Mark III...quick question

[bradg]

Does the full/half power toggle on the front of a Mark III mean it's simuclass or does it just cut the power in half from 75 watts on full? If it does mean it's simuclass, does that mean you can use el34's in the outer 2 sockets? Thanks in advance.

 

[MrMarkIII]

More questions:
Is this a so-called "long" head? (Eight knobs on the front panel?) If so, it's 99.99% certain it's Simul-Class, and it's 75/15 watts, with the outside sockets capable of switching El-34s to 6L6s. Is there a Simul-Class sticker on the left rear panel? 100% Simul-certainty.
Are there EL-34s in the outer sockets now?
What color is the stripe above where the A/C cable exits the rear panel?

 

[bradg]

Yep, 8 knobs. I don't see a SC sticker and it has all 6L6's in it. It's blue stripe. Thanks!

 

[edward]

Yes, your "long head" had the simul switch moved from the rear to the front. And yes again, EL34s on the outer pair. And wattage as MrMark said for all stripes except greenies.

Edward

 

[JOEY B.]

Yep, 8 knobs. I don't see a SC sticker and it has all 6L6's in it. It's blue stripe. Thanks!

To be sure, pull the chassis and look at the output transformer serial #. Or look for a screen grid (2 watt) resistor attached to pins 3 & 4 (triode), and a 1/2 watt resistor connecting pin 5 to either pin 1 or 8 (ground) of the outer power tube sockets (inside the chassis). :shock: BE CAREFUL AROUND THE HIGH DC VOLTAGE!!!!!!

 

[camsna]

Isn't 'full / half' pentode, triode? And 'Simul / Class A' simul class?

 

[JOEY B.]

Isn't 'full / half' pentode, triode? And 'Simul / Class A' simul class?

NO.

The Full/Half on the long chassis heads can be a Simul / Class A or a 60/100 switch. The Pentode/Triode only comes into play with the 180 watt Coliseum models with the Full/Half power switch. The short heads with the rear panel switch are either 60/100 or Simul/Class-A. If you have a Simulclass Coliseum model the half power switch will take it from 150 watts to about 90 watts IIRC.

 

[SymenTimmermans]

More questions:
Is this a so-called "long" head? (Eight knobs on the front panel?) If so, it's 99.99% certain it's Simul-Class, and it's 75/15 watts, with the outside sockets capable of switching El-34s to 6L6s. Is there a Simul-Class sticker on the left rear panel? 100% Simul-certainty.
Are there EL-34s in the outer sockets now?
What color is the stripe above where the A/C cable exits the rear panel?

Great! I guess my Mark III is simul-class after all.
Not sure why I should be happy, I never use half power.

 

[bradg]

Thanks for the replies.

I'm still a little confused though. I called MB today and they said if the output transformer doesn't say simuclass then it isn't. I don't see it written on my ot. Everything I've read says that if it's a long head and has the fp/hp switch on the front, it's simuclass. :?

 

[JOEY B.]

Everything I've read says that if it's a long head and has the fp/hp switch on the front, it's simuclass. :?

Did you understand my posts above? And, yes, the output transformer will be a dead giveaway. What are the numbers stamped into your OT?

 

[phyrexia]

if that's a blue stripe it should be a 60/100. Green stripes were simuls only IIRC.

 

[tony777]

OH COME ON BRAD!!!!

you've pushed us this far, now we need a pic of your OT transformer :lol:

 

[bradg]

I don't have it yet, should be here tomorrow. I got it off ebay http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=320318172930

He has a link to a zip folder on the auction that has a ton of pics but I can't tell anything from them.

 

[JOEY B.]

I don't have it yet, should be here tomorrow. I got it off ebay http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=320318172930

He has a link to a zip folder on the auction that has a ton of pics but I can't tell anything from them.

The last picture in the zipped file (labeled "guts") confirms that it is a 60/100 and NOT a Simulclass model.
CASE CLOSED!

 

[bradg]

Thanks for checking.

Is there that big of a tonal difference between the two?

 

[JOEY B.]

Thanks for checking.

Is there that big of a tonal difference between the two?

NO.

 

[psychodave]

Interesting stuff.

I have a Mark III long head green stripe with a Simul-class sticker. The half power switch is on the front. If I am reading this thread correctly the switch is a Class A switch? When I have it in the down position, only the outside tubes are on...

 

[JOEY B.]

Interesting stuff.

I have a Mark III long head green stripe with a Simul-class sticker. The half power switch is on the front. If I am reading this thread correctly the switch is a Class A switch? When I have it in the down position, only the outside tubes are on...

Correct .