First post! Getting into amp building. Hot rodded Super Lead

[fretwizard]

Alright. I finished

Pics to follow

Voltage testing tonight!

R

[julkke]

Nice! Hope testing goes well!

[fretwizard]

[fretwizard]

I was starting with a Variac because in my flat i can get up to 265V.
It's the only way I could run my Egnater full blast without frying it, because it's wired for 230...

With this one instead, I started from 235 but I had to crank it up to 100% to get the heaters around 3.0/2.9v

I'm getting about 254V from the wall socket...

R

[fretwizard]

Pin5-V5 and Pin5-V6 give a range between -32 and -48 v.

[fretwizard]

Ok now I think I still have to use the variac. The closer i got to V3 the voltages started to get very different from the chart. Until I measure the plates and they were 512v instead of 498.

I measured the wall voltage again and it was about 260v

Is it normal that some pins on V2 and V3 have about half the suggested voltage, when the power tubes are unplugged?

and by the way, I could get any voltage until I turned on the standby switch, but the Metro instructions do not say so...

R

[fretwizard]

For the low voltages (like 3v, 24v, 48v) I read almost the half of it. But it might be my cheapo multimeter.

Now that I've lowered the wall voltage to around 240v the readings on V1 and V2 seem closer to the chart. But the heaters dropped to 2.5 V on each wire.

But on V3 I read this (pins 1-2-3 and 6-7-8):

314 - 11 - 28 - - - 229 - 3 - 42

Isn't it too off?

Plate voltage now dropped to about 455-460 on all powertube sockets...

I wired the PT for 240v and I actually get more of that withouth a variac, so what should I do? Are these values in the range?

R

[fretwizard]

I thought I could try it after all.
I have 2 1x12, with V30 and Lead80.

It was 00:30 am here. I cracked it up to 10, but playing very softly sounded very quiet, I mean my 30w Egnater is way louder...

I only heard a slight hum when cranked to 10, but consider that I don;t have a shielded cabinet yet and I was testing on the bench.

The guitar sounds very clean, it's a 2009 LP Custom with 490R neck and 498T bridge.

I'll see what happens tomorrow with an attenuator...

[fretwizard]

I tried with a 200w dummy load resistor, with a lineout into Logic+impulse responses...

Usually when I play for 2h with my egnater cranked the resistor gets quite hot, like 54 °C.

Now with this plexi kit, it doesn't get hot at all, it's very cold (21 °C) and I kept the amp cranked all the time . I didn't blow any fuses.
Is it possible that it's not outputting the right power?
way less than 30w?

The PT gets warm but I can touch it... I'm running with the variac at 240v.



R

[fretwizard]

Ok

I told Nik about the problem and he told me the PPI values were strange considering pins 8 and 3 are shorted. Then I looked at the layout and I realized...

I TOTALLY FORGOT TO SHORT THOSE 2 PINS....

I re-measure all the pins and now the voltages ov V1-2 are a bit closer, V3 is definitely in the trends of the chart and the plate voltages are all about 486v, at 240v wall voltage.

Let's see what happens...

R

[fretwizard]

It's definitely alive now!
The dummy load is getting hot. The tubes are glowing and buzzing and the voltages on V3 are matching pretty close.

Now the controls are really working and I'm getting the high pitched squeal when cranking the presence...

Do you think it's that thing about OT primaries being inverted?

EDIT: I get the squeal when presence is just over 6, I read somewhere it's because of the chassis being out of the shielded cabinet.
I'm still waiting for that one. Can you confirm this?

R

[julkke]

I can't see well from your pics (maybe because I'm on my phone) but where does your nfb wire run? It needs to be located away from all the other wires.

[fretwizard]

I can't see well from your pics (maybe because I'm on my phone) but where does your nfb wire run? It needs to be located away from all the other wires.

It's running along the OT secondaries, which happen to be just under the turret from which the wire is taking off. It's basically strapped to them, it doesn't cross any preamp stage wire.

The presence pot wire runs under the board, away from the bass pot and turns into a right angle straight to its connection. But I haven't checked if the other pot wires are too close honestly.

I'm gonna try with aluminum foil taped on a table to see if it's the missing shielding. I'm still waiting for the cabinet.

Interesting thing: if I plug a tube screamer, bypassed, the squeal goes away. It' comes back whenever I plug the guitar straight into the amp...

[fretwizard]

Alright. I made searches about all the possible hum problems, squeals, bad tubes, V2-pin2 noise... etc.

Its should be fine but... I've never had a plexi before and I don't know how much is too much noise/hum.

I'm gonna describe what tests I did and all the voltages I could pickup for now but I can only post clips using a dummy load and impulse response in logic, because I cannot be loud here.

Also I think I'm gonna close this thread and start another for trouble shooting, since the title might be misleading...

Stay tuned

BY THE WAY! To begin with... what kind of speaker/mic setup you wanna hear the amp with.
I got some free IRs from redwirez with a 4x12 greenback cabinet and basically any microphone in any position... please tell me!

[fretwizard]

Hey folks. I've opened a new thread here to get feedback about how the amp sounds. Also for the noise and voltages.
http://forum.metroamp.com/viewtopic.php?f=7&t=40863" onclick="window.open(this.href);return false;

Anyway just to close this thread nicely I'll repost the clips I've recorded