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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

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Old 19th Nov 2018, 4:49 pm   #1
Hobbit1234
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Join Date: Nov 2018
Location: Ninove, East Flanders, Belgium
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Default Leak Trough line 3 stereo tuner

Hi,
This is my first entry on this forum.

My question.
I have a Leak Trough Line 3.
A coax connector is fixed on the 75 ohm screws.
Antenna is a coax coming from the internet, tv, radio provider.
Question is.
Why are all, certain more than others so silent.
I have an amp to which the Leak is connected, a JVC AR600X. Very powerful amp.
Opening it full and I cannot imagine what will happen.
Anyway.
A station on 98.8 MHz needs 95% of the volume knob open to have a decent volume.
My Sansui 301, far less powerful needs 20% for the same volume.

I am no expert at all. Just a melonane. But this bothers me.
Also because of the strain put on the amp and speakers.
Compared to a tuner the leak needs far too much power !

Is it something inside that needs reviewing !?
By whom ??

All ideas welcome.

Greetings from Belgium,
Ignace
Hobbit1234

Last edited by AC/HL; 19th Nov 2018 at 9:50 pm. Reason: Thread split
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Old 20th Nov 2018, 12:33 am   #2
Grubhead
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Default Re: Leak Trough line 3 stereo tuner

That sounds like a pre-amp problem to me. If it happens on all devices.
What you are listening to is just the device, such as the tuner itself. To get it louder it must have a pre-amp to make it loud enough, so the main power amp can do the work then.
It's rather like having a magnetic cartridge record player just connected to a tape socket. You have to really turn it up before you can hear it.

Each device has to be boosted before the main amp can really blast it out.

Depending on the main amp complexities each device socket will be fed into a pre-amp first. More modern amps will have them going into a single IC. Even then certain parts of the IC could fail, leaving some devices normally amplified. Earlier amps could have individual pre-amps. Or just one with a selector switch for the input. Though magnetic cartridge amps, will have a separate pre-amp for that before going into the main pre-amp.
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Old 20th Nov 2018, 12:48 pm   #3
G8HQP Dave
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Default Re: Leak Trough line 3 stereo tuner

Turning up a volume control because a particular audio source is low in voltage level does not put any strain on the equipment.
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Old 20th Nov 2018, 1:11 pm   #4
valveaudio
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Location: Diss, Norfolk, UK.
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Default Re: Leak Trough line 3 stereo tuner

I could not find a JVC AR600x, the AR series are all car radios, are you sure about the type number?

The JVC JR-600x has a line input sensitivity of 250mv.
The Sansui 301 has line input sensitivity of 200mv so this will sound slightly louder but not as much as you have said.

The output of the Leak is 1v, so more than enough to drive either amplifier.
The problem could be a fault in the input circuitry on the JVC, have you got another tuner or other source you could try?

Trevor
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Old 20th Nov 2018, 5:08 pm   #5
DangerMan
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Default Re: Leak Trough line 3 stereo tuner

This thread is very similar to a previous one, here:

https://www.vintage-radio.net/forum/...d.php?t=148548

The important information is probably in post 13, the spec. for Troughline Stereo FM tuner where:

[snip].. " Leak say (quote):

Audio Output: 150mV per channel from 75kc/s deviation i.e. 50-80mV per channel from normal transmissions. The impedance of the associated audio amplifier should be between 47,000 ohms and 100,000 ohms. "

The Leak output impedance in Stereo mode is unbuffered and quite high, so output levels will be further reduced by any amplifier with lower input impedance than is recommended above.
There is further information in post 5 of that thread, and in fact throughout.

HTH, Pete

Last edited by DangerMan; 20th Nov 2018 at 5:13 pm.
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