Ever had a box where Line In was too SOFT?

[Reli]

We've all had plenty of boxes where the input jacks are too loud and distorted, because they were intended to receive Phono signals, not line in. All you need to do is hook up a phono attenuator, and the problem is solved.

But what if the opposite problem happens, and it sounds way too soft? This is a Sankei TCR-S90EE, by the way. The jack and the switch both say AUX.

 

[k2j]

have to ask riker but I think my old 9797 was soft

 

[Superduper]

Many boxes are like this. Sometimes, it has to do with mismatching impedances. If the input impedance on the boombox is lower than the output device expects, then it could drag down the signal. Those line-in and line-out jacks were designed for an era where the source signals maybe be more robust. To confirm, supply a line-in signal from an old school cassette deck and see if you have the same issue. If yes, then maybe the line-in circuit on the boombox is calibrated too low, or maybe the circuit is weak, not necessarily by design but from aging components? If however the signal is now up to where you would expect normal to be, then it's possible that the (low) source device is unable to supply enough power to a low impedance load, or not designed as a line-out source. An MP3 headphone jack is not a properly calibrated line-level signal. It is designed for use with earbuds.

 

[Reli]

I have two Sankei's like this. Both are way too soft, basically useless. They're both European versions with a DIN 5-pin input/output, but that shouldn't make any difference, because it's labeled Aux, same as the switch. And the owners manual says it's meant for regular line-in sources. They also describe an international version of this model with traditional RCA ins and outs.

I tried not only my MP3 player but also a CD player and another boombox. Same result.

In both Sankei's they labeled it Aux, but it sure as hell doesn't work like Aux. WTF were they thinking? These are Japanese by the way.

 

[jimmyjimmy19702010]

All my Sanyo M9998Ks line ins were a little low in sensitivity. My National RX-C45 on the other hand requires your MP3 volume to not exceed 75% volume.

James....

 

[Reli]

Yeah, its weird. I set my devices at max volume, and still all I get is faint, tinny sound with no bass at all.

Norm, it's an AKA of your Kings Point. Mechanically identical. I have two of them, both are like this.

 

[Superduper]

Maybe if I can dig it up next time I go to storage, I'll look into it. Try an old school cassette deck, not a portable headphone type of output and see if it makes a difference?

 

[jimmyjimmy19702010]

I have two Sankei's like this. Both are way too soft, basically useless. They're both European versions with a DIN 5-pin input/output, but that shouldn't make any difference, because it's labeled Aux, same as the switch. And the owners manual says it's meant for regular line-in sources. They also describe an international version of this model with traditional RCA ins and outs.

I tried not only my MP3 player but also a CD player and another boombox. Same result.

In both Sankei's they labeled it Aux, but it sure as hell doesn't work like Aux. WTF were they thinking? These are Japanese by the way.

I've had the exact same issue with an M90 and Hitachi TRK-9140 with 5 Din line in inputs. People said I was crazy saying that 5 DIN units had very quiet line ins but it's obviously a common problem.

James....

 

[Reli]

But I've got several other boxes with 5-pin DIN's that have no problem at all.

 

[jimmyjimmy19702010]

But I've got several other boxes with 5-pin DIN's that have no problem at all.

Yep, it's not consistent. All my Euro boxes have very quiet (useless) 5 DIN inputs. I've heard that there isn't a theoretical difference in sensitivity between RCA and DIN inputs so maybe it's just a brand/model specific issue.

Although my TRK-9140 with 5 DIN inputs is useless, my TRK-9150 with RCAs is perfect!

You're question was, can this issue be fixed? Not by me, sorry dude.

James...

 

[goodman]

I Have the same problem when connecting a MP3 player to the boombox:
I check 3 MP3 players, volume is on max, but output level is so lower.
In electronics sites found assembled preamplifier with TL 082.
The gain is determined by the value of the resistor in the feedback.
The picture shows how to connect:

I decided to embed this preamplifier in one of my boomboxes.
I found a place to mount the board.
When I finished, it's time to tests.
The level indicators show +3db.
MP3 player volume is on 40%, equalizer is off or flat.
Now, the sound is good!!!

 

[caution]

I've heard that there isn't a theoretical difference in sensitivity between RCA and DIN inputs so maybe it's just a brand/model specific issue.

Actually there is. Here's the link I posted about it some time ago.

https://suite.io/richard-mudhar/1qvf2nh

 

[Superduper]

Hmmm. I thought there might be an impedance related issue. I suppose depending on how those in/outs are calibrated, this might indeed be the case.

 

[Reli]

Hmm, interesting link. But let me clarify: The only problems I've had were with these Sankei's, whose DIN jack provides a combined in/out capability. The DINs on my other radios are "in only", and they work fine.