2 x el84 Rocket thin and shrill!!

[mbailey]

I built this using the layout based on MFowlers build using Hammond 270EX P.T & 1608 O.T. No serious start up problems but the out put is very very low!
voltages
V1 V2 V3
1 171v 237v 266v
2 143v 230v
3 144v

6 114v 267v
7 234v
8

[KT66]

Nice looking build. It looks like your problem lies in the PI - your grid voltages of 230 and 234 are way too hi. For the voltages in your amp the reading at pins 2and 7 of the PI should be around 40, give or take a few. I also notice that the point I have labeled "G" in the pic below goes to the preamp ground bus in the layout, but you have no wire visible there. My bet is that you decided to ground that point at the bias resistor ground point under the board, but connected it to the PI plates by mistake.

[mbailey]

GOOD CATCH! I went over it with your drawing a dozen times and missed this missing ground every time?? LOL. She sounds great...really bright! thinking about putting a vvr in this one! anyway thanks for your help.

[M Fowler]

The amp shouldn't be really bright maybe it is the speaker used. I generally use a Celestion Vintage 30 and engage the bright switch 500pf to get mine bright.

Mark

[mbailey]

just the initial test run but it was thru an old alnico 15? will know more about it once i get it tweaked out!

[mbailey]

def. got problems, plenty of volume but shrill and thin thru sev. speakers. guess I need to check everything over again. anyone got any ideas I'm open!

[surfsup]

shrill and thin

Are you passing too much treble? Do you have any different caps to use for the tonestack? I would also be interested in any responses from the resident experts here.

[mbailey]

voltages all to chassis gnd except reading across cathode bias res.
any suggestions fellows?

[angelodp]

Nice layout, can you show the complete layout please.

Ange

[surfsup]

I don't see a lead from pin1 treble to the bass pot. If there's no lead there, you aren't getting any mids or bass which means it will be thin adn shrill. Please confirm?

[mbailey]

its there just hard to see in the pic. thanks for taking the time to look. I'm still trying to figure this out!

[Lonely Raven]

TIP: When you're sticking your camera up to the amp to take photos, set it to the MACRO setting...that's the little flower icon. That way, you might actually FOCUS on the amp, and not the background.

[mbailey]

layout i used

[angelodp]

Or use a simple tripod of some sort in indirect daylight- shade but bright. Set the camera to the smallest aperture f11 or f16 and use the shutter setting that the camera tells you is the correct exposure. This way you have maximum depth of field, even light and a steady image. Shoot from a medium distance so that you can see all the details you want to see. This should produce an image that has deep focus and lots of fine detail.

[mbailey]

pics updated hope this helps!