ODS 6V6 build?

[Smokebreak]

Thanks guys I spaced the higher surge on startup

The two main caps should come before the standby switch so they charge when the power is applied.

so I'm still a little confused about this. I understand that the res caps before the standby lets those caps charge first, before the rest of the circuit gets voltage, but I don't understand what this is protecting....and how, of course.
Is this to protect the rectifier , or components downstream?

[Structo]

Caps can appear as a short for the first milli seconds they are charged.

I think the reason for the res caps to charge first is to protect the power tubes and reduce the surge of all the caps being charged at power up.

[Smokebreak]

Thanks Structo. I'll make the necessary changes.

Can you comment on the tonal differences in the tweeked D'lite(and PS changes) vs. the regular ol D'lite? Also, I've noticed in some documents the 22M/22M/cap between grid and plate in preamp is omitted. Why would that be?

[rock_mumbles]

From what I've read the original D'Lite by thenormster was designed to use Deluxe iron so it was built/tuned to work with that ... the Tweaked D'Lite is closer to a real 'D-styled' amp ...

The local negative feedback --22M--0.05uf--22M-- is switched on some amps, switched out the amp works better with a Strat because that stage is left 'wide open' with higher output guitars the LNFB is necessary ...

Steve Dallman wrote:
-The negative feedback loop in V1B is crucial to the sound. 0.047uF/44M works well there. 0.047uF/22M tightens up the sound and feel even further, but it's overkill for my ears. Removing this feedback loop gives the overdrive a more compressed, Boogie-ish character. Something you might want to make switcheable, but be sure to put the switch on the grid side of the capacitor or you might end up with high voltage on the switch.

[Structo]

As rock_mumbles said, the original D'lite's were designed around 6V6 power tubes.

So more like a 20-25w amp.

When the D'lite 44 came along Moss didn't change a whole lot so a few guys tweaked the circuit to sound better with 6L6's.

That is the kit I bought.
I ended up replacing the OT for a larger Fender one and tweaked the preamp and plate voltages to align better with the Dumble model.

I can give this advice since I was guilty of not following it.

Don't change too many things at once without listening to the amp first.

Change one thing like the high plate load resistors and cathode resistors on V1, then listen.
That is 220K/3K3 150K/2K2
Like that and want more?
Change V2 to high plate loads as well.

It will be a journey and you will learn a lot in the process.

[Smokebreak]

Concerning the balancing resistors on the res caps in series, is 220K and 200K alright to use? I'm short a big 220K.

Also, I'm seeing what I've read in an older post by Structo is 150K FET simulator on the last filtering stage to ground(on some layouts and not others. What does that do?

[martin manning]

Miss-matched balance resistors will result in unbalanced voltages, 10% in this case. Not a show-stopper, but I'd get the right part.

The FET simulator draws a couple of additional mA through the whole dropping string and lowers the preamp voltages. It allows keeping the original PS resistor values and makes a convenient bleeder, draining the filters when the amp is shut down.

[Smokebreak]

I'm nearing the end of the build, and this is without a doubt the most complicated build I've done. On paper I didn't think it would be, but once I got to work...geez.

I would really appreciate some extra sets of eyes here. I've got to do some shielded runs and the input jack, then recheck everything. I ran into all sorts of problems, including simple stuff like not having the correct values, to fabricating the PS board backwards, to having to redo some heaters, so there is some splicing here..

I'm more concerned with wire placement of the different sections. NFB wire, OT, and mainly, the tone stack wiring. I haven't built anything with this many controls, so everything just got shoved into the bottom of the chassis by under the tone stack.

I welcome any comments and suggestions concerning anything that may be wired plain incorrectly, or lead-dress related.

I started with the tweaked PS, and regular, non-tweaked preamp. Also, I like to leave my lead wraps rather long at first, to ease in removal .

Thanks, J
[img2448]http://www.whiteghostshivers.com/images ... 140131.jpg[/img]
[img2448]http://www.whiteghostshivers.com/images ... 140132.jpg[/img]
[img2448]http://www.whiteghostshivers.com/images ... 140133.jpg[/img]

[Smokebreak]

I got it fired up and the amp is working as it should, but I have 475V on the plates, which I believe is high. I'm using Hammond 290dx rated 325-0-325 loaded and 355-0-355 unloaded, 230mA. With 6L6GC's in at idle and biased around 42mA, I'm getting 720VAC across PT secondaries, a hair above even the unloaded rating. What could be going on here?

[10thTx]

Very nice looking build. I like how you did the board with easy access to the wires.

with respect, 10thtx

[da Geezer]

I got it fired up and the amp is working as it should, but I have 475V on the plates, which I believe is high. I'm using Hammond 290dx rated 325-0-325 loaded and 355-0-355 unloaded, 230mA. With 6L6GC's in at idle and biased around 42mA, I'm getting 720VAC across PT secondaries, a hair above even the unloaded rating. What could be going on here?

Measure your wall voltage. If it's like most places nowadays, it'll be somewhere around 122v to 125v (if not higher)
Is your PT new? Older Hammond stuff was designed around 115v (117v?) supply, but they have recently upgraded to more modern specs.
But if your PT is spec'd for the higher supply, then that's probably not the problem, unless the wall voltage is extremely high(?). Hammond is now 120v primary, so if you have 125 to 128v (or more!) then you're going to get corresponding higher secondary voltages

I have to run my ’74 SFTR off of a "vintage voltage" rig (12v bucking transformer) to get the voltages into normal range

$0.02

G

[Smokebreak]

Thanks guys. This is a new 120V Hammond . My wall is getting 121-122V. I made my initial readings with a new pair of Chinese 6L6gcs. I have swapped in 2 other sets of new Sovteks and TAD, and with proper bias, and they actually read even a little higher on the plates, around 480. I can't see any other option besides contacting AES. Im not going to go shoving zeners in there I also found a thread elsewhere in which someone else was getting nearly the exact same voltage off the secondaries of this PT with a similar setup.

[Smokebreak]

I called AES and they were nice, but I have to do the whole song and dance with Hammond- they will have a tech look at it and deem whether it is defective or not

[ToneMerc]

You need to hang a 150k bleeder off of B5+ to draw down the preamp voltage rail, without it V1-V3 wil be about 22-25V too high. Also bias should be adjusted to around 32-35mA.

TM

[Smokebreak]

You need to hang a 150k bleeder off of B5+ to draw down the preamp voltage rail, without it V1-V3 wil be about 22-25V too high. Also bias should be adjusted to around 32-35mA.

TM

Thanks TM, i just put it in, but my issue still is upstream at the 6L6gc plates, or what I believe to be the PT. My plate voltage, at 33mA is 480VDC. Increasing the bias to 45mA or so only drops Vp a bit.
Even if I was looking for 480V plates, are these amps usually biased that cold? And are there voltage charts around for these 50W D'lites?