Before I buy a solarus...

[chovied]

This guy has what he says is a 120 watt Solarus head and cab for 300$. I play heavy , low, sludgey doom rock and need an amp that is LOUD, and can withstand touring. Imma check it out tomorrow. This thing really 120 watts? is it what I'm lookin fer? Thanks

[JoeArthur]

Take a look at the catalog page... is this the amp?

http://www.sunnamplifiers.com/catalogs/1968/solarussonaro.jpg

[creitzel]

A Solarus is your basic 50-watt, 2-el34 tube amp.  For a few reasons, it is not as loud as my Marshall 50-watt (thru the same cabs).   It has one less gain stage in the pre-amp, different transformers and a lower gain power tube driver (7199 on the Solarus vs. 12AX7 on the Marshall).

On the plus side, it has reverb, which is great for dirge material.  Also on the plus side, it is not as loud!  Thus, you can crank the bitch up without causing permanent hearing loss (yes, I am too old).  Also on the plus side, it does not have that Marshall cranky midrange that grates after a while.   Both amps have a great clean sound.  The Marshall ('78 JMP) does better w/ crunch, the Sunn sounds better at 10.  Go figure.  My favorite is still my Sound City 50R.

take it easy,
Charlie

[JoeArthur]

Hmm... interesting concept Critezel... but so wrong I can't help but disagree.  While the triode stage of the 7199 may have less gain than a single side of a 12AX7... the pentode side has more gain than any triode can hope to have.

Plus... the Marshall doesn't have an additional gain stage.  The second stage, which is a common cathode directly coupled to a cathode follower that drives the tone controls... is only a single gain stage.  The cathode follower has a gain factor of about 90 percent - less than unity.  It is used because it offers a low impedance output to drive the tone controls, and a high impedance input for the preceeding common cathode stage - to achieve a slightly higher gain from that stage than RC coupling can achieve on it's own.

Besides... the gain factors of the preamp stages has nothing to do with the power output of the amp.  As long as the power amp can be driven to clipping, then the maximum output of the amp will be achieved.

The Marshall 50 watt is slightly under-rated, meaning that it does put out slightly more than 50 watts.  Even at that... the loudness difference would not be noticed through the same speaker cabinent

What you may be hearing as a difference... is the effect of the tone control settings, and a preference for the way the Marshall sounds.

[JoeArthur]

<sigh>... I apologize for my misspellings...

[creitzel]

Thanks for the corrections and insights.   Your comments about EL34 wattage are true enough (27.5 watts apiece), but the two amps use the same tubes!    Some folks say you can get even more: http://www.tone-lizard.com/lesson6.htm  

Some thoughts:

I really don't know anything about the 7199.  My comment was a successful troll for some info about this tube.  Do I get you right: this is a triode/pentode pair in a single tube?  Interesting.  That explains the extra lines on the schematic :sheepish grin:.   The driver circuits look real different in these amps.  Do you know anything about the Sunn circuit?  Basically, I wonder if the Sunn amp drives the power stage as hard and, when cranked, we are not hearing as much driver tube distortion as power tube.

I won't pretend to know why the impedance conversion of the extra triode stage gives more gain, but you say it does?   Also, the tone controls don't do much on either amp!   I guess, you would have to measure RMS power delivered to the power tubes to confirm or deny our respective theories.  I suppose the percieved volume difference could be entirely psycho-acoustic.   I.e. distortion in the harmonics, especially odd-order.  

My guess is that the power supply and output tranny makes the biggest difference.   I did A/B the two heads through the same cabs with the same guitar.   Also I do not equate perceived volume with better.  Almost the opposite, but chovied says he wants LOUD.   Whatever the reason, the Marshall is definitely louder.

take it easy,
Charlie

[JoeArthur]

Yes, the 7199 is a pentode/triode combo.  The pentode stage provides the majority of the gain for the power stage, and the triode is the phase splitter (no gain).  The triode circuit is sometimes called a concertina phase splitter.

In the Marshall... (just like in a first generation Model T or the classic 1959 bassman circuit), the low output impedance of the cathode follower stage provides a better drive to handle the necessary losses through the tone circuit.  

By the grid of this stage being directly coupled to the previous common cathode stage, there is less of a load on that stage due to the high impedance provided by the grid - there is no additional grid leak resistor to ground.  The load of a voltage gain stage is roughly the combination of the plate load resistor and the grid leak resistor of the next stage in parallel.  With a higher resistive load... essentially the load resistor by itself, a slightly higher gain is achieved.

[sunn amp fixer]

Comparing apples to oranges is always interesting,both are good and healthy for you,but it has nothing to do with the original question.Look at a schematic of the Dynakit MarKIII 60 watt amp,then look at a schematic of a model 1987 50 watt marshall.KT88'S or 6550's as opposed to EL34's.Some Solarus's were fitted with EL34's,and came originally with a 2-12 cabinet.Other Solarus's were fitted with 6550's,and later mixed with larger cabinets like the 412S Sceptre type.Solarus is clean.Marshall's break up with more emphasis in the presence area.,and different EQ parameters.Two totally different sounds.Like comparing Gibson to Fender.For seven string grunge dark sounding music,perhaps Marshall,Mesa,Orange,or Soldano would be best suited.For clean and loud,then Solarus.It is always in the ear of the beholder.There is no right answer.Makes for interesting discussion between techs at Waffle House at 3:30 am...Especially if you just fixed some idiot's Ampeg SVT during a show...and NO..it really does not go to 11.