5F10 Harvard, Cathode bias, Point-2-Point. and thank you.

Thanks @bigguy12321!

What makes it even MORE amazing is that I have new components and a fraction of the wiring and yet I think my build is probably more noisy than the original rat's nest EVER was! I'm stoked to have been able to make something work but I think it's going to take me a little bit of tweaking to tidy up my wiring so that it doesn't induce any hum or contain nasty ground loops.

I haven't had much time to really play around with it...especially at HEALTHY volume levels...so I can't say for sure but I get the sense this thing will stay pretty clean right up to full volume so I might swap out the 6AT6 preamp tube for a 6AV6 I bought at the same time just to see if it gives me some earlier breakup. That was actually my original plan but I did all my tube socket wiring with the 6AT6 in there just in case I wound up breaking something.

Like you, I got a lot of help from @robrob directly AND his amazing web site...wouldn't have been able to do ANY of this without either (I followed his lead specifically when adding my FX Loop and Negative Feedback mods). I was also chatting with Anthony from At Mars and he was a great resource as well; in fact, he was the one who suggested I go with the 5F10 Harvard circuit when I was trying to figure out what to do with the original Filmosound.

Anyway, now that the amp APPEARS to be running properly, I'll try to clean up this bit of hum, adjust the bias a little cooler (Anthony's calculations put me closer to 14 watts dissipated from each tube which he thinks might be a little too much), test drive the 6AV6 tubes, and then see if I can share an audio clip or two...

- brad -

 

Well, I still haven't really had the chance to test drive this thing because my wife was upstairs watching TV when I snuck down to play but, OMG, I might have spoken too soon when I said I'd probably need the 6AV6 preamp tube to get more drive out of this thing!

Up until tonight I've been running all of my tests with a Strat but tonight I plugged in the Telecaster and immediately noticed a huge difference...the amp jumps from 0 to LOUD and then I've got overdrive starting around 4 on the volume know (even though I'm playing light and dialing the guitar's volume back to keep from driving my wife and my neighbour's nuts!). I did crank it full tilt but, again, I was plain light and REALLY dialing back on the volume know. Flicking the negative feedback on gave me a notable volume cut and a cleaner tone but I'm sure it would still be pretty dirty if I banged it hard...especially at max volume.

After a little of that; I swapped the 6AT6 for my 6AV6 and I *THINK* there was more gain and a little sweeter tone but I got the sense the tube might be a little sensitive or "microphonic" but I don't have enough experience with that to really tell. Truth be told, the 6AT6 might have been making a few odd noises. Anyway, the 6AT6 definitely enough gain do I put it back in for now.

Having done enough experimenting, I plugged in the LP and, as expected, it took the Tele experience and raised it to the next level! LOTS of drive to say the least (I was playing the amp at noon on the volume with the LP volume on 2 (!!!) and thought it was sounding pretty good and then my wife starting flicking the basement lights and asked me if I could turn it down!).

So...still a few wrinkles to iron out but I'm feeling pretty good right now...I think this is going to be fun!!!

 

Thanks for sharing your experiences with your build. So far I have just been running this head into the 12" cab of my Traynor YCV40 combo (I swapped out the original Celestion 70/80 with an Eminence Wizard several years ago) but my plan is to build a custom cab with either dimensions similar to those of the original 5E3 or 5F10 cabs at some point. I don't have any experience with 10" speakers other than playing a Fender Hot Rod Deville once or twice at my local Rehearsal Factory jam space but I've been reading many good things about them (and a few recommended speakers). Your comments just make the idea of a 10" cab all the more enticing!

After speaking with @robrob over the weekend, I am planning to pick up a new pair of 6V6 output tubes...hopefully they fix rather large bias difference between the two I have in the amp right now and hopefully that, in turn, helps eliminate some of the noise I think I'm experiencing. I will also take your advice and look at some of the alternate approaches to quieting the hum.

In the meantime, I have to get to work on that light switch...

; - )

- brad -

 

My apologies again for hijacking @bigguy12321 's thread but I figured I should close the loop now that I've done so. Here is the final result of my Filmosound converted into a cathode biased 5F10 Harvard with an added FX Loop and switchable negative feedback. It's running into a 1x10" cabinet loaded with an early Eminence Legend speaker supposedly similar to the Legend 1028K but I cut the baffle for a 12" opening and built an adaptor ring to hold 10" speakers. So far I am really enjoying this one and, as you can see by the snow on the deck, the weather is making it easy to stay inside and crank things up!!!