Sluckey Matchless Lightning Build Preparation

[RadioComm]

Hello,

Thanks @sluckey for sharing your work on the Matchless Lightning Makeover page:
https://sluckeyamps.com/lightning/matchless.htm

I'm in the preparation stage to build this amp, and am about to do a parts list to order the components from Doug. Checked on Doug's and sluckey's page for one, but did not find one. So before doing one, just wanted to make sure there wasn't a BOM already available. Let me know. Thanks again.

Also, I'll be using a chassis that my old company excessed back in 2004. It's a 19" rack chassis (photo attached) that would include a whole lot of extra real estate. Any suggestions as to what I could use it for  I was thinking tube spring reverb with dwell, but then again the design has an effects loop. I have reverb pedals.... So I probably just run with building it as is.

Also, I'm seeing the 1ohm/3w resistors for checking bias on v4/v5, but there's no bias adjustment pot.... Never mind! Cathode biased. Got it.

Thanks

[RadioComm]

Starting with the board. Will be cutting my garolite sheet and drilling according the attached modified template provided by sluckey. Modification shown in the attachment is the removal of the redundant 220K/100K resistors from the board, since I will be implementing this build with an effects loop. Also there is some space to the right of the board where I will be installing the 47K grid stopper. Will be using rg174 from v1 to resistor.

[sluckey]

You can trim all the blank space at the ends of the board if you want. The only reason for the extra blank space is because I made the Lightning board the same size as the November board it replaced. No extra chassis holes had to be drilled.

Hope you enjoy this amp. I never bonded with it and it became a donor for my AC-15 project.

[RadioComm]

You can trim all the blank space at the ends of the board if you want. The only reason for the extra blank space is because I made the Lightning board the same size as the November board it replaced. No extra chassis holes had to be drilled.

Hope you enjoy this amp. I never bonded with it and it became a donor for my AC-15 project.

lol  Indeed, you made it fairly clear in your article this was not your favorite amp. You even cranked it up all the way and gave it your best shot. Not surprised at all that since 2009 you recycled it. I was just in the process of cropping both sides of the board in order to print the template with correct dimensions. As stated earlier, I'm leaving just a little extra space on right for the grid stopper.

Will also be putting together a BOM this week. Will share once it's done. Thanks again @sluckey.

ttfn

[RadioComm]

Here is the parts list for sluckey's design (attached):

Transformers:
PT    - Hammond PT270FX: 550VCT @ 173mA
OT    - Hammond PT1615: 15W / 5k ohms
Choke - Hammond PT193B: 12H / 100mA

Can Capacitors:
2 - 32uf + 32uf / 450V

Electrolytics:
2 - 22uF  / 500V
2 - 22uF  / 50V
1 - 250uF / 50V

Capacitors:
4 - .022uF  / 630V
2 - .01uF   / 630V
1 - .0012uF / 630V
1 - .0047mF / 630V

Mylar:
1 - 180 pF
1 - 51 pF

Resistors:

3 - 1M   / .5 W
1 - 1.2K / .5W
2 - 47K  / .5W
1 - 22K  / .5W
2 - 1.5K / .5W
5 - 100K / .5W
1 -  56K / .5W
1 -  10K / .5W
4 - 220K / .5W

2 -   1 / 3W (not using since cathode biased)
4 - 22K / 3W

2 - 100 / 5W

1 - 120 / 10W

Potentiometers:
5 - 1M Audio

ttfn

[Bieworm]

Why put the grid stopper on the board? It's common knowledge they are best put as close to the tube socket as possible,  i.e. on the tube socket directly

[sluckey]

Why put the grid stopper on the board? It's common knowledge they are best put as close to the tube socket as possible,  i.e. on the tube socket directly

Sometimes I don't follow the herd. 

Yes, they would be better mounted on the socket. Hoffman connects the stoppers between pins 1 and 2. Very neat. Just be aware that some EL84s and 6BQ5s have pin 1 internally connected to pin 2 and would short out the stoppers. You'd probably never know unless you measure resistance between pins. Also, you could use a chassis mount insulated turret close to the socket (like I did for V1) and mount the resistor between the turret and pin 2. Then you don't care if pins 1 and 2 are internally connected.

I have built 6 EL84 amps. Grid stoppers are on the board for 5 of these amps. My final EL84 amp, Dual Lite, has the grid stoppers mounted directly on the sockets between pins 2 and 8. Phew, I feel better now! Probably why the Dual Lite is one of my most favorite amps.   

[RadioComm]

Why put the grid stopper on the board? It's common knowledge they are best put as close to the tube socket as possible,  i.e. on the tube socket directly

Sometimes I don't follow the herd. 

Yes, they would be better mounted on the socket. Hoffman connects the stoppers between pins 1 and 2. Very neat. Just be aware that some EL84s and 6BQ5s have pin 1 internally connected to pin 2 and would short out the stoppers. You'd probably never know unless you measure resistance between pins. Also, you could use a chassis mount insulated turret close to the socket (like I did for V1) and mount the resistor between the turret and pin 2. Then you don't care if pins 1 and 2 are internally connected.

I have built 6 EL84 amps. Grid stoppers are on the board for 5 of these amps. My final EL84 amp, Dual Lite, has the grid stoppers mounted directly on the sockets between pins 2 and 8. Phew, I feel better now! Probably why the Dual Lite is one of my most favorite amps.   

Have not cut out my garolite board yet, or drilled holes... So, in order to follow the herd *and* take @sluckey's counsel from the Dual Lite project, I'll remove the two 1.5K resistors from the board, connect them to pin 2 & 8 (for v4/v5), using pin 8 as a post. Yeah/Nay?

Also please a yeah/nay... The 47K resistor on v1, I was going the move it to the board and connect the socket to the board with rg174. Or just should I just keep it hooked up to a post?

Thanks again

[sluckey]

I'll remove the two 1.5K resistors from the board, connect them to pin 2 & 8 (for v4/v5), using pin 8 as a post. Yeah/Nay?

yes

Also please a yeah/nay... The 47K resistor on v1, I was going the move it to the board and connect the socket to the board with rg174. Or just should I just keep it hooked up to a post?

Keep it on the post.

[RadioComm]

I'll remove the two 1.5K resistors from the board, connect them to pin 2 & 8 (for v4/v5), using pin 8 as a post. Yeah/Nay?

yes

Also please a yeah/nay... The 47K resistor on v1, I was going the move it to the board and connect the socket to the board with rg174. Or just should I just keep it hooked up to a post?

Keep it on the post.

Understood. Will do. Thanks sluckey. ttfn

[RadioComm]

Attached is the updated board template. ttfn.

[mresistor]

Probably why the Dual Lite is one of my most favorite amps.    

And my replication of your dual lite is a great little amp that is becoming my fave too, however it's in a tie with the Hoffman Super reverb. :-)   

[RadioComm]

Greetings,

For this build, I have selected as an OT a Hammond P-T1615 which has a 5K primary. From what I have read, this is the primary impedance that a Matchless Lightning uses. Since a pair of 6BQ5's are rated at 8K in a class ab push/pull configuration, there is obviously an intended mismatch. Since I'm not too clear on OT primary/secondary ratios, I have the following hook up questions for the secondary taps:

1) What secondary impedance would be optimal to reduce mismatch: 4 or 8 ohms?

2) The ML offers two output jacks, one at 4 ohms, the other at 8 (see attached schematic). In general, how does one determine the coupling (dependency) between the primary and secondary taps?

The following questions references the Hammond's hook up diagrams on which I made some notes (attached):

4) If a secondary has two taps, do both of them need to be used? The get 8 ohms out of the OT, couldn't I just hook up Yel & Blk/Yel? To get 4 ohms, couldn't I just just hook up Grn/Yel & Blk/Yel or even just Grn & Blk?

5) Looks like their 16 & 8 ohm diagrams are mislabeled (swapped). I'm not understanding their 4 ohm hook up. Looks to me like the two 4 ohm taps are hooked up in parallel, outputting 2 ohms... (yes/no?)

Here is a link to the OT's specs:
https://www.hammfg.com/electronics/transformers/classic/1608-1650

Once again, thanks so much for the answers.

Just answered one of my questions, from Hammond page:

"Due to the unique interleaving of the windings BOTH secondary windings must be engaged to meet specifications (see hook-up diagrams below)."
So still not sure about the 4 ohm hook up....

[sluckey]

Don't buy that 1615 OT. Buy the 1615A Easy Wire Secondary OT instead. Makes life more simple.

Hawk Electronics usually has the best prices on Hammond iron.

[sluckey]

For 4Ω... tie the green to the green/yellow. And tie the black to the black/yellow. Now connect the black to the speaker jack sleeve and connect the green to the speaker jack tip.

For 8Ω... tie the green to the green/yellow. And tie the black to the black/yellow. Now connect the black to the speaker jack sleeve and connect the yellow to the speaker jack tip.

I don't know who put the red writing on the Hammond diagram, but it ain't right. Ignore it.

Like I said earlier, make your life simple. BUY THE 1615A INSTEAD!

[RadioComm]

For 8Ω... tie the green to the green/yellow. And tie the black to the black/yellow. Now connect the black to the speaker jack sleeve and connect the yellow to the speaker jack tip.

1615A still an options... But, for 8Ω hook up on the 1615... This is for my understanding of how the two secondary taps interact... I'm guessing connecting the two 4 ohm outputs (Grn & Grn/Yellow) couples the two 4 ohm taps, and hooking up the yellow and black to the speaker jack yields and 8 ohm output?

[PRR]

... ... ...Looks to me like the two 4 ohm taps are hooked up in parallel, outputting 2 ohms... (yes/no?)...

No.

Think in terms of Turns Ratio. Not labels.

Two identical windings, parallel, is still the same turns ratio, but half the parasitic resistance.

This is convenient for the transformer maker. Not the transformer user.

There can still be overheating...... of the brain. Do as Sluckey says: find a less confusing part.

[RadioComm]

... ... ...Looks to me like the two 4 ohm taps are hooked up in parallel, outputting 2 ohms... (yes/no?)...

No.
Think in terms of Turns Ratio. Not labels.
Two identical windings, parallel, is still the same turns ratio, but half the parasitic resistance.
This is convenient for the transformer maker. Not the transformer user.
There can still be overheating...... of the brain. Do as Sluckey says: find a less confusing part.

Great explanation. Got it. Thanks PRR. Sluckey's 4Ω & 8Ω hook ups now makes sense.

Indeed, I was thinking of a discrete winding as a resistor of "label" value, not realizing the resistance is only parasitic to the turns ratio and not relevant to the hook up of the different windings. Thinking in terms of turns ratio did the trick. I realize now that the "label" doesn't describe the output of the OT, but describes to the user the impedance of the correct speaker to use.

Thanks @sluckey and @PRR for the knowledge and the help. Take care.

ttfn

[sluckey]

Any progress? Made your board yet?

[RadioComm]

Any progress? Made your board yet?

Ordered the parts last week. They just arrived yesterday. I'm moving forward with the 5K OT and an 8 ohm speaker. This is to meet ML15 specs in hopes that the mismatch has some unique tonal characteristics (fingers crossed lol). Also gave up the idea of using the posted chassis above. It's just *way* too big. I'm using a Hammond 17x8x3.
 
Haven't started cutting/drilling the board yet. I'm building the combo cabinet first with baffle board, speaker, and empty chassis (face plate will just be tacked on with double face tape). I would like to get it all assembled and mounted before I start drilling and punching the chassis. Not only do I think it would be easier to get the faceplate/chassis flush with the baffle board, but it would also give me an idea of what kind of clearance I have for the transformers and choke. Then I'll unmount the empty chassis, plan the chassis layout, and then start the amp build.

Making a cabinet is not my usual MO. Typically I start a build with a corporate made chassis/cabinet. Then degut, drill, punch, nibble, and build from there. The only cabinet
 I built was my very first amp build, a 5e3 clone (picture attached). I made this amp a little over 20 years ago.

With that amp, I turned the iron and the tubes upwards. This way I could make the amp and the cabinet separately without having to worry about clearances or getting things flush.

For that build, I had used the PT/OT from a friend's Mother's hi-fi set. PT voltage was too high so I followed instructions from Dan Torres's book (Inside Tube Amps), and installed a zener diode to ground from the center tap.

Thanks again sluckey for the help and sharing your work. I'll post pictures when I'm done.

ttfn

[RadioComm]

Changed my mind. Instead of a combo with iron and tubes down and hidden. I'm going with a head and mini cab. Iron/tubes up and exposed as with my first (and only) cabinet build. Gives me more flexibility for the chassis layout. And anyway I really like seeing those tubes glowing. Starting this week end with chassis layout and cutting the board.

[sluckey]

I just realized that I still have my Lightning board. If you want it I can send it to you 1st class USPS for $20. Send me a pm if interested. Here's a current pic...

[RadioComm]

Thanks sluckey for the offer. But no, building my own board is way too much fun. I have more amps than I'd like to admit to (corporate and my own homebrew), so building this amp is strictly for recreational purposes only. I really shouldn't say 'strictly', I have just as much fun playing on them afterwards. 

[RadioComm]

Was going to add a standby switch, but after reading this article, I am not. As alway The Valve Wizard has informative articles to read.

http://www.valvewizard.co.uk/standby.html

Headed to my workbench to cut the board and start chassis layout

ttfn

[ok_state_blues]

I just realized that I still have my Lightning board. If you want it I can send it to you 1st class USPS for $20. Send me a pm if interested. Here's a current pic...

@sluckey PM'd

[RadioComm]

Have the chassis and the board ready to drill, punch, etc. Will be doing that tomorrow.

For the front panel, I'm going to be drilling through both the Duraplex face plate and the aluminum chassis. I'm a little shy about doing this, because I've never had too much luck drilling though plexiglass. I crack the plexiglass and then have to start again with another piece... My approach tomorrow will be to use masonry bits to get through most of the face plate, until I hit and mark the aluminum. Apparently the bit needs to be water cooled occasionally  Then switch over to a standard drill bits to finish the hole. Does that sound reasonable? Any tips, recommendations, or better way of doing this.

I bought the Duraplex sheet at Lowes (a US hardware store):
https://www.lowes.com/pd/DURAPLEX-0-08-in-T-x-18-in-W-x-24-in-L-Clear-Acrylic-Sheet/3143519

These are the masonry drill bits I'll be using:
https://www.amazon.com/Ankey-Masonry-Concrete-Ceramic-Ceramics/dp/B09NM7W9ML/ref=sr_1_12_sspa?crid=1QL0N2EQTZGSA&keywords=plexiglass+drill+bits&qid=1643487021&s=amazon-devices&sprefix=plexiglass+drill+bits%2Camazon-devices%2C49&sr=1-12-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExTEI0TUZKMUg0OEVIJmVuY3J5cHRlZElkPUExMDE2OTE1QU5STjc3WlJLSkxMJmVuY3J5cHRlZEFkSWQ9QTAzODU5NzMxNTFFSFFBTkc5RVhKJndpZGdldE5hbWU9c3BfbXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

Thanks.

Just re-read the masonry drill bit description. It does say it handles soft metals and aluminum alloys. Maybe I'll just drill all the way through with the masonry drill bit...

[sluckey]

Drill press is very handy. I would first drill a 1/16" pilot hole with plexi taped to chassis with double sided tape. Then separate the plexi and tape to a sacrificial board with double sided tape. Now drill to size with a brad point bit.

[RadioComm]

No drill press. I'd like one. But not enough room in my basement. Thirty years of accumulating junk... Plus a playing area with drum set and all...

Sounds like a great approach. Will do. Didn't like the idea of the masonry bits, especially without a drill press. Too sensitive to angles. Thanks again sluckey.

[RadioComm]

Drill press is very handy. I would first drill a 1/16" pilot hole with plexi taped to chassis with double sided tape. Then separate the plexi and tape to a sacrificial board with double sided tape. Now drill to size with a brad point bit.

Been busy the last two weeks, finally got to drilling the faceplate this morning.

Thanks again Sluckey, All went well the first time around. Used the plexi that was drilled with the chassis as a template to drill pilot holes on another piece. Just in case... Did have to use a step drill bit for the 11/16" pilot light and the 15/32" power switch. Also don't have a drill press, but I do use a 'not-sure-what-to-call-it thingy' to help me drill straight. It can be seen in the attached picture. Taking a quick lunch break, but will be back at it for the rest of the weekend starting with finishing the chassis and putting the metal grommets into the board.

Will post pictures and an amp review in a new thread when the build is all complete. Hope everyone has a great weekend.

ttfn

[RadioComm]

Finished chassis and faceplate. Started the wiring, and in preparation I'm labeling the resistors in the layout.

When starting this project, I had downloaded a copy of sluckey's visio notes from his page. I noticed that his visio layout has since been updated. The 5 band resistors have been replaced with 4 band resistors, even though they are the same value/tolerance. The ones I checked anyway...

@sluckey - Why the update. Are there any other changes I didn't catch? Can I just continue with the original visio notes? Thanks again.

[sluckey]

@sluckey - Why the update. Are there any other changes I didn't catch? Can I just continue with the original visio notes? Thanks again.

I don't remember why. Maybe just bored. You should be safe using either drawing.