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EL34 Baby Huey Amplifier
EL34 Baby Huey Amplifier
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Old 7th September 2018, 04:46 PM   #21
bandol83 is offline bandol83  France
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Join Date: Nov 2004
Location: near Bandol, French Riviera
Default External Power Supply Option

Hello All,

I am pleased to see that there is a lot of tweaking on the EL34 Baby Huey PCB
That was the purpose of this layout : to put everything on a single PCB, including all power supply circuitry, therefor it could be easy to build a tube amplifier by only adding the transformers, but still to give a lot of flexibility for those who will try to test different solutions, like different output tubes, different output transformer wiring and of course different power supply...

The most recommended modification is to use DC power supply for heaters instead of AC to have a silent amplifier (no hum) as several builders have confirmed, but, as I have just answered in th GB thread, it is totally possible to use an external power supply with bigger capacitors and even a choke to power the EL34 Baby Huey In that case you can connect the DC high voltage to the AC connector and the diode bridge will connect the good polarity to the capacitors, it is the safer method with a small price to pay : you will loose 2 V in the diodes !

If you have enough knowledge of electronic circuits, you may even remove ALL the UF4007 rectifiers and to replace D1 and D3 with two jumpers, AC2 will become the positive input and AC1 will be the negative input, but in this case you should be careful to connect the B+ correctly

In all case always refer to the schematic and check twice before to do the last solution because if you reverse the polarity you will kill you amplifier

Don't hesitate to put your questions on this forum it case of doubt, it may help others.

Best regards,
Marc
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Old 8th September 2018, 06:54 AM   #22
huggygood is offline huggygood  France
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Join Date: Mar 2011
Location: france (bretagne)
Quote:
Originally Posted by bandol83 View Post
Some more precision about the PSU (see attached diagram) :


2) Even if you can supply the heater directly from the 6.3V AC outputs of the power transformer, I recommend to use a 6.3V DC approach to have no hum at all from the 50 or 60 Hz main. Today DC/DC converter are so cheap that it should be an error not to take advantage of them, but don't hesitate to take a big one, like 20 A, because their specification are very exaggerated : 1 PC DC 300 W 20A CC CV Courant Constant Reglable Step Down Converter Tension Buck Z09 Drop ship dans Circuits integres de Composants electroniques et Fournitures sur AliExpress.com | Alibaba Group


Best regards,
Marc
I send you a pm for more explication in french ,it feels good to write in French from time to time
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Old 9th September 2018, 05:20 PM   #23
bandol83 is offline bandol83  France
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Join Date: Nov 2004
Location: near Bandol, French Riviera
Hi,

The EL34 Baby Huey enclosure is nearly finished (see Picture) and now the final wiring will start... The holes for the vu-meters have been made and the last problem to solve is the hole for the infra-red detector, since the pin are on the side and not on the back like a LED and the front panel is 6 mm thick, it is not evident to mount it

If you have any suggestion, they are welcome

Best regards,
Marc
Attached Images
File Type: jpg Front view with vu-meters 9 Sept 2018.jpg (152.8 KB, 797 views)
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Old 9th September 2018, 05:57 PM   #24
Bfpca is offline Bfpca  Canada
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Join Date: Feb 2007
Location: Nova Scotia
EL34 Baby Huey Amplifier
Quote:
Originally Posted by bandol83 View Post
Hi,

The EL34 Baby Huey enclosure is nearly finished (see Picture) and now the final wiring will start... The holes for the vu-meters have been made and the last problem to solve is the hole for the infra-red detector, since the pin are on the side and not on the back like a LED and the front panel is 6 mm thick, it is not evident to mount it

If you have any suggestion, they are welcome

Best regards,
Marc
Marc, Can you enlarge only the back side of the hole? I have sometimes done this on thick panels to allow for the mounting of RCA jacks or switches that do not have a long enough thread to reach through the thickness of the chassis. It is not for the faint of heart, because if you make a mistake you could ruin the panel.

Brian
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Old 9th September 2018, 06:17 PM   #25
silasmellor is offline silasmellor  Denmark
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Join Date: Nov 2016
Location: Denmark
EL34 Baby Huey Amplifier
You could use a counterbore bit to enlarge the hole on the back like Bfpca suggested. It is a lot easier to control than a regular drill bit and also makes a nice flat edge.

Something like this (not knowing the diameter you need):
? Mu ? Tools HSSE Countersink Drill Bit with Pin Counterbore 6 - 20 Mm / M 3 - | eBay

There are many cheaper options on flea bay as well.
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Old 10th September 2018, 08:24 PM   #26
pvphil is offline pvphil  France
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Join Date: Jan 2018
Location: Six Fours les Plages, French Riviera
Hello,




I made a counterbore with a strawberry of 8 with my old drill press.


The IR cell is in place.


For information, a view of the area of 220v and DC power circuits.



The mechanical part and chassis integration is now complete, now place to wiring ....





Regard,


Philippe
Attached Images
File Type: jpg chassis PP EL34 51.jpg (149.6 KB, 744 views)
File Type: jpg chassis PP EL34 50.jpg (125.7 KB, 731 views)
File Type: jpg chassis PP EL34 49.jpg (107.7 KB, 723 views)
File Type: jpg chassis PP EL34 48.jpg (228.9 KB, 728 views)
File Type: jpg chassis PP EL34 52.jpg (200.2 KB, 318 views)

Last edited by pvphil; 10th September 2018 at 08:37 PM.
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Old 10th September 2018, 11:01 PM   #27
Vunce is offline Vunce  United States
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Join Date: Jan 2014
Location: LI, NY
EL34 Baby Huey Amplifier
Well done Philippe!
That Baby Huey looks looks really cool
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Old 11th September 2018, 01:00 PM   #28
pvphil is offline pvphil  France
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Thanks Vunce


Sorry , not "strawberry" but "milling cutter" ... ....




Philippe




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Old 11th September 2018, 02:03 PM   #29
Grumpish is online now Grumpish  United Kingdom
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Default KT66

OK, it is a little bit putting the cart before the horse, I am looking at using KT66 (or similar) tubes because I have a pair of Hammond 1650FA transformers I can use - are there any components that would need to be changed? Also, any idea of how much power I would lose against using EL34's (with something like the 1650N transformers)?
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Old 12th September 2018, 01:35 AM   #30
gingertube is offline gingertube  Australia
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Join Date: Oct 2004
Location: Adelaide South Oz
The Hammond 1650FA are 7k6 Raa, 25 watt rated.
They don't really suit KT66. Could be made to work with B+ of 390V and Screen Voltage of 270V in Class A Push Pull for 30W output, Tetrode connected, but the BH Board is not really set up to provide that lower screen voltage.

Possibly some JJ 6V6S (which have higher voltage rating than many 6V6) would work with the 1650FA, output would likely be 15 Watts.

Cheers,
Ian
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