Hey All,

I modded this Panasonic Radio into a guitar amp by wiring the guitar signal to the center tap of the volume potentiometer. I want to get rid of the other stages of the radio and only use the audio amplifier stages as an amp.

I drew out the portion of the schematic that I am going to isolate, and I was wondering if it would work as is?

Thanks

 

My suggestion would be, if you want to build a transistor amplifier for a guitar, there are easier and better ways to do this.
You will be very disappointed with the amplifier in the radio. Leave the radio alone as is.

 

My suggestion would be, if you want to build a transistor amplifier for a guitar, there are easier and better ways to do this.
You will be very disappointed with the amplifier in the radio. Leave the radio alone as is.

The whole reason why I'm doing this is because I love the way this sounds.

 

Well, for one thing, that circuit is connected live to the AC mains.
I would not want to be playing my guitar with no protection from being electrocuted.

 

Well, for one thing, that circuit is connected live to the AC mains.
I would not want to be playing my guitar with no protection from being electrocuted.

Sounds good so add an isolation transformer?

 

Sounds good so add an isolation transformer?

What else would you recommend doing for it to be stand alone?

 

The Question is why? You can buy a powerful class D amp for just a few dollars. Add a an old laptop supply and it costs way less than a mains isolation transformer with far more power and performance. You would need a preamp, but these can be built for practically nothing.

 

The Question is why? You can buy a powerful class D amp for just a few dollars. Add a an old laptop supply and it costs way less than a mains isolation transformer with far more power and performance. You would need a preamp, but these can be built for practically nothing.

Which question?

 

My question.

 

My question.

Why what tho?

 

The Speaker(s) and the Speaker-Cabinet(s) are what determines the "sound" not the Amplifier.

I also vote for the Digital-Amp and LapTop-Power-Supply.

You can use any High-Fidelity-Speaker if You are also using a Guitar-Oriented-DSP-Program
and get tons of phenomenal Guitar-Tones, for CHEAP.
( DSP = Digital-Signal-Processor )

Using a Speaker specifically designed for a Guitar-Amp limits the types of "Tones" You can produce
and will result in very weird and uneven sound-dispersion-properties from the Cabinet,
so why handicap yourself right from the start ?
Go to a Pawn-Shop and get a complete Home-Stereo for cheap, then work on the DSP part.

Many DSP's will also produce a Stereo-Output.
Here's an excellent Guitar-DSP from Fender ...........
.

.
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Thanks guys, I'm definitely gonna go with that way for sure. Thank you

 

The comments about safety are certainly correct! And that is a serious issue. Now liking the way it sounds is a separate concern.
There are several choices as to the way to remove that shock hazard. An isolation transformer in the mains power feed is both simple and quite expensive. A much less costly approach will be a very small transformer at the input side. Finding a transformer like that new will not be too difficult, but a used one from a small radio will be much cheaper. The exact transformer ratio is not super critical , but probably lower that ten to one, or one to ten, will be the best choice..
And that transformer will be small enough to mount inside the radio enclosure.

One more thing: Guitar amplifiers would seldom be described as "Hi Fi" systems. So using a standard "HiFi" amplifier will usually require adding quite a bit to get that same "sound."

 

Why what tho?

Why you want to use the amp from an old radio that is going to be terrible compared with current day technology that is super cheap.

 

Why you want to use the amp from an old radio that is going to be terrible compared with current day technology that is super cheap.

Yeah I forgot about all the new technology and I just randomly started working on an old radio simply because I forgot that it's 2024

 

The comments about safety are certainly correct! And that is a serious issue. Now liking the way it sounds is a separate concern.
There are several choices as to the way to remove that shock hazard. An isolation transformer in the mains power feed is both simple and quite expensive. A much less costly approach will be a very small transformer at the input side. Finding a transformer like that new will not be too difficult, but a used one from a small radio will be much cheaper. The exact transformer ratio is not super critical , but probably lower that ten to one, or one to ten, will be the best choice..
And that transformer will be small enough to mount inside the radio enclosure.

One more thing: Guitar amplifiers would seldom be described as "Hi Fi" systems. So using a standard "HiFi" amplifier will usually require adding quite a bit to get that same "sound."

Mr Bill thank you for this! I'm going to go this route. This is what I was asking about in the first place. Thank you

 

The transformer does not even need to have a power handling rating, it can be the size of a microphone transformer. I am guessing that the guitar is not a bass guitar. The low frequency might be a problem.
I have seen some transformers made for microphone inputs. They connect an XLR connector cord to a 1/4 inch plug. But I have not checked the ones that I have to see if they are isolated or not.