You will need to put a resistor in parallel with the input (you can use the second input connnector on the board for that), which should be the appropriate input resistance for the cartridge. For a MC system, this could be between say 100Ohm and 2000Ohm - please check the documentation of your cartridge, pretty sure they recommend a value.
I found this http://www.benz-micro.de/high-fidel...ver_Gold_files/MC Gold Produktinformation.zip
they say its between 2000 and 47000 Ohm on homepage but in this pdf it is 47000Ohm.
If you keep having fidly trebble, you can increase load (reduce load resistor value)... I believe you should try 1200 ohm because your cart has 120 ohm output impedance and a good measure is to use 10x that value: Benz Micro | Cartridge Data | Vinyl Engine
On the basis of the above, I have a (slightly OT) question - or thought - to post.
Bearing in mind that this is a very high performance cartridge eq amp, I am wondering if perhaps some of the problems being experienced by some posters are caused not so much by the Paradise, but by previously un-obvious problems with arm/cartridge (including set up, stylus wear, VTA etc) TT set up and underlying quality, being drawn to greater attention with such a good bit of kit in the chain? I would certainly expect any faults in the down stream chain to be highlighted with this head amp. I would also expect shortcomings upstream of the Paradise to be more obvious....even if the overall sound quality were improved! What does anyone think?
In the case of a fizzy treble, for example, I would look at tracking weight and VTA, and carefully adjust these settings before changing any loadings etc. provided these suit the cartridge in the first place.
I obtained a pair of quite analytical speakers a short time ago; I had to go right through the chain before I was happy. You would be surprised at the minor problems I found and put right, when it would have been far too easy to blame the speakers!!
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The Paradise it not a super high input impedance design so a loading resistor of more then 10kOhm will not give you a higher input impedance because that is approximately the input impedance of the Paradise alone.
On the other hand a Moving Coil Cartridge has a low impedance in itself.
The highest impedance i came across is the DL103 with 40 Ohm. As i already told you this is not a good design in terms of noise ( the DL103 ). The Johnson noise of this cartridge alone is 4 times higher then the Paradise manages. Anyway, many people like this cartridge or can not afford anything better so i rufuse to go into an argument if this is a good cartridge or not. Even this cartridge does not need high impedance loading.
Using the rule of thump that the input impedance is 10 times higher then the cartridge 400 Ohm is fine. The only disadvantage i can see is that around 10% of the energy from the cartridge will be dumped to ground. In volume this is a fraction of a dB and maybe just audible. If that bugs you try 1kOhm. More then that and we are into a philosophical discussion. The type of resistor and the cable may be audible though.
On the other hand a Moving Coil Cartridge has a low impedance in itself.
The highest impedance i came across is the DL103 with 40 Ohm. As i already told you this is not a good design in terms of noise ( the DL103 ). The Johnson noise of this cartridge alone is 4 times higher then the Paradise manages. Anyway, many people like this cartridge or can not afford anything better so i rufuse to go into an argument if this is a good cartridge or not. Even this cartridge does not need high impedance loading.
Using the rule of thump that the input impedance is 10 times higher then the cartridge 400 Ohm is fine. The only disadvantage i can see is that around 10% of the energy from the cartridge will be dumped to ground. In volume this is a fraction of a dB and maybe just audible. If that bugs you try 1kOhm. More then that and we are into a philosophical discussion. The type of resistor and the cable may be audible though.
DL103 is really good for the money it costs.
Of course there are many who choose carts by the price and if not wealthy enough, are "blind" to higher cost ones.
I know a TT builder that claims the best cart he ever heard is a DL160.... He can not afford a lyra so he did not like it when he heard it.
IMO the type of resistor is determinant in this case.
Some say the DL103 must be loaded at 100r..... do not know why.... maybe that is a market taboo because most MC amps come with a fixed 100r load for those carts.
What load do you use with your Lyra ?
I run a Benz LP, also a 40ohm cartridge and one that is happiest running into a higher impedance. I was running it at 2k and swapped to 10k last night just to check how it sounded. It wasn't as good, so it will be going back to 2k. There was a hint of whistles and birdies at 10k. Just the odd feeling that you were listening to badly tuned radio. I'll recheck my earthing and swap back to 2k today- it sounds great at 2k anyway.
It was not designed for such high output carts, but it works perfectly with a DL160 that has 1.6mV output and 160r impedance..... just load it a bit more to tame the highs..... It will also improve low freq damping making it sound tighter.
The question certainly is not stupid. Reducing the resistor values will give the servo more authority, and the amplifier will then be capable of handling bigger asymmetries and mismatch in the input stage and rest.
There are people that say ( and I believe it) that a servo should have just enough authority to keep the circuit at optimum bias point, but not more. If your amplifier requires more servo drive, then there may be an imbalance you may want to fix.
Originally, I think your question originated from the low frequency output fluctuations we have been seeing. These result from the 1/f noise of the bipolars, and some leakage current noise from the elcaps, I believe. Please note that reducing these resistors does not change the corner frequency of the servo, so that part of the fluctuations will not change, it will stay as before - only the servo will not have to work as hard.
In order to reduce the fluctuations in the current design, I think it may be useful to increase the servo corner frequency (a.k.a. reducing C5, try 220nF). The higher the corner frequency gets, the more the low bass may be impacted, as this servo is a single pole design.
Another idea , albeit more radical and not easy to implement, would be to use a servo with 12 or 18db per octave (two or three poles), to achieve a sharper cutoff - the corner frequency could be, say, 5Hz, so it would get rid of this low frequency noise really well, and less impact bass.
We need to hold that thought for the "Paradise Platinum Edition"
The question certainly is not stupid. Reducing the resistor values will give the servo more authority, and the amplifier will then be capable of handling bigger asymmetries and mismatch in the input stage and rest.
There are people that say ( and I believe it) that a servo should have just enough authority to keep the circuit at optimum bias point, but not more. If your amplifier requires more servo drive, then there may be an imbalance you may want to fix.
Originally, I think your question originated from the low frequency output fluctuations we have been seeing. These result from the 1/f noise of the bipolars, and some leakage current noise from the elcaps, I believe. Please note that reducing these resistors does not change the corner frequency of the servo, so that part of the fluctuations will not change, it will stay as before - only the servo will not have to work as hard.
In order to reduce the fluctuations in the current design, I think it may be useful to increase the servo corner frequency (a.k.a. reducing C5, try 220nF). The higher the corner frequency gets, the more the low bass may be impacted, as this servo is a single pole design.
Another idea , albeit more radical and not easy to implement, would be to use a servo with 12 or 18db per octave (two or three poles), to achieve a sharper cutoff - the corner frequency could be, say, 5Hz, so it would get rid of this low frequency noise really well, and less impact bass.
We need to hold that thought for the "Paradise Platinum Edition"
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