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If you are interested in a layout for a 30W, I posted them:

Untested Layout at:
http://www.trinityamps.com/ForumGallery ... layout.gif

This is Ken Smith's prototype layout. I have emailed him to see if there is an update and will post any updates here as well.

Schematic at:
http://www.trinityamps.com/ForumGallery ... ematic.gif

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Ken replied to me. Looks like a project. Any takers?
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I quit working on that some time ago and decided to just go with the Lightning, built from your layouts, I might add. It works perfectly for me. Since I play mostly low gain, I decided to just build the 12AX7 channel and forgo the EF86, plus the 15 watt power section of the Lightning is MORE than enough noise for me! I need 30 watts like I need a hole in the head.

That layout has some significant errors in it, BTW. It might be a place to start, but it does need lots more work.

Thanks for asking, and I wish you well in your venture. I have seen your forum, and it is great.

Thanks,
KS

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

I'm kinda interested but want something more high gain like the hotcat 30r which I hear is a similar circuit.

Stephen, I'm kinda regrouping from working full-time and going to grad school at the same time. Kinda fried right now.

I have most of the components at home to start building a HC-30/15, but need to regroup right now. I figure towards the middle of the summer, after the 4th of July, I'll get some momentium happening.

The head I am building is using a Hammond Black chassis and the screened in top cover, so my layout will differ. I'll keep you posted.

I'll be running the EL84's in pairs with separate cathodes so it can run 15 watts on one pair. Also will run without the impedance mismatch and will be using a VOX output tranny leftover from their HW series (essentually an Abion Clone).

So correct me if I'm wrong but if your run the output tubes in pairs to separate cathode resisters then when you change from 30 watt operation to the 15 watt operation you do not have the impedence mismatch.? Got a diagram as opposed to the schem orginally posted in this topic. It's something that needs to be visual forme to completely understand.

I'm just sitting here thinking about it( the switch in power options) and I can;t see how the separate cathode resisters would actually fix the impedance mismatch?! Granted i don;t have the equipment to tell whether or not it does fix the impedance problem, but this topic is one that's really getting under my skin. Any takers?!

There is only 1 effective cathode resistor for each configuration. 62 for Hi and 130 (68 + 62) for Lo.

When the 4 tubes are in parallel, the impedance is 4K, when only 2 (Lo power) the impedance is 8K. When they switch this to low power on the 30W OT, which is 4K, you get the "Lightning" output stage with the mismatch and 130 ohm cathode resistor. Back to Hi, you get matched impedances and 62 ohm cathode resitor.

Kind of like getting two amps in one. Matched & Unmatched.

All is Well!

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

I'm just trying to figure out how I can fix the mismatch. Screw it. I'll probably never use it anyways.

Well, I just finished a 30W "Lightning" . Matchless 'designed in' a mismatch for the Lightning. The 30 doesn't. The bonus is, if you build it that way, with the switch, you get a lower power amp that is a Lightning, and a higher power amp that has a DC-30 "Lightning" channel a bit cleaner. So far it works on mine, but I have to do some more testing. I put a 2PST switch in the back to switch in the cathode resistors.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

I'll still add the switch. I think I'm gonna go with the 30 design but I'm leaving out the ef86. I built one for a friend and it sounded great but just not my style.
Anyways, my big concern is the long term effects on the OT and power tubes operating in 15 watt mode because of the mismatching impedances.

I mean, what do you think? To me I'm building my dream amp and I don;t what it to turn into a nightmare. corny, but fun.

I've got the cab built with a pair of BBQ blue dogs and some hardwood slated for the head cab, can't wait to heat up the iron, but, and a big but, I got too much repair work to start right now.bummer.

Get some EL84M (military) tubes. They sound good and will last longer. Some people do complain that the tubes don't last as long on a Lightning. If you match the impedance, they may last longer and still sound good. Up to you, but it wont be a nightmare!

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

I'm bringing this post from way back, but couldn't you just use an OT with multiple taps to rematch the impedance by switching taps via the speaker impedance selector?

I have done this in a 5E3 based amp with an 8 ohm speaker. With a correctly specified PT and OT, I used a 5Y3 rectifier and 6v6 power tubes in the 4 ohm tap and both 5U4 and 5AR4 with EL34 and 6L6 tubes using the 8 ohm Tap. Voltages were correct, no excessive heat and great sound. OT primary was 4,000 ohms / 8 ohm tap and should double that in the 4 ohm tap, right?

You are correct. You can mismatch the OT / speaker and thereby change the refelcted impedance the power tubes see. And it will work just fine.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

This information was very useful for me thanks for sharing this information.

All I'm doing is attempting to determine how to correct the discrepancy. Forget about it. Besides, I doubt I'll ever use it. 
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