Not important are strong words.
But accurate. A quick run of the numbers puts this effect somewhere in the residual background noise of the Big Bang.
Like this Chris? The schematic will have to be updated since it is about 44 years old. '-)
Perzactly!
Thanks, as always,
Chris
But accurate. A quick run of the numbers puts this effect somewhere in the residual background noise of the Big Bang.
Thats a really, really, really tiny amount of noise. But since the void is limited is size, there might be some big reflections coming back.... echos and in these circuits, there are equivelents -- residuals too --
There are other bennies of cascoding besides lowering distortion.... and the two transistor (differential) also has added beneifits in rejecting common-mode and other undesirables etc. BUT did we already say the differential has the two devices in series for noise increase? So to get every benifit possible a complimentary differential arrangement works well... keeps the noise and the distortions low and rejections high. The best of all worlds.
If you dont have to worry about common-mode noise in your short cable runs nor RFI, nor psr issues, then a simpler compl. push-pull works and the two transistors are in parallel for inherently lower noise with a minimum of parts.
Thx-RNMarsh
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ns high. The best of all worlds.
If you dont have to worry about c-mode noise in your short cable runs nor RFI, nor psr issues, then a simpler compl. push-pull works and the two transistors are in parallel for inherently lower noise with a minimum of parts. etc etc etc.
But this is the one part of the audio chain where balanced really DOES offer an advantage. I can actually touch a pin of my cartridge and not get hum and I don't have to take heroic shielding measures in the interconnects. The 3dB noise disadvantage is real, though- one can either design the stage so that the 3dB is unimportant (i.e., a stage with noise well below the cartridge's Johnson noise) or use a transformer (my own preferred solution). Or live with the extra noise, as many tube aficionados do, but not this tube aficionado!
yes, there are good apps for balanced inputs... esp for very low level signals. Like a phono preamp. When I had a MC cart, I used a Denon MC step-up transformer and then later I tried my hand at a compl push-pull pre-pre. i never had noise problems with either approach IF I didnt touch the pins of the cartridge(!).
Thx-RNMarsh [BTW - compl push-pull can be easily configured to do balanced duty]
Thx-RNMarsh [BTW - compl push-pull can be easily configured to do balanced duty]
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My single input preamp doesn't hum.
Maybe it doesn't know the tune
jan
Maybe I know what I am doing. '-)
You're designing for compatibility with mass-market standards, a restriction diyers don't have but commercial designers do. We can go "no compromise" without worrying that it will affect sales because the average buyer won't want to redo his turntable wiring.
mass-market standards
Maybe it's because the standards are wrong.
[me all-balanced from TT/CDT(AES) to loudspeaker in/out, aka including the LSP cables]
Makes me wonder if a 2013 MC phono design could include a phantom powered head amp up near the phono cartridge. Would remove the desire for differential inputs, but would need to work with existing two-coax signal cables (only).
Thanks,
Chris
Salas has one here
http://www.diyaudio.com/forums/analogue-source/188730-2sk170-bl-mc-step-up-amp.html#post2567139
Joachim has shown more than many circuits.
I saw his latest one (balanced to single ended) here
http://www.diyaudio.com/forums/analogue-source/226508-openamp1-mm-phono-preamp-open-project.html#post3301025
I am planning to try it without the servo with AD620 instr amp (one ic per channel) I have. AD8221 has better specs, if one wants to try this approach. Being balanced input / single out, I don’t find it beneficial to mount it on the cartridge shell.
For balanced in/ balanced out, AD8222 fits in there with the same minimal construction complexity.
George
Not Mr Curl's fault that he's forged to poop out a less than perfect omelet, because the customer's key-menu top doesn't read Quail.
100% agreed. Fortunately, we diyers can have square rectums if we so desire.
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