Please Teach a MKIIC+ Newbie about his Amp

[supergenius365]

Just like the title says please.

1984 MKIIC+ basic. No reverb or EQ. Has 4 12AX7's and 2 6l6's. Emi 150 Watt speaker.

1) What do the V2 and V3 do on this amp?

2) Phase inverter - I put a Mullard 12AT7 (CV4202 I think) in the PI and the amp was unhappy. Lots of static and crackling if I moved the tube. No noise with a 12AX7 in it. Can it use a 12AT7, or is that a no no?

3) What were most likely the original tubes in this given it's 1984 B-Day?

4) Do I want to use 6l6 GC's in it? Is the "STR" on the tube important when choosing new tubes?

5) Would getting an EVM 12L be a big improvement over the EMI?

Thanks

 

[Boogiebabies]

Just like the title says please.

1984 MKIIC+ basic. No reverb or EQ. Has 4 12AX7's and 2 6l6's. Emi 150 Watt speaker.

1) What do the V2 and V3 do on this amp?

Loop and Lead

2) Phase inverter - I put a Mullard 12AT7 (CV4202 I think) in the PI and the amp was unhappy. Lots of static and crackling if I moved the tube. No noise with a 12AX7 in it. Can it use a 12AT7, or is that a no no?

12AT7 is fine. The noise may be a coincidence.

3) What were most likely the original tubes in this given it's 1984 B-Day?

Probably Ei 12AX7's. Really.

4) Do I want to use 6l6 GC's in it? Is the "STR" on the tube important when choosing new tubes?

If you have $ 300, the STR-415 is the best, other wise your only option is the STR-440 or non-mesa branded tubes.

5) Would getting an EVM 12L be a big improvement over the EMI?

Not necessarily. The MS-12 is an awesome speaker with less harsh high end than the 12L. It's a very balanced speaker, but it does have an effect on frequencies that the 12L allows through. The MS-12 has more of a voicing alteration than the 12L. It's smoother. For a closed back, the 12L is unbeatable.

Thanks

 

[Elpelotero]

Just like the title says please.

1984 MKIIC+ basic. No reverb or EQ. Has 4 12AX7's and 2 6l6's. Emi 150 Watt speaker.

1) What do the V2 and V3 do on this amp?

2) Phase inverter - I put a Mullard 12AT7 (CV4202 I think) in the PI and the amp was unhappy. Lots of static and crackling if I moved the tube. No noise with a 12AX7 in it. Can it use a 12AT7, or is that a no no?

3) What were most likely the original tubes in this given it's 1984 B-Day?

4) Do I want to use 6l6 GC's in it? Is the "STR" on the tube important when choosing new tubes?

5) Would getting an EVM 12L be a big improvement over the EMI?

Thanks

tubes were probably str415's, which are no longer made. They are rare and expensive, but well worht their pricetag. The evm12 would probably be an improvement. I am planning to replace my speaker to an ev12l someday. Boogiebabies can furhter answer your questions.

 

[JOEY B.]

You will only need $150 to get two STR-415's from Boogie (just wait for me to get mine, please). And if you want an EVM-12L, get it in a Boogie thiele cabinet and put it under the combo! Leave the Eminence Black Shadow in the combo for now.

 

[Boogiebabies]

The MS-12 in the open back and the 12L in the ported cab is a very nice mixture. The highs are not so harsh from the MS-12 and as I mentioned before, the 12L in a ported cab is very well balanced. The only way I like the 12L for the C+ is in an open back hardwood cab. The Imbuya cabs seem to sound more balanced and even than with a birch ply combo.
The only amp I really like with the 12L in an open back combo is the MK IV. It seems like a perfect match with birch ply or hardwood.

 

[igfraso]

5) Would getting an EVM 12L be a big improvement over the EMI?

Not necessarily. The MS-12 is an awesome speaker with less harsh high end than the 12L. It's a very balanced speaker, but it does have an effect on frequencies that the 12L allows through. The MS-12 has more of a voicing alteration than the 12L. It's smoother. For a closed back, the 12L is unbeatable.

Thanks

Boogiebabies: I have only one Eminence 150W. Would you use it on a Mark IIB combo (lead a little bit harsh) or on a Mark III (a more aggressive sound)? Where do you think it will make the sound smoother?
Thanks and best regards
Daniel

 

[Boogiebabies]

I can only comment on the MK III. I am sure it will take a bit of the sizzle off. I have not been within 600 miles of a IIB.

 

[supergenius365]

4) Do I want to use 6l6 GC's in it? Is the "STR" on the tube important when choosing new tubes?

STR stood or stands for "Special Tube Request" and is related to the orders for tubes from (pick a mfg). It may not mean the same thing today as it did back when Sylvania etc. were manufacturing tubes.

Short answer": No, it is not critical STR be on the 6L6 tubes you buy.

It's more important they be a properly spec'd for your Boogie's fixed bias. If you buy from Boogie they are ok already, if from another dealer like "Dougs Tubes" (highly recommended) just let him know what amp they are for and he'll sell you appropriately spec'd tubes.

Who made the 415 STR's? Would there be a NOS option out there right now?

 

[Boogiebabies]

Phillips 6L6GC or Sylvania 6L6GC. You may generally find them labeled Phillips STR-387 as well. The STR-415 and STR-387 have different getter rings, If I remember that is the only visual difference . Another option that works well in Boogie's is the Phillips 7581A. It's a 35W tube with endless headroom.

 

[supergenius365]

Phillips 6L6GC or Sylvania 6L6GC. You may generally find them labeled Phillips STR-387 as well. The STR-415 and STR-387 have different getter rings, If I remember that is the only visual difference . Another option that works well in Boogie's is the Phillips 7581A. It's a 35W tube with endless headroom.

Thanks.

I have been contemplating some Sylvania 6L6 GC's from KCANOS Tubes. Can't find any 7581A's for sale anywhere.

Thanks for all the help B Boarder's!

 

[jay]

I don't want to turn this into a tube post but just wondering what BB thinks of this ad for a Phillips 6BG6 tube that is made exactly like a Phillips 6L6GC it just has the plate connection at the top of the tube and you also have to use adapters?http://cgi.ebay.com/6BG6-Vacuum-Tube-Matched-Quad-Great-6L6-Substitute_W0QQitemZ220137548106QQihZ012QQcategoryZ67816QQrdZ1QQssPageNameZWD1VQQcmdZViewItem

 

[Boogiebabies]

I don't want to turn this into a tube post but just wondering what BB thinks of this ad for a Phillips 6BG6 tube that is made exactly like a Phillips 6L6GC it just has the plate connection at the top of the tube and you also have to use adapters?http://cgi.ebay.com/6BG6-Vacuum-Tube-Matched-Quad-Great-6L6-Substitute_W0QQitemZ220137548106QQihZ012QQcategoryZ67816QQrdZ1QQssPageNameZWD1VQQcmdZViewItem

On a IIC+, I don't think so. I'm not too keen on adapters, plus matching at 400V is not good enough for me. At 485V, they may stray all over.
If you have a head, you can forget about adding another 1 5/8 inches.