texts will tell you that an LCR meter will give you a wrong reading of the inductance due to lack of DC in the choke while measuring (LCR meters use AC excitation only).

BUT
All the chokes I have measured with my LCR meter have given readings about 20% low. That is probably within the meter accuracy, choke tolerance etc., so use your LCR meter with a reasonable confidence of getting about the right value.

Cheers,
Ian
 
OK, so I have not got an exact value for the choke yet but I have had a bit of a read and experimented with PSUD2. Not sure that it is perfect but I think I have what looks like a fairly smooth arrangement for my power supply.

Is it OK to add resistors before the diodes in order to tweak the final B+?
Also I only know the resistance of the choke without load, I presume this will rise under load.

Can you have a glance at the design and confirm that it is OK.

Cheers Ian.
 

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One of the downsides of these LONG threads here on DIYaudio is that the information is spread out across many pages.

With that in mind, I apologize if my question has already been answered.

I am planning to build one of these babies, and originally wanted to use tube rectification. I've now decided to go with solid state for practical reasons.

I have two of these power trannies:
Transformatoren - Voedingstrafo Buizenapparatuur - EOO - ElectronicaOnderdelenOnline

Nice quality stuff for not a lot of money really.

But the downside is that they don't have a 5v winding, so I need a separate transformer for the CCS'

Here's the actual question: Given that the original PSU design uses a voltage doubler, can I use a tranny other than 5v? I'm thinking of using a 9v one, and I have a 15v one laying around, so if I could use that even better!
 
Baby Huey power supply advice wanted.

Hello all. I have not built a power amp before so would appreciate a bit of advice re Baby Huey power supply design. I have modelled the attached design with PSUD2 but want to check that it is good before going ahead with component purchase. My transformer has 240v taps as well as 290v which may be more appropriate for solid state rectification. Any advice greatly appreciated as I am not at all confident re calculations or ideal PS design..
Thanks. Ian M.
 

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