18 Watt to Matchless Conversion

[dunner84]

Hello all,

I have been feeling very bad for my 18 Watt TMB lately. I just don't play it anymore. It was my first hand built amp, and at first it was versatile. I loved the cleans, and a few different rock tones. As my amp collection grew, I realized it only did one thing well; a very specific OD sound. It is a sweet tone, but not one that I have needed for years now.

Enter Matchless.

I was thinking about what to do with the amp. It is my only el84 amp, so I wanted to keep it that way. A friend of mine has a 15W stereo el84 Gibson that I absolutely love, but the 18W chassis is just a bit tight. I decided to do a Matchless Lightning/Spitfire Clone. The schematic situation for these amps is a bit dicey, but I found a few, and I noticed the Ceriatone Layouts were very close to my 18W board which was originally a Weber 6M18 kit.

The conversion is complete. It is not nearly as pretty now, (or as it could be. I will tidy things up in a few weeks), but I am very happy with the conversion.

The very first thing I noticed after I fired it up is it's not as loud as it was before. I confirmed this with a side by side shootout with my 5e3 (same speaker), and the 5e3 is indeed louder. This was not the case before. I find this very odd because the power section is basically unchanged. I then noticed that the original transformer has a 4k primary... This doesn't seem right for an el84 amp. I never questioned it with the original build though, and the amp was loud before with the same tranny.

I will post my voltages, and pics of the layouts used. The only component modification I made was to the 22k dropping resistor to the PI I used 10k as that is all I had on hand, and the internet seems to be divided on the correct values anyways..

The only other issue with the amp is minor, but the treble control on the lightning is fairly unstable. It introduces a lot of hiss when cranked, and squeals at max. I am attributed this to the lead dress, which is not ideal at the moment due to the spitfire/lightning switch. I will be cleaning all that up now that I know it all works.

Any thoughts on the possible volume issue?

Voltages:Pins in order left to right.

V1:145, 0, 1.16, htr, htr, 145, 0, 1.1, htr

V2:186, 0, 1.3, htr, htr, 314, 187, 187, htr

V3:256, 37, 56, htr, htr, 262, 38, , htr

V4&5: 0, .01, 10.31,-,-,-, 334,-, 316

V6:5ar4 pins 2 and 8 340v

Cathode Resistor is 126.2r so approx 40mA on each el84 but approx. 13w plate dissipation

[sluckey]

Any thoughts on the possible volume issue?

Most of the Lightning schematics I've seen show a voltage divider between the wiper of the treble pot and the input cap for the PI. This voltage divider consists of a series 220K and a 100K to ground, so you will only get 1/3 of the signal into the PI. Just remove the 100K and you will get all of the preamp signal into the PI and your amp will be much louder.

[dunner84]

I will definitely try that, but when I switch to Spitfire mode, I believe it bypasses the voltage divider. The Spitfire side is also not as loud. It is also missing a gain stage, but all in all, I feel its missing.... something..

I know "not as loud" is subjective, so I will try explain more. The "clean" settings on my 5e3 will hang with my drummer, but the clean on my 5f2a wont. I don't think the clean on the matchless conversion would hang with my drummer.. The punchy, crispy matchless tone is there, but not at the volume I was expecting

[dunner84]

The lightning rev1.jpg didn't show as a thumbnail. It outlines the spitfire/lightning switching I employed.. Could the 2M2 resistors I added to reduce popping be killing my signal level?

[sluckey]

I see the Lightfire_rev_1_1.pdf just fine. The spitfire mode will definitely be quieter than the Lightning. Nothing you can do about that. Those 2.2M ain't loading the signal down. But that 100K in the Lightning preamp certainly is. Just lift one leg of it and see for yourself.

That Lightning should scream just as loud or louder than that TMB. Of all the amps I've built the Lightning is the only one I never liked.

     http://sluckeyamps.com/lightning/matchless.htm

[PRR]

The lightning rev1.jpg didn't show as a thumbnail.

No "thumbnail", but the link works fine.

It was large and rotated, so to save wear/tear on everybody's PDF readers here's a fixed GIF.

[nandrewjackson]

+1 on removing the 100k to ground after the treble.


Also, 0.0015 uF after the first stage? That's a tiny cap, which means high resistance.  Try bigger, then try way bigger. 0.0068  ,  0.01

[dunner84]

Thanks everyone for the input! A few things to note:
the .0015 cap after the first stage is a .0022(all I had on hand), and I will experiment with rasing the value.

I cleaned up the switch wiring, and the amp is nice and quiet against

Clipping the 100k resistor to ground was 100% the right thing to do. It gave the volume boost I was looking for. However, after spending some time with it, there is "hair, fuzz, fizz" on all the low notes on the lightning, even with the volume at 0.5.... The overdrive sound sounds like I have my Sam Ash fuzz pedal on.. it's not bad, just not what I expected. That "fuzzy" thing is even present on the spitfire mode, but with the volume at much higher levels... I also hear a swirling noise in the overdrive...

It just doesn't seem right, so I tore through the amp, component by component..

the V2 cathode measured at 1.1k even the the color code is 1.5k 1%.. bizarre, but I swapped it for 1.8k.. It gave me slightly more clean, still buzzing though.

I swapped a 120k plate resistor in for V1. No change

I lowered the phase inverter bias from 1.2k to 900k..
No change

Rolled through about a dozen preamp tubes.
No change

Any ideas? I'm guessing it's an issue in V1 or PI onwards because its present in both modes to some degree..

Also, I typed this out on my phone, so apologies for spelling/grammar...

[sluckey]

Any ideas?

Yeah, but you won't like it.   


I scrapped my Lightning and built a nice sounding Vox AC-15. No regrets.

[dunner84]

Haha, not opposed at all! After listening to more YouTube videos, I have come to terms with the fact that there is an inherent fizz to these amps, and I do like the Vox AC15 sound clips I have heard.. I will look over some schematics.. there are so many AC15 variants out there.. my understanding though, is that these Matchless circuits are "improved" AC15s though, so where is the fizz coming from?

I will say, the Spitfire side sounds very nice. I can see it being very serviceable for me. Much more so than the 18w TMB.. The fuzz effect in the Lightning is kind of cool, but maybe not useful for me.

Any ideas what that swirling sound is? I want to rule out issues in the power supply, power section, and PI before I go down a more serious path like building an AC 15 instead.

Cheers

[sluckey]

Put a 47pF cap between pins 1 and 6 of the PI. Fizz any better?

[dunner84]

I tried various snubbers earlier today, and no fix, but I did permanently change the V1 plate resistor to 120k. Everything is a bit sweeter that way... However, I took a break from yardwork today, and spent a good chunk of time playing the thing, and playing it against my 5e3.. 5e3 still louder and clearer than the spitfire, and same volume as the lightning when driven. Different beasts, and I like the tonal differences between them. You can't hear the fizz in a jam setting, and the magic with this Matchless clone is with "reasonable" volume and tone settings... The lightning sounds best around 3-3.5 on the volume, and the treble/bass around the same. Spitfire sounds best with the volume between 4 and 5 with tone around 6-8..

I think I am happy enough to leave it for now, and use it for a few practices, and a gig or two. I will report back after that...

I am still intrigued by the idea of an AC15.. I will spend some time listening to them over the next few weeks... If I make the switch, I want it to be worthwhile.. I looked at Sluckey's AC15 project, and I noticed it replaced a Lightning clone, so I am curious to hear any thoughts on the differences. I know I wouldn't want a trem circuit though, so I am not sure how that changes things.

[sluckey]

I know I wouldn't want a trem circuit though

Maybe my dual lite would interest you. It's an AC15 with EF86 preamp plus 18W IIB preamp.

     http://sluckeyamps.com/dual_lite/dual_lite.htm

[dunner84]

Thanks for the link Sluckey, that looks like a sweet amp! I noticed it shares the same PI as the matchless amps. Can someone school me quickly on the differences between this PI and the marshall 18w? After some reading, I get the sense that this really separates the vox sound from the marshall sound, but could it also be responsible for the still noticeable output volume difference?

Grid leaks: 470 to 220k - not sure of the overall effect.. more clean room?
Cathode - 820 - 1k2 - cools the PI bias - I experimented with these, and didn't notice a difference.
Tail resistor 56k to 47k - increase gain?
8.2k to 1.5k grids - not sure
470k to 1M on pins 2 and 7 - not sure

If there a single move here that would have dropped the volume output of the amp?

[turtle441]

Dunner84, you're pretty far along in the process at this point, but if you're looking for another schematic for comparison, see attached.  If I remember right, I bumped up the value of R22 slightly, but otherwise the schematic reflects the final result.  I called mine the "Splitfire", but concept is very similar.  It's been my main amp at church ever since firing up.  Spitfire is dialed in to a nice chimey clean tone, Lightning cranked a bit more for the base overdrive sound.  Did not note any fuzziness that you described on the Lightning side, so I'm not sure what's driving that. 

[dunner84]

Thanks for posting that. It's pretty much what I have going on. Oddly enough, the fuzz, fizz, and swirling is gone... The only thing that remains that I would consider an issue is the over all output. The clean is definitely not as loud as my 5e3, and overdriven they are close. If I switch my cascade switch on the 5e3 it's REALLY loud, and this matchless clone doesn't keep up.

I have a feeling that some of the changes in the PI could be responsible, but I just don't know enough to say for sure.

If I change anything else, it would be anything for a bit more volume, because I'm digging the tone, and perhaps placing the preamp switch on a footswitch somehow

[vampwizzard]

I built a spitfire.. louder than all getout. Did it with AO-39 iron, 4ohm output. Its stupid loud and stupid clean. My modification was to make the master volume control a tone cut. I wound up not using the trem portion of this circuit. schematic available on my thread

https://el34world.com/Forum/index.php?topic=23769.msg255632#msg255632