Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: etneccas on July 27, 2015, 09:34:52 am

Title: tweed overdrive build
Post by: etneccas on July 27, 2015, 09:34:52 am

I have a Tweed Overdrive circuitboard from a few years ago that i'd like to start working on and i'm in the information gathering phase and have several questions already...........I noticed that the amp circuit has evolved to a totally different circuit and circuitboard.
 
Question 1.) What revisions were made to these before a whole new board layout came about?  I would still like to work on the pre-drilled board that I bought from Doug but would like to know if the schem,BOM & layout below still applies

Question 2.) Are  there any sourcing or quality issues with a 5879 tube and are there better alternatives without changing the existing circuitboard too much?


                                               http://el34world.com/Forum/index.php?action=dlattach;topic=9636.0;attach=15949 (http://el34world.com/Forum/index.php?action=dlattach;topic=9636.0;attach=15949)

                                               http://el34world.com/Forum/index.php?action=dlattach;topic=9636.0;attach=19250 (http://el34world.com/Forum/index.php?action=dlattach;topic=9636.0;attach=19250)

                                               http://el34world.com/Forum/index.php?action=dlattach;topic=9636.0;attach=22024 (http://el34world.com/Forum/index.php?action=dlattach;topic=9636.0;attach=22024)

Title: Re: tweed overdrive build
Post by: tubenit on July 27, 2015, 02:13:23 pm

Yes, you can go with all the original schematic, layout and BOM.  IF you want to change anything, you can simplify the entrance to the OD & still use the original board.

I would stay with the 5879.  I've bought a bunch of them and maybe had one only that was too microphonic to comfortably use in a combo amp but would have worked in a amp head.  I got all mine off ebay.

With respect, Tubenit

Title: Re: tweed overdrive build
Post by: etneccas on July 27, 2015, 03:00:30 pm

Thanks for your help!....I hope I don't wear out my welcome.......

  1.) What does the attached simplified circuit do to the tone and response of the amp design?

I play mostly strats and tele vintage low output single coils

Also In regard to the schematic,
  2.) a .001 cap is in parallel with a 100K R at V2b pin 6 but the layout shows no cap.
Which is correct?

The schematic also shows no connection point on V4  the 2-1 meg Resistors and the10K and 470R wherepins 2 and 7 intersect on the schematic But the layout shows that  they are connected where they intersect on the schematic........
 
  3.) Which one is right in regard to V4? the schematic or the layout?..........

Title: Re: tweed overdrive build
Post by: tubenit on July 27, 2015, 06:40:13 pm

1)  Not much tone difference just simplier to wire.  The revised does allow more gain on hand.

2)  Schematic is correct

3)  They all intersect both on the schematic and layout

with respect, Tubenit