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Mystery cartridge hiss .

E

early

pfm Member
Can anyone shed any light on this ? .

I have been using the following without any problems - Technics SL1200G with AT VM750SH into the onboard phono stage of a Yamaha AS2100 .
It sounds good and more importantly it is deathly quiet ( when there's no music playing ) .

Then I introduce a seperate phono stage , Teac PE-505 , which works beautifully with the exception of a hiss / rustle when there's no music or when the music is quite .
Sounds just like a bad valve in a valve based phono . So I fiddled with everything I could think of , grounding ( although it's not hum ) , cables , headshells , gain and capacitance options . All with absolutely zero effect .

Felling like I've got a duff unit I resigned my self to sending it back . As one last roll of the dice I decided to change the cart , popped in a Benz Ace SH into the same MM settings on the Teac and there it is .................................................. silence , no hisses at all just wonderfull silence . So then I tried a DL103 on the MC side , again ghostly silence .

Back on with the VM750SH and back comes the noise , so I start thinking it's the cart . I connected the TT back into the built in 'stage on the Yammy to double check and it's back to having a silent background and working perfectly .

I've never experienced anything like it .

Anyone got any idea what is happening ? .
 
Are you running the audio-technica into RCA input on the Teac with gain set to low (i.e. 34dB)?

Although not published, the Yamaha has 220pF input capacitance on MM; suggest setting the Teac to this such that you are comparing apples to apples wrt possible EMI/RFI breakthrough.

Another thing that comes to mind is, if you've had the A-T stylus off, make sure that this is properly seated with the 2 x magnets properly centred wrt the pole extensions (little metal tabs) for and aft of each magnet.
 
Craig B said:
Are you running the audio-technica into RCA input on the Teac with gain set to low (i.e. 34dB)?

Although not published, the Yamaha has 220pF input capacitance on MM; suggest setting the Teac to this such that you are comparing apples to apples wrt possible EMI/RFI breakthrough.

Another thing that comes to mind is, if you've had the A-T stylus off, make sure that this is properly seated with the 2 x magnets properly centred wrt the pole extensions (little metal tabs) for and aft of each magnet.
Click to expand...

All done , none made any difference :-(
 
Seem like there is a leakage current finding its way to the cartridge. May be input stage bias, may be related to the various test and demag gizmos of that preamp.

This current interacts with the MM cartridge's high impedance, creating a noise voltage. Less so with the much lower impedance MC cartridges.

Are you at the latest firmware?
 
Can you use Balanced XLR connection
248736-3-1200Wx1200H
 
Werner said:
Seem like there is a leakage current finding its way to the cartridge. May be input stage bias, may be related to the various test and demag gizmos of that preamp.

This current interacts with the MM cartridge's high impedance, creating a noise voltage. Less so with the much lower impedance MC cartridges.

Are you at the latest firmware?
Click to expand...
Certainly a possibility.

The demagnetizer appears to be passive in that the cartridge outputs are shorted (with the input muted) with the cartridge then allowed to play 20 or 30secs of a record side (i.e. letting its own magnets supposedly do the demagnetizing, which of course they can't possibly do).

Then again, Teac lists the following as improvements that their firmware update v1.04 is intended to address:
  • Improved a sound lekage [sic] problem while using demagnetization function
  • Improved stability of operation.
 
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Are you using the Demag function with the AT cartridge !
Have one but MC only not MM/MIb

demagnetization similar to a tape head degausser. A fixed high frequency
signal is gradually increased from zero amplitude up to a maximum level where it is maintained for a fixed length of
time. The signal is then gradually reduced in amplitude to zero again. Differing from other cartridge demagnetizers,
the -1 signal is a very pure sine wave with ultra low distortion.
:
Important note: Do not use the demagnetizer with a Moving Magnet (MM) or Moving Iron (MI) cartridge.
Damage to the cartridge will occur.
 
daytona600 said:
demagnetization similar to a tape head degausser. A fixed high frequency
signal is gradually increased from zero amplitude up to a maximum level where it is maintained for a fixed length of
time. The signal is then gradually reduced in amplitude to zero again. Differing from other cartridge demagnetizers,
the -1 signal is a very pure sine wave with ultra low distortion.
:
Important note: Do not use the demagnetizer with a Moving Magnet (MM) or Moving Iron (MI) cartridge.
Damage to the cartridge will occur.
Click to expand...
Your Google scrape doesn't quite apply in this case.

From Teac:

Using the easy demagnetization function​
​
Using the easy demagnetization function to demagnetize MC car-​
tridges with iron cores and step-up transformers, for example, could​
improve the sound quality by making it clearer and giving it greater​
definition​
  1. Set the impedance selection knob to DEMAG.
    The load impedance is set to 0 Ω and both ends of the cartridge
    are short-circuited
  2. Play a record.
    The playback signal current goes through the cartridge and
    demagnetizes it
    • Demagnetization takes about 30 seconds. Keep the record
      playing for about 30 seconds
    • Playback sound is not output when the impedance selec-
      tion knob is set to DEMAG
  3. Reset the impedance selection knob to its pre-
    vious position.
 
Genuine question, how does a MC cartridge become magnetised, in a bad way, as opposed to the has to be to work way?

Cos coils aren't magnetic and you'd need a fair smidge of current to demagnetize an armature, assuming its iron. Coil melting levels, surely. Just checked typical tape head demag runs c 0.2 amps.

I'd love to see before and after measurements.

And yeh, you'll kill a MM or MI cart trying it
 
Is everybody sure that the TEAC phono is not just noisy? It's not unusual for some phono stages to be pretty noisy. I mean how much hiss are we talking about here? from what distance can it be heard etc?
 
daytona600 said:
Have one but states MC only not MM/MI , never used the Teac one
Click to expand...

You are correct in that 'active' phono cartridge demanetizers are dangerous, even for MC cartridges.

I doubt that the Teac 'passive' (run cartridge whilst short circuited) actually does anything useful.

gez said:
Is everybody sure that the TEAC phono is not just noisy? It's not unusual for some phono stages to be pretty noisy. I mean how much hiss are we talking about here? from what distance can it be heard etc?
Click to expand...

The OP reports hearing hiss/rustling noise both at idle and at low volumes, so some sort of bleed through is likely.
 
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sq225917 said:
Genuine question, how does a MC cartridge become magnetised, in a bad way, as opposed to the has to be to work way?

Cos coils aren't magnetic and you'd need a fair smidge of current to demagnetize an armature, assuming its iron. Coil melting levels, surely. Just checked typical tape head demag runs c 0.2 amps.

I'd love to see before and after measurements.

And yeh, you'll kill a MM or MI cart trying it
Click to expand...
The theory is that iron core armatures may become magnetically saturated and somehow interfere with the cartridges linearity. What most don't realize is that iron core armatures are not that common anymore, as MC cartridge makers have long since been pursuing far lower moving mass options. Having said that, I wouldn't be surprised if the Denon DL-103 still has iron cores; after all, this one dates back to the early '60s. A lot of classic Japan Inc. and Ortofon have them too.

Where things get ridiculous is when we consider that iron core coil formers sit within a constant magnetic field from the moment the cartridge is assembled (well, at least from the moment that the fixed magnet is magnetized). Playing music is hardly likely to make a jot of difference as to how much magnetism these minuscule cores will retain whilst otherwise constantly sitting within the same magnetic field.
 
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Werner said:
Seem like there is a leakage current finding its way to the cartridge. May be input stage bias, may be related to the various test and demag gizmos of that preamp.

This current interacts with the MM cartridge's high impedance, creating a noise voltage. Less so with the much lower impedance MC cartridges.

Are you at the latest firmware?
Click to expand...

This is most likely the answer .

I'd like to thank everyone for their input , it's most appreciated .
 
Hello fellas, what a coincidence! I am experiencing some type of abnormal sound as well - like the sound of the runout grove, if one does not lift the tonearm off the record in time.

I recently acquired a Dynavector P-75 IV which was configured for MM initially. I installed it in my system where the TT/cartridge is a MM (AT7V) and it sounded great. A few days later I reconfigured the P-75 to MC PE mode for a TT/MC cartridge (AT33EV) and hear that abnormal sound without the needle in the grove! As I raise the volume, the sound grew louder! I checked all connections and they seemed ok. So I replaced the P-75 with the iFi iPhono 2, which was what I intended to replace with the P-75 and all was fine, no abnormal sound! All connections are the same.

I again reconfigured the P-75 for MM and fed it via the AT7V (TT/cart) and all sang well!? Anyone can think of a possible solution? Thank you.

I have 2 TTs - Thorens TD166 II/RB300/AT7 and Gyro/RB600/AT33EV.
 
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Dynavector's phono enhancer mode can be adjusted to suit low, medium, or high coil resistance (aka 'coil impedance', or 'internal impedance' in some makers specs) via jumpers that optimize gain in PE mode.

IIRC, like most audio-technica MC models, AT33EV has a specified 10 Ohm* internal so likely best to go with 'medium' here. According to the manual, 10 Ohm is on the cusp between Dynavector's 'low' and 'medium'.


* vs. Dynavector's own which are typically 6 Ohm, i.e. 'low', hence the default being set to this.
 
Craig B said:
Dynavector's phono enhancer mode can be adjusted to suit low, medium, or high coil resistance (aka 'coil impedance', or 'internal impedance' in some makers specs) via jumpers that optimize gain in PE mode.

IIRC, like most audio-technica MC models, AT33EV has a specified 10 Ohm* internal so likely best to go with 'medium' here. According to the manual, 10 Ohm is on the cusp between Dynavector's 'low' and 'medium'.


* vs. Dynavector's own which are typically 6 Ohm, i.e. 'low', hence the default being set to this.
Click to expand...
Hi Craig B, I went with the low, I will try with medium and see how it goes. Thank you.
 
A basic rule here is that the noise generated in an amplifier shows up as a combination of 'current noise' and 'voltage noise' generators. The result - even ignoring magnetisation - is that the noise level will vary with the impedance of the 'source' connected to it. Hence there will be an 'optimum source impedance' for the noise and this may *differ* from the optimum for the *signal* being conveyed.

This is the case even when we can ignore factors like changing the amp's input arrangement alters things like the capacitance, frequency response, etc.

Noise values quoted in amp specs tend to use a specific 'standard resistor' across the amp's input to mimic the cartridge. But of course most cartridges are NOT simply a frequency-independent resistance.
 
Hi Craig B, I tried with the medium, unfortunately that abnormal sound is still there :(.

Any other possible solutions, ideas ? Thank you.
 
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