Dlite not very loud

[danotron]

I built a Dlite, it sounds great but not very loud. Where should I look for problems? The preamp doesn't seem to draw very much current...about .7mA pre triod........is this ok?

[Structo]

What power tubes are you using?

I have 6L6GC's in mine and it is very loud!

[Bob-I]

We kinda need more information.

What output tubes are you running?
What's the bias current?
What are the voltages on the preamp tubes, plate and cathode?

[danotron]

I am running 6L6GC's..they have 480 on the plate(pin 3), 474 on the screen grid(pin 4), -50 on the cotrol grid (pin5), I am measureing a bias current of 31.6mA.

The Preamp is:

Plates:
CL1-187v
CL2-205v
OD1-186v
OD2-201v
PI1-320v
PI2-309v

Cathodes:
CL1-1.54v
CL2-1.6v
OD1-1.71v
OD2-1.49v
PI1&2 - 51v


PI1&2 Grid-32v

[Bob-I]

Your voltages are all in spec. I'd make sure that you're not losing signal throughout the signal path by looking at each stage with a scope.

[moj067]

Check your speaker output jacks for proper wiring and your grounds. It's plenty loud enough for most. Post pics when stuck, everyone here is most helpful when stuck in the mud.

[phsyconoodler]

One thing about dumble amps is the local negative feedback,the negative feedback and the presence.They all form what the dumble sound is all about.However,they do suck a litlle power.If you crank the presence all the way up,lift the feedback off v2 and lift the negative dfeedback off the speaker jack,the amp turns into a raging beast.If you would rather have a raging beast than a controled sound like the D'Lite,then do those things and the 'lost' volume will be yours.
I use a switch on the local feedback on v1 for a nice difference in tone.
i have been contemplating a negative feedback switch for the grit lovers.

[heisthl]

[quote="phsyconoodler"]If you crank the presence all the way up,
[quote]

you lose the low end - amp is louder with the global feedback disconnected.

[Normster]

Don't assume anything's wrong with the amp until you've explored the range of the front panel controls. Today's pots can be very low taper, sometimes 10% (PEC, CTS). Alphas typically run 15%. Try setting the volume control at 3 o'clock and run the other controls at 12 o'clock. From there, crank the master and see if you can drive the clean channel into breakup. It should start getting pretty loud at around 2 o'clock.

If that doesn't do it, the most common volume problem (based on feedback from kit builders) is a bad ground connection from the OPT to the speaker jack. The jack must have a good ground to the chassis to provide a reference for the OPT.

[Structo]

Also check your grounds.

Did you run the ground wires from V1 & V2 bypass to the ground buss?

Check the second layout out, it shows grounds and heater wiring.

Also some of the layouts show what looks like a connectionon the volume pot center lug to the red wire coming from the right lug. This layout shows this as well.
This is not correct.

Only the bright cap and shielded cable center conductor actually are connected to the center lug.

The first layout with the relays shows how the volume pot should be wired.

[danotron]

I took the tone stack (Bass and Mid) out of the circuit and I have a ton of volume now. I used pot that I had just laying around so maybe there is a problem with them...I will try some new ones.

A question about the layouts from Structo? Why is the first 22uF/450 volt cap grounded separately? Is there a reason for this? Why not just attach the ground to the ground of the cap right beside it? Like this:

[Structo]

Perhaps this schematic will answer your question.

The first 22mf cap is by itself for HT +B voltage.

I'm not sure if it would matter if it was grounded with the others but is probably to minimise noise.

But electrically, they are at the same potential ground wise.


If you got a major volume jump by removing the tone stack, I would have to think that there is a wiring error there somewhere.

Do you have it wired like this with the bass pot lugs jumpered or like the one called No Bass Mod?

Do you have relays in your amp for PAB and OD?

Did you use the same resistance values as in the layout for the pots?

[Bob-I]

I took the tone stack (Bass and Mid) out of the circuit and I have a ton of volume now. I used pot that I had just laying around so maybe there is a problem with them...I will try some new ones.

I'd double check with a meter, and double check the wiring. It's really easy to mess up.

A question about the layouts from Structo? Why is the first 22uF/450 volt cap grounded separately? Is there a reason for this? Why not just attach the ground to the ground of the cap right beside it? Like this:

There are 3 grounds on the filters. 1) Main filters, 2) Screen filters and 3) preamp filters. It really does make for a quieter amp so stick with that scheme.

[Normster]

Yes, the grounds are seperated to keep the preamp ground away from the screen ground. Dumble actually ran the ground for the preamp caps up to the ground point at the input jack. I found that a couple of inches actually worked just as well, hence the ground location.

As for removing the tone stack and getting a dramatic increase in volume, that's to be expected. A passive tone stack bleeds signal to ground. In a similar fashion, the BM PAB does the same thing and gets about a 6dB (I think that's what Scott measured) increase in volume...very significant.

[danotron]

Well after some checking, I found that the tone stack was wired incorrectly. I also found that one of the pots was intermittant. I also found a problem with one of the 6L6's...the tube socket had gone bad and wasn't making a good connection.

Finally the amp sound really nice and loud. I do need to separate the power supply grounds and see if this quiet down a bit...but it is pretty quiet already.

Thank you everybody for your help and guidance with this issue.