The Grail arrives - IIC+ content

[Boogiebabies]

It's the Phase Inverter.

RCS was pretty much done teching amps by the time the IIC came out. It's a publicly accepted myth that the all IIC+'s had to be signed "MB".
It's probably why I got mine so cheap.

So far, you, me and one other guy are in the club. My amp is identical to yours, but I did not get a sticker on my EV.

 

[JOEY B.]

I'm glad that you saw this amp before I did. My hotrod fund would have taken another hit, for sure (another expensive hobby). Carrying one back breaking combo in each hand might have turned me into a hunchback, as well. I hope you will enjoy this rare find for many more birthdays to come.

 

[Boogiebabies]

I'm glad that you saw this amp before I did. My hotrod fund would have taken another hit, for sure (another expensive hobby). Carrying one back breaking combo in each hand might have turned me into a hunchback, as well. I hope you will enjoy this rare find for many more birthdays to come.

Your HotRod Fund !!!

That GN already looks museum quality and concourse grade. Are you trying to say you would not be able to buy $ 1700 in Q-Tips and white velvet gloves for the next year !!!

How is the new C+ BTW. Did the 62K help?

 

[sundaypunch]

OK, I have a Boogiebabies question here.

I have a Weber Bias Rite. I'm no amp tech but have used it along with these bias tables (http://members.shaw.ca/house-of-jim/Html/bias_tables.html) to adjust the bias on other amps of mine.

I know that bias on Boogies isn't adjustable. I'm curious if the tubes I have in mine are running in the proper range. I checked it in Simulclass mode.

All four have a plate current of about 475V. The inner pair of 6L6's run 26.0 mA and 27.1 mA. The outer pair run 48.2 mA and 52.9 mA.

I know that this is a bit hot on the outer pair and ice cold on the inner pair. Ideally what should I be running in a IIC+? What if I use EL34's in the outer sockets?

Thanks

 

[Boogiebabies]

47ma is 75% of MPD so your fine and 52ma is not too high. Running EL-34's is a crap shoot regarding current draw. Since the inner tubes are running cooler, switch them with the outer an get another reading.

 

[Anonymous]

Post removed.

 

[sundaypunch]

47ma is 75% of MPD so your fine and 52ma is not too high. Running EL-34's is a crap shoot regarding current draw. Since the inner tubes are running cooler, switch them with the outer an get another reading.

OK, I did the switch. I moved the inner pair to the outer sockets and they were too high (60-63 mA). Apparently they are the hotter pair. I put them back in the middle.

I also put a set of NOS Mullard EL34's I have in the outer sockets and checked them. They were 47mA and 51mA which is way too hot so I'm back to the original setup.

One thing I'm not up on - I know that the inner & outer sockets are biased differently. Is the pair of tubes that goes in each susposed to end up at the normal 60%-70% of MPD? If someone were to run new Mesa 6L6's (or NOS STR-415's) in all 4 sockets I don't see how you could end up without a pair running way hot or cool?

 

[fpoon]

How does it compare to the Mark IV?

 

[sundaypunch]

How does it compare to the Mark IV?

Sorry, I haven't spent any real time with one. The MK III's are the "high tech" new Boogies to me. Once I get past '85 or so my experience with amps tapers off pretty quickly.

 

[Elpelotero]

One thing I'm not up on - I know that the inner & outer sockets are biased differently. Is the pair of tubes that goes in each susposed to end up at the normal 60%-70% of MPD? If someone were to run new Mesa 6L6's (or NOS STR-415's) in all 4 sockets I don't see how you could end up without a pair running way hot or cool?

this I believe is part of the nature of a simul class amp. 6l6 tubes biased one way, el34 tubes another way. a 6l6 put in the el34 slot is run hotter than the others. but an el34 sits "just right." if i'm wrong, someone correct me.

 

[JOEY B.]

When I asked a very informed person at Boogie about this, he gave this reply: "If you want to run a quad of the STR-440 6L6's , put a green or grey color code on the inner pair and a red color code on the outer pair." He also recommended a green or grey EL-34 STR-447 for the outer sockets if I wanted the 6L6/EL-34 flavor. The red color code 6L6's are a cooler running tube, and will help to balance your current draw on a simul-class all 6L6 amp. Or if you are lucky enough to have the bias-rite, you can do your own testing. 8)

 

[sundaypunch]

He also recommended a green or grey EL-34 STR-447 for the outer sockets if I wanted the 6L6/EL-34 flavor.

It sounds like the STR-450 might be a better sounding EL34? I take it if I were to try those I would still want to go with a green or grey pair?

 

[Boogiebabies]

The Siemens do not have very good longevity running at 474 volts. They are more comfortable at 450 volts. But if they are running a lower bias they can handle the voltage better. I have a set of Mesa 450's and I will check the bias on them. I think they are Gray's. I also have two other quads stashed away for Marshalls.