yes, i made a photo with my new smartphone but i am too stupid to send that photo here.
maybe my son can help.
maybe my son can help.
By the way I modified my Paradise boards with a DMOS CCS because they got reactive again for rail noises although it was calm after putting in the alternative faster Toshiba semis in the reg's CCS/CVS back then. It stays put now so I will be able to give it a few spins again. Looks a bit toothless across the sink now, but what the heck.😀
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Not much progress with the noise measurements. I can only get a signal/noise of 12dB.
Maybe i think wrong but i give up for today.
Maybe i think wrong but i give up for today.
" I never give up " Peter Forsell
I think i have now readings that i trust.
One problem is dynamic range, the other adjusting for gain.
I run the Curl on 8mA. A ZTX851 can handle that, a BC550 will run out of steam so it has much less GM with this idle.
I am still improving the setup but what i get makes some sense.
I use 5.5 Ohm driving impedance, that clones my Lyra Atlas.
Under this conditions the BC550/560 combination is 10dB worse then the ZTX851/951.
The BC140/160 ( my secrete souce ) is around 3dB worse so two pair are nearly as good as one pair of the ZETEX.
When the cartridge has an even lower impedance i think the Zetex will really show their
superiority. In my system it does not make a big difference. My Atlas is 5.5 Ohm and it shoves out nearly 1 mV at 7cm/sec. The Tuble Weed is dead quiet under this conditions.
I think i have now readings that i trust.
One problem is dynamic range, the other adjusting for gain.
I run the Curl on 8mA. A ZTX851 can handle that, a BC550 will run out of steam so it has much less GM with this idle.
I am still improving the setup but what i get makes some sense.
I use 5.5 Ohm driving impedance, that clones my Lyra Atlas.
Under this conditions the BC550/560 combination is 10dB worse then the ZTX851/951.
The BC140/160 ( my secrete souce ) is around 3dB worse so two pair are nearly as good as one pair of the ZETEX.
When the cartridge has an even lower impedance i think the Zetex will really show their
superiority. In my system it does not make a big difference. My Atlas is 5.5 Ohm and it shoves out nearly 1 mV at 7cm/sec. The Tuble Weed is dead quiet under this conditions.
Nice, The extra mirror gives room for some extra voldtage swing at The I/V resistor. This is better, I left the idea of DC coupling as I did not have enough dynamic range.
According to some measurements, the BC3x7 have relatively high 1/F noise. Does this make them unsuitable for this kind of circuit?
The BC337 is ok. The BC327 has a problem with 1/F.
Somewhere here online is a list dome by R.Mash that shows that.
On the other hand with A weighting the era is not that sensitive for low frequency noise.
The Paradise uses this transistors and is subjective quiet.
Somewhere here online is a list dome by R.Mash that shows that.
On the other hand with A weighting the era is not that sensitive for low frequency noise.
The Paradise uses this transistors and is subjective quiet.
I suspekt that it still Will be beneficial to insert a capacitor going to the next stage. Lowers the flapping of base drivers, when there's a mass mismatch in arm and cartridge.
I listed Marsh's noise results here:
http://www.diyaudio.com/forums/analog-line-level/218373-discrete-opamp-open-design.html#post4157226
According to that it's the 337 that is noisy.
Looking back, in my MPSA18 model I chose RB=750 based on the ONSemi datasheet charts. I wonder if this is too low.
http://www.diyaudio.com/forums/analog-line-level/218373-discrete-opamp-open-design.html#post4157226
According to that it's the 337 that is noisy.
Looking back, in my MPSA18 model I chose RB=750 based on the ONSemi datasheet charts. I wonder if this is too low.