Phono pre amp to amp issues

[RDarko15]

I don't know if this is the right place to ask but I have a phono pre amp attached to a 1980s technics stereo receiver. When attached the sound is distorted and screwed with. When my turntable is directly attached to the amp it works fine.. What am I missing here and what's the issue?

[esldude]

Okay, what is the phono preamp you are using specificially?

 

It could be the phono pre-amp presents a line level signal (1-2 volts). If you then plug that into the phono input of the old stereo receiver, it will get too much amplification and be very distorted. Could damage the phono input on the receiver as well. If that describes what you are doing, try putting the output of the phono preamp into a tape input on the receiver. That might work well for you.

 

Of course giving us details of what phono preamp you are using, and which input you are using on the Technics receiver will make it more likely we can help you figure it out.

[RDarko15]

Thanks for your response! It's a pro ject audio phono DC MM/MC box

[RDarko15]

I tried to plug into the tape rca and it didn't help.. Its a good pre amp that I have used for a while now and I would still like to be able to use it .. But it seems like I'm going to have to get a new stereo amp receiver..

[sandyk]

When my turntable is directly attached to the amp it works fine..

Does the receiver have a Phono Input that you plugged the TT directly into it , when it sounded fine ?

The level from the TT should have been waaaay too low via a normal input and sound tonally unbalanced.

If the Phono Preamp sounded distorted when plugged into a normal line level input, it suggests that the Phono Preamp may have become faulty.

[RDarko15]

I ran my rca cables with a ground from my TT directly to my stereo and it plays fine which I don't understand. And the pre amp is fine because I had it hooked to speakers earlier today and it worked (no stereo receiver)

[sandyk]

I ran my rca cables with a ground from my TT directly to my stereo and it plays fine which I don't understand. And the pre amp is fine because I had it hooked to speakers earlier today and it worked (no stereo receiver)

 

Did you try the TT directly into a normal LINE LEVEL input such as CD? A typical moving coil cartridge is likely to have an output of around only 5milliVolts The level would be far too low for a normal line level input without additional amplification.

How can a Phono Preamp DIRECTLY drive loudspeakers ?

Are your speakers PASSIVE, or amplified ?

[RDarko15]

I had the pre amp hooked up to computer speakers that were like 90 bucks and had a sub. I just ran my rcas to the back of them and it sounded great for what it was.

[RDarko15]

And when I'm having the issues.. I am running cables from my turntable to pre amp, then pre amp to phono rca inputs on the receiver..

[RDarko15]

The receiver is a technics SA-GX130 if that helps anyone

[sandyk]

And when I'm having the issues.. I am running cables from my turntable to pre amp, then pre amp to phono rca inputs on the receiver..

 

Dennis answered that in the very first reply.

A Phono Preamp is designed to work into a normal LINE LEVEL input such as CD ,Tuner etc., NOT a Phono Input !

 

The attached link shows why you overloaded the Phono Input.

http://elektrotanya.com/PREVIEWS/63463243/23432455/technics/technics_sa-gx130.pdf_1.png

[esldude]

Okay, just looked at your receiver back panel. If this is the right one:

 

http://img.canuckaudiomart.com/uploads/large/445559-technics__sagx130_stereo_receiver.jpg

 

First you definitely need to feed the Pro ject output into either the Tape, VCR or CD input on the Technics

 

How are you connecting the receiver to your speakers? If you are using speaker leads in the spring clips on that Technics and the other end has an RCA type plug, that is your problem. Though looking like the right plug, it will be too much voltage for your powered computer speakers.

 

What you need is a line level preamp or receiver with line outputs that can control the volume. I don't see any outputs on your Technics that would do that.

 

You might get away with getting an adapter that plugs into the headphone jack, and the other end is stereo RCA's. That would probably work alright for you. Run that into your powered speakers.

 

Just to be clear, maybe you can give us the model of the speakers you are using.

 

Also, make sure you are using the correct gain setting for your cartridge. MC will be about 20 db more gain. If used with a MM cartridge, you might get distortion from the Pro ject because the input level is too high. So match MM or MC to your cartridge. I am guessing you likely have an MM (moving magnet cartridge).

[RDarko15]

I have infinity primus p363 speakers and a ortofon 2m MM cartridge. I am eventually going to change out the stereo receiver

[esldude]

I have infinity primus p363 speakers and a ortofon 2m MM cartridge. I am eventually going to change out the stereo receiver

 

Okay, I got confused along the way. You are using the Technics to power the Infinity speakers. As a test you directly connected the Pro ject phono pre-amp directly to some other powered computer speakers and it worked well.

 

So, you connect your TT to the phono on the Technics while powering the Infinity speakers and it works. You connect TT to the Pro-ject phono preamp to the tape or CD input on the Technics powering the Infinity speakers and it sounds distorted. Okay, I think I have it now.

 

Unfortunately, I don't know what would be causing your problems now. Sorry I could not be of help.

[sandyk]

And when I'm having the issues.. I am running cables from my turntable to pre amp, then pre amp to phono rca inputs on the receiver..

You need to run the Phono Preamp into an input such as a CD or Tuner Input, not a Phono Input which has another RIAA Phono Preamp internally.

A Tape Input may also have gain and equalisation to suit different EQ. standards such as NAB etc. so it may not be suitable

[sandyk]

Further checking shows that the Tape Input is at Line Level, so it should be suitable provided that the output level of the Phono Preamps isn't too high, as it has an input sensitivity of 200mV, as does CD input.

It is possible that the Phono Preamp is overloading the inputs. Does the Phono Preamp have an adjustable output level ?

[RDarko15]

No there is no gain control. I think it's the pre amp overloading the inputs.. I need to look into a new receiver anyways.

[esldude]

No there is no gain control. I think it's the pre amp overloading the inputs.. I need to look into a new receiver anyways.

 

I think you are right. One spec for your phono unit showed a max output capability of 9.5 volts. Now it isn't likely you are getting those levels with your cartridge. But if you haven't done it, try the CD input. It should be okay up to around 2 volts as that was somewhat standard for CD levels. Otherwise, it does sound from everything you have tried like the input is being overloaded on the Technics.

[sandyk]

I think you are right. One spec for your phono unit showed a max output capability of 9.5 volts. Now it isn't likely you are getting those levels with your cartridge. But if you haven't done it, try the CD input. It should be okay up to around 2 volts as that was somewhat standard for CD levels. Otherwise, it does sound from everything you have tried like the input is being overloaded on the Technics.

 

Dennis

Unfortunately, Input Sensitivity for CD is stated as 200mV/22Kohm

 

Alex

[gmgraves]

I don't know if this is the right place to ask but I have a phono pre amp attached to a 1980s technics stereo receiver. When attached the sound is distorted and screwed with. When my turntable is directly attached to the amp it works fine.. What am I missing here and what's the issue?

 

 

If your Technics receiver already has a phono input for a moving magnet cartridge (which I'm 100% sure it does) then you don't need or want another phono preamp outboard of the receiver. If you want to use the external phono preamp with your receiver, plug it into one of the high-level inputs such as the Tape-in, Auxillary inputs or CD inputs. But don't use both the external phono preamp and the receiver's phono inputs together. You are just overloading the phono inputs on the Technics.

[sandyk]

If your Technics receiver already has a phono input for a moving magnet cartridge (which I'm 100% sure it does) then you don't need or want another phono preamp outboard of the receiver. If you want to use the external phono preamp with your receiver, plug it into one of the high-level inputs such as the Tape-in, Auxillary inputs or CD inputs. But don't use both the external phono preamp and the receiver's phono inputs together. You are just overloading the phono inputs on the Technics.

 

George

He has already tried the higher level inputs which are all rated for 200mV sensitivity.

Perhaps he just prefers the sound of the outboard Phono Preamp over the internal Phono Preamp section ?

A DIY person could readily knock up a simple attenuator using just 4 resistors (perhaps 10dB or so ?) in a small Jiffy box with In and Out RCA sockets.

Alex

[RDarko15]

Alex

Yes I prefer the phono that I have over the phono inputs on the receiver. Are there plans online for an attenuator that I could put together?

[Audio_ELF]

Alex

Yes I prefer the phono that I have over the phono inputs on the receiver. Are there plans online for an attenuator that I could put together?

Unlikely, a phono pre-amp isn't just about increasing line level as there is also a form of EQ as part of the circuit.

 

As everyone is saying, just use the Cd/Tape/Video whatever's other input. The only input your CAN'T use is the Phono input.

[sandyk]

Alex

Yes I prefer the phono that I have over the phono inputs on the receiver. Are there plans online for an attenuator that I could put together?

 

If you can use a soldering iron, and would like to experiment, try the attached. You could also mount 4 RCA sockets, (2 for in, and 2 for out) in a small Jiffy box and wire the resistors between the sockets. I would suggest trying only 10dB for starters, but buying resistors to suit 20dB at the same time.

Regards

Alex

DIY 10dB attenuators - AudioKarma.org Home Audio Stereo Discussion Forums

 

 

Eloise

The Phono Preamp appears to be overloading the other 200mV sensitivity inputs too.

[gmgraves]

George

He has already tried the higher level inputs which are all rated for 200mV sensitivity.

 

 

You mean that his Technics has no line-level inputs?

 

Perhaps he just prefers the sound of the outboard Phono Preamp over the internal Phono Preamp section ?

 

Well, that's fine, and while I agree that quality stand-alone phono stage is most likely sonically far superior to the phono stage included in the receiver, plugging the output of ONE (outboard) magnetic phono preamp into the input of another magnetic phono preamp is definitely NOT the answer!

 

A DIY person could readily knock up a simple attenuator using just 4 resistors (perhaps 10dB or so ?) in a small Jiffy box with In and Out RCA sockets.

Alex

 

No doubt. In fact, one could actually build such a voltage divider across the actual high-level RCA jack on the receiver chassis itself and eliminate the need for a box and two more RCA jacks. But I have a hard time with the notion that Panasonic (Technics' parent) would market a receiver with that high a sensitivity for the "line-level" inputs!