Rerurn to Romy the Cat's Site


In the Forum: Melquiades Amplifier
In the Thread: Planning my DSET
Post Subject: They are for mAPosted by anthony on: 2/16/2018
 Romy the Cat wrote:
You decided to go with mA or are they mV against 1R resistors? I prefer the second approach personally and I feel that I can moderate the quality of resistor and I can’t moderate the quality of the milliampere meter coil. 
 


The ammeters that I have here are quite inexpensive but were one of the few that I could find with a specified coil resistance.  It is 3000ohm.  So I use a 0.6R resistor to set the ammeter scale to 250mA, 0.75R resistor for 200mA and 3R for 50mA at full deflection.  All are quite low values so I think it should be ok.

 Romy the Cat wrote:

You are right now in a very interesting state when you do the internal wiring. The internal wiring. Is to a degree is an art form and it might be very interesting. There are low and high voltages, AC and DC, twisting and not, crossing with minimum angles, some transmission line considerations, signal wires, grounding, approximations, shortening wire paths, maintainability, ease to access and many other considerations that you need to keep in perspective. It is very interesting and creative phases, do not harry to go through with it, spend some time and do it better and methodological. Do the same wiring schema for both R and L amplifiers. When you will be doing the second amp you will find better way to wire it. It is debatable if you want to improve the second one or to the second one as a direct replica of the first one. 


Yes, I built both amplifiers to the same stage (about half finished) and once things got a bit murky regarding the limitations of the wiring I left the second one at a sensible stage and have gone on with the first.  In particular I am hoping that the 6.3V filament wiring for the first and single stages is far enough removed from anything that matters.  I am not sure if it is but that will show up in the measurements.  I have an audio analyser here that I will use to assess and fine-tune the noise levels so hopefully my preparations have been thorough and not to much will need to be altered.
 Romy the Cat wrote:
BTW, did you do it as two identical or you went full-throttle and made it mirroring? 
  

Yes, the amplifiers and the power supplies are both mirrored.

 Romy the Cat wrote:

Also, if everything is works fine then the only part that you might need access it future will be the input filters in case you want to experiment with drivers or do channels adjustments. Make it accessible. Do not forget to do a full sweep of the individual channel after you will be done. You need to make sure that the channels and the filters are working properly. 
  

Yes, the filters are very easy to get to and hopefully relatively easy to alter.  
 Romy the Cat wrote:

The last thing. Do buy for yourself a Phase Testers. This is absolutely mandatory tool for your speakers. They call it “Speaker polarity tester”. I use the track #23 from Sheffield Labs 
  
https://www.amazon.com/Sheffield-A2TB-Test-Disc-My/dp/B000V93NKY 
  
Depends what tester you use you might not have a sensitivity of you tester to test at LF. There are some techniques how to deal with it. Anyhow, even a cheap $10 tester for Car Audio is better than to spend half of life to worry where is black and where is red binding posts.


Thanks Romy, I'll do that.

Rerurn to Romy the Cat's Site