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Problems adding 3.5mm jack to record turntable

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Every single resistor in my amp except for the fusibles and the metal oxide
on the nobel network are all 1% metal films. The amp is built with a 100%
ground plane on the circuit side. The ground is a single point where all
the grounds and signal returns terminate.

The bias adjust is 10 turn.

Yep, that's why you use metal film ones and I did, nearly throughout.

There's no need to use them throughout, only in a few critical positions - but personally (as I imagine with many others) I tend to use them everywhere, because I only stock metal film resistors.

Try again.

Nothing to try, normal amps don't do what you claim your's does - so it's design or construction errors in your amp.
 
It works perfectly now!

Shout out to 4pyros for giving us the simple, yet exact advice needed. When I put the jack in, I initially did not ground it. After going back and "putting the black wire in" the output jack worked like a champ.

Thanks again to everyone who took the time to help me out on this issue. This is a great community of well-informed and talented folks.
 
Should I top post a new question

Or can we take it from this post since I think it is the same question;

My question(s)

I have brand new Crosley CR704 Turntable/am/fm/cd w mem/casset/line in/ and it does not have phone jack or line out. It is 18watt supply with 10watt output. Sterio.

I have no idea what ohm the speakers in the Crosley are (I assume 8 ohm).

I have no need for the headphones but I want to have a line out to my 1,000watt sterio amp.

I have not looked at the Crosley PCB yet but I assume these are mass produced and it "might" have via(s) for the phone jack. Does anyone know what I should look for on the PCB for this idea?


Do I need to worry about a resistor or could I just set up an output jack from the speakers on the Crosley? (since this is not for headphones). It would be the same as a 10watt pre-amp.....right?

I am concerend about the load on the new Crosley and thought about using two 8 ohm audio transformers as a way to be sure the load on the Crosley is correct?

Any ideas on this?

Thanks in advance.
 
Just tap it off the speaker connection using a 10K resistor - no load on the Crosley then - and solid state amplifiers shouldn't be impedance matched (which would destroy them anyway - 8 ohms isn't matched!).
 
I have also a problem same as yours.The first thing I did is to series a 10k from the output of your stereo and bleeding it w/ a 1k resistor.this might fix your problem,one talented genius give me this idea i forgot his name.he is a member of this forum.if still not fix open your car stereo and use a capacitor to find the output of your preamp.the easiest way is on your vol.control but sometimes not always the case.
 
Thanks NG and 4pyros,

I am not exactly a beginner but I am new to how to make this work. I am digital dumb. But analog I have worked with making my own guitar stompboxes, compressor, mixer, powered splitter, tremolo, and a bipolar 9VDC power supply. Most of what I have made is cookie cutter but I have made some of my own mods, my own PCBs and my own PCB design, and I have an HO train layout.

First of all... can't believe how many audio products do not come factory with this very much need feature. OK that's my rave.

Both solutions above have the same message that is clear to me; speaker output signal is to much for line out. But this makes start to think of a bunch of other things now.

Using the volume pot; I am not familiar with the components concerning right/left speaker control and the Crosley unit does not have a pot that controls the right left speaker outputs. The balance must be factory set. Perhaps there are trim pots for R/L on the PCB. Or maybe I could figure this out after I open the case.

I do like the idea working with a signal voltage that is lower to start with since the tech advise provided above is advising to use a low signal strength.

However, I am old, crabby, and very picky about my sound quality. (when I was 30 I swore I would never be like this....oh well).

I want the speakers off when using a new line out connection so I will have to cut the speaker leads no matter what. As long as I am cutting them anyway I might as well use the speaker leads for my line out connection.

I can tell by the speaker terminals which leads are positive and negative. Q) I assume negative is common ground and thus it should also share ground with my power amp....right? (i.e. the ground is not isolated?)

Q) So wouldn't I need two resistors; one from the right positive speaker lead and another from the left positive speaker lead? How can I get the same resistance on R/L using resistors at +/- 10% or 5%? I guess I could cherry pick about 20 with an ohm meter and try to get as close as possible.

Q) What type of resistors can I use? Can I use a 10K trim pot and then have some control over the signal strength from each channel? Or is the carbon resistor going to cause noise problems?

Q) If it is OK to use trim pots to reduce the speaker signal, is there an output signal strength that I should try to set up that is a good overall strength? Could I measure this at the existing volume pot?

I know I have a lot of questions.......not sure about what I am doing on line out stuff. If I can learn how to do this I will no doubt put line out jacks on everything I have that is missing this major feature.
 
Many low-end systems used a 470K resistor in series with the speaker output to drive headphones. I find the quality of the sound there to be lower because of the current noise across the resistor. i.e. IMHO, it amplifies the hiss.

A manual would make this easy.

You could look for OP-amps and coupling caps on the order of 1 uf.

They might be a friendly company: **broken link removed**

Try requesting a service manual.
 
Many low-end systems used a 470K resistor in series with the speaker output to drive headphones. I find the quality of the sound there to be lower because of the current noise across the resistor. i.e. IMHO, it amplifies the hiss.

You certainly don't have a 470K resistor feeding a headphone socket, that's MUCH too high :D

Using a resistor (or two) to feed headphones from the output of an amplifier is standard practice, and doesn't introduce any ill effects, including hiss.

Fairly obviously, a resistor can't 'amplify' anything.
 
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