sunn sonaro 60 watt conversion/low power

[wormdirt]

I have a sunn sonaro 1x15 combo, dead mint, except for the filter caps, which I replaced with some sprague atoms. The tubes are ge 6550s, but I'm tracking that they shipped with el34s. The output is pretty low, much quieter than my other 50 watt amps.
I've heard rumors that you could boost the output to 60 watts by replacing the rectifier tube with diodes. I already did that, and I didn't really see a volume improvement.
How loud are these supposed to be really?

[EdBass]

Does your amp have the 40 watt transformers?

[loudthud]

The answer to your 40W/60W question should be in this thread: http://sunnforum.ampage.org/index.php/topic,4895.0.html

For the loudness question you need to try the amp with a known good speaker and try the speaker with a known good amp.

[wormdirt]

I'm pretty sure it has the 40 watt tranny, because it is a combo and it has a 7199 PI, buuutt it had 6550s in it when I got it. I got it from the original owner and he said it is bone stock (at least that is what he said)


I tried it with 3 different know to be loud speaker cabs and saw no improvement in volume.
I mean this thing can't even keep up with a drummer at all.

[wormdirt]

The answer to your 40W/60W question should be in this thread: http://sunnforum.ampage.org/index.php/topic,4895.0.html

For the loudness question you need to try the amp with a known good speaker and try the speaker with a known good amp.

That thread didn't really answer my questions about boosting the watts.

[loudthud]

Power output will actually go down with 6550s. This is a vintage amp. It is what it is. If you try to make it into something else, the value will go down by half. Put it back to stock, sell it and get a Peavey, a Crate or Line 6.

[wormdirt]

Power output will actually go down with 6550s. This is a vintage amp. It is what it is. If you try to make it into something else, the value will go down by half. Put it back to stock, sell it and get a Peavey, a Crate or Line 6.

I'm not trying to make it anything, just trying to be heard over a drummer, but thanks for the jab dude.

[EdBass]

With the 7199, as you mention it probably is a 40 watt amp; unless THAT tube was substituted. As far as I know all of the KT88/6550 amps used a 6AN8 driver.
If this is the case, whoever put those 6550's in there actually reduced the output as 'thud says.
That amp will produce the most output with EL34's.

Of course whether or not ANY 40 watt amp with a single 15 has enough oomph for your particular situation depends on how hard that drummer hits.

[wormdirt]

With the 7199, as you mention it probably is a 40 watt amp; unless THAT tube was substituted. As far as I know all of the KT88/6550 amps used a 6AN8 driver.
If this is the case, whoever put those 6550's in there actually reduced the output as 'thud says.
That amp will produce the most output with EL34's.

Of course whether or not ANY 40 watt amp with a single 15 has enough oomph for your particular situation depends on how hard that drummer hits.

Cool, good to know.
There are sooo many nuances with old sunn stuff sometimes its hard to know what is original or not.

[wormdirt]

Another question,
Why does it reduce to output power?

[bonosurf]

Power output will actually go down with 6550s. This is a vintage amp. It is what it is. If you try to make it into something else, the value will go down by half. Put it back to stock, sell it and get a Peavey, a Crate or Line 6.

I'm not trying to make it anything, just trying to be heard over a drummer, but thanks for the jab dude.

Nice - a newbie with an attitude.

[wormdirt]

Power output will actually go down with 6550s. This is a vintage amp. It is what it is. If you try to make it into something else, the value will go down by half. Put it back to stock, sell it and get a Peavey, a Crate or Line 6.

I'm not trying to make it anything, just trying to be heard over a drummer, but thanks for the jab dude.

Nice - a newbie with an attitude.

Same for you dude.

Well if we can get this on track I put some new el34s in it. Still very quiet.

[EdBass]

Dead mint or not, it's about a 45 year old amp. It needs to be gone through, and just bumping up the power supply may have induced some of those 45 year old components to drift. It's possible that the added current via the rectifier/filter cap upgrade can even cause a failure by stressing things internally.
It's not like there is a set answer to why it's quiet, if it is indeed quiet; "quiet" being a subjective term. That amp is considered powerful for the 40 watt rating, mostly because it was rated for 40 watts continuous at 20h-20Khz at about 1% THD which is probably somewhere around 3-4 on the volume knob.
A lot of MI designed amps are rated for marketing purposes at 1Khz and 5%+ THD.
As loudthud posts, just swapping to a higher dissipation output tube won't do anything but hinder the circuits potential; indiscriminate "hot rodding" is generally counter productive, everything in there was designed around the stock tubes. You can't "add power" by upgrading the tubes without modifying the rest of the circuit.
The SS rectifier mod just gives you a more consistent and unimpeded current supply allowing the rest of the circuit to operate more efficiently, which is why the output increases. Altering the signal path generally will not have that same effect.
Sunns are based on hi-fi amps designed to be as clean as possible, when used as an MI amp cranked up it will output appreciably more power. 

So it could be almost anything causing it to be too "quiet" for your application. My first guess would be inefficient speakers, secondly would be component(s) not performing to spec.

Scope it and see what it's actually putting out, that's the only way to tell if the amp is actually too "quiet". Those numbers aren't subjective.