I am a scientist by profession, but I'm also recovering from a cold, so.
Based on my limited understanding, the only things that should matter to the Id of Q9, which is what R27 will impact, are the rail voltages, the Vgs of Q9, and the value of R27. The SMD parts Q1-Q4 are at the other end of the circuit so I'm not sure why that is relevant.
What's unnecessary?
I am getting a 7.5mV MM cart on monday.
Just to annoy people a little more with math:
-with the conservative 46dB number floating around (there are a 46 and a 49dB gain showing on the scheme for low gain settings and I am a little confused).
10^(46/20) = 200 (Vout/Vin)
200x0.0075=1.5V output or 2.1V with the 49dB figure.
I don't expect to be able to move my volume knob by more than a couple of clicks before hitting 85dBs at the speakers.
I don't know at which point things will blowup but another point to consider is current derived noise. Having 25mA (x2) or anymore current than necessary circulating where is not needed, will cause more PS sagging and ripple noise and more output stage noise. Those j112 seem to be noisy enough to start with.
“What's unnecessary?”
The snippy attitude. Taking a shot at the guy who has single-handedly helped more people to achieve great things than nearly anyone in this forum is not cool.
Maybe if you asked for advice and help instead of criticizing you might end up enjoying that cartridge more.
The snippy attitude. Taking a shot at the guy who has single-handedly helped more people to achieve great things than nearly anyone in this forum is not cool.
Maybe if you asked for advice and help instead of criticizing you might end up enjoying that cartridge more.
Measurements?
Not just complaining.
Did that. I adjusted the feedback loop as you suggest. I adjusted the feedback resistors and watched the distortion on the AP Analyzer. The resistor values will lower the gain, however at the price of distortion performance.
Thanks DT
Ohhhh well..... guess you´re in for a surprise.
This recording is almost impossible to get hold of in Mint or NearMint condition, so unfortunately I had to settle for a little less.
Never mind.
And don´t get fooled. This version/pressing from Audio Analogue Association is the only one to go for.
You get the picture in the link below. This may sound different form my previous samples made with the AT-PTG/II.
This sample is made with the Shure V15-IV-MR. Love it and weep 😎
Shure V15-IV - Pearl 3 - Recording programme - PC - Dropbox
Been up all night listening. It´s 5:30AM in Denmark now..... going to bed 😆
Earlier in life, I had a V15-V-MR. It didn´t work for me at that time.......... Probably because of the riaa´s that were avaialble
to my limited budget then.
Then some friend of mine some years ago asked, if I wanted a cartridge. He "found it somewhere" and wasn´t interrested.
It turned out to be a V15-IV-MR (this one), that had been in it´s unopened box for 35+ years.
It was with great scepticism, I opened it. The suspension had to be totally hardened/stiff I thought.
Well..... love and behold......... It was absolutely immaculate..... just as good as the day it was produced.
I only use it on limited occasions each year, and so far it has run a little less than 100 hours 😍
to my limited budget then.
Then some friend of mine some years ago asked, if I wanted a cartridge. He "found it somewhere" and wasn´t interrested.
It turned out to be a V15-IV-MR (this one), that had been in it´s unopened box for 35+ years.
It was with great scepticism, I opened it. The suspension had to be totally hardened/stiff I thought.
Well..... love and behold......... It was absolutely immaculate..... just as good as the day it was produced.
I only use it on limited occasions each year, and so far it has run a little less than 100 hours 😍
A quick question regarding c1 and c12, has any of you used smaller values? Like 470nf ? Is the 1uf a problem with below 20 hz? Will smaller pass caps not act as a Rumble filter?
Reason i ask is that i have some very nice 500nf polystyrene capacitors
Reason i ask is that i have some very nice 500nf polystyrene capacitors
1+1 parallel = 1µF 😎
Btw..... If you have a decent turntable, you don´t need a "rumble"-filter.
Okay..
Assuming i have a shitty turntable and need a low frequency cut off higher than 3hz, i see low pole is set in two places, might be wrong, beyond my knowledge, but c1 and especially c8 , which to change? I have no reason to have subsonics, some time ago i played with my af oscillator, i could not hear anything at 20hz, so why bother.
Assuming i have a shitty turntable and need a low frequency cut off higher than 3hz, i see low pole is set in two places, might be wrong, beyond my knowledge, but c1 and especially c8 , which to change? I have no reason to have subsonics, some time ago i played with my af oscillator, i could not hear anything at 20hz, so why bother.
I asked about that earlier, my Idea was to use better sounding PIO caps.
I was told that because of the feedback, the caps don't influence the sound much.
Any talk of impedance matching is above my paygrade. Could R28 be 100-220k instead of 47k and c12 be 0.22 or .47uf like in a tube amp? I don't know. It's an academic question at this point. The riaa is design is done and working. Maybe something for Wayne to consider in the P4? If there is a P4..
The board space is limited and I have decided I am not messing with these caps.
AFA the subsonic filter, it is implemented elsewhere in the circuit, I remember reading about it somewhere.
See #4937 for the simple voltage and R values. Have a reverse-riaa component coming next week and will be able to provide more complete specs at that time. As you likely know, measuring a phono pre is complicated by this EQ and the noise floor is open to additional equipment issues.
Hello grataku,
the value of C8 (100µF - 1000µF) determines the low frequency roll-off. If I remember right? In the LowFrequency-RIAA-section.
Cheers
Dirk
the value of C8 (100µF - 1000µF) determines the low frequency roll-off. If I remember right? In the LowFrequency-RIAA-section.
Cheers
Dirk