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Question about gain and my chain of components.

Andrew Heck

Andrew Heck

Active Member
Howdy y’all, I’ve had new and very exciting changes/improvements to my system in the past few weeks and I’m not sure I’m utilizing these very powerful and awesome tools correctly. I’m hoping for an understandable explanation of gain as it applies to me and my system. As of right now, I’m trying to decide between a LOMC cart (.3mV) through a Parasound ZPhono set to MM following a pre-pre amp with a gain of 30dB (for MC cart levels) into or not into a passive pre with an attenuator (that’s my first choice) into a Schitt Vali 2 as a tube pre stage not sure of the gain at this stage, into my power amp, Parasound HCA 800ii At 100 WPC, which is going to change as soon as UPS gets here into an Acurus A150 At 150 WPC then into my Legend Audio LEG7000s rated for 150 @ 8 ohms....
As an option, I can also utilize a NAD 1300 pre, except the MC portion of the phono stage is not fully functional, so I still have to use the pre-pre in front of the MM amp, but I’m not sure how the preamp gain compares to the Schitt.
Am I ending up with too much at my power amp? How does one compute this so I can be better informed as I build and upgrade, should I use the passive in between phono stage an preamp? Is that a good way of tempering my 70+ dB phono gain? I feel like the sound is cluttered and constrained during complex passages. What does it all mean?
 
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This is the pre-pre stage, are R3 & R5 the determinants of gain in this circuit? In whatever case. Where can I change the resistant values so as to adjust closer to 20-23 dB? I’m gonna build a Salas Phono Stage in a few weeks set to 63 dB so all of this is temporary.image.jpg
 
If I understand what you are saying, you want to feed a MM phono stage into a second MM phono stage to get the necessary gain required to utilize a LOMC cart?

If so--this won't work. Yes, it will double the gain, but it will also apply the RIAA equalization twice--throwing the signal WAY out of whack. You could use a SUT (step up transformer) between the LOMC to achieve the gain necessary to feed into a MM phono stage--many folks do this (in fact, many prefer it over just a MC phono pre). The SUT essentially brings the LOMC cart signal up to the level of a MM cart (without applying the RIAA equalization), and then the MM phono stage continues to increase the signal and applies the RIAA equalization.
 
savatage1973 said:
If I understand what you are saying, you want to feed a MM phono stage into a second MM phono stage to get the necessary gain required to utilize a LOMC cart?

If so--this won't work. Yes, it will double the gain, but it will also apply the RIAA equalization twice--throwing the signal WAY out of whack. You could use a SUT (step up transformer) between the LOMC to achieve the gain necessary to feed into a MM phono stage--many folks do this (in fact, many prefer it over just a MC phono pre). The SUT essentially brings the LOMC cart signal up to the level of a MM cart (without applying the RIAA equalization), and then the MM phono stage continues to increase the signal and applies the RIAA equalization.
Click to expand...
Nosir, the pre-pre is nothing but a head amp that pushes the signal with a JFET, it’s just a simple amplifier with 30dB’s gain and no RIAA equalization. I’m wondering about how much signal is actually being fed into my power amp, and if it’s too much for it’s input sensitivity. And I haven’t even started fretting about impedance matching.... damn, now I’m fretting about impedance matching.
 
E-Stat said:
Pre preamp is flat stage with gain like SUT. Since Schitt has volume control, no need for passive and extra set of cables .
Click to expand...
Okay, true, but would a passive pre be good for taming the 70+dB of gain I’m pushing straight off the cartridge? I know I don’t need it for volume control, but I’m worried I’m about 10 dB of gain ahead of the game straight out of the gate. For example, to get to a good, healthy 60-70 dB listening level in my room, the Schitt’s volume knob is at about 7:30 on the dial, I have very little dynamic option or control right now, but with the passive in line, I can turn both knobs to 12 o’clock or so and can zero in a bit more on the sweet spot,.
 
Andrew Heck said:
Nosir, the pre-pre is nothing but a head amp that pushes the signal with a JFET, it’s just a simple amplifier with 30dB’s gain and no RIAA equalization.
Click to expand...

Sorry--I misunderstood. Just a quick check--plug another source into your pre-pre and note the volume level at any setting--then try again with the phono--generally you want the phono to be below a regular line source like a CDP.
 
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