amp not outputting full wattage

[johnhoef]

Chuck H, Indeed, I become more and more aware of this, and more and more disappointed that these manufacturers are doing this. The owner of the above mentioned Harbinger speakers is the lead vocalist in one of the bands I play in. I have observed him now and then bragging about his PA system, and the 1200 watt rating. You should have seen the look on his face when I told him it's really only a 200 watt system! I assured him that 200 watts is more than sufficient for our needs. If and when we make it to Carnegie hall, there will be no issue, as then we will be employing a sound company that uses their own 1200 watt PA!! (A REAL 1200 watt system!). You mention car amps...indeed, grossly over rated. I have always been aware of that, but guitar amp companies....you would think they have more self respect. Back in the 60's and 70's home hifi equipment was spec'd out at true RMS undistorted power output. I miss those days!

[Helmholtz]

Still it must be possible to get more than 70 clean "RMS" watts (more exactly: average or mean power) from 4 6L6s with the measured voltages.

What are screen voltages at full power?

Did you try to measure RMS output voltage directly at the secondary leads of the OT?

[johnhoef]

Helmholtz, It's been a while since I have worked on any amps that use four 6L6 tubes. Next time I do, I'll come back here with further observations.

[J M Fahey]

You can indeed get real 100W RMS out of 4x 6L6 or EL34 BUT you need scary 520/530V +V to do so , plus feed screens not more than 400/420V so they survive or tie them to Ultralinear taps so when plate saturates they get less than 60% of +V which also saves them.

391V +V as was measured on old amp? ... forget it.

[Vucinic]

I have two times volume problem with my SC200plus MKIV. First time i have a big ball of solder under the turret board touching the cassie, second time it was 470K instead 470R at PI

[J M Fahey]

I have two times volume problem with my SC200plus MKIV. First time i have a big ball of solder under the turret board touching the cassie, second time it was 470K instead 470R at PI

WHO put that solder ball there and a 470k instead of a 470r?

[Vucinic]

WHO put that solder ball there and a 470k instead of a 470r?

Someone before. Turrets have holes in the middle. With too many soldering, solder leek through that hole and go under the turret board and make a contact with the cassie.

470K.... I dont know

[frus]

Happened to me once... only it was fiber/eyelet board mounted on standoffs, blob was almost touching, and when that (combo) amp started to vibrate, made B+ short to chassis... took out house's breaker

Fortunately, this was before the gig started and we had a spare

[Chuck H]

Early in my learning/modding phase I had found that it made a better joint if you flow new solder rather than just melt the old solder when changing components. I hadn't been paying attention to excess solder buildup on an eyelet board and during a modding session I actually saw a blob of solder fall out the bottom of an eyelet. I never had the unfortunate circumstance of a short, but I learned then that you need to monitor this and occasionally suck out the old solder to avoid buildup. I use a plain ol' bulb sucker for this and have learned to get by with it, but really I should have bought a de-soldering station over a decade ago.