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Post by Peegoo 🏁 on Feb 12, 2023 23:53:28 GMT -5
Since I finished the last amp a month ago, the bug just has not flown off.
The problem is this: as I was rifling through my pile of stuff for my last build, I uncovered a few more U/I turret boards, a few chasses, power transformers and output transformers, caps, resistors, amp handles and other hardware and a whole lot more.
So today I made up a list of stuff I need to build another amp in the realm of the Matchless Lightning. It'll be a single-channel thing with three 12AX7s and two EL84s with an EZ81 rectifier, active tone controls and a master volume. Like a Vox AC15 on steroids. And I have all the parts to slap one together. The only thing I don't have is a cabinet, but that can come later.
I know I'm sick. I know I have a problem. It's hard to sleep!
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Post by Pinetree on Feb 13, 2023 16:21:18 GMT -5
Pics or it didn't happen.
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Post by Peegoo 🏁 on Feb 13, 2023 21:03:55 GMT -5
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Post by Pinetree on Feb 13, 2023 21:07:58 GMT -5
Geno, we're going to have to get together someday over a bottle of Flux.
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pdf64
Wholenote
Posts: 557
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Post by pdf64 on Feb 14, 2023 9:56:25 GMT -5
Active tone controls?!
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Post by Peegoo 🏁 on Feb 14, 2023 13:17:37 GMT -5
I misspoke ("misstyped?") calling them active; they're interactive, with one affecting the other. This circuit has the master volume after the phase inverter. There is a discussion in the amp building world that it's a bad idea. I don't understand why this is, because it works well in some amps. Any thoughts on this?  |
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Post by Pinetree on Feb 14, 2023 13:41:40 GMT -5
Well, it's got an awful lot of squiggly lines.
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Post by Leftee on Feb 14, 2023 14:32:30 GMT -5
I always burn the paper when I try to solder the lines.
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pdf64
Wholenote
Posts: 557
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Post by pdf64 on Feb 15, 2023 11:55:51 GMT -5
I misspoke ("misstyped?") calling them active; they're interactive, with one affecting the other. Yes indeed! eg turning the bass full creates a deep mid scoop, turning treble up full cuts bass. Have you had a play with the simulations on this? site www.guitarscience.net/tsc/info.htmThis circuit has the master volume after the phase inverter. There is a discussion in the amp building world that it's a bad idea. I don't understand why this is, because it works well in some amps. Any thoughts on this? Under Ken Fisher's nomenclature, that's a type 3 master. Its benefits are that it's really simple and is fine for shaving off a few dB from a cranked amp. Downsides are the signal gets muted before even -20dB attenuation is achieved and they're only really suitable for 12AX7 LTP phase splitters. The type 2 (and its LarMar variant) aren't really much more complicated (especially for a cathode biased amp such as a Lightning), and have a much better range of control for lower volume use, and work great with any type of phase splitter. See p23-26 of this pdf (says p41 on the page) robrobinette.com/images/Guitar/Trainwreck/The_Trainwreck_Pages_searchable.pdf |
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Post by Peegoo 🏁 on Feb 15, 2023 13:03:26 GMT -5
I misspoke ("misstyped?") calling them active; they're interactive, with one affecting the other. Yes indeed! eg turning the bass full creates a deep mid scoop, turning treble up full cuts bass. Have you had a play with the simulations on this? site www.guitarscience.net/tsc/info.htmThis circuit has the master volume after the phase inverter. There is a discussion in the amp building world that it's a bad idea. I don't understand why this is, because it works well in some amps. Any thoughts on this? Under Ken Fisher's nomenclature, that's a type 3 master. Its benefits are that it's really simple and is fine for shaving off a few dB from a cranked amp. Downsides are the signal gets muted before even -20dB attenuation is achieved and they're only really suitable for 12AX7 LTP phase splitters. The type 2 (and its LarMar variant) aren't really much more complicated (especially for a cathode biased amp such as a Lightning), and have a much better range of control for lower volume use, and work great with any type of phase splitter. See p23-26 of this pdf (says p41 on the page) robrobinette.com/images/Guitar/Trainwreck/The_Trainwreck_Pages_searchable.pdfSee? It pays to ask an expert! Thank you sir. I'm sure Matchless knew what they were doing when they designed this circuit; it was intended for lower-volume/studio work. But it can still get plenty loud. I've played through one and as simple as it is, the tone is meaty and juicy and complex. So this is a bucket-list build for me. I've got an original copy of The Trainwreck Pages--got it from Steve Melkesithian when he was running Angela Instruments in the 1980s. It's been years since I read through it. Thank you for the reminder, and thank you for the info! |
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Post by Peegoo 🏁 on Feb 15, 2023 13:08:06 GMT -5
Holy smokes, the Tone Stack Calculator is a lot easier than using a calculator and about 30 pencils!
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pdf64
Wholenote
Posts: 557
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Post by pdf64 on Feb 15, 2023 15:47:27 GMT -5
Oh, I forgot to mention, an often significant downside of any master volume after the phase splitter (ie types 1, 2 & 3 under the Trainwreck system) is that it’s incompatible with a transparent fx loop. ie as the depth of overdrive is increased, the wet signal will get muddied up / distorted / compressed. And if the amp has a negative feedback loop (not the Lightning), the degree of negative feedback will be affected by the master volume setting. And an associated presence control will quickly lose its efficacy as the master volume setting is reduced. A type 4 master volume overcomes the above issues, but for a given depth of overdrive, it requires more preamp gain (eg another amplification stage). Here’s the LarMar robrobinette.com/images/Guitar/Trainwreck/Type-2orLar-Mar_Master_Volume_Schematic.png |
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Post by Peegoo 🏁 on Feb 15, 2023 20:05:22 GMT -5
^^^I'm learnin' this stuff!
Thank you, maestro.
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Wrnchbndr
Wholenote
Posts: 353
Formerly Known As: WRNCHBNDR
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Post by Wrnchbndr on Mar 30, 2023 21:56:44 GMT -5
Love it. Once you start you can never stop.
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Post by LTB on Jul 6, 2023 15:20:55 GMT -5
Well, it's got an awful lot of squiggly lines. That is what happens when a worm hits a brick wall at 60mph |
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