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PostPosted: 20 Feb 2009, 14:34 
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Just a couple of days ago I finally purchased some Oak wood to begin construction of my Williamson amp that I have been planning and collecting parts for about a year now.

The chassis uses a 17"x17" piece of aluminum were all the guts will be mounted on. It is a working progress and I had to simplify certian areas a little, such as the power supply. I originally wanted to go full regulation for the driver stage but found that it was too hard to purchase all the parts needed, plus it added about $100 worth of components to the amp and I would rather spend the money on decent coupling caps for the moment.

I still have yet to find a pair of LM317HV TO-3 regulators for the bias, unless there is a different circuit that used Fet's or something, but I want to keep it simple and reliable with many types of tubes.

I do have one final question before I finalize installing them, I have two 200ma meters I would like to use for each amplifier to monitor their current consumption on the output stage. My power supply will put out between 400 and 450 volts maybe more, I'm not sure if these meters are designed to handle that much voltage, so will they?

Here are some pics....
Attachment:
Amp meters(small).jpg
Attachment:
Amplifier construction(small).jpg
Attachment:
Amplifier construction plans(small).jpg


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PostPosted: 20 Feb 2009, 19:09 
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If any metering is done, it should be by utilizing a simple volt-meter to monitor the cathode voltage, thus the current though them.
Assuming of course, you're using cathode resistors.


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PostPosted: 21 Feb 2009, 08:22 
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Joined: 27 Jan 2009, 10:17
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Location: Montreal, Canada
Quote:
I still have yet to find a pair of LM317HV TO-3 regulators for the bias

Try a TL783 from Texas Instruments Will go to 125 Volts@700mA, much better chip than LM317 except less current output, which in this case should not be of concern, but I have not seen your schema.

Here is the Texas Instruments TL783 data sheet.
Luc


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PostPosted: 21 Feb 2009, 16:21 
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Nice! Where are the audio output transformers from?

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PostPosted: 23 Feb 2009, 16:45 
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The bias circuit is with a LM317 regulator, same as in Bruce's Odd Watt amplifiers, so I will have a bias of 150-185mA. If the chip you can be used in the same set up as the Odd Watt amplifiers than that is a much better choice, especially if it is capable of that much voltage. I will look it up and see if I can find a TO-3 version for the heat sink I have. ;)

As for the meters, I thought it would be neat If I could install these meters for both testing and monitoring purposes, plus they would look really cool. I want to install them either between the power supply rails to each amplifier, or as a bias current meter, but the power supply sounds like a better place if it is possible.

I suppose I could get a volt meter but I am more worried about current consumption, plus I can just use my multimeter to measure the voltage, I have these plugin posts that I can use.

All power transformers are Hammond, and the outputs are salvaged from original W5M amplifiers. Peerless 16458 10K 45 watts. The amplifier weighs like 50 pounds all ready and I only have like 2/3 of the weight on it!!! :eek:
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Partially constructed Williamson(small).jpg
Attachment:
PS section of amp(small).jpg


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PostPosted: 23 Feb 2009, 17:12 
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wow!
if the photo with all the tubes on is what it will look like, how did you get your head round where to put everything?
Williamson amp? is this based on an existing amp?


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PostPosted: 23 Feb 2009, 19:05 
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Well, it is rather so based around multiple designs, there is a picture in the gallery of a similar amplifier someone built, and I wish he had more information on it because it looks really cool.

It actually took me about a year to finally decide how to throw it all together, and by the time it is done I will have used about 5-10 bits and pieces of other designs, people such as Bruce used a voltage regulator to bias his amplifiers output stage. The amplifier itself is based on the Heath W5M mainly. I have a pair of these amps (non functional) that I salvaged the output iron from.

I have not seen very many people use this design recently, but I have the original Heath W-1 Williamson amp that my grandfather constructed in the 50's. I cleaned it all up and added mods and new capacitors to it and it sounds really nice and has a decent amount of power too, so decided on this circuit.

Trust me it was not easy to figure out the arrangement with only one piece of aluminum, and after this, I am never building a stereo amp of this size again, it's soooo darn heavy, I can barely lift it on to the bench top!! :down:

I would like to see others reconstruct a Williamson of this type, because I have yet to see one. :up:
But be warned! There is 800V at 465mA present in this amplifier, and because the power transformer is so massive (465VA strangely enough) I feel the need for a soft start circuit. :down:

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PostPosted: 23 Feb 2009, 22:48 
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CrazzyAbtTubes wrote:
Well, it is rather so based around multiple designs, there is a picture in the gallery of a similar amplifier someone built, and I wish he had more information on it because it looks really cool.

Hi Alan, post a link to the photo and I will see if I can get you some more info.
Cheers

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PostPosted: 24 Feb 2009, 15:50 
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Now that I look at it I'm not sure if the amplifier is entirely based on the Williamson circuit, but it uses the same pre/driver stage.

Here is one of the pictures:
Image

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PostPosted: 02 Mar 2009, 19:20 
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I now have all of the socket holes drilled, and now time to start carving the wood chassis for the meters and switches, which is going to be a challenge with the antiquated tools I have for drilling holes. I will soon order some more parts, but I have to do it bit by bit you know that little thing called :$: . :2c:

If I am lucky I may have this thing together and working before the summer and I'm hoping I won't have any bugs to work out.

Stay tuned! :headphones:

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