Looky what I gots on da way...

Drumoid said:
Hey 67plexi - If I were to build an around the EF86 is there a specific amp/schematic you'd recommend?
Cool deal on the servicing amps with the wife. I'd love to be able to get a business going were something like could happen.

My wife was one day older than I. we would have been 60 this June she was murdered 2/2018 She was strong lasted 6 days in ICU.
Click to expand...
 
Interesting, its always good to have a chassis to experiment & tried ideas on. You have some parts to work with there, PT & 6X4 (6.3VAC heater) rectifier. The 6AG5A power tube & OT. Room for a couple pre amp tubes. Be interested to see what you do with it. Cheers
Edit: In the past I've made little single ended amps out of similar. I used a small stereo phono amp to make a frriend a stereo (2x single ended EL84) guitar amp. Caught up with him over 10 years later & he told me it had been used on several recordings & was still going strong. Cheers
 
Last edited:
ivan H said:
Interesting, its always good to have a chassis to experiment & tried ideas on. You have some parts to work with there, PT & 6X4 (6.3VAC heater) rectifier. The 6AG5A power tube & OT. Room for a couple pre amp tubes. Be interested to see what you do with it. Cheers
Edit: In the past I've made little single ended amps out of similar. I used a small stereo phono amp to make a frriend a stereo (2x single ended EL84) guitar amp. Caught up with him over 10 years later & he told me it had been used on several recordings & was still going strong. Cheers
Click to expand...

Got a bunch of other parts laying around too, so parts aren't an issue.
This chassis had a 5879 and a 12ax7 preamp tube, so hoping to use both.
At the moment I'm just brain storming and drawing up a schematic of idea's.
I'm thinking about hitting the 5879, then into a volume control, then into the 12ax7, not sure if I want to parallel the 12ax7 or possibly dice it and stick a tone stack in there. I do want to use a master volume just before the 6aq5.
Still thinking about it.

Feel free to chime in...
 
You have 3 triodes, one needs to do driver duty to the power tube.
i'm no tube circuit guru.

in>5879>vol w/bright cap + single tone>12ax7 v2a gain stage>12ax7 v2b driver stage> mv> output tube?
Similar ckt to Tweed champ + 1 additional gain stage?
This would be pretty gainy I think.

You could put a on-off-on SPDT with 2 different or none v1 cathode bypass cap for voicing variety.

In>5879>vol w/bright cap>12ax7> v2a cathode follower> tone stack>12ax7 v2b driver stage> mv> output tube?
Depending on B+, this might have some higher head room and take pedals better.

The coupling cap values will have a lot to do with the tone shape and especailly the low end freq. / + fartyness factor

The MV could obviously go before or after the driver / PI. I think the choice has a lot to do with whether the output tube is cathode or fixed bias, but dont recall the details.

Just my limited experience $ .02, poke as many holes in it as you like.
 
The 5879 is a sharp cut off pentode C__Data_Users_DefApps_AppData_INTERNETEXPLORER_Temp_Saved Images_5879-1.gif so if using, choose your bias point wisely. Can be prone to noise (commonly is noisey etc, see notation at top of data sheet) & has low amplification factor of 21. Cheers
 
Ya - pentode pre amp tubes are a wee bit more picky than the standard ole twin triode's for sure, but hey - Gibson used the 5879 in a few amps - which is mainly why I got this one. Well, that and it was cheap - so, what the hey type thing. I've got another 5879 that's just been sitting in a drawer for a while. They both test good in the ole tube tester, hopefully one or both behave. Worse comes to worse I wire the socket up with a twin triode, grab some ef86 tubes somewhere, or sump'n'nutter. I've got to search the yard sales and flea markets for something I can contort into a cab, possibly find a speaker for a combo set up for it that gels with the chassis. No telling how long it may be before I gather up enough odds and ends to Frankenstein it together. I think one chassis sat around completed almost a year before I found what I considered to be the proper yard sale wood box to make a cab for it ;)
 
Drumoid said:
Ya - pentode pre amp tubes are a wee bit more picky than the standard ole twin triode's for sure, but hey - Gibson used the 5879 in a few amps - which is mainly why I got this one. Well, that and it was cheap - so, what the hey type thing. I've got another 5879 that's just been sitting in a drawer for a while. They both test good in the ole tube tester, hopefully one or both behave. Worse comes to worse I wire the socket up with a twin triode, grab some ef86 tubes somewhere, or sump'n'nutter. I've got to search the yard sales and flea markets for something I can contort into a cab, possibly find a speaker for a combo set up for it that gels with the chassis. No telling how long it may be before I gather up enough odds and ends to Frankenstein it together. I think one chassis sat around completed almost a year before I found what I considered to be the proper yard sale wood box to make a cab for it ;)
Click to expand...
I like your attitude, hopefully you've got at least one good 5879 there. I mean like, the one that came with the chassis was being used as such so you'd think its a good one. Looking forward to how it turns out. Little Frankenstein amps are a blast. Cheers
 
I try to both take amp building/repairs seriously and stay laid back enough to have fun and enjoy it. I'm the same way about bands. I want to be 'professional' about it, but also want to feel/be relaxed and have fun, too. Being serious and doing the hard work to be professional doesn't have to be miserable - at least I don't think so. The whole pins and needles thing isn't conducive to healthy musical potential, not to mention it's just not hippy-da-do-da cool either ;)

Not sure where that came from - maybe the raisins in my trail mix fermented or something - any ways...
 
I have learned to pace myself and keep it fun too; I used to get a bit frustrated at times.
Time to step away and take a breath....

The only time I feel hurried is sometimes I swear I get a glimpse of the Grim Reaper over my shoulder; holding an hourglass.
He is pointing at it laughing and singing at me:
Iron Maiden Hallowed by Thy Name "the sands of time for me, are running low, running low yeeeeaaahhhh!!!".

Metaphor, getting older sometimes scares me a bit.
 
Trying to find a suitable knob set that contains a concentric knob may probe harder than finding something to put the chassis in...
 
Last edited:
Just a quick update. I'm trying to find a cab/head for this chassis before doing more on it...
 
Drumoid said:
Just a quick update. I'm trying to find a cab/head for this chassis before doing more on it...
Click to expand...
Mojotone may have something suitable. I have a couple of their head cabs & they are very well built. Weber also may have something to suit, I have a Fender Champ type cab from Weber & it is also very good. Hope this helps. Cheers
 
ivan H said:
Mojotone may have something suitable. I have a couple of their head cabs & they are very well built. Weber also may have something to suit, I have a Fender Champ type cab from Weber & it is also very good. Hope this helps. Cheers
Click to expand...

I'm hoping to find something I can convert ideally. Hopefully something from a yard sale, along side the road, etc.
 
You must log in or register to reply here.
Back
Top