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In the Forum: Melquiades Amplifier
In the Thread: Planning my DSET
Post Subject: Do not rashPosted by Romy the Cat on: 2/27/2017
 anthony wrote:
That is what I meant, an ammeter for the DHT plate current.  I don't see that the plate current is adjustable anywhere in the circuit, and you don't show the meter in the circuit diagram so I wondered if you actually used one.  In my situation it will be difficult to fit a sixth meter as the amplifier chassis is currently laid out so I am tempted to leave it out.

 
Note there is no adjustment for DHT plate current. It is direct coupled and it set but power supplies voltages and driver gain. So, there is no truly need for a meter in there, still you do want to know how much current you drive over the tube. So, make two externally accessible contact point with a pair of test jacks, something like this:
 
http://www.newark.com/tenma/spc15338/test-jack-combination-insulated/dp/79K4930
 
Put between them a good quality 1R, relatively powerful resistor of higher accuracy and measure the voltage drop over the resistor. This way you will be using voltmeter instead of ampermeter and the plate voltage will not flow over ampermeter. You can even decouple the voltmeter with a pair of very large resistor (like mOhms) to make sure that plate current do not “see” the bad voltmeter and then to recalibrate what voltmeter you would use. I actually did experiment with it and I find that there is no difference  to sound and 1R voltage dropper works very fine.


 anthony wrote:
Yes, I have five pairs of YO186 that I wish to try out as well as some 45's in particular.  The amplifier will be designed so that I have relatively easy access to the parts that I am likely to alter once I get it operational and I start fitting the amps into my playback.  Perhaps I will play with DHT drivers...the 841 looks interesting...but first I have to get everything built and tuned and then look at what, if anything, I wish to change.

  Hm, you managed the get YO186? That is very cool. She sound very much along with RE604 but has lower support and more “meety”. Be advise that relatedly low operation point that it set in my DHT makes her to sound a bit “distorted” and very underpowered, which is perfect for my overly clean MF channels.  If you are willing to play with other DHT driver then do NOT implement my MF channel and keep your option open. You do Milq DSET for the rest of the channels you will be able to drive your MF from Milq DSET. Then, after some listening IF you feel that you need to change anything you will be able to add a discreet  DSET of your choice.

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