I have all the parts for EL34 version as well and only need the boards for the EL84 but I don’t have any time right now to start building. At this moment I’m listening to Paul Desmond - Bossa Antigua a CD featuring the great guitar player Jim Hall.
My entire system is DIY - Pi 3 speakers, Aikido pre, First Watt f5 turbo monoblocks and a DDDac 1794 front end.
Another piano player I recently discovered is Bill Charlap. Love his recordings.
My entire system is DIY - Pi 3 speakers, Aikido pre, First Watt f5 turbo monoblocks and a DDDac 1794 front end.
Another piano player I recently discovered is Bill Charlap. Love his recordings.
Excellent reasons! I had hoped that somebody would know how much the BH board could swing on the power tube grids for given operating conditions - perhaps we will hear soon.
Apparently Marc’s experimentation had not included the 6L6 family of power tubes at >350V B+, which require more drive swing for full power. Perhaps someone who has a built EL34BH could swap out the EL34 power tubes for 6L6s, or 7581s and report back (will require bias adjustment, or course).
I read some of the previous BH thread (as Marc had pointed out) and it provides a lot of good information. I stamd corrected about the experimentation with BH 6L6 amps. See:
https://www.diyaudio.com/forums/tubes-valves/72536-el84-amp-baby-huey-188.html#post5307496
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
I bought this power transformer
TSTA 0250/001 - Mains transformer for tubes - Shop Toroidy.pl
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.
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:
https://www.diyaudio.com/forums/tub...ce-simulations-speaker-loads.html#post5674063
Could we please have more discussion on this topic based on experience and observations of previous BH EL84 builders.
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:
https://www.diyaudio.com/forums/tub...ce-simulations-speaker-loads.html#post5674063
Could we please have more discussion on this topic based on experience and observations of previous BH EL84 builders.
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/ProjectManager/ProjectDetail.aspx?AccessID=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
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/ProjectManager/ProjectDetail.aspx?AccessID=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
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 ?
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 ?
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
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