big bob Posted January 6, 2011 Posted January 6, 2011 Hey guys, Ive been looking for a while and finally found a amp I just had to have. She's an odd fish. a 1972 sound city L-120. This amp is LOUD 120 watts, she has partridge transformers, six EL 34"s and five 12ax7's. The preamp is active, but the circuit is very simple. They are known for being very loud and clean, little break up even pushing tens. They are also said to handle effects boxes real well. I have two questions. the first is simple. when she gets here can I hook her up to the speaker in my marshall combo (only 75 watts) to check her out. I would run her low. Second. what type of cab should I look for. I'm thinking either 4 X 12 or 2 X 15.. I'm planning on building the cab. 3/4 birch. and would probably go with speakers that break up early. Thanks for your thoughts Lance
mars_hall Posted January 6, 2011 Posted January 6, 2011 Hey guys, Ive been looking for a while and finally found a amp I just had to have. She's an odd fish. a 1972 sound city L-120. This amp is LOUD 120 watts, she has partridge transformers, six EL 34"s and five 12ax7's. The preamp is active, but the circuit is very simple. They are known for being very loud and clean, little break up even pushing tens. They are also said to handle effects boxes real well. I have two questions. the first is simple. when she gets here can I hook her up to the speaker in my marshall combo (only 75 watts) to check her out. I would run her low. Second. what type of cab should I look for. I'm thinking either 4 X 12 or 2 X 15.. I'm planning on building the cab. 3/4 birch. and would probably go with speakers that break up early. Thanks for your thoughts Lance To answer the first question... Yes but don't crank it and try to match the impedance of the speaker to the amp (16 ohm?). 2nd Question 4x12 and it doesn't have to be birch. If you are covering it a multi-ply plywood will suffice. Remember, the stiffer the wood, the more the sound will be clear. If you are wanting chunka chunka, fewer plys on the large surfaces will move and get a chunka sound. A rule of thumb is to have your speaker wattage be twice that of the amp... i.e. 240W total for the cabinet in your case
yoslate Posted January 6, 2011 Posted January 6, 2011 I'm planning on building the cab. 3/4 birch. Lance Might want to do just the baffle in birch, Lance.
big bob Posted January 6, 2011 Author Posted January 6, 2011 Might want to do just the baffle in birch, Lance. Why so. cost. or something else... I have plenty of cabinet grade 3/4 birch ply at the shop.. no cost. I bought it with a grant I got to make wood cut prints. My real evil plan is to glass the cab (fiberglass) with a art work in the middle so it will appear embedded in the surface.. I know it will be heavy.. my one worry is making the sound too crisp in an already clean head. thats why I'm leaning towards 2x15.
mars_hall Posted January 6, 2011 Posted January 6, 2011 Why so. cost. or something else... I have plenty of cabinet grade 3/4 birch ply at the shop.. no cost. I bought it with a grant I got to make wood cut prints. My real evil plan is to glass the cab (fiberglass) with a art work in the middle so it will appear embedded in the surface.. I know it will be heavy.. my one worry is making the sound too crisp in an already clean head. thats why I'm leaning towards 2x15. It sounds to me like you are going to end up with a hi-fi cabinet, good for clean PA sound reproduction.
mars_hall Posted January 6, 2011 Posted January 6, 2011 Better off with 12" speakers that lack highs, so use the bigger voice coils for less highs. Twelves will break up easier.
mars_hall Posted January 6, 2011 Posted January 6, 2011 I was looking for my reference links for cabinets I believe this was a good one DIY Audio Also
kbp810 Posted January 6, 2011 Posted January 6, 2011 Why so. cost. or something else... I have plenty of cabinet grade 3/4 birch ply at the shop.. no cost. I bought it with a grant I got to make wood cut prints. My real evil plan is to glass the cab (fiberglass) with a art work in the middle so it will appear embedded in the surface.. I know it will be heavy.. my one worry is making the sound too crisp in an already clean head. thats why I'm leaning towards 2x15. For the baltic birch, its a light yet strong void free ply that makes for good tonal reverberation (or something like that!) I use baltic birch ply for all of my baffles (not that I consider myself a genuine subject matter expert, its just sort of a rule of thumb passed down to me and thus far it's served me well) On the speaker setup... you could always mix and match, that's always fun! As in a 4x with 2x15 on bottom and 2x10 on top, or something like that.
Steiner Posted January 6, 2011 Posted January 6, 2011 For the baltic birch, its a light yet strong void free ply that makes for good tonal reverberation (or something like that!) I use baltic birch ply for all of my baffles (not that I consider myself a genuine subject matter expert, its just sort of a rule of thumb passed down to me and thus far it's served me well) On the speaker setup... you could always mix and match, that's always fun! As in a 4x with 2x15 on bottom and 2x10 on top, or something like that. Oh! Variation! Good idea!!! The 3/4 birch ply is what is used on the high dollar cabs. Have at thee!
big bob Posted January 7, 2011 Author Posted January 7, 2011 Sound City L-120 I think I have cornered the market of LOUD
Steiner Posted January 7, 2011 Posted January 7, 2011 Jumpin' Jehusafits! 6 EL34s! When you start jumping channels with pigtails in that it will look like a telex board. Throw a 4X12 on that and you're going to get calls from NASA to turn it down
kbp810 Posted January 7, 2011 Posted January 7, 2011 Holy moses thats a lot of EL34's batman! That's one serious looking PT powering that monster too Probably no need to post clips for this one, just let me know when your going to crank it and I'll open a window and have a listen
NoNameBand Posted January 7, 2011 Posted January 7, 2011 Better off with 12" speakers that lack highs, so use the bigger voice coils for less highs. Twelves will break up easier. The bigger the voice coils and cones, the slower the reaction time.
FredZepp Posted January 7, 2011 Posted January 7, 2011 Woooww, Big Bob. That is some Serious Power there. I remember looking at big super powerful Sound City amps many years ago. They had a real appeal to them. It will be interesting to hear your reviews of this one. Rock and Roll, brother.
big bob Posted January 7, 2011 Author Posted January 7, 2011 Holy moses thats a lot of EL34's batman! That's one serious looking PT powering that monster too Probably no need to post clips for this one, just let me know when your going to crank it and I'll open a window and have a listen The transformers should be partridge, same as the early hiwatt's. I'm thinking of doing two mods for sure.. one Master volume mod. two, passive preamp. I'm also wondering what it would sound like with six yellow jackets in it?
kbp810 Posted January 8, 2011 Posted January 8, 2011 The transformers should be partridge, same as the early hiwatt's. I'm thinking of doing two mods for sure.. one Master volume mod. two, passive preamp. I'm also wondering what it would sound like with six yellow jackets in it? I'm not sure if I ever really bought into the yellow jackets... but I've also never tried them personally so I should just keep my big mouth shut If you do try them I'd certainly be interested in hearing how they worked out. Master volume and passive preamp mods sound like a dandy idea! I just would stear clear from that "half power"-Pentode/Triode(well, "tetrode" to be more technically correct) mod that seems to suck more tone than actually reduce volume (not to mention it wouldn't be much fun to set it up across 6 power tubes!)
big bob Posted January 8, 2011 Author Posted January 8, 2011 I'm not sure if I ever really bought into the yellow jackets... but I've also never tried them personally so I should just keep my big mouth shut If you do try them I'd certainly be interested in hearing how they worked out. Master volume and passive preamp mods sound like a dandy idea! I just would stear clear from that "half power"-Pentode/Triode(well, "tetrode" to be more technically correct) mod that seems to suck more tone than actually reduce volume (not to mention it wouldn't be much fun to set it up across 6 power tubes!) If I want less power I should be able to pull 2 or 4 of the el34's I was thinking of the yellow jackets because you can run 2, 4, or 6 you can also run them mix match sets with el34 so I could run 4 el34's and 2 yellow jackets or 2 el34's and 4 yellow jackets and have that el84 tone mixed in. before I do anything I'm gonna play her loud for a while..
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