2000S-we'll try it again

[volume freak]

sunnheads,


what can cause a seemingly healthy 1969 2000S (strong tubes,
caps up to spec) to be weak in volume output.  i've had some
extremely powerful marshall 100 watters and currently run
a great sounding and loud 200s, so i know a behemoth amp
when i hear one and the 2000S ain't there.  i need this amp
for shows so please, help as quick as you can...

                                                          thank you

[JoeArthur]

"my amp sounds weak, please help quick"?    

A little additional information would be helpful.  

From your first post, you mentioned using a Marshall cabinet... but neglected mentioning the impedance of that cabinet and what amp output impedance you are using.  First check to make sure these match.  For example, if the Marshall cab is 16 ohms and you are using the 8 or 4 ohm output impedance from the 2000s... you won't be transferring a maximum amount of power.

You also didn't mention if you are using the same speaker cabinet with both heads.  If you are using the stock 200s cabinet with the 200s head and the Marshall cab with the 2000s, it wouldn't surprise me at all if the 200s combination turned out to be louder.  15" JBL's in this cabinet are extremely efficient... meaning less watts can be transformed into more sound.  The Marshall cab... probably a totally closed cab, wouldn't be as efficient.

Your previous post mentioned all of the tubes with the exception of the GZ34 rectifiers.  These (and both of them are needed for full power capability) also have to be in good shape... unless you have a solid state rectifier.

You should also be aware that the tone control circuits are completely different between the 200s and the 2000s.  Adjust the 2000s separately... don't expect the control settings to be the same between both amps.

[volume freak]

hello joe,

i was hoping i'd be fortunate enough to hear from you regarding my volume difficulties.  i really try to pay attention to your  responses
here on the sight.

i run both the 200 and 2000 through the same marshall cab (obviously
not at the same time) and i am aware of a certain penalty due to
ohm mismatching, but i've also compared them through other cabs
and the difference is still dramatic.  some resistors did read a bit
weak in the power supply area so i'm changing those hopefully
today.  the transformers seem to be in fine shape, so i'm at a loss
as to what could be the real problem.  right now it sounds more like
a weak 30 watt amp than a 120 watt sunn behemoth.

i truly appreciate you taking the time to help.  thank you very much.

[volume freak]

joe,

the amp has solid state rectifiers installed that are brand new.  
they brought the sound up some, but it wasn't a dramatic change
in power.

[Anonymous]

I would say try cleaning the Pots or clean the sockets.
check the amp very closley and look for any bad connections.
you might have a pot.

[JoeArthur]

I don't know what a "weak resistor" is... but in the power supply, if they are within 10-20 percent of their marked value (probably their normal tolerance value) chances of them being your problem is pretty remote.

What bias are you running the output tubes at?