Mpp

[john curl]

No, only Syn08 speaks German. I know a little French, that's all. I have visited, Munich, Hamburg, and Berlin over the decades, even went to E. Berlin, once, and nearly got myself shot. ;-)
Really good test equipment is nice, but not for this task. I just turned down the use of an Audio Precision for a new phono project, for example. Stick with open loop if you can.
I too do the 75us time constant in the first stage as part of the transconductance out gain structure. Works for me. Where is your arm resonance?

[Joachim Gerhard]

Semiconductors are:
Input stage: 2SB737, 2SD786
Caskode: BC550C, BC560C
FET: BF246A

[Joachim Gerhard]

my arm resonance is around 10Hz. i use a wheaton triplanar with fluid damping

[Joachim Gerhard]

i just come back from a meeting with donald fagen, louis armstrong, duke ellington and matia basar end forgot to tell you that i use a mono subwoofer that sums the channels under 70 Hz. my midrange drivers have quite a stiff suspension, that helps to suppress high extension too.

[Joachim Gerhard]

and you build without serious listening. i only can conclude that you are both geniuses.

[syn08]

Originally Posted by Joachim Gerhard

and you build without serious listening.

That is incorrect. I only don't trust my ears enough, to talk about the results.

[Netlist]

OT posts moved here:
Some serious workspace

[janneman]

Originally Posted by Joachim Gerhard

Here is the circuit diagram of the DIY version of the MPP unbalanced head amp.
I will listen to it on the weekend and you will be very surprised how good the measurements look with this really simple topology. I can not hear any noise at the listening seat even at quite high volume and i live in a very quiet rural place. i will ask my son who has frequency extention to 20kHz ( i check that from time to time) if there is something unpleasant.

Aha! An AD844 in disguise.... Except maybe for the noise?

jd

[john curl]

What would you estimate the 'Q' of your tone-arm-cartridge combination, JG? Or high many dB do you rise at resonance?

[Joachim Gerhard]

i will try to measure it. i have software from dr.feikert that can do that. anyway did mark levinson not say a long time ago "i am not interested in theory, i am intested in results".
anyway, i asume 4 to 6dB. allen perkins and i found that too much damping destroys other aspects of the sound like immediacy and a certain feeling of freshness and "jump" factor.
a good example of a high amount of damping is the original firebough turntable. it never cut the mustard for me in terms of dynamics and feeling of being in the presence of the musicians. it sounded tired and slow for me. comparing the sound of equipment to the life sound experience is alien to many here i found. it is simply not enough for good sounding equipment to copy and amplify the input signal because that signal is already flawed. one example: a friend and me designed an amplifier for Dr.Forsell. the good doctor likes to fumble so we gave him four potmeters he could adjust: bias current, dc offset, feedforward and feedback. jonathan scull wrote in stereophile that this was the best amp he ever heard. john atkinson in the lab was toally shocked to find enormous amounts of traditional crossover distortion. anyway, human perception is not a simple maschine with input and output. if it where that way then take any aplication from analog devices, nat semi or burr-brown, shut your mouth and make tons of money. you know that john, it´s not that easy.