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Old 18th October 2010, 05:35 AM   #1
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Default First time baby Huey amplifier build

I have chosen to build a monoblock version of the baby huey amplifier design for my first build. For those of you who have done this before, I have a few questions.
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First off, could I use a 5Y3GT rectifier tube instead of the solid state rectifier shown in the diagram? Additionally, what is the CCS subcircuit, and what role does it play? I am confused about what the function of the LED is, and why the schematic shows two wires going the other channel's CCS. Since I am building a mono amp, what becomes to those two wires? Additionally, since I am building a mono amp should I change the pair of resistors on the leads going to HT left and right to a single resistor equivalent to the parallel set? If you have any input I would really appreciate it.

Thanks,
-Matt
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Old 18th October 2010, 06:52 AM   #2
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re 5y3gt, yes i dont see why not as long as you obey it's max cap ratings etc. You will need to use the 5v winding on you power tx, so will have to think how you will get the -15v for the CCS.

The CCS is a morgan jones design (see book 'valve amplifiers') the led provides a Vref, take the VBE of the lower bc547b (0.7v) from the 1.7V led ref to give the voltage through the 1k. 1v / 1kr = 1ma CCS for the phase splitter. two wires go as you need a -15v supply, and the ground.

just use the single 47R, you may need to tweak for the final desired B+. If you are using a valve rectifier you will probably need choke, do a CLCRC supply, tweaking for the first C for setting B+. use the duncan amp tools PSU simulator to help.
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Old 18th October 2010, 02:54 PM   #3
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220uf on a bottle rectifier????
And the bottle rec will decrease the b+ like adding a 150ohm resistor in line...
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Old 18th October 2010, 04:57 PM   #4
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so will have to think how you will get the -15v for the CCS

If you're using the Freed transformer I think I saw a spare 6.3v (0.9A) tap that could be used to provide your negative supply, will give about -17v but thats ok ( see post 5 of Baby Huey thread )
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Old 18th October 2010, 05:06 PM   #5
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Originally Posted by Soonerorlater View Post
If you're using the Freed transformer I think I saw a spare 6.3v (0.9A) tap that could be used to provide your negative supply, will give about -17v but thats ok ( see post 5 of Baby Huey thread )
Yes, I am using that Freed transformer, thanks for the info.
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Old 18th October 2010, 05:27 PM   #6
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That's good, voltage doubler draws very little current so can be used for your second channel later on
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Old 18th October 2010, 08:41 PM   #7
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Another question, my power transformer is rated at 750 volts center tapped, in order to get the voltage closer to the 350 range, I was planning on wiring the rectifier between the center tap and one outer tap to get half the voltage. Will this work for the Baby Huey design, or am I looking at it the wrong way?
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Old 18th October 2010, 08:56 PM   #8
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you are looking at it the wrong way. 750V CT is 375V per side of the centre tap, each operating on opposite phases - in effect two 375V OPTs operating side by side. Just follow the diagram sir. And download Duncan Amps PSUDII and get used to using it! It saves heaps of time and answers a lot of questions.
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Old 18th October 2010, 08:59 PM   #9
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Originally Posted by mossmamc View Post
Another question, my power transformer is rated at 750 volts center tapped, in order to get the voltage closer to the 350 range, I was planning on wiring the rectifier between the center tap and one outer tap to get half the voltage. Will this work for the Baby Huey design, or am I looking at it the wrong way?
You want a full wave center tap, see pic:

Note: Disregard the component values, the FWCT config is what is relevant.
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Old 18th October 2010, 10:48 PM   #10
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Originally Posted by boywonder View Post
You want a full wave center tap, see pic:

Note: Disregard the component values, the FWCT config is what is relevant.
Ok, I got the power supply design software, and I have what I believe is a working arrangement. It puts out 350 volts and draws .33A plate current once the transients die out. Take a look at this arrangement and let me know if you see any flaws.

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