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EL34 Baby Huey Amplifier
EL34 Baby Huey Amplifier
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Old 17th January 2019, 02:57 PM   #251
ckwong99 is offline ckwong99  Hong Kong
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Join Date: May 2005
Location: HK
Hi Marc. for EL34 pcb . I got a opt (about 40 W) it is from Harmond (seem from guitar amp dismental). But it only have a triode mode connection. Not sue how many output power can deliver . and i use B+ about 400vdc. Do u think with this arrangement is ok ?

I bought this power transformer
TSTA 0250/001 - Mains transformer for tubes - Shop Toroidy.pl
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Old 24th January 2019, 12:14 AM   #252
Francois G is offline Francois G  United States
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Join Date: Jun 2004
Location: Champaign, Illinois
Guess Marc is not answering so I will try. First, what is the primary impedance of your transformers? If the guitar amp used 6L6 type output tubes it probably is around 6k. In that case it should work well with the EL34 BH PCB. Marc had previously stated that triode connection is fine. However, if it is used as triode output it probably could be used in tetrode mode without screengrid connections, which Marc had said works fine too.
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Old 24th January 2019, 12:26 AM   #253
Francois G is offline Francois G  United States
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Location: Champaign, Illinois
Default Best operating conditions for EL84 BH

In this thread I had previously asked what the best operating conditions were for EL84 BH. The answer provided was not very specific. Perhaps that was the “correct answer” in that it seems the EL84 performs well over a wide range of conditions.

See this thread:
Question regarding EL84 loadlines in push-pull; LTSpice simulations and speaker loads

Could we please have more discussion on this topic based on experience and observations of previous BH EL84 builders.
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Old 24th January 2019, 01:38 AM   #254
ckwong99 is offline ckwong99  Hong Kong
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Hi Francois G. thanks for your answer. Actually, the OPT is 6K5 ohm. I will try teo connections mode, thank you !
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Old 24th January 2019, 03:49 AM   #255
carlthess40 is offline carlthess40  United States
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Location: Lake Mary Florida
Hi
I just got my boards in today
Great work in them. Is there a GB for all the parts and if so could I get the link for it
Thanks
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Old 24th January 2019, 04:05 AM   #256
Francois G is offline Francois G  United States
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Location: Champaign, Illinois
Carlthess40,

I also posted this information to the GB thread, but Marc and Prasi requested that this type of information and discussion should preferably take place in this thread.

Since you seem to be located in the USA there was a Mouser buylist in the old Baby Huey EL84 tread. I did not check it now, but it should save time in finding the right items to order from Mouser.com

Mouser Electronics: https://www.mouser.com/ProjectManage...sID=21e0043f5d

This list does not include transformers, connectors, case, power cord, etc.

The builders in NA are likely to buy their transformers in NA, and EDCOR or Hammond both make suitable, not very expensive transformers (and chokes, if you wanted to use a choke). Several folk imported their trannies from Toroidyi in Poland as recommended by Marc. Some used a ClassicTone 40-18069 power transformer which offers all the needed voltages and currents for the EL34 version.

There is very good information in the old, very long Baby Huey EL84 thread, so current builders of the new batch of PCBs may find answers already discussed to questions they may develop. This is available at:

EL84 Amp - Baby Huey
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Old 24th January 2019, 04:14 AM   #257
kp93300 is offline kp93300  Malaysia
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Join Date: Mar 2007
This transformer must
supply 150 to 200 mA for a 6V6 version and 300 to 400 mA for 6CA7 or EL34 version.

You will also need an other power supply for the MOSFET driver stage and the negative bias of
the output tubes, typically a small 10 W transformer with a voltage between 48 and 65 V and
50 mA current will be enough. Again the amplifier include the rectifiers and filters on board.
Last but not the least, heaters must be powered with 6.3 V… It is better to use DC supply to avoid
all hum at 50 Hz(or 60 Hz), however if you are using an AC power supply there will be no
damage for the amplifier. Beware that the output tube are consuming a lot depending of which
ones are used it can go up to 1.6 A per tube, that mean nearly 7 A (including input tubes) for a
stereo amplifier !!!

I copied this information from the building instructions kindly provided by Marc.
I want to confirm that these ampere figures refer to one board or one stereo pair ?
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Old 24th January 2019, 12:18 PM   #258
bandol83 is offline bandol83  France
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Join Date: Nov 2004
Location: near Bandol, French Riviera
Hi analogadikt,

Yes, you can use a 2 x 300 V transformer with center output, THIS HAS ALREADY BEEN DISCUSSED IN THIS THREAD... See post 156, 158 & 164, please read the thread before to ask question that have already been answered

Hi ckwong99,

Yes, your output transformer can be used and as explained abose the triode and tetrode or pentode connection have already been discussed here : EL84 Amp - Baby Huey

Hi carlthess40,

The last BOM fort BOTH EL34 Baby Huey & EL84 Baby Huey is in post 198 ! This is a forum for DIY fans, it is not a hot line for a Company selling expensive kit like Heathkit in the past, PCB are produced without profit and schematic or layout are done for free, but it is expected that people buying PCB will work a little bit to find the parts and buy them...

Hi Francois G,

Thank you for answering the questions and remind people that they were already discussed in the two EL34 & EL84 Baby Huey thread The last BOM is in this thread post 198

Hi kp93300,

You are right with your infos for the PS transformer, this will be enough for a stereo amplifier, for the EL34 BH you can also use a single transformer like the TSTA 0250/001 used by ckwong99, pvphil, myself and many others builders...

Best regards,
Marc
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Old 24th January 2019, 12:34 PM   #259
analogadikt is offline analogadikt  India
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Join Date: Jan 2011
Location: Mumbai, India
Hi Mark,

Thanks. Had checked several pages but could not find that information, my bad obviously. Apologies for the trouble.

Regards,
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Old 24th January 2019, 04:25 PM   #260
carlthess40 is offline carlthess40  United States
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Join Date: Oct 2017
Location: Lake Mary Florida
So do I order one or two of these kits ? Looks like just one kit for two boards!
Thanks
I also need to find the tube sockets , that should be pretty easy to do
Thank you for the help and I hope you guys don’t get tired of hearing my questions as there will be a few. Lol
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