trinityamps.com

Hey guys,

I just finished the lightning...I had a few concerns regardling the voltages....I think they're a little high, Here they are:


Recto p#8 375v (I've been under the impression that B+ for this thing really should be no higher than 360ish, am I wrong?)

el84s (v4 / v5)

#3 - 7v
#7 - 370v
#9 - 241v

PI (v3)
#1 - 248v
#2 - 26v
#6 - 245v
#7 - 26v
#3 - 71v
#8 - 71v

V2
#1 - 144v
#3 - 1.9v
#6 - 281v
#7 - 145v
#8 - 151v

V1
#1 - 131v
#3 - 1.3v
#6 - 131v

Let me know what you guys think. Regardless, I still took the amp for a spin with the tele....holy sh*t what ungodly awesome tone!

-F

looks good
B+ is fine as long as '84 screens V+ are in that region (or even a tad higher)
it looks like your running about ~10W or so per '84
I really like they way Mark S dealt w/ the screens on these amp designs.

_________________
the bastard son of Jack Parsons
http://www.rotten.com/library/bio/mad-s ... k-parsons/

That's good to hear....because I really don't want to change a thing on this amp, it sounds killer!

-F

B&V,

I think the voltages are a bit high. Other voltages for comparison are posted in this forum at

viewtopic.php?t=151

But if you got the tone...they'll beg for mercy!

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

Yeah, Stephen...I've cross referenced with those voltages too....I dunno...tone is great, flippin great. But I don't want to change these tubes like they're light bulbs either...

What transformer are you using? I'd try to take the voltage down 10-15V

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

s2 PT

Should be good. Same as 18W. Why so high. Did you use 22K dropping resistors? Boy, you and transformers, I gotta tell ya...

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

Yeah, you mean the 22K's connecting the filter caps? sure did!

Yeah, I dunno man, transofrmers are driving me crazy

Frank
First, what is the voltage drop across 22k screen2 dropping resistor. Or better yet, what is voltage drop across 100 ohm screen resistor (just one).

What I'm getting at is that EL84's are inherently capable of 500+ volts on the plates. I'm prob going to catch flak for this. As long as the Pv2 is below 2W and plate dissipation is below 12.1W (on each '84...they're fine. Look at the Traynor plate voltages. You can check w/ Zaphod Phil over on the 18W board re: this. As long as you control the power dissipation on the plate and G2, your voltages are fine.

The Lightning seems to be the only Sampson design that even addressed this (well, I used the Chieftan power amp design in another amp that worked well, too).

Aw hell, don't listen to me. I'm using a 15k dropping resistor/33uF cap and diodes on my G2 screens to counter G2/plate interaction. What the hell do I know

_________________
the bastard son of Jack Parsons
http://www.rotten.com/library/bio/mad-s ... k-parsons/

Chief Mushroom,

I'll have to get back to you later this afternoon...I have to finish the fence in my backyard today, So I'm going to be busy most of the day doing back-unfriendly labor.

However, I will take additional measurements by 3ish.

-F

Frank.

I'm running the Bluesbuster P18 at those knid of voltages. The 20 Watt Marshalls run 385 V B+.

If I were you, I'd get a 1K 3 to 5 Watt and put it inline from Pin 8. That'll drop ya 10 Volts or so and won't scare ya to death like the heat off a 10 to 15 Watt Zener to ground.

CR ><>

_________________
WoodCross Amps

http://www.geocities.com/woodcrossamps/

Macabee , what's frustrating is that everyone out there runs this circuit without having to chuck resistors into the power supply to get voltages right...especially with common transformers.

So until I determine that I didn't miswire something, I'm going to keep doublechecking my work....wondering whether there might be a culprit in the circuit...and not the ps..

But once I do that, then I might resort to some variety of limiting resistor.


What's considered optimal B+ voltage for the lightning?

You did put a choke in there right?
Optimal? Maybe nominal 350?

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

Bwahahaha...Wait, is that what that thing was on the schematic? I thought that was an optional resistor!
(/sarcasm off)

seriously....Yes, I did put a choke on the amp.....It's a hammond 158M. (the one I never sold)

-F

Part of me suspects the rectifier...I'm using a JJ GZ34....and maybe it's just not dropping the right amount.

Guys, on your lightning builds, what are the voltages of your PT secondaries and B+ coming off the recto?

Don't have one I can measure right now, sorry B&V.

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

No problem Stephen. If this is still an issue when you build your next T-15, maybe give it a looksie for me. otherwise, not really a big deal.

Anyone else, if you have your lightning cracked open, I'd love to hear...but don't go out of your way.

Let those Bottles Glow, Bro! If it sounds good, it's right!!!

CR ><>

_________________
WoodCross Amps

http://www.geocities.com/woodcrossamps/

I like that attitude....if only I can shake this obsessive compulsive disorder regarding the voltages...