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Showing content with the highest reputation on 04/10/2025 in all areas

  1. Remember Şirin/Cutiepie? She is 9 years old now and still as energetic as she was.
    3 points
  2. Hi! i iz bak. Gonna bombard you with pics of kitties soon. <3
    3 points
  3. its not obvious what this is? first stage is the input section from the uberamp 2. current mode voltage gain. (not that you actually need voltage gain) differential input, differential output. then balanced step attenuator. constant input impedance load. output stage is the same input section with the darlington input removed because its not needed and some of the cascoding removed because its also not needed, tied to a voltage buffer. many of the expensive preamps out there convert everything to single ended internally to save on parts and board space. this is balanced from input to output. and 6db or more less noise. many features of preamps of the past include things that are no longer useful. so they are removed. like tape out and second zone. seriously i have never heard of anyone actually using second zone. and except for the really expensive ages old professional gear, there are no tape machines with balanced inputs. maybe the new revox has balanced inputs. so consider it as a balanced buffered volume knob. turns out the signal to noise boost really is audible. krell fpb600 vs mc611. more than 12db signal to noise boost on the mc611 partially because of the low input impedance and rail to rail input buffer.
    2 points
  4. Alec and I were trading mid-90s rock bangers via text and it's the usual stuff you'd expect, but I got him with this one he'd never heard before. I love educating the younger generation.
    2 points
  5. finally. higher signal to noise ratio, more than 110db. takes signals up to 20 volts peak to peak unbalanced, 40v peak to peak balanced. no input attenuator that adds noise for those stupidly high voltage dacs. ( requires 30v power supplies) (volume control in the middle) thd about .005% no feedback. work in progress 4 layer board. preamp2025f.PDF
    1 point
  6. I may be a hack, but I switched from using 4-gang pots to shunting stereo pots because I think they work better. A big part of the reason why I would build a balanced circuit is to benefit from its CMRR (and even order distortion cancellation by proxy). I measured the matching between gangs on a 20k RK27; it's better than the specified 20% tolerange, but it's not great. Here are some measurements at arbitrary rotations. Gang A Gang B Matching 51.4 51.6 0.4% 255.7 252.8 -1.1% 623 624 0.2% 1299 1300 0.1% 3042 3089 1.5% 4230 4368 3.2% 8470 9080 6.7% 14680 15420 4.8% 19100 19930 4.2% 19900 20380 2.4% The matching is directly proprotional to the CMRR. So I took a measurement of CMRR using the following circuit. The idea is that this simulates the balanced input of an amplifier and will tell us how balanced things actually are. Not very, it seems. Each trace is a different rotation angle on the pot, with the -115dB one being with the signal fully shunted. (There is some resitual resistance with the pot at 0.) -35dB of CMRR will significantly degrade an amp's performance. I repeated the measurements with a shunting pot configuration, using Yageo 1% 2k resistors and the same 20k pot. Although the AP input capacitance degrades CMRR at high frequencies, even the worst 1kHz measurement is about 12dB better than the best measurement with the series pot. The low frequency degradation is most likely caused by the AP's 1/f noise-- we're measuring microvolts at this point. If I wanted to further improve performance, I'd use resistors with better matching. The Vishay ORN arrays are available in 0.01% and would probably be my pick. LT5400 isn't bad either. https://www.mouser.ca/ProductDetail/71-ORNTA1001ZUF I don't know that this is necessarily relevant to the design in the first post-- looks like it doesn't use a pot at all-- but the circuit has its place.
    1 point
  7. Welcome back! So sorry for your captivity.
    1 point
  8. Thanks @skullguise and @guzziguy well yea, we still got cats hanging around in our garden, unfortunately nearly all of the cats I was familiar with are gone considering stray cats life expectancy and the amount of time I was "gone". 2 of our family is gone too. One of them, Pamuk died cuz of FIB, other one (Şirin's son) Duman cuz of pneumonia. But my father took good care of them while I was "gone". I'll post pics from our garden shelter soon. And thanks for the warm welcome back guys. I thought I won't be remembered. And title system changed i guess, I lost my beloved title.
    1 point
  9. 1 point
  10. Welcome back!! I hope you and cats are all well!
    1 point
  11. chicken pot pie was on the menu tonight so I figured what else could go wrong?
    1 point
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