Phono stage is hissing, what to do?

[Justinasia]

I have an Alpine/Luxman LE-109 phono stage. It seems to be making noise! It is second hand, and, I am not sure if maybe this is normal for phono stages?

It was giving a hum if I turned the volume above normal level on the amp. This amp (audiolab 8000s) gives no noise at all turned right up with the CD player, so this is definitely coming from the phono stage.

I now try it without the turntable attached. On the phono stage there are 2 phono inputs, one for MC and one for MM/MC.
At normal volume I don't notice any noise (though my room is not exactly silent anyway). With the volume turned up, MC/MM setting gives a smooth white noise kind of sound. MC straight setting gives the same but with a kind of buzz in addition.

Also there are buttons on the front, for MM/0 dB, 22dB, 32dB, and for 3ohms 40, and 100. They are anyway not used in MC straight mode. But just to let you know, they make noise too when switching them (only while in MC/MC mode though). Also the noise increases in MC/MM setting when the setting is changed from 0 to 22 and then more to 32.

I opened it up and could see nothing obviously wrong. No burned parts or anything obviously loose.

Any ideas? I can post a picture if that will help

Thank you!
Justin

[analog_sa]

It all seems absolutely normal. Do you know what are the published noise/sensitivity specs? What is your cart?

[Justinasia]

Originally posted by analog_sa
It all seems absolutely normal. Do you know what are the published noise/sensitivity specs? What is your cart?

Specs for the phono stage:
Rated output 150mV
Harmonic distortion factor 0.005% (at the time of 1kHz and 1V output)
Input sensitivity PHONO 1160 μV
PHONO2 2.5mV (0dB), 220μV (20dB), 80μV (32dB)
Input impedance PHONO 1100 ##
PHONO 247 kΩ (MM)
　　　　　　　 3Ω, 40Ω and 100Ω (MC)
SN ratio PHONO MM 95dB (MM, 1V output)
PHONO MC 80dB (MC STRAIGHT, 1V output)
Frequency characteristic 20Hz~20kHz
Crosstalk 85dB
Power source 100V 50/60Hz
Electric power consumption 25W
External size 438W×63H×310Dmm
Weight 4.5kg



And the cart is DL 103, with a Pro-ject Perspective deck. But this noise comes even when the deck is not plugged in at all to the phono stage. So I am figuring it is the stage.
Justin

[sreten]

Hi,

All sounds normal - you should get less noise with the cartridge plugged in.

Hum (not noise) is usually bad earthing practise in the turntable.

/sreten.

[bulgin]

Hi

How is your phonostage powered - ac or batteries?

I have a few phonostages, including 2 old Lenteks - one of these acquired about a week ago. They are battery powered with a 9V battery. The one I had originally started hissing on the right channel. The second one does exactly the same on the same channel.

I now use them in a tandem fashion. the phonoleads from the arm go into each one's silent left channel.

The batteries I use in them are rechargeable. Someone suggested to change to ordinary 9V batteries. I haven't tried it yet.

bulgin

[Justinasia]

Originally posted by sreten
Hi,

All sounds normal - you should get less noise with the cartridge plugged in.

/sreten.

Really?? With the cartridge plugged in, I should get less noise than with no turntable at all connected to the phono stage??

[Justinasia]

Originally posted by bulgin
Hi

How is your phonostage powered - ac or batteries?

bulgin

With a power cord that goes to the mains.
Also in Japan there are only 2 pins in the plugs. I come from England where we have 3, the 3rd being earth. So I don't quite get how it works with only 2, but I have been told that somehow it does work and there is an earth.
Justin

[ashok]

You might find only two pins on the plug, but is there a metal strap on the plug ? That is the earth connection . I've seen plugs like that but can't remember if it was in Japan.

[Justinasia]

Originally posted by ashok
You might find only two pins on the plug, but is there a metal strap on the plug ? That is the earth connection . I've seen plugs like that but can't remember if it was in Japan.

Metal strap? It is just a cord with a plug with 2 pins. I guess it is the same across continental Europe too. The guy in the shop said the earth is the negative, or something. Anyway, it's all like that here so it must be right I guess.


Ah.... now I have looked it up on wikipedia.
"Type A (North American/Japanese 2-pin)
An American ungrounded polarized plug and a Japanese ungrounded socket. This plug can only be inserted into the socket in one manner, with the wider pin — the neutral contact — being inserted on the left.
An American ungrounded polarized plug and a Japanese ungrounded socket. This plug can only be inserted into the socket in one manner, with the wider pin — the neutral contact — being inserted on the left.

NEMA 1-15 (North American 15 A/125 V ungrounded)

Standardized by the U.S. National Electrical Manufacturers Association [5] and adopted by 38 other countries, this simple plug with two flat parallel pins, or blades, is used in most of North America and on the west coast of South America on devices not requiring a ground connection, such as lamps and "double-insulated" small appliances."


So, maybe has no earth then!?!? That is the standard in the US right? And the Europlug (most standard in Europe) also is an unearthed 2 pin plug. So what do you guys in the US and Europe do when you stick a knife in your toaster? Do you just get fried? And, more to this point in question, how are your phono stages earthed?!

Thanks!
Justin

[analog_sa]

Originally posted by Justinasia



Really?? With the cartridge plugged in, I should get less noise than with no turntable at all connected to the phono stage??

Why so surprised? The effective noise source at the input dependes on the source impedance and with a cart connected is always less than without.