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Messages - Enzo

#2071
PV uses the 4EB2C1B pan in just about all their stuff, and looking at the circuit, I'd say that should work here too.  The 9EB2C1B would also work fine.

The 4EB2C1B sells for $23-25 at www.tubesandmore.com
#2072
What "better" reverb might you have in mind?  What is in there now?  The transtubes are not old enough to have an old OC reverb, so it would be an Accutronics.  You could go from a two spring to a three spring for a small increase in reverb sound complexity, but in spring reverbs, Accutronics is pretty much the game in my estimation.  I am not much of a Belton fan.

Other than not digging it, and wishing it was more Fendery, what is the complaint?  In what ways is it less Fendery than desired?  One can massage the circuit to an extent.
#2073
Amplifier Discussion / Re: Fender SRM 6302 Trouble
December 23, 2008, 02:50:36 AM
This is solid state, so it doesn't need a speaker load, so no need to burn up speakers.  If there is DC on the output, then something in the amp circuit is bad, if not the output transistors, then open bias or bad driver/predriver or something like that.

See if the filter cap or caps has cracked its solder.  Otherwise, if the cap is not filtering there will be tons of ripple instead of smooth DC.  Set your meter to AC volts - or scope it -  and measure the DC voltages.  The reading should be pretty low for the higher voltages and almost non-existent for the 15v rails.  If there is like 20VAC where 30VDC should be, then I'd suspect a filter cap.


#2074
Amplifier Discussion / Re: Class A solid state
December 17, 2008, 05:11:01 AM
70v transformers are cheap, either pulled off a speaker or just purchased alone.  Parts Express $4.25 for a 10w after a quick look.

I don't really know, but wouldn;t the transformer have to have a gap in the iron like a SE OT in a tube amp?  The steady DC current through it might not make it happy.  The typical 70v transformer wouldn't be made that way.  Then again this is low power.

Is this project meant for germanium?
#2075
Amplifier Discussion / Re: New Google Style
November 19, 2008, 09:03:19 PM
Google has a "style" now?
#2076
Amplifier Discussion / Re: replace jack squier 15
November 19, 2008, 09:02:12 PM
The nut is sized for the jack, you won;t be finding them at the hardware store.  Your local amp repair should be willing to gove you one, or if they are hardcore, they might charge a quarter or half dollar for it.

CHances are real good your jack is stripped, look at it closely.  If the threads are rounded over, then the nut cannot be tightened completely.
#2077
Amplifier Discussion / Re: A bit of Amp HIstory
November 08, 2008, 12:00:47 PM
I guess it has been awhile, April 1995 according to my warranty listings file..  At the time they sent us this schematic set:

EQ15S
EQ31M
GS100S/100SB/100D
GS130D/130SB
GS18/45/45B/65D/75
GS90D/150D/200B
GV60/100/100S
GV60D/100D
MC Mixers
ME12-75
ME15-150
PBM6-150
PBM8-300
PM4-75
PM6-150
RP150
RP500S
SE12-75
SE15-150/200/250/300/400
XV100SD
Pedals
#2078
Amplifier Discussion / Re: Crackling sound from Ruby amp
November 05, 2008, 04:29:47 PM
Please connect the amp to a different speaker before considering the electronics.  That wil tell you if it is indeed the electronics or just a speaker with a rubbing voice coil.
#2079
Amplifier Discussion / Re: A bit of Amp HIstory
November 03, 2008, 10:06:10 PM
KMD - unless there was more than one KMD, we are talking about a division of Kaman - as in Kaman Music Division or something like that.  Kaman is mainly a distributor, so I have no idea who made their KMD line.  COntact them and ask.

We were a service center for them back when they distributed TraceElliot, Dean Markley, and KMD amps.

http://www.kamanmusic.com/
#2080
The power amp is that 5-leg TDA2040 on the little heat sink off the rear edge of the board.  FLip the board over and resolder the legs.  WHile back there, resolder the large filter caps.  They are right behind the headphones jack.

Check the solder, and why not reflow it, on the jacks and controls along the panel.

If yuo think the transformer gets too hot, pull the red wires off the board and power up the chassis - that will be the transformer powered with the secondary connected to nothing, all by itself.  it will get a little warm, but if it gets real hot, that is not good.
#2081
The Newcomer's Forum / Re: Loud hum and no sound output
October 20, 2008, 04:33:29 AM
Before you do anything else, watch the speaker cone when you power on.  If it moves one direction then stays there, TURN IT OFF IMMEDIATELY.  That means you have DC on your speaker.  It will ultimately burn up your speaker if left on.  If so, disconncet the speaker until teh amp is fixed.  You can monitor the output with a voltmeter while servicing the amp. 

If you are techie, then disconnect the speaker now and check for DC afterwards.  DC on the output alone won;t blow fuses, but WITH a speaker it usually will.

And as mentioned above, DC on the output is usually from shorted transistors.
#2082
Power shares, yes.   Series or parallel, doesn;t matter, they still share.  FOur 25w speakers wires series/parallel in a 4x12 cab will make a 100 watt cab.  Two 15 watt speakers wired together will take 30 watts.

If you have two different impedance speakers, they will not share equally.  That is if you place a 4 ohm and an 8 ohm speaker parallel in a cab together, the 4 ohm speaker will take 2/3 of the power applied.  But mostly let's deal with groups of similar speakers.

You can ignore the cab wiring length and resistance.  The length doesn;t matter, electricity travels a foot of wire in only a nanosecond.  The resistance is going to be a small fraction of an ohm.  100 foot cables is one thing, but inside a cab, wire resistance is small.
#2083
Amplifier Discussion / Re: buzz in Princeton Chorus
October 18, 2008, 02:30:12 AM
Pull the chassis.  There will be a pair of main filter caps standing near the center of the board, if I recall the layout.  Dismount the board flip it over and resolder them.  I'd bet my lunch money that is your problem.

After restirong hte board to poistion, run a large glob of silicone sealer or hot melt between them to glue them together into one mass.  Also run a bead around the base of each.  Those measures will help prevent them shaking around and cracking their solder in the future.

And for the record, that would be 120Hz hum in this case.
#2084
Amplifier Discussion / Re: Heatsinks for your poweramp
October 16, 2008, 12:30:20 AM
One source of cheap heatsinks is dead stereo receivers.  America is full of them, and they don't usually cost anything.

Much commercial heat sink material is straight extrusion, but I have been seeing in these commercial stereo receivers what I call "shaved" fins.  Instead of extruding the fins, the heatsink is more of a block of aluminum, then every centimeter or so there is a fin shaved from the block.  Imagine a piece of wood and a chisel.  You push the chisel along the wood and a shaving curls up from the wood.  Further imagine you did this every cm up the wood, you'd have a row of shavings standing out from the board.  That is how these aluminum ones appear to have been made.  Obviously the original block was shaped to optimise the process.

The fins wind up perpendicular to the base block, but at the root of each fin, the material is curved and from markings you can tell it was curled out from the block.  I imagine a block of aluminum moving down a conveyor while a large chopper slices into it as it moves, liek a sushi knife slicing a fish.  The block itself appears extruded.



Also, I would think the important question is not whether one way might cool "better" than another, but rather does the method used do a sufficient job.

For example the photo above with the horizontal fins might cool more eficienctly if the fins were vertical, but the question is: does it cool the circuits sufficiiently as is?  To make it vertical might have meant two pieces and thus twice labor to assemble.  Always a consideration in a commercial product.  For a given amount of cooling, maybe a fan is more expensive than a larger but less efficient heatsink on its own.
#2085
Amplifier Discussion / Re: Stoopid Question.....
October 15, 2008, 04:26:29 AM
If you are looking for a simple  "just do this" answer, you won;t find it.  The two circuits are designed by different people with differnt goals. They are different circuits.  If you want to compare, get both schematics and redraw them in the same style and then AB them.  The actual circuit configuration will make a lot more differnce than brands of resistors.

Is your SUpreme a "transtube" version?  If so, it will be based on darlington pairs of transistors instead of op amps, at least to some extent.  I don't have the prints on the Carvin handy, is it op amp based?  Transistor versus op amp would be a large difference right there.