Very faint sound out of TW Build

General discussion area for tube amps.

Moderators: pompeiisneaks, Colossal

Post Reply
Pongo316
Posts: 51
Joined: Wed Oct 18, 2006 2:40 pm

Very faint sound out of TW Build

Post by Pongo316 »

Just finish my First TW Clone

my question is I have only very faint sound ? Any idea's where to look ? or what to look for.

got no cammera at the moment but i'll try and get one to post a pic , but in the mean time I'm very open to sugetions
User avatar
fishy
Posts: 377
Joined: Fri Jul 20, 2007 12:09 am
Location: Chandler, Az

Re: Very faint sound out of TW Build

Post by fishy »

I'm not the most knowledgable person on this but I believe a few pictures will help in addition to some voltages.
Someone will be better able to help if you can provide these as a starting point.

If you don't have pics yet, voltages will help.
Pongo316
Posts: 51
Joined: Wed Oct 18, 2006 2:40 pm

Re: Very faint sound out of TW Build

Post by Pongo316 »

working on pics
Andy Le Blanc
Posts: 2582
Joined: Sat Dec 22, 2007 1:16 am
Location: central Maine

Re: Very faint sound out of TW Build

Post by Andy Le Blanc »

go over the simple stuff...... make sure every thing is connected properly
double check it following the schematic.....etc ... it could well be a simple error
lazymaryamps
User avatar
Phil_S
Posts: 6048
Joined: Tue Oct 23, 2007 10:12 pm
Location: Baltimore, MD

Re: Very faint sound out of TW Build

Post by Phil_S »

Without picture, just a hunch or two. Look for an improperly wired input jack, an omitted ground, or a cold solder.

Check all component values to see they are the correct ones, for example, you may have used a 100 ohm resistor where you needed 100K. This sort of error is all to easy to make.
Pongo316
Posts: 51
Joined: Wed Oct 18, 2006 2:40 pm

Re: Very faint sound out of TW Build

Post by Pongo316 »

I used the layout from ceriatone ,

http://www.ceriatone.com/images/layoutP ... iatone.jpg

I take it that the layout is good.

Ill go over and check thing over again . I'll try and get some pics happening.

I've got a name for the amp :D DISASTER [/url]
moj067
Posts: 129
Joined: Fri May 18, 2007 4:51 pm

Re: Very faint sound out of TW Build

Post by moj067 »

Check your grounds.
User avatar
sliberty
Posts: 1324
Joined: Fri May 26, 2006 5:03 pm

Re: Very faint sound out of TW Build

Post by sliberty »

No sound or faint sound conditions are perfect situations to use the Gerald Weber audio probe for troubleshooting (I know, he probably didn't invent it, but that's who I learned about it from).

The probe is basically a capacitor with an alligator clip attached to one end and the other end sticking out. You would tape the cap to a chop stick for safety.

Then, you could probe each part of the amp from input towards output, making sure that the signal got louder each time, and once it didn't get louder, you woud know you had reached the problem area.
User avatar
fishy
Posts: 377
Joined: Fri Jul 20, 2007 12:09 am
Location: Chandler, Az

Re: Very faint sound out of TW Build

Post by fishy »

Here is a link for some info on the audio probe if you need it. Note the cap rating

http://www.diystompboxes.com/pedals/debug.html
User avatar
sliberty
Posts: 1324
Joined: Fri May 26, 2006 5:03 pm

Re: Very faint sound out of TW Build

Post by sliberty »

Sorry, my description of the probe was incomplete (got a phone call while typing and became distracted).


The idea is to use the cap as a coupling cap for connecting to another amplifier that is known to be working. So what you do is take 2 wires, twist them together, and connect one ond of one of them to one end of the cap. Connect the other end of this same wire to the tip of a 1/4" jack. Then, connect the end of the second wire to the ground on the 1/4" jack, and put an alligator clip on the other end of this ground wire. The cap is then taped to a chop stick and mostly covered up by the tape. Just leave some of the unconnected lead exposed. This is what you will use to probe around the amp under test.

Now, plug the 1/4" jack into a known working amp, and clip the alligator clip onto the chassis of the amp under test. I usually attach an iPod to the input of the amp under test as a sound source.

Now, turn on the amp under test, and strt up the iPod. Keep the volume on the amp under test fairly low at first, and keep the voluem of the known working amp low as well.

If you touch the exposed tip of the cap (probe) to the tip of the input jack, you should hear some of the iPod's music coming from the other amp. Now, if you move deeper into the circuit, and touch the cap tip to the plate of the first preamp tube, you should hear it louder as it has been amplified by the first stage. Keep moving deeper into the amp, stage by stage, and eventually, the approximate location of the problem will reveal itself by either no sound or low sound. Once you probe past the various pots, they will effect the sound coming out of the other amp too, so you can test whether or not the pots are working as expected. You don't have to restrict your probing to just plates either. If you understand the circuit, you will see other probe points that make sense to further pin down the location of the issue.

Steve
User avatar
Allynmey
Site Admin
Posts: 1406
Joined: Sun Mar 06, 2005 12:38 am
Location: Dighton, MA

Re: Very faint sound out of TW Build

Post by Allynmey »

make sure you connected the 10K tail resistor from the PI to ground.
strato17
Posts: 167
Joined: Mon Apr 28, 2008 6:34 am
Location: Nashville, TN

Re: Very faint sound out of TW Build

Post by strato17 »

Phil_S wrote:Without picture, just a hunch or two. Look for an improperly wired input jack, an omitted ground, or a cold solder.
Ditto this.... I did not have a good ground on my input jack. I soldered a wire from the ground lug on the input jack to the copper buss bar behind the pots. Adding this, as well as reflowing alot of the solder joints, fixed all of my issues.
Pongo316
Posts: 51
Joined: Wed Oct 18, 2006 2:40 pm

Re: Very faint sound out of TW Build

Post by Pongo316 »

:shock: Grounds :oops:

shes all good now but a little bit wild need to tame her down a tad

lots of white noise hopw do i get rid of that , still no cammera hopefully I can pry it of the kids to take some pics.
Pongo316
Posts: 51
Joined: Wed Oct 18, 2006 2:40 pm

Re: Very faint sound out of TW Build

Post by Pongo316 »

:shock: Grounds :oops:

shes all good now but a little bit wild need to tame her down a tad

lots of white noise hopw do i get rid of that , still no cammera hopefully I can pry it of the kids to take some pics.

Thanks for all the help so far
Pongo316
Posts: 51
Joined: Wed Oct 18, 2006 2:40 pm

Re: Very faint sound out of TW Build

Post by Pongo316 »

Heres a pic

http://i267.photobucket.com/albums/ii29 ... 191036.jpg

She's all good now 8)

I Know there are some mistakes caps wrong way around , I rushed it and build it over the weekend , rush job.
Post Reply