If memory serves me , the speakers where 16ohm , with 2 12inch and a 4 or 5 inch midrange and a large horn, I don't remeber the wattage, but from the diagram I would use at least a  75 watt speaker to be on the safe side.

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I doubt if you will find any jacks for this thing , break out the soldering iron.

Try , a battery powered set of computer speakers.

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If you can find one try the Peavey Musician 400 , I have one they have more than  enough power(200 watts) and have great tone. plus ya can't go wrong with a old peavey.

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Teemuk is right, as usual, if your not familiar with electronic repairs take this to a tech(Service Center). 

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bro all I can tell ya is email me the diagram at Jackylatham1962@wmconnect.com and I will look at it at then we can go thru it.

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nothin to it bro , that's what where all here for.

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Try replacng the 2 12AX7A tubes.

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Go to duncanamps.com , I think there is a link there to a free version of spice. However, I do agree with JM , but , you can use fet's if that is what you have in mind , I would use just plain old jfet's , I would also consider raising the voltag to 18 to 32 Volts. For tone, gain an volume controls , check out schematicheaven.com or any of the link for schematics on this forum , when I have to actually build an amp I generally build off a schematic of 1 or more amps.

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Thanks for the schematic link , I don't see a lot of Markley amps , always winged it on those repairs. lol

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Basically , in theory , it will operate , in practice it has no controls so, until they are added it's really hard to even do a spice model to simulate, let alone prototype.

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1. if it is hissing at this moment, the fuse isn't blown (can't have sound without voltage)
2. never pull tubes on a powered up amp
3. every amp has a small hiss , this is called the amps breath or the amp is breathing.
4. check it with something pulled in .
5. post more info on how you have the amp setup, where you have the knobs turned to,    etc. 

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The TL072M OP amps in the preamp are jfets , so redesigning your preamp won't do much for ya, but if you want to , have at it. The zeners , sure loose them and replace with regulators for sure. Finally are the caps bad? If not I wouldn't change them the new caps are not made the same as the older ones, this could effect your tone.

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I would do as JM is saying with the power amp section however I would use breadboard to build the individual section, I would buffer each of these sections to reduce  interference and noise. It is do able I did it years ago , building a TS9DX into a Plexi.

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sounds like a winner, I agree with Nashville , I always have the Wah as my 1st stomp.

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I too Like the Peavey's (older ones actually), the Tech 21 is good the B52 is great, also check out Crate, Randalls i just don't like the tone. as for tube amps being mushy , not all amps tube and Solid State are created equal, I have a Solid State , that the reason I keep it is because it come real close to the tube amp sound , but I can keep it running cheaper (I run a shop and bro , the profit made on Solid State verse's Tube is amazing).
Check out a lot of amps before you buy, also if you use amp modeling find the cleanest amp you can, with a generic amplified tone.

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