Single ended 6L6 / 6V6 D'lite

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TBN
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Location: The Netherlands

Single ended 6L6 / 6V6 D'lite

Post by TBN »

Hi All,

After a month lurking on the forum to absorb the necessary knowledge I started on my own hotrod build a few days ago.

I still had a Hammond 125 ESE OT and a 372BX PT lying around, and decided I wanted to use them for a Dumble-like amp.
After studying on the forum I chose the D'lite preamp, without foot switching, to couple to a SE 6l6 output stage. Rectification will be done by a GZ34, just because I like the sight of glowing tubes. To reduce B+ hum I added a Hammond 158M Choke and an extra filterstage before the B+1 tap.
.

On the picture below you can see all the hardware mounted on the chassis, all the components still have to be soldered. This will happen in the next week(s).
The purple knobs will be changed to blach chickenheads too, when I receive my next batch of parts :)

IMG_20180123_002331280_HDR.jpg
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Last edited by TBN on Mon Jan 29, 2018 3:40 pm, edited 3 times in total.
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pompeiisneaks
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Re: Single ended 6L6 D'lite

Post by pompeiisneaks »

I look forward to the progress!

~Phil
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telentubes
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Re: Single ended 6L6 D'lite

Post by telentubes »

Me too
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xtian
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Re: Single ended 6L6 D'lite

Post by xtian »

Looking good! I prefer to have different colored knobs to help identify functions. Especially helpful on dark stages.
I build and repair tube amps. http://amps.monkeymatic.com
TBN
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Re: Single ended 6L6 D'lite

Post by TBN »

Just ordered an old school Dymo label writer, so I can make some stylish indications of which knob does what.

Just finished work: off to home to do some more assembly and begin soldering!

Also got a test-box to make to establish the outer foil side on all of my newly arrived mallory 150's that will be used as coupling and tone caps.

update 3 hrs later:

Determined the placement of the board and filter terminals and placed standoffs for those. Drilled holes for the ground-lugs and planned what should be grounded where.
Mockup of the inside, with test fitting of the 5x 30u filter caps (limited the power amp filtering as well so i could use a 5y3GT if I want):
IMG_20180123_202356541.jpg
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TBN
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Re: Single ended 6L6 D'lite

Post by TBN »

Done for tonight...

Soldered the power inlet, power switch, heater terminal, connected the pt. Installed all the ground points. Soldered the rectifier + 2 HT fuses and backup diodes and installed the filter caps.

Happy with my layout: except for the 6,3V all AC stays in that little corner of the chassis.

Time for a snooze ...
IMG_20180124_003724671.jpg
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TBN
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Re: Single ended 6L6 D'lite-ish

Post by TBN »

Did some capacitor testing and a bit of soldering this evening:
IMG_20180125_005808208.jpg
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IMG_20180125_012228356.jpg
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TBN
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Re: Single ended 6L6 D'lite-ish

Post by TBN »

Progress this evening: Soldering further after dinner and probably first powerup later tonight :D :D :D
IMG_20180125_194924894.jpg
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TBN
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Re: Single ended 6L6 D'lite (update: IT'S ALIVE! )

Post by TBN »

It's alive!!

Finished it tonight and couldn't wait to power up. Sounds good, no oscillations but there is a little bit of crackle (actually, more of a hiss, esp when engaging OD) that I will have to trace down tomorrow. EDIT: other tubes fixed the problem! All functions working as they should. 8)
IMG_20180126_000342481.jpg
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TBN
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Re: Single ended 6L6 D'lite (update: IT'S ALIVE! )

Post by TBN »

Did some more playing today and discovering some of the feautures of the dumble preamp (this is my first d-style amp...).

I noticed that I liked the OD-trim in the first 20% of its range, so I repaced the 220K series resistor with a 1Meg, and I can far more accurately tune the range of the OD stage. That I left out the LNFB network on the second preamp stage might have something to do with that.

Really impressed with the clean tones of the amp, keep jangling about on the neck pickup of my tele :)

I used mostly the values listed in the schematic below, but after the MV controll, on mine there's a 0,022 coupling cap into the SE 6L6 power amp.
Further changes I made:
-4,7 U for all cathode bypass caps
-300p caps for bright and tone stack
-120K resistor in tonestack (was 150)
-Left out NFB on V1B
-Changed series resistor to OD-trim to 1Meg (was 220K)
-Grid stopper on v2a 56K (was 68K)
-Changed series resistor to OD Level to 220K (was 180K)
DLite_amp (1).jpg
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TBN
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Re: Single ended 6L6 D'lite (update: IT'S ALIVE! )

Post by TBN »

Got me a bunch of 10M resistors at a local electronics store and soldered in the LNFB on V1B today. I put the feedback loop on a switch to choose from the following options:

-FB on "Normal":10M-10M-0,047u-10M-10M
-FB OFF
-FB on "Intense" 10M-0,047u-10M

Interesting to be able to switch between the options. No feedack makes the sound a bit looser and hairier, while the strong fb tightens it up very much. The standard value somewhere in between. Intersting too what the effect is on the overdrive, it seems more defined with fb on.
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Guy77
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Re: Single ended 6L6 D'lite (update: IT'S ALIVE! )

Post by Guy77 »

Great looking amp! I also used the same choke 158M in one of my several JM/Wonderland builds and I really like how the amp sounds with that choke. It sounded better than the standard fender 4H 90ma choke that fender used in most all of there 2x6L6 amps. The 158M did not sound as stiff and tight as the fender or Hammond 194B choke did.

Cheers!

Guy
TBN
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Re: Single ended 6L6 D'lite (update: IT'S ALIVE! )

Post by TBN »

Thx Guy!

Perhaps worth mentioning is that, since it's a SE amp, the B+ for the OT branches off the supply line after the choke. Reduces SE hum immensely, especially when not using oversized filter caps.

my supply line looks like this:

300-0-300v from 372BX ---2 ht fuses ----GZ 34 --- 30uF ----choke --- 30uF (B+ OT) --- 1K 5w ---- 30uF (B+ screen) --- 6.8K 5W --- 30uF (B+ V2) ---- 10K 5W ---- 30uF (B+ V1) ----220K to ground
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Colossal
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Re: Single ended 6L6 D'lite (update: IT'S ALIVE! )

Post by Colossal »

TBN wrote: Sat Jan 27, 2018 11:21 pm Thx Guy!

Perhaps worth mentioning is that, since it's a SE amp, the B+ for the OT branches off the supply line after the choke. Reduces SE hum immensely, especially when not using oversized filter caps.

my supply line looks like this:

300-0-300v from 372BX ---2 ht fuses ----GZ 34 --- 30uF ----choke --- 30uF (B+ OT) --- 1K 5w ---- 30uF (B+ screen) --- 6.8K 5W --- 30uF (B+ V2) ---- 10K 5W ---- 30uF (B+ V1) ----220K to ground
Nice build! You've got it exactly right.

I use a CLC filter on all SE amps and following the CLC, I don't need large caps. In fact, I think the amp sounds better with lower filtering.
TBN
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Re: Single ended 6L6 D'lite (update: IT'S ALIVE! )

Post by TBN »

Still mesmerised by the sounds coming out of this thing, can't stop playing. When I did stop for a while I added a second speaker jack, soldered with a hard wired L-pad for a 1/4 power output jack and at the same time a failsafe for if I forget to plug any speaker in.

This is how it works:

On the speaker main output, the switching contact connects via a 4 ohm power resistor to tip of the reduced power output jack. On that jack i solderd another 8 ohm power resistor to ground.

When no speaker is plugged in, the OT sees the 2 resistors in series: 12 ohm (Far better than an open loop or a dead-short)
When plugged in to the main out, the reduced power jack is disconnected, includng resistors.
When plugged in the reduced output jack the OT sees 4ohms in series with the speaker and an 8 ohms resistor parallelled to that speaker. for a total of 8 ohms. (4ohms + (8ohms || 8ohms)). A quarter of the power flows through the speaker in this case.

Next to that I added a switchable cathode resister for the poweramp tube, so now I can switch between 330 and 470 ohm and use both 6L6 and 6V6 in this amp at the flick of a switch.
Nedless to say, with 6v6 and 1/4 power out, it's an ideal home - amp as well with 1,5 watts at the speaker :)

This is wat it looks like on the inside now:
IMG_20180128_145012458.jpg
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