Mystery cartridge hiss .

[Craig B]

Hi Craig B, I tried with the medium, unfortunately that abnormal sound is still there .

Any other possible solutions, ideas ? Thank you.

Can you post a photo of your jumper settings?

This would need to be hosted elsewhere with an image link posted here. I use postimages.org, no sign-up required.

 

[KKG]

postimages.org

https://postimg.cc/bZtG0ZpP

 

[Craig B]

All jumpers appear to be in the correct positions, however, although it is a bit difficult to make out clearly, it looks as though there could be a bent over jumper pin 1 at JB8 (i.e. where the red arrow is pointing in the copy of your pic below). If so, the Rch won't be in PE mode, and cartridge Rch will be running into 0 Ohms on what would be a regular voltage gain stage. This is likely to generate some back EMF that your AT33EV won't be too happy dealing with (likely even negatively interacting with the other channel, although no harm will have come of it).

If I am wrong wrt the pin, then there exists the possibility that AT33EV just isn't happy into PE mode. The manual does mention that some MCs aren't (but doesn't list examples, nor symptoms).

 

[KKG]

All jumpers appear to be in the correct positions, however, although it is a bit difficult to make out clearly, it looks as though there could be a bent over jumper pin 1 at JB8 (i.e. where the red arrow is pointing in the copy of your pic below).

If so, the Rch won't be in PE mode, but will be running into 0 Ohms.

Hi Craig, yes I noticed that and I removed and re-inserted the jumper but to no effect. I will turn the umper position and see how it goes. The sound is mostly from the right channel.

 

[Craig B]

Hi Craig, yes I noticed that and I removed and re-inserted the jumper but to no effect. I will turn the umper position and see how it goes.

The pin will need straightening such that it can insert itself straight up into that side of the jumper. IOW, the jumper bridges pins 1 and 2 together via a metal clip within the jumper red plastic housing. With one pin bent over there is no way for these two pins to make electrical contact with one another.

 

[KKG]

The pin will need straightening such that it can insert itself straight up into that side of the jumper. IOW, the jumper bridges pins 1 and 2 together via a metal clip within the jumper red plastic housing. With one pin bent over there is no way for these two pins to make electrical contact with one another.

I've just replaced the jumper and will try out now but in case it does not work, (i.e. AT33EV just isn't happy into PE mode) which position should the jumper be - 33 Ohms 100 Ohms? Thanks for your time.

 

[KKG]

The AT33EV just isn't happy into PE mode.

 

[Craig B]

I've just replaced the jumper and will tr out now but in case it does not work which position should the jumper be - 33 Ohms 100 Ohms? Thanks for your time.

The AT33EV just isn't happy into PE mode.

Did you manage to get pin 1 straightened such that it slid into the jumper properly along with pin 2?

If running the AT33EV into standard MC (voltage gain) mode then A-T recommend 'More than 100Ω' (which isn't really helpful). Internal resistance is 10Ω, so 100Ω is the textbook match*, however, it is always worthwhile experimenting here. I'd start with 100Ω and listen for a good while before chasing rabbits. Regardless, 33Ω is definitely too low.

It's too bad that PE mode didn't work out for you here. AT33EV is a lovely cartridge and I've no doubt that it will still sound great into such a quality standard MC stage as the DV75 has in.

* General rule of thumb is 10x internal resistance as minimum.

 

[KKG]

Did you manage to get pin 1 straightened such that it slid into the jumper properly along with pin 2?

If running the AT33EV into standard MC (voltage gain) mode then A-T recommend 'More than 100Ω' (which isn't really helpful). Internal resistance is 10Ω, so 100Ω is the textbook match*, however, it is always worthwhile experimenting here. I'd start with 100Ω and listen for a good while before chasing rabbits. Regardless, 33Ω is definitely too low.

* General rule of thumb is 10x internal resistance.

Pin is straight and slid into the jumper properly.

Changed to 100Ω, still the noise/sound is still there.

 

[Craig B]

Pin is straight and slid into the jumper properly.

Changed to 100Ω, still the noise/sound is still there.

Did you also move the jumpers off JB7 & JB8 pins 1 & 2 and onto pins 3 & 4? If not it will still be in PE mode (but with 100Ω rather than 0Ω).

IOW, JB7 & JB8 pins 3 & 4 put it back into standard voltage gain mode.

Speaking of gain, you'll want to have a play with JB3 and JB4 as the jumper positions are different from those for PE mode. Highest gain is 63dB which is a single jumper across the right most pair of pins ('medium' 60dB requires 2 jumpers, and 'low' 56dB requires 3, see pg 4 in the manual). IIRC, we last had your gain jumper across the middle two pins, which appears to be nothing in standard MC mode. I'd just go with high (pins 5 & 6) for now, and back off as necessary later.

 

[KKG]

Did you also move the jumpers off JB7 & JB8 pins 1 & 2 and onto pins 3 & 4? If not it will still be in PE mode (but with 100Ω rather than 0Ω).

IOW, JB7 & JB8 pins 3 & 4 put it back into standard voltage gain mode.

Yes, jumpers on pins 3 & 4 for JB 7 & JB8.

 

[Craig B]

Yes, jumpers on pins 3 & 4 for JB 7 & JB8.

Did you happen to catch my edit re: the gain jumpers?

 

[KKG]

Did you catch my edit re: the gain jumpers?

Yes, just did shift to the high gain, still the same.

I give up for today. I'll try another cartridge, Ortofon Kb, when I have the next opportunity. A daunting thought - changing cartridge.

Thank you very much Craig, for your time and effort. I'll update here when I'm done changing the cartridge.

 

[Werner]

The AT33EV just isn't happy into PE mode

even then it should not make funny noises. it should function, while sounding perhaps a bit off.


what might bepossible is the phonostage getting unhappy with whatever hangs off its input, gettin instable. but this is very rare.

 

[KKG]

what might bepossible is the phonostage getting unhappy with whatever hangs off its input, gettin instable. but this is very rare.

Hi Werner, greetings, its been some time since AA (Audio Asylum), hope you are keeping well.

If it is due to something from the input, which could be either the cartridge, tone arm or the TT itself, the noise is not there when the iFi phonstage is connected. Could it be that the iFi phono has better tolerance?

What can I check?

Thanks

 

[a.palfreyman]

If all is good with a different phono amp, with no other changes in the front end coming into the stage, then it all points to a problem in the Rch of the P75. If the P75 is also fine in MM mode, that narrows it down to the MC section. Possibly a dodgy solder joint or poor jumper contact.
If you are happy doing this yourself, take the pcb out and examine the phono connector to pcb solder joints first. The lower gain of MM and very light loading might just not show up a cracked joint where the much higher gain / loading of MC is a different matter. If the phono connectors are ok, check around the jumper networks next as flexing of pcb can crack solder or even very fine pcb tracks.

 

[Craig B]

I'll echo Andy's suggestions above, and only add that you'll particularly want to inspect the PCB trace that is beneath pin 1 at JB8. With this pin having been accidentally bent over to circa 90 degrees and then straightened back up again, there may well be a problem beneath. Possibly one that affects a common trace that is shared with pin 3 on the standard MC side of the same jumper(s) block.

EDIT: Should these pins appear to share a common board trace, and you aren't able to visually confirm whether this be cracked or no, then suggest testing for continuity between the pins using a multi-meter.

 

[pavel_p]

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 ? .

Hello!
I also use the Teac PE-505 preamplifier and found exactly the same problem in working with MM cartridges (increased noise). When using the MC cartridge, the noise is much smaller and does not interfere in the pauses of the phonogram. I also noticed that the noise in the left channel is a little more than in the right, tell you the same?