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In the Forum: Melquiades Amplifier
In the Thread: Planning my DSET
Post Subject: Very good.Posted by Romy the Cat on: 1/4/2019
 anthony wrote:
I woke up this morning ….
It was funny that you named it “In my dreams”. Whan I was “designing” and building the Milq I had a lot of dreams about the problem I had. I am not am amplifier designer or some kind of DIY evangelist. In fact I had no truly DIY audio experience before it. I did my phonostage and the power amps because I did not had around me somebody who would do it for me at the level I want to do it. So, when I start to do the damn soldering I was learned a lot and for some period of time it become a very much become full time labor, not time wise but mind-wise. There was a period when Milq took so much time in my life that stopped do anything, literally anything but making Milq to sound right. In the epicenter of that period there was six months when I stopped working, stopped dating, stopped socializing with other people. I woke up 7 AM and went to beg at midnight, all time working on the amplifier and having 100% of time dedicated to thinking about the amplifier. My mind was so saturated at the time by the applier need that I have dream about Milq circuitry, Milq’s problem, Milq’s need… It was a lot of Kafka like dreams…. very certifiable. I am not sorry about that time and I even then had very defined feeling that after I do it I am not planning to do it anymore. So, nowadays if I need to dive into Milq to make some changes then I feel that I am rereading the dairies of my life… very interesting…
 
 anthony wrote:
Then I swapped the used YO186 I purchased just for this testing stage and put in a NOS 1939 vintage tube and the circuit worked straight away with all voltage and current targets just perfect.  Put in a 45 and it was just as perfect.

Congratulations… the old DHT are very finicky…

 anthony wrote:

The DC Offset would not trim to zero and 0.1mV was as low as it would go before running out of trimpot.  The pot from one end to the other would only adjust the DC Offset by 0.7mV, which is much less than I thought it would.  My 0A2 are quite closely matched for voltage and are within 0.3V of each other.  Swapping the tubes had no effect on the DC Offset so I might have to play with another tube to cancel that offset to zero.

 
Yes, I also was not able to make 0mv at DHT. This is fine. The best that I was able to do is 0.4 at one and 0.6 at another amp. That all are very fine numbers. Anything below ~10mV are perfectly fine. If you stick you head to the MH hosts and to correlate the auditable buzz with DC offset on DHT then you will not hear anything under 10—15mV. So, whatever you have: if you do not hear from the speaker then you are fine. Mind you that as the amp juts start you might have a minor HF noise and some glassy sound from speaker – this is from aging 5E6P that will go away as the tube worm up.  The DC offset at the amp input is more friendly and you should be able to make it 0mV

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