*umbolt lite done.

[phsyconoodler]

Volume and overdrive issues.Not enough of either.I have obviously done something wrong but it's eluding me.The only difference between this one and the last is the addition of the reverb.That works great.
 Loose,keep up!

[jgriffes]

i had the same problem, i don't know if it's the same problem, but on the input jack to ground i used a  500 ohm resistor ( green, black, brown) instead of a 1 meg (brown, black, green). just a shot.

[navdave]

Is the tone stack responsive at all with all that gain behind it? I've tried a trainwreck style tone stack with three extra gain stages behind it kind of like that of the this Dumble Lite. I cant get any real tone shaping from this type of tone stack attached to the input tubes anode. I always end up going back to the cathode follower when using a high gain preamp.

[phsyconoodler]

My previous build was very responsive.I had none of the problems i'm having with this one.It drove like a muther and the tone stack was very sensitive.This one is pissing me off. >:(I did nothing different and I'm using the same parts and transformers.

  You have to use a 1 meg on the input.
i am however,using CTS volume and master pots.They may be my issue if the taper is funky.I used Alpha's on the other one.The OD is not giving me the gain either.????

[jgriffes]

yeah, I was in a hurry and put in the 500 ohm by accident.  

[phsyconoodler]

Here's a dilly for you:I was not getting the drive out of this reverb amp like the other one I built and guess what?After I triple and quadruple checked everything I looked at the pots.
  It calls for linear pots in the circuit in the bass,OD and OD level positions and guess what I had put in there?Yes,audio pots! DUH!!!!
 Popped in some linears and problem solved.Reverb works great,OD is great,and the amp sounds killer.I prefer the 6V6's for drive but the 6L6's are nice and round.
  I bought a big batch of 100k pots and never even though of whether they were log or linear.The bag says linear and the pot has this big 'A' o it.

[phsyconoodler]

Just a big THANKS to Tubenit for his reverb circuit.It works very well.
you want reverb and can't figure it out?Ask Tubenit.He has it worked out and is very generous with his work.
He is the MAN!!! :)

[tubenit]

Wished I could take credit for this one!  [smiley=smiley.gif]

However, I took PRR's advice about this reverb circuit (& amp design in general ) .........  "plagerize, plagerize, plagerize " ........ or something like that.   [smiley=wink.gif]

Still I am glad it worked out good for you, I am enjoying that circuit on my amps too. It does seem to adapt well to amps with LTPI.

Best regards & with respect, Tubenit

[tubenit]

Phsyconoodler,

Out of curiousity, I know it's difficult to get high gain amps quiet at idle.   With the boost stuff engaged, ....... how does the "noise" level compared to say the Fender AB 763 type amps you've done?

Looking forward to sound clips of these amps.

With respect, Tubenit

[phsyconoodler]

This amp is as quiet as can be.There is some noise at the highest gain setting but it is far less than a JCM800.
  I used cliff jacks isolated from the chassis and a ground buss that is grounded to a bolt next to the input jack.Really quiet.
  An AB763 is different so it's not really a good comparison.This amp is so quiet at idle you have to hit a string to tell it's on.

[phsyconoodler]

Here's another shot before it disappears into it's cabinet.

[jgriffes]

looks nice, as usual.  Hey, this might be a stupid question but on the overdrive tube there are (2) 270 pf caps that run between pins 1 and 3, and pins 6 and 8,  what do these do exactly?

[jgriffes]

alright, i just checked my voltages on preamp tubes 1 and 2. I have a little over 300 volts running to each one.  does this seem a little high?

[phsyconoodler]

I don't know what those capacitors do either.But I do know they need to be there.I ran out of 270pf caps and used 500pf's and it sounds fine.
  Your preamp voltages need to be taken in context to the rest of the amp.What is the B+ and plate voltages at the tubes?What is the voltage at the 'Y' of the plate resistors?Are you measuring with all tubes installed and the bias set properly?
  Do you have the wire hooked to the proper filter cap?Did you use the right size decoupling resistors?
  We need to see what the rest of the amp is doing before we can determine if your voltages are ok.

[phsyconoodler]

I found out what those caps do.They prevent oscillations from the high gain preamp signal.I guess when you put the amp on a scope it can oscillatebadly even at frequencies you can't hear.The caps prevent it and also help define the OD tone too.A larger cap like 500pf is not as defined sounding in overdrive.The seventies D amps had 500pf and later models switched to 270pf or so to help the amp sound more focused.I used 500pf in this build just because I ran out of 270's and I rather like the overdrive.
  I'm using Winged C 6L6's in this one.I guess you can play around and tweak it to taste.

[tubenit]

The SCH files of the D'Lite have been updated and edited. A reverb version has been included given Physconoodler's success with it.

Additional layout designs were added using the terminal strips on the V1 & V2 tubes. As always, CHECK for errors and compare with original schematic and layout. Please PM me with any errors you may find.

http://www.el34world.com/Forum/yabb2/YaBB.pl?num=1193532616

Tubenit

[jgriffes]

heres a shot of the guts. not quite as clean as yours physco!

[phsyconoodler]

The important thing is you did it!
How is it working?The speaker choice is critical with this amp.A speaker that breaks up too early cannot get all the great tones out of this amp.I am using the Mojo Greyhound speakers and they are fabulous.
   This amp is way easier than an AB763 build!

[jgriffes]

I really like the clean on this amp!!  the distortion not so much, but i am gonna go back over the power supply, I still think the voltages are way too high for v 1 and 2.  at the Y or the resistors feeding 1 and 6 the voltages are about 503 volts. I have a resistor under the board so I am gonna pull it out and see whats doing under there.  Thanks for all the help, and I will keep you posted.  Oh, I am using a closed back 2x12 cab with 80 watt celestions I think.  I hate em.  I bought it just to play some shows filling in for my friends band.  I need to get my 4x12 cab out here to cali.  it has greenbacks on one side and naylors on the other.  sounds good.

[phsyconoodler]

Here's a shot of the amp in it's cabinet.I'm using a Mojo Greyhound speaker.The jury's out until it gets broken in.

[ganzonimx]

very nice! how did you attach the chassis to the cab? I can't see any screws on top..

Chris

[phsyconoodler]

It's just jammed in there and I glued it in. ::)
Just joking! Look at the bolts on the side of the cab.It has a shelf inside the cabinet and the chassis slides in like a drawer and attaches from the sides.I use rivet nuts in the chassis and 1-1/2" bolts with 'v' heads in dress washers.

[markmalin]

Hey Psyconoodler,

I fired up my *umbolt for the first time and tested the voltages before installing the tubes.  Turns out I'm getting 12V at the relays for power.  The Heyboer transformer I have has a 5 V winding with no center tap, which I used, but that must be 5v plus and minus from the center, so that's ~10V DC when rectified.  D'oh!  Questions:  Will the 5v relays handle 12v until I have a chance to get some 12volt ones?   Or, is there some way I can divide down the voltage easily?  (there's not much room left in that chassis!).  Any other suggestions?

Kind of dissapointing -- so close but I don't want to run the tubes in it until I know I'm not going to blow up the relays running them at 12v...


Thanks,
Mark

[sluckey]

You could use a 7805 vr chip and a couple small components. It's about the size of a nickel.

[phsyconoodler]

With no load from the tubes the voltages will be higher.When you get tubes in the amp everything will settle down nicely.You definitely don't need a centre tap for the 5v winding.If you had one it would double the voltage and fry up one of the diodes on the relays.Remember,the relays use DC voltage which is rectified & doubled at the power supply board by the diodes and caps.The AC voltage you are measuring is not a concern.If the relay volts are too high after installing the tubes,you can use a voltage regulator as Sluckey suggests,but it unlikely you will need it.
  By the way,check you E-Mail 8-)

[markmalin]

Wonder where I could get one locally....  I'm thinking if I have to order anything, maybe I'd just order 2 12v relays and rewire the board.  A pain in the neck because of where it's located, but maybe that's the best thing.

The heaters are at 6.3v.... could I tap into the heater supply secondary on the PT somehow?   Man... I sure don't want this to be a big kludge.  

[phsyconoodler]

12v,two relays sharing it, means 6v per relay right?The current is the important thing here.Correct me if I'm wrong.If they don't draw over 35ma a piece there should be no problem.I used 5v omron relays on both the last 2 builds and they are 100% fine.
  Make sure your relay board is wired properly and the diodes are oriented right.You cannot use the 6.3v heater supply because it's got a ground reference and it will blow the diodes immediately and smoke your supply board.

[sluckey]

Wonder where I could get one locally

RadioShack

[markmalin]

I'll re-check my wiring....   And thanks for the warning on the heater. Ouch!

I did notice those 12v relays at Radio Shack.  Thanks for the tip.

Mark.

We've got the grandkids coming over any minute, so I may not get to this until tomorrow :(

[phsyconoodler]

Sluckey's talking about the voltage regulator.The relays will not work if they are 12v.you should be just fine with the 5v relays.

[markmalin]

12v,two relays sharing it, means 6v per relay right?The current is the important thing here.Correct me if I'm wrong.If they don't draw over 35ma a piece there should be no problem.I used 5v omron relays on both the last 2 builds and they are 100% fine.

I just used the ammeter across the swtiches to short the relays and I'm measuring 52ma on either one.  So that's current drawn by the coil.  I did check the wiring again and it looks like it's right, but I can check again.  The relay power is wired in parallel (i.e. each relay coil is seeing the total relay power supply voltage of 12v).  When you say they are "sharing" the 12v, did you mean if they were wired in series with respect to the 12v supply voltage?

Mark.

[markmalin]

Sluckey's talking about the voltage regulator.The relays will not work if they are 12v.you should be just fine with the 5v relays.

All right.  I'll just slap the tubes in there and start testing.  Even if the 5v realys werent' happy, what's the worse that could happen?  They'd just fail eventually, which won't hurt anything ;)  

Mark.

[phsyconoodler]

All those D'lite owners that have the 5v relays can't be wrong.Two relays draw 52ma or 26ma a piece for a TOTAL of 52ma.
  And two relays share the 12v supply.
If the wiring is right you will have no problems.