D'lite 6L6 build: Bright!

[Structo]

I think what Normster was saying with the taper is not so much that it would change the tone but give you more adjustability of it.

If you look at the layout I posted it shows where the treble bleed goes.

I suggest using a trimmer there so you can dial it in and see what changes from a large resistance to small make.

Gil Ayan was the one that clued us in on that treble bleed circuit.
He makes a small circuit board with the cap and trimmer (or fixed resistor) and piggybacks it over the main preamp board using one of the screws that holds down the main board.
You could do that with an additional nylon spacer or standoff and just stack it on top of an existing one.

If you haven't installed the relays and footswitch set up you really should.
It makes the amp much more user friendly and also the ability to disconnect the bass pot jumper when the PAB is switched on.

Also if you like using an FX loop, I installed the Ironsounds FX active loop and it works great!

It's just finding room for the additional power boards that is a challenge.

I put my relay PS between the bias board and pilot light on the side of the chassis and the Ironsounds PS board between the PT and IEC connector.

The FX board goes over in the corner just above the foot switch jack.

I also installed a dual bias system so that I can bias each power tube independently so mismatched power tubes are not a problem.

This is an older picture and before a lot of changes but it shows the PS board locations.

[heisthl]

I also installed a dual bias system so that I can bias each power tube independently so mismatched power tubes are not a problem.

If you have 2 meters connect them to your bias points and look at the difference a little conduction makes with current draw on unmatched tubes, separate bias does not match tubes, it just makes them idle the same. A lot of "matched" tubes are not matched either, of course unless you have the high end test gear to check tubes you can't know how much mismatch is cause by the amp itself. As long as the tubes are close matching is probably only relavent if you're trying to milk the last bit of headroom out of an amp.

[lbradshaw]

I think what Normster was saying with the taper is not so much that it would change the tone but give you more adjustability of it.

That makes more sense to me.

Also if you like using an FX loop, I installed the Ironsounds FX active loop and it works great!

I was thinking of adding an FX loop of some kind? How does Ironsounds FX compare to an D'lator?

[Structo]

Yes Henry, I understand that. But it makes me all warm and fuzzy inside having the two bias pots to play with.

Look, I've bought matched pairs of 6L6 tubes that were 10ma off from each other at idle.

A guy that was smarter than me said I could put the dual bias pots in and buy separate NOS tubes and get them close even if they are not matched on a tube tester.

What do I know.........

Would you agree it would be best to have them at least match at idle verses not?

lbradshaw,

Well I don't know how the Ironsounds compares to a Dumbelator because I haven't heard the Dumbleator.

But we're comparing tubes to solid state so I'll let you be the judge.

My FX loop cost $50 compared to whatever it will take to build or buy the tube version.

I also understand the the tube loop compliments the amp very much since they are made to be used together.

Maybe one day I will build one but for right now, I have something that works very well for reverb and delay in my amp.

[novosibir]

Lastly, I recall Brandon having a problem with an overly bright amp that turned out to be the brand of PS capacitors. Apparently Nichicon is not nearly as smooth and warm as F&T, Sprague, or Xicon.

Another smooth axial filter cap is the light blue BC, formerly Philips and still made on the Philips tooling. The ones seen on these photos:

[img562]http://www.larry-amplification.de/Smart ... 0_0790.JPG[/img]

[img562]http://www.larry-amplification.de/Smart ... 0_0791.JPG[/img]

[img562]http://www.larry-amplification.de/Smart ... 0_0793.JPG[/img]

Here in Germany I get it at Farnell, so in the USA presumably Newark does have it.

Larry

[novosibir]

Another cause for the overly brightness of an amp might be the tubes!

Chinese Shuguang and JJ's are more on the brighter side, while NOS Tungsram, Mullard or RFT (in this order) do darken an amp's sound.

A RFT ECC83 as V2 and a Telefunken smooth plate ECC83 as V3 might be the trick!?

Concerning the 270p/330p snubber caps on V2 - as you i.e. use in interstage filters 2kV or even 3kV ceramics instead of 1kV or 500V ceramics of the same value, to darken and smooth the sound - used as snubbers it's vice versa! There you shouldt use a cap, what in interstage filters usually is known as 'clean & bright', i.e. a Silver Mica or a Polystyrene foil cap.

Just some ideas

Larry

[Structo]

Concerning the 270p/330p snubber caps on V2 - as you i.e. use in interstage filters 2kV or even 3kV ceramics instead of 1kV or 500V ceramics of the same value, to darken and smooth the sound - used as snubbers it's vice versa! There you shouldt use a cap, what in interstage filters usually is known as 'clean & bright', i.e. a Silver Mica or a Polystyrene foil cap.

Just some ideas

Larry

Larry, could you expand on what you said there. I'm not getting what you are saying.

Are you saying the higher voltage ceramics sound darker than a ceramic of the same value but lower voltage rating?

[lbradshaw]

The PAB is a funky circuit in a way because if you have the bass and treble turned up quite a ways the difference when you turn on the PAB isn't as great of a boost would be if the bass and treble are turned down and PAB is switched on.

Is this related to what I seem to be finding with this tone stack. That is, I am getting more volume as I turn the Bass, and Treble up. I thought I would check to see if this is the way this tone stack works, or if maybe I need to recheck my wiring for errors. ?

Here is what I am finding with and without the Bass pot jumper. With it on, it seem to work quite well with my Strat, but with my ES335 type guitar it's a little too boomy over all. If I remove the jumper the amp is much happier with the 335. I guess I could put it on a switch. Also, maybe if I used a different slope resistor and can find a happy medium for both type of guitars.

[Structo]

Yes I discovered the same thing and it's why early on I took the jumper off.

It seems to be a real balancing act on this amp to make it right for both Fenders and Gibson's or humbucker guitars.

Maybe a manual switch is the answer for that. Not sure if it could lead to noise problems if ran long. Maybe a two conductor shielded wire with the shield grounded at one end.

The tone stack on these amps are indeed very interactive.

It seems I remember someone saying that when at 12 O'clock they are at neutral or not adding or taking anything away. (I could be wrong on that).

The PAB circuit is also fickle because if you have the bass and treble turned way down and engage the PAB there will be a huge boost.

But if you have them turned way up, the boost will not be significant.

[novosibir]

Larry, could you expand on what you said there. I'm not getting what you are saying.

Are you saying the higher voltage ceramics sound darker than a ceramic of the same value but lower voltage rating?

Correct! The higher the voltage rating, the bigger the Xc (capacity reactance) usually is, what you may regard as a resistor in series with the cap, but a resistor who's increasing in value successively with frequency.

There are some (acoustically) exceptions, that a ceramic with a high voltage rating sounds brighter. But that's not, because the rule above is abrogated, it's because ceramics are producing additional odd order harmonics (the grain in the tone, or let's say some 'salt & pepper'), and when especially K7 & K11 (7-th & 11-th harmonic) are high, this then adds an awful brittleness, what might be confused with brightness.

Try the mustard colored Panasonic 2kV ceramics, which you can get from Newark - I think, that you'll like it! They're smooth w/o an overly brittleness. Maybe the 'right amount' of Salt & Pepper in the tone?

Larry

[cornel moldovan]

My sugestion is to change the output transformer with a bigger one.. may be the core section is not enough for the frecvency band you wish to hear.. the common rule says: bigger section for more bass.. see bass amplifiers .. they lack ultra light frecvencies , ..IF YOU WANT BRIGHT SILVER HIGHS , KEEP THE small OT. I HAD A SOUND CITY CONCORDE WITH SUCH A SMALL OUTPUT TRANSFORMER ..GET RID OF THAT SMALL OT. USE A BIGGER ONE...THIS IS THE WAY YOU CAN TUNE THE GENERAL TONE RESPONSE OF THE AMP WITHOUT CHANGING THE BASIC SCHEMATIC WICH IS OK FOR EVERYBODY. YOU ONLY HAVE TO RESPECT THE RAA RESISTANCE OF THE PIMAR WINDING FOR 6L6, EL 34, EL 84 ... WHATEVER ..MORE IRON , MORE BASS FRECVENCIES.. SAME RULE FOR THE GUITAR PICKUPS.. MORE IRON MORE WARMTH. SEE ALNICO PICKUPS MINIMUM IRON MAXIMUM HIGHS FOR STRATS OR TELECASTERS. THIS IS WHY JAZZ PICKUPS HAVE MORE BASS FRECVENCIES.. THEY USE MORE IRON.INSTEAD OF ALNICO , YOU WILL FIND FERRITE BLACK MAGNETS ... THERE IS A POSSIBLE VARIATION OF THE FRECVENCY RANGE , ACCORDING TO EACH KIND OF POWER TUBES PAIR , KEEPING THE SAME POWER , BUT OBTAINING DIFFERENT CURVE RESPONSE .. I CAN GIVE EVEN SOME PROCEDURES TO CALCULATE THEOUTPUT TRANSFORMER TO HET THE TARGET IN THE MIDDLE .. YOU HAVE THE SOUND IN YOUR EAR BUT IN REALITY THE AMP SOUNDS HIGHER .. THIS IS WHY THE OVERDRIVE SOUNDS BUZZY. THIS IS A POINT OF WIEW.. HERE IN ROMANIA WE BUILT EVEN THE TRANSFORMERS .. KNOWING FROM THE BEGINNING HOW THE AMP MUST SCREAM .

[Structo]

OK, lets take for example the treble cap on the D'Lite or Dumble.

It is traditionally a ceramic cap with the value of .002uf or on the D'Lite we change that to 330pf. (tweaked version)

The D'Lite in it's stock configuration uses a 270pf ceramic.

I have changed that to a 330pf but I'm not sure what the voltage rating was on it.

I've been thinking about changing that to a .002uf PS orange drop to possibly smooth the top end a bit.

[JimiB]

the .002 is a mid boost cap value - it is supposed to be in series with a 330p or so for a normal treble cap value. If you just put a .002 in there you will have mid boost all the time - which I wouldnt recomend.

[Structo]

Well my amp does not have the mid boost switch.

It just goes from the 330pf to the input of the treble pot.

[lbradshaw]

OK, I swapped the 270p snubbers for 330p. I am not sure how I feel about it. It may have made the OD a little smoother, but I feel I might have lost something. I might have to switch back to 270p just to see. Changed the slope resistor to 100K, and then back to 150K. I think I'll leave that alone for now. I also played around with taking away the LNFB on V1b. I like the rawer guitar sound, but at the same time may have lost some smoothness. It seems it's all a trade off one way or another.

Next on the list is an Treble bleed.