D'Lite 44 Build Progress

[lord preset]

With lots of help from the kind folks on this board I have been plugging away at my 1st amp build, a D'lite 44. Perhaps not an obvious choice for a 1st build but I really wasn't interested in the usual suspects - 18watters, Deluxes, etc and I wanted an amp that I would otherwise probably never have. A Dumble inspired amp would fit in that category.

The early stages of this effort are in this thread: https://tubeamparchive.com/viewtopic.php?t=22256

I started with a 80's KMD 100 watt tube/SS hybrid and planned to use the cab, speaker chassis an iron, but it turned out that the PT and OT are only suitable for a MusicMan style high plate design that is for now out of my league. So I ordered Classictone 50W iron and proceeded. The PT arrived with a dented bell and I am waiting for a replacement. In the meantime all of the boards are built and I have wired up the chassis as much as I can without the PT. The Chassis is wider and shallower than the standard D'lite Chassis and is not as deep. It also lacked punchouts for the 12ax7s. I tried to stick as close as possible to the original layout but ran into some snags. When the impedance selector switch arrived it was bigger than I imagined and I couldn't fit it where I thought it would go. I ended up placing it in the bias pot position on the top of the chassis and placed the bias pot on the rear panel.

But that's not my big conceptual fail. It is this. The original OT was located at the far end of the chassis opposite the PT. I assumed that would not do as it would be right next to V1 and the input jack. So I placed it in the middle of the chassis as per the D'Lite layout. Cool, Right?

Not cool. It turns out that in this position the OT runs smack into the speaker in the combo cab. It's not a matter of moving it slightly to make it fit - it's not even close. Not enough room to move the speaker off-center either. I have built furniture, rooms, wired and plumbed houses - I am not an unhandy guy- I can't believe I this didn't occur to me until I tried to stick the chassis into the cab.

Sooo.. my plan to repurpose a donor amp has been reduced from reusing the cab, iron, chassis and speaker to just the chassis and speaker. I don't feel nearly as clever and thrifty as I did before, although the original PT and OT will eventually get used.

But before I throw in the towel on the existing cabinet, I just want to confirm that it really is bad to locate the OT close to V1 and the input jack. Everything I have read would seem to indicate so but what do I know?

[lord preset]

More Pics

[lord preset]

More pics

[CHIP]

Impressive first build.

[Smokebreak]

I'm no expert here, but technically you never want output near input, as you can possibly impress noise upon sensitive input signal lines. That said, in an effort to be able to use the cab, I'd try it and see. To help minimize noise, you could try running the OT wires on top of the chassis, and making sure your grid wires are shielded. Also, would it fit in the cab if you put the OT right smack against the PT? It almost looks like it would fit in front of the PT too. I've also seen, in some old amps, where the OT is mounted in a different part of the cab, not actually on the main chassis, but I'm just brainstorming now.
Great looking build!

[M Fowler]

You can put the OT back where it originally was just route the wires away from the preamp tubes.

I have built amps with PT on one side and OT on other side without any problems. See my JCM 800 combo chassis in photo. 2nd photo shows wire routing.

Mark

[JazzGuitarGimp]

Good looking build, LP. And I really like the yellow back panel (not being sarcastic).

[lord preset]

I'm no expert here, but technically you never want output near input, as you can possibly impress noise upon sensitive input signal lines. That said, in an effort to be able to use the cab, I'd try it and see. To help minimize noise, you could try running the OT wires on top of the chassis, and making sure your grid wires are shielded. Also, would it fit in the cab if you put the OT right smack against the PT? It almost looks like it would fit in front of the PT too. I've also seen, in some old amps, where the OT is mounted in a different part of the cab, not actually on the main chassis, but I'm just brainstorming now.
Great looking build!

It might fit right next to the PT. It didn't seem like it would when I was looking at it yesterday but I should give it a second look. That would be one lopsided combo Here is a pic of the original iron in the amp to give you an idea of the space i have to work with.

[lord preset]

Good looking build, LP. And I really like the yellow back panel (not being sarcastic).

Thanks. The yellow spray paint can nozzle was not clogged so I used that.

[lord preset]

You can put the OT back where it originally was just route the wires away from the preamp tubes.

I have built amps with PT on one side and OT on other side without any problems. See my JCM 800 combo chassis in photo. 2nd photo shows wire routing.

Mark

So looking at your build it would seem that it's more important to keep the OT wires way from V1/V2 than from the input jack area. That might work. The original OT position was smack dab on top of where the 2nd preamp tube is now, but I could shift it to the front as far as possible away from V1.

OTOH I've had a whole day to ruminate over building a cab. The KMD cab is plain old particleboard. I would have been happy enough to use it but there is some appeal in doing the whole thing from scratch ..and about that speaker...

[lord preset]

It Lives!

I decided to leave the OT where it is and proceed with the build with a new cabinet. The cab is built and will get tolex this weekend.

I finished wiring everything up. Did the light bulb tests and got no flash or glow when flipping the standby switch. Turns out the Carling switch was DOA. Grrrrr. Got a new switch and with great trepidation fired it up. Nothing went boom or pop, but then again no sound whatsoever emerged. Fail.

I double checked everything against the D'Lite Tweaked Layout and everything matched. WTF? So after going back through the moribund Brown Note Forum posts I ran across a guy who had the same issue. It turns out that the Tweaked Layout does not show the V1 and V2 Cathode ground wires. Perhaps obvious to most of you but not to me. I had already noted that the Tweaked Layout lacked a ground from the rectifier board and added that, but missed these. I realize it's not a great idea to rely solely on a layout, but there are so many un-versioned D-lite layouts and schematics out there I could not easily tell which ones matched and wanted to build from a single plan.

So with cathodes grounded I have an amp. It works! Even sounds pretty good. I still have an issue with the relay board. When I was ordering parts I noted that I would be using the 5V PT tap for the relay power supply, and made the assumption that I should get 5V relays. Of course the relay PS doubles the voltage and I was supposed to use 12v relays. Doh. Needless to say the footswitch is not working, but hopefully once I get 12V relays that will get sorted out.

Thanks again for all the help here. I will post pics once the cab is done.

[lord preset]

The 12v relays are installed and working. The amp sounds pretty good but it is a good deal brighter than I think it probably should be. I will go back over everything to make sure I didn't install any incorrect value parts, but in researching this I came across what I expect is a difference of opinion over how the presence pot should be wired. The Dlite Tweaked Layout has it with the pot ground lug connected to the bus wire, but apparently some think it should not be. The recommended scheme was this:

[img:145:178]http://i260.photobucket.com/albums/ii9/ ... /DL-pr.jpg[/img]

Is this "correct"? Or more to the point would it sound any different than the stock Dlite Layout?

[ToneMerc]

The 12v relays are installed and working. The amp sounds pretty good but it is a good deal brighter than I think it probably should be. I will go back over everything to make sure I didn't install any incorrect value parts, but in researching this I came across what I expect is a difference of opinion over how the presence pot should be wired. The Dlite Tweaked Layout has it with the pot ground lug connected to the bus wire, but apparently some think it should not be. The recommended scheme was this:

[img:145:178]http://i260.photobucket.com/albums/ii9/ ... /DL-pr.jpg[/img]

Is this "correct"? Or more to the point would it sound any different than the stock Dlite Layout?

Yes, that's the correct functioning way per Dumble; NFB to termimal 3, Pres cap to term 2, other side of cap and tail resistor is grounded.


Many will say that they have amp bright amp; some have used a high freq trim control, trim network in the loop and or the tube buffered loop .

TM

[lord preset]

Yes, that's the correct functioning way per Dumble; NFB to termimal 3, Pres cap to term 2, other side of cap and tail resistor is grounded.
TM

OK I tried the Dumble method - it seems to have helped the brightness issue a bit but I need to play more to tell if that's going to do it or I need to tweak more.

In checking things over again I came across a bit of a mystery. The plate voltage on V2b is significantly higher than V2a. I measured the plate resistors and they check out with the Tweaked Layout - 220K for V2a and 150K for V2b.

Overall plate voltages are:

V1a: 209
V1b: 218
V2a: 191
V2b: 251
V4: 469
V5: 469

B+ voltages 1-5 are 475, 470, 463, 365, 356.

Everything is a bit high compared to readings I have seen from others. I am using a Classictone PT that puts out 355-0-355 and I have not changed any resistor values on the power board. But why the big difference between the plate voltages on V2? they are being fed by the same B+. I am using old 12ax7 of questionable integrity but I have tried a few different ones in V2 with basically the same results.

Do I need to do something about this or is it OK if it sounds OK?

Thanks!

[ToneMerc]

Yes, that's the correct functioning way per Dumble; NFB to termimal 3, Pres cap to term 2, other side of cap and tail resistor is grounded.
TM

OK I tried the Dumble method - it seems to have helped the brightness issue a bit but I need to play more to tell if that's going to do it or I need to tweak more.

In checking things over again I came across a bit of a mystery. The plate voltage on V2b is significantly higher than V2a. I measured the plate resistors and they check out with the Tweaked Layout - 220K for V2a and 150K for V2b.

Overall plate voltages are:

V1a: 209
V1b: 218
V2a: 191
V2b: 251
V3: 469
V4: 469

B+ voltages 1-5 are 475, 470, 463, 365, 356.

Everything is a bit high compared to readings I have seen from others. I am using a Classictone PT that puts out 355-0-355 and I have not changed any resistor values on the power board. But why the big difference between the plate voltages on V2? they are being fed by the same B+. I am using old 12ax7 of questionable integrity but I have tried a few different ones in V2 with basically the same results.

Do I need to do something about this or is it OK if it sounds OK?

Thanks!

Several things are amiss here; first document plate and cathode voltages at V1,V2 and V3, not too concerned with V4 & V5 right now.

TM