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#3,581
Joachim Gerhard said:
If i would have the final saying then i would prefer to get the job done just right and not over engineer it. Too much heat is not what i want. The circuit itself had superb suppression of PSU anyway. Cascoded mirrors, cascodes with mirrored and shunted bias everywhere.
This is not a simple single ended phono where the break through of the PSU is clearly audible.
Click to expand...

And I agree to that!
 
#3,586
Thanks Michael and Frans. So we only need the final schematic and make the decision if we make the EQ adjustable and how.
By the way i found now a really god replacement for the ultra low Rbb´ unobtainiums.
They are the Sanyo 2SA1208 and 2SC2910. They are in full production. Please do not redesign the circuit though. The multi degenerated input gives us less distortion then a pair of those with 5 ohm degeneration so i simply put this here for completing my list.
 

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#3,589
Lets not make it too complicated.....Stick to the man...!!
 

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#3,592
men are more predictable, but who want that in life. there women are wonderfully complex and at least to me fantastic and mysterious....

I do believe the problem here is the switching, i have experimented at lot with volume controls and input-switching...and it does not come for free, relays and mechanical switches does add a layer of haze that is simply not there with a direct soldering, so the question is weather we want to degrade the 90% for the last 10% or less...

I have in my RIAA thread made comparison of the different De-emphasis curves, With those in mind it should be possible to develop networks to the additional curves, this can be done on a add-on board, with relays or mechanical switches
 
#3,594
Is this really what we want ? Of cause i had the idea too of modules stacked a top of each other. My idea of a variable EQ is different. I would for example setup the gain of the Paradise Lost for 40dB straight with simply inserting a resistor instead of the RIAA. The rest would then be done in the equalizer that also provides the rest of the gain, say 20dB.
It could then be setup in such a way that we can boost and cut at 20Hz and 20kHz by 20dB plus a filter in the midrange, also plus minus 20dB. When we fully advance the bass EQ and fully cut the treble we have RIAA. The rest lies somewhere in between. The Tanzmusik can do that, although here it is part of the phonostage and it works very well also allowing to tame problems of the recording and help even EQ the speaker-room interface somewhat.
I say no, no other EQ then RIAA, please people, do not stumble over this stepping stone.
For most transparent sound, please no switching. We really need the 10% or all of our work is useless.
For input loading i would suggest the following : first simulate the input impedance of our circuit, how high it is and how linear. Then we chose a fixed resistor of say 10kOhm that is always there. Parallel to this resistor we use a high quality wirewound potmeter of say 1kOhm that can be switched in. Have we found out the best setting for sound we switch off the wirewound and insert the fitting resistor into phono jacks that are parallel to the input jacks. I found really excellent wirewound potmeters made in Germany that are very smooth action and very low noise. I look it up for the model.
 
#3,598
For this we could connect the amplification stage and the buffer with wire jumpers, we could then have a RIAA section that could be populated or not, or in your case fitted with a fixed resister for even better performance, then you could buffer your EQ with the buffer and your set... A Swiss Army knife with everything, then people can also just build the riaa with fixed deemphasis circuit
 
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