19 responses Add your response
Most preamps have a volume control at the input of the line section. This makes it impossible to overload the line section without also playing the system very very loud.
So really if this is not a problem on all LPs, the possibilities are a problem in setup or a defective pressing. My pressing of the LP in question is fine but that does not mean all of them are OK.
Playing the LP on another system might be one way to find out...
If the phono stage doesn't overload until 17.75 mV then that should not be an issue as a 1 mV cartridge is probably maxing out around 10-12 mV on peaks.
What about the phono stage overloading the preamp ahead of it? Seems that is a not an unusual occurrence when high output cartridges are paired with high gain phono preamps.
"The issue is can a cartridge of 1.05 mV or so overload a phono section set up for a low output moving coil cartridge."
The OP's phono stage has a stated sensitivity of 500 uV in for 300 mV out with an overload margin of 31 dB.
Any thoughts on what it would take in terms of mV at the input to overload based on those specs?
Thanks for all the advice. I just purchased a long overdue copy of hi fi news and it checked out totally fine so I am pretty confidant that my set up isn't the issue and the issue has to be that particular cut on that record.
That all being said I am on the market for a better phono stage so if anyone has a suggestion with a variable gain or even more ideally one that is spec'd for this type of medium output MC I am all ears.
The issue is can a cartridge of 1.05 mV or so overload a phono section set up for a low output moving coil cartridge.
1.05mV is about 6 db more than 0.5mV which is considered low output. That represents a doubling of voltage from 0.5mv to 1.05mV.
If that 6 db is making a difference in the overload of the phono section its overhead is poor. That is the long and short of it. In our phono section which works with 0.2mV, it cannot be overloaded by a high output 5mV cartridge.
55db is on teh low side as low output moving coil phono sections go; we have 60 db (I am of the opinion that you don't need that much gain if your circuits are low noise).
So I really think that you need to look at loading and the setup of the cartridge in the arm- its very likely that some other factor has been overlooked. IOW I am sure you are hearing something but overload of the phono section isn't (or shouldn't be) it.
I agree. It is surprising how much gain matching seems to be ignored in terms of really optimising sound quality, not just here but on many forums.
IMO, even with a good quality phono stage, probably more so in fact, the window for optimum sound quality is very narrow. Probably within 2 dB with low output MC's.
Ultimately, I think it's a lot easier to come to this conclusion if one has a phono stage with infinitely variable gain as opposed to fixed gain, but most stages on the market do indeed have fixed gain.
And 55 dB of gain is a whopping ton of gain for a 1.05 mV cartridge. 48-50 would probably be the sweet spot in most systems.
It surely cannot be true. Perhaps you or Al can elaborate, but overloading is a function of the cartridge's output AND the phono stage's gain/sensitivity setting, isn't it? Theoretically, you could probably overload with a low output MC cart if you have a gain mismatch large enough. From your post, it sounds like you can only overload with MM carts.
I'm always baffled how much gain matching is ignored in discussions on this forum. This thread is a good example. On my modest (compared to many A-goner) system, a difference of a few dB between an optimal and sub-optimal gain setting can easily be heard. The sound becomes unpleasantly shrill and just sounds too loud even at lower volume settings. 55 dB of gain with a cartridge with an output of 1.05 mV is a huge mismatch under most circumstances, in my opinion and experience. Perhaps with a passive line stage it may be ok, but never an active one. I'd guess anything above 50 dB would be too much gain for this cart. I have a Hall & Oates record that's recorded so hot that it sounds just too loud even on the setting that works with every other record. I'd look into it first.
Thanks for the advice, making me feel a little less crazy.
After posting this I spent a good few hours going down the compliance rabbit hole only to find out that all of the manufacturers weight measurements were way off and my cart/headshell/screw were spot on where I wanted the whole time. At first I thought I was running a bit heavy, around 6hz, but after throwing everything on my scale there was a whole 10g difference from the specs I was using to calculate.
To further what Diggory has said, in the cutting process, it is impossible to overload the cutter system. The dynamic constraints exist in playback only. It is the engineer's job to understand what can be played back easily and what cannot.
However I have a copy of the LP in question and it plays fine without compression or mistracking (Triplanar and a Grado Sonata). This suggests that your setup is not optimized- the mechanical resonance of the arm and cartridge together should be between 7 and 12 Hz, else you can have mistracking problems.
Another thing that can contribute to this issue is cartridge loading. With moving coil cartridges the effect of loading occurs at Radio Frequencies. However if your preamp is sensitive to RF the effect of loading can be dramatic, and you have described what it can sound like if there is a loading problem.
Every cartridge has its tracking limits. Sometimes a record is just cut too hot for the cart to handle and it starts to mistrack. You can try raising the stylus force to the maximum. I have one direct-to-disc piano recording that causes some mistracking when he really hits it hard, but since it's only one record, I'm not going to drive myself crazy.