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EL84 Amp - Baby Huey
EL84 Amp - Baby Huey
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Old 12th January 2018, 09:52 PM   #1871
bandol83 is offline bandol83  France
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Location: near Bandol, French Riviera
Hello SCD, hello all,

I already answered the subject of a new thread in my post 1833 to Patrick (reaper996) !

As I explained, the EL34 Baby Huey is 98% schematically compatible with the EL84 version, the only difference is the output tubes and the value of some resistors... In this thread there was already 6V6, 6L6 and others version of EL34 Baby Huey

I don't think this approach is bad for the thread, on contrary it has wake up the thread which was a little bit quite for some time

However, if Ian (gingertube) think that I must start a new thread only for EL34 and ask me that, I will do it without any problem since he helped me a lot in this project. I am sure that when I started to ask him some recommendations, he did not believe, like me, that more than 200 PCB will be sold for EL 34 Baby Huey

Cheers,
Marc
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Old 12th January 2018, 11:52 PM   #1872
adam1016 is offline adam1016  United States
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Alright, I've bought the parts for the preamp that will (eventually) drive my baby hueys, and ordered the transformers from edcor. I got a pair of xpwr064s, and called edcor about adding 6 ohm taps to the cxpp24-8k, which they graciously added at no extra charge

However, I'm now faced with a dilemma. My speakers are RATED at 99db/W(not sure how accurate this is, as they're a fairly new DIY design). I have an old receiver I've been using to drive them until now which is rated at 50W, so I keep the volume as low as it can go. My question is:

The EL34 seems to put out about 50W, but seems to have more of the tone I am looking for (warmer mids, better bass). My transformers are only rated for 25W, and my speakers would never use all this power. Is there a way to limit the power put out by these tubes without having to redesign much of the circuit? Are there significant tonal differences between the EL34 and the EL84, or are they just different power ratings?

I guess at the end of the day, I'm leaning hard towards the EL84, but have been hesitant to pull the trigger.
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Old 13th January 2018, 12:40 AM   #1873
crispycircuit is offline crispycircuit  United States
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6v6 tube is the same power as a EL84. So use 6v6s with the ability to also use EL34s, if wanted. It should work out fine.
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Old 13th January 2018, 05:26 PM   #1874
bandol83 is offline bandol83  France
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Location: near Bandol, French Riviera
Hi,

I fully agree with crispycircuit, the big advantage of this PCB with the octal socket is to accept a large choice of output tubes from the 6V6 (equivalent of the EL84) to the KT88 or even KT120

With different tubes and power supply it is possible to build your amplifier with an output power from 10 to 50 W but with the same Baby Huey shunt feedback design introduced more than 10 years ago by Yves on an ECL86 amplifier and Ian with the original EL84 amplifier

I have added two comparisons of several output tubes which can be used with this EL 34 PCB and a new BOM with different capacitors values for those who want to use higher voltage ( I didn't made test at more than 380 V however !).

Rgds,
Marc
Attached Files
File Type: pdf Comparaison pentodes et tetrodes.pdf (185.3 KB, 126 views)
File Type: pdf CHOICE OF POWER TUBES FOR THE EL34.pdf (164.6 KB, 140 views)
File Type: pdf BOM Ampli EL34 Jan 11, 2018.pdf (91.9 KB, 122 views)
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Old 14th January 2018, 09:15 AM   #1875
Rene is offline Rene  Netherlands
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Join Date: Mar 2004
Location: the Netherlands
Hi,

For nice looking Torodial Power supply and OPT see this site.

Mains Transformers - Shop Toroidy.pl
Push-pull - Shop Toroidy.pl
Also option for a nice Transformer Cap. In case of on TOP assemblage.

For output transfomer the ASV Aot40
ASV output transformers
I bought it for my 6B4G PP amplifier but not yet started, so i can use them for this project. The specs are very good, but can't say anything yet about the sound.
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Old 14th January 2018, 05:57 PM   #1876
adam1016 is offline adam1016  United States
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Alright, I've made my decision and begun ordering parts:

I have decided to stick with the 'classic' baby huey as was posted in post 602. I am going to stick with the EL84 for now, and because I am not using a PCB for the entire project (though I may use proto-boards for the bias sections), I can always swap a couple resistors and the sockets/power supply/transformers later if I decide I want to try different tubes (Or just build another amp with octal sockets )

Much thanks for all the advice,
Adam
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Old 16th January 2018, 09:59 AM   #1877
mctavish is offline mctavish  Austria
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Can anyone help me understand what r13 is doing in the circuit?

Also looking for a source of octal pc-mount sockets in EU.....
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Old 16th January 2018, 01:59 PM   #1878
jazbo8 is offline jazbo8
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EL84 Amp - Baby Huey
You may want to read the Wiki.
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Old 16th January 2018, 02:03 PM   #1879
mctavish is offline mctavish  Austria
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many thanks!!!
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Old 17th January 2018, 11:21 PM   #1880
silvercosworth is offline silvercosworth
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Please start a new EL34 version thread.
Many thanks for the awesome GB !
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