Phono pre settings for signet tk7su...?

Discussion in 'Turntables' started by EL Duke-A, Mar 7, 2018.

  1. EL Duke-A

    EL Duke-A AK Subscriber Subscriber

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    hello all. I have a signet tk7su with a micro ridge nude diamond, sapphire cantilever (retipped).

    I want to set it up with a pro ject phono box se ii which has these jumpers on the back.

    My mm cart options on the pre for each channel are 100pf, 220pf or no jumper at all.

    Anyone know if/how i should set the pre?
     

     

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  2. revox-b77

    revox-b77 AK Subscriber Subscriber

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    My initial guess would be 220pf. The truth of the matter is that you will not hurt anything by trying all 3 settings and then pick the one that sounds best to you. You will be listening for changes in high end presentation.
     
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  3. jackmowbray

    jackmowbray AK Subscriber Subscriber

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    No jumper or 100 pf - you want low capacitance for this cart. The resistance should be around 50k.

    Jack
     
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  4. EL Duke-A

    EL Duke-A AK Subscriber Subscriber

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    Thanks for the reply. The pre has other settings for mc carts... same there? Just play around and see what i like or are mc carts different in terms of pre setup?
     
  5. jackmowbray

    jackmowbray AK Subscriber Subscriber

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    Totally different
     
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  6. EL Duke-A

    EL Duke-A AK Subscriber Subscriber

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    Glad i asked. How so?
     

     

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  7. EL Duke-A

    EL Duke-A AK Subscriber Subscriber

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    Bump...
     
  8. hugo454

    hugo454 Gold Member Subscriber

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    nice cart.
     
  9. mprince

    mprince Super Member

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    Short answer is that MC stages incorporate a lot more gain (60+ dB) than MM (40-45 dB) as the MC cartridge has a lot lower output voltage (less than 1mV typically) than it's MM counterpart (3-5 mV). Also, there are usually resistive loading diffrrences between the two (MM typically 47K ohms, MC 100 ohms), so a MM cartridge run through a MC stage will generally be heavily distorted from both the excess gain as well as the resistive loading.
     
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  10. rothwellaudio

    rothwellaudio Forums Sponsor Sponsor

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    MC cartridges have a much lower impedance (round about 10 ohms) and a much lower output voltage, hence requiring much more amplification. They are generally insensitive to small changes in capacitance loading such as 100pF or 200pF.
     
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  11. EL Duke-A

    EL Duke-A AK Subscriber Subscriber

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    Thanks. I generally follow that but need to study up on some of the figures and terms used.

    So, another question. For my denon 103 it has output impedence of 40 and load impedence of 100. The phono pre has settings for 220, 100 and 22 ohms for mc carts. The manual is not clear (set off output or load impedence), but i think the ideal setting for the denon is 100 ohms based on the 103’s load impedence... correct?

    At that setting it sounds almost over amplified. Once the stylus hits a record, the pre music grooves make a fair amount of noise and the needle comes down with a heavy sound. I’ve checked and rechecked alignment of cart and tracking force using a just calibrated digital stylus force gauge. The denon 103 uses a lot of tracking force 2.3-2.7g so wondering its just a function of that. Once the stylus gets into the music, it seems to sound fine, but sure does make a lot of noise before it hits the track...

    The referenced signet running into the built in mm phono stage of my reciever does not have such a noisy pre-music sound and once it gets into the music track it sounds just as good if not better... like it has less of that pre-music noise in the background... if that makes sense...
     

     

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  12. mprince

    mprince Super Member

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    I run my DL-103 at around 500 ohms, quite happy with it there, also run it at 60db.
     
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  13. EL Duke-A

    EL Duke-A AK Subscriber Subscriber

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    Was doing some research online and think my issue is how i set up my rega tonearm (incorrectly). Will adjust when i get home and it should fix my issue. I basically had too much tracking force because i was setting that using the counterweight in the back of the tonearm vs the adjustment knob to the right side of the tonearm... ops... rega instructions That came with the turn table are not very informative.
     
  14. EL Duke-A

    EL Duke-A AK Subscriber Subscriber

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    Still interested to know the answer to the impedence phono pre amp setting for the denon though... assuming i set the pre based on load impedence of 100 vs output impedence of 40...? Phono pre amp just says if your cart has impedence of (blank) set the jumpers to (blank) ohms, but it does not say if i should be looking at load or output impedence of the cart. All this makes me feel like such a newb...
     
  15. rothwellaudio

    rothwellaudio Forums Sponsor Sponsor

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    The load impedance should be about 10 times the source impedance to minimise signal loss. That means a 400 ohm load for a 40 ohm cartridge. A 100 ohm load will be ok too, but you'll get slightly lower volume; about 2dB lower. The tonal balance of the cartridge may be slightly different at 100 ohm and 400 ohm loads, but not very much.
     
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  16. EL Duke-A

    EL Duke-A AK Subscriber Subscriber

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    Thanks rothwell. So pre should be set off output impedance of cart. With the abulity to jumper up to two ohm setting on the pre (pre has three options 220, 100 and 22)... how best to set...? I have it on 100 now and it seems a bit too much. Not sure if its just a matter of adding the ohm value of two settings if i jumper two and a hogher number is louder? For example, if i jumper 220 and 100, thats 320 and would be louder? I dont think this is correct but not sure how it works.

    Mprince said he runs at 500ohms with his 103...

    Is all this just a matter of amplification of sound? As long as i get close on the pre settings, then i could just tine tube with amp volume...? Is it that simple or other factors at play?
     

     

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  17. rothwellaudio

    rothwellaudio Forums Sponsor Sponsor

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    I'm not familiar with the phonostage you have but if you put two loads in parallel, such as 220 ohms an 100 ohms, you will not get the two numbers to add up - you will get a smaller figure. In this case it would be 69 ohms.

    I recommend you don't get too hung-up on the load impedance and what is "correct". It isn't all that important. As a general audio electronics principle the load impedance should be a lot higher than the source impedance. "A lot higher" means about ten times, or more. For example, microphones have a source impedance of about 200 ohms and microphone preamps have a load impedance of about 2000 ohms. Things like CD players usually have a very low source impedance of a few tens of ohms, but maybe a few hundred or even up to about 1000 ohms. They're fed into preamps with a load impedance (or input impedance) of about 10k, which will be more than 10 times the source, whatever it is. Loudspeakers present a load of about 8 ohms and should be driven from a source with an impedance of less than 1 ohm. Transistor power amps can easily have a source impedance much less than 1 ohm. Valve power amps have a source impedance not quite as low, but should still be much lower than 8 ohms.

    Anyway, the load impedance on an mc cartridge may affect the tonal balance slightly, but not very much. I suspect that when many people claim to hear tonal differences they're either very slight or they're actually hearing a slight difference in level which they mistake for a difference in tonal balance.

    BTW, "Mprince said he runs at 500ohms with his 103... ", but how many options does he have?
     
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  18. EL Duke-A

    EL Duke-A AK Subscriber Subscriber

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    wow. A lot going on here. I think i need to pull some articles on this topic to try an learn more.

    The phono pre instructuions for jumper settings are attached along with cart specs. Since the 103 has output impedence of 40 ohms... it falls between the 22 jumper or using 100+220 so in my simple mind, i should try those two and see what i get....?

    Lastly, okay to run the phono pre into the tape stage of my reciever or does that influince all of this too?

    Really apprdciate your time respomding!!! Thank you.


    6C2298B1-C9CE-410D-B568-1FA8A6333706.png 5C5EB93B-E680-429D-AD7E-4D66B88F8F50.png
     
  19. rothwellaudio

    rothwellaudio Forums Sponsor Sponsor

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    No. The output impedance of the 103 is 40 ohms, therefore it should see a load impedance of about 400 ohms. It should not see a load impedance of 40 ohms. This is one of the common fallacies that too many people believe - that the cartridge should "match" the load impedance, so a 40 ohm cartridge should see a 40 ohm load. It's wrong. It's origins stem from the world of step-up transformers, but even then it's wrong.
    220 ohms is the nearest setting to 400 available to you, so use that. You're at liberty to try other settings and there's no risk of damage to anything if you do. You'll find that the lower settings give you a bit less volume. The lowest setting will give quite a noticeable drop in volume and probably a noticeable change in tonal balance.
    Yes, the tape inputs will be fine.
     
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  20. EL Duke-A

    EL Duke-A AK Subscriber Subscriber

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    I follow. Many thanks!
     

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