Amplifier TOO loud

Vilinova

Member
2019-09-27 4:25 am
Hi All,

First time posting and new to the DIY scene, so hopefully someone here can help me out!

I've 'successfully' built my first amplifier at home (just the basic starving student with 19J6's), but am running into an issue with the volume of the output.
I've got 50 OHM impedance headphones hooked up and have lowered the volume to about as low as it can go.
I find that even at the lower volume settings (not even a 1/4 of a turn around the pot.) can I handle the sound generated.

Any suggestions to maybe taper or modify the output?


Side note, I believe that the pot could possibly be wired backwards as right is low and left is high.
 

Mooly

Administrator
Paid Member
2007-09-15 8:14 am
Welcome to diyAudio :)

It does sound like your pot is wired backwards if it is working in reverse, and given that most volume controls have a logarithmic law this error will compound your issue.

So first thing is to wire the control correctly. Make sure the middle pin of the control goes to the amplifier input as you can still get a control to work if that is wrong as well.

If the middle pin is correct then simply swap the two end connections around.

See if that fixes the issue. If it's still to loud then you have two choices:

1/ Add an input attenuator which is just a series resistor in line with the feed to the input of the pot (not the middle pin ;)).

2/ Add an attenuator at the headphone output using an 'L Pad' attenuator which is nothing more than a divider using two resistors.
 

Vilinova

Member
2019-09-27 4:25 am
OK!
Fixed, thank you guys for the help. I realized after examining for a few mins that when I had re-soldered to switch the ground earlier I had to de-solder pins 2 and 5 for cable management and got them switched with 1 and 2 on the re-solder.

With that, it completely fixed the issue. Huge shout out to the forum for helping to solve this issue :)

Thank you!

Off topic question though, I got a hold of an old AM/FM radio player with an assortment (6) of hopefully good tubes. (6A8, 2x 6K6's, 5Y3, 6SK7, and 1 I can't make out)
Are there any good suggestions to testing tubes or a tester that would cover all of these?
 
Off topic question though, I got a hold of an old AM/FM radio player with an assortment (6) of hopefully good tubes. (6A8, 2x 6K6's, 5Y3, 6SK7, and 1 I can't make out)
Are there any good suggestions to testing tubes or a tester that would cover all of these?
The tube subforum may be of more help there.

That said, this tube complement doesn't sound like your average All-American Five. What you've got there may be older and more collectible than you think, and as such possibly worth restoring. These are rather old types, most commonly used in the 1940s.
 

PRR

Member
Paid Member
2003-06-12 7:04 pm
Maine USA
www.diyaudio.com
> doesn't sound like your average All-American Five

Cuz it is a seven tube. With power transformer! Field-coil speaker.

$29.95 new, 8-inch speaker.... this was an expensive table radio!

6A8GT (converter) 6SK7 (IF) 6SQ7 (1st audio) 6J5GT (phase inverter) 6K6GT 6K6GT (power bottles) 5Y3G (rectifier)

This front-end line-up (in 150mA form for 5-toob) was introduced late 1939. The radio is 1941. With an extra big tube, and a PT, it runs all 6V tubes.
 
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