doing my homework
I've been doing my work here and have found all your suggestions helpful about tube choice and circuit design.
I did find 2 great articles about the Long-Tail Pair at aikenamps as suggeted by Tom in a previous post here:
Long-Tail Pairs
and
Designing Long Tail Pairs
Still have questions about rewiring old speaker outputs and installing a 1/4" jack (or two)
thanks for your patience
*mystro2b*
I've been doing my work here and have found all your suggestions helpful about tube choice and circuit design.
I did find 2 great articles about the Long-Tail Pair at aikenamps as suggeted by Tom in a previous post here:
Long-Tail Pairs
and
Designing Long Tail Pairs
Still have questions about rewiring old speaker outputs and installing a 1/4" jack (or two)
thanks for your patience
*mystro2b*
Ok- I'll ask again, but this time I have pictures😀:
I plan to use this amp with a 1x12, 8 ohm speaker cabinet.
My guess is, I will have a speaker cable with a 1/4" jack at one end (to plug into my 8 ohm cab) and the other end of the cable wired somehow to the output section of the amp. This is where I need guidance- how to prepare the speaker cable and where to hook it up.
I have attached a schematic of the speaker plugs and their connection to the transformer and power tubes.
In my next post, I will have a picture of the inside of the the speaker outputs (J2 & J4) as seen from my amp. I have labeled the pins on the speaker sockets since the amp was turned upside.
All very confusing to me. Salieri said of Mozart, "Too many notes!"
I'm saying too many wires?
I plan to use this amp with a 1x12, 8 ohm speaker cabinet.
My guess is, I will have a speaker cable with a 1/4" jack at one end (to plug into my 8 ohm cab) and the other end of the cable wired somehow to the output section of the amp. This is where I need guidance- how to prepare the speaker cable and where to hook it up.
I have attached a schematic of the speaker plugs and their connection to the transformer and power tubes.
In my next post, I will have a picture of the inside of the the speaker outputs (J2 & J4) as seen from my amp. I have labeled the pins on the speaker sockets since the amp was turned upside.
All very confusing to me. Salieri said of Mozart, "Too many notes!"
I'm saying too many wires?
Attachments
Wow! What a mess! I suggest that you throw away everything and tape off the unused impedance ratings. Then take the 8ohm wire and the ground wire and solder them to a 1/4" jack, in which you will put the speaker plug. Easy 😀
But pay attention to those resistors coming off some secondaries and returning to the amp... those are NFB resistors... you want to keep them (but try to disconnect them and you'll get much bluesier sound... maybe you want to tweak their value...)
Good Luck!
I want pictures!!!!!!! 😉
But pay attention to those resistors coming off some secondaries and returning to the amp... those are NFB resistors... you want to keep them (but try to disconnect them and you'll get much bluesier sound... maybe you want to tweak their value...)
Good Luck!
I want pictures!!!!!!! 😉
trouble with pix
Hi Gaime-
ok- thanks for the reply. I'll need to digest what your saying.
I'm having trouble posting the other pic othe speaker jacks. The size restrictions for the forum makes it hard to attach.
I will try and post a url ASAP.
*mystro2b*
Hi Gaime-
ok- thanks for the reply. I'll need to digest what your saying.
I'm having trouble posting the other pic othe speaker jacks. The size restrictions for the forum makes it hard to attach.
I will try and post a url ASAP.
*mystro2b*
Pics on-line!!
All the pictures you would ever want and more of my amp are at this link:
http://mystro2b.tripod.com/SCAU33/
Check 'em out and let me know what you think.
Things are getting interesting. The soldering iron may come out this weekend😀
*mystro2b*
All the pictures you would ever want and more of my amp are at this link:
http://mystro2b.tripod.com/SCAU33/
Check 'em out and let me know what you think.
Things are getting interesting. The soldering iron may come out this weekend😀
*mystro2b*
Hello! Great looking amp btw. I've seen the photos... It won't be easy to figure the speakers out, but I'm sure you can... just do as I told you: desolder all the wires, solder the 8ohm one to the output jack and tape all the others. 😉
Btw have you asked to that guy (Adam)? He can suggest you some mods...
Btw have you asked to that guy (Adam)? He can suggest you some mods...
6SJ7 pentode amps
the 6SJ7 pentode is an awesome sounding tube, properly configured it has a sound depth and compression you cannot get with dual triodes. NOS tubes are available for 3.50 each at www.tubesandmore.com I am the original designer of the Octal Fatness, and several other octal pentode input amps, I have a schematic archive at www.freewebs.com/jonesamps check it out, the PA amp you have would probably make a nice platform for the Octaluxe. The fender dual professional, 5C1 champ, gibson lespaul jr, gisonette, and several other guitar amps used this tube, usually in grid leak bias, I use this tube in hot cathode bias and it sounds excellent, check out doug hammonds version
http://dhammond_1.tripod.com/RocktalFat.mp3
dont be afraid to use the 6SJ7, it sounds bada$$!
the 6SJ7 pentode is an awesome sounding tube, properly configured it has a sound depth and compression you cannot get with dual triodes. NOS tubes are available for 3.50 each at www.tubesandmore.com I am the original designer of the Octal Fatness, and several other octal pentode input amps, I have a schematic archive at www.freewebs.com/jonesamps check it out, the PA amp you have would probably make a nice platform for the Octaluxe. The fender dual professional, 5C1 champ, gibson lespaul jr, gisonette, and several other guitar amps used this tube, usually in grid leak bias, I use this tube in hot cathode bias and it sounds excellent, check out doug hammonds version
http://dhammond_1.tripod.com/RocktalFat.mp3
dont be afraid to use the 6SJ7, it sounds bada$$!
Dave-
Thanks for posting to this forum. I haven't been here in awhile but now that summer is here, I plan to do some mods to this amp. Thanks for the web links and the 6SJ7 recommendation. I'm still new to all this.
I'll keep you posted on my progress.
*mystro2b*
Thanks for posting to this forum. I haven't been here in awhile but now that summer is here, I plan to do some mods to this amp. Thanks for the web links and the 6SJ7 recommendation. I'm still new to all this.
I'll keep you posted on my progress.
*mystro2b*
500 ?MMF
I just lucked into a Stromberg Carlson au32 pa amp. It is in nice shape but I want to go thru and change out the caps, they are 40 or 50 years old after all... One cap is listed on the schematic as a 500 mmf. I've never seen this before. Could this be a 500pf cap?
I just lucked into a Stromberg Carlson au32 pa amp. It is in nice shape but I want to go thru and change out the caps, they are 40 or 50 years old after all... One cap is listed on the schematic as a 500 mmf. I've never seen this before. Could this be a 500pf cap?
mmF = pF - older terminology. The schematic is on the bottom plate, but you still might find the Sams folders useful - on my website: http://www.audiophool.cjb.net/MadeInRoch.html
Hopefully the last question... The schematic also lists resistors with the values .33meg, and .1 meg. What are these in today's numbers???
i just got an A-20 Stromberg--hasnt been checked out yet--all original in working condition--anyone have any advice--will be a guitar amp
labrat119 not sure why I cannot see your pics... but I would gut it like others have said in this thread and rebuild it. I have a little Stromberg PA and just rewired a little of it and it sounded pretty good. But I had some issues with it and decided that a complete rewire following some standard guitar amp designs would be in order. The one I have has el-84's. I cannot remember the model number offhand.
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