Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Filmosound L-1 6V6 Volume pot issue
Filmosound L-1 6V6 Volume pot issue
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 5th September 2008, 01:11 PM   #1
atmars is offline atmars  United States
diyAudio Member
Join Date: May 2008
Default Filmosound L-1 6V6 Volume pot issue

I am working on converting a filmosound projector amp to a guitar amp. So far I have removed the oscillator circuit and the negative feedback circuit, in large part to make room in the chassis.

When I turn the volume pot past three quarters a crazy static type distortion/feedback type sound occurs, but not squealing. This phenomenon existed before I removed the negative feedback loop.

I have tried the following to remedy this situation:

Bad pot? I replaced the pot with a new 500K pot. No change.

Pot value too large? Original pot is supposed to be 500k but is really closer to 350k. I reduced the value to 300k with a resistor. No change.

Bad preamp tube? Tried a different 6SL7. No change.

Layout? Tried moving wires. No change.

Also changed wire to grid to a shielded cable. No change.

Any ideas on what might be causing this effect? Another post had a similar question about a filmosound, but the i don't believe the problem was ever solved.

I have only been working on tube amps for about a year, so my knowledge is pretty limited. Any ideas are greatly appreciated, no matter how obvious they may seem to the more educated.

Also, any other potential changes the anyone notices, that would be an improvement, I'd like to hear about.

thanks in advance.

here's the link to the schematic:

  Reply With Quote
Old 5th September 2008, 03:21 PM   #2
atmars is offline atmars  United States
diyAudio Member
Join Date: May 2008
New link that I hope will work

  Reply to this post


Filmosound L-1 6V6 Volume pot issueHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Filmosound - Guitar - Ground atmars Instruments and Amps 9 2nd April 2012 09:53 PM
Filmosound - Tone Knob - Tertiaries atmars Tubes / Valves 5 16th March 2012 01:55 PM
Yamaha RX-V1 Volume Control Issue tone2222 Solid State 2 24th August 2010 08:22 PM
Filmosound dual pot atmars Tubes / Valves 3 29th June 2008 05:00 AM
sony TA-1010 volume issue pezza89 Solid State 2 28th January 2008 05:43 AM

New To Site? Need Help?

All times are GMT. The time now is 10:49 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio