Which EL34 tubes

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RocketRick

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I'm gonna try some el34's and was wondering;

1. Which ones to choose . There are so many.

2. Joey said to make sure that pin one was grounded. Once I fig out which pin one is, I can check with the VOM ...right?

I have 2 marshall amps. I'm gonna cheek to see if they use those..Might save some money huh?

Tanks
 
Rick, I will take a picture of the tube pin 1 mod for you on my C+, I have one lying around.

I really like the SED =C= EL34s, I use them in my C+ and my Mark IV and they're fantastic tubes.

The mod to pin 1 is very easy and very essential (ask Joey B :D )

I would not borrow tubes from your Marshall, you cannot guarantee they are in the proper bias range for your Mesa!
 
I also like the SED, but these are my favorite.


http://cgi.ebay.com/Vintage-Philips-6CA7-EL34-Vaccum-Tubes-Matched-Pair_W0QQitemZ130293816668QQihZ003QQcategoryZ73380QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
 
Platy,

Are you sure
I need to do a mod to use the EL34's. I asked Mesa but had to leave voice mail.

Also I read on a tube info site this:

Basing refers to the order that the tube's elements (cathode, plate, grids, heaters) are connected to the pins at the base of the tube. The 6L6, 7581A, 6V6, 6550, EL34, 5881, KT66, KT88, KT90, KT100, etc. are all common guitar amplifier power tubes, and all share similar basing. The whole 12AX7 family (12AT7, 12AY7, 12AU7) which are commonly used in guitar amplifiers also share the same basing.

So biasing prob won;t be aprob will it.

Also, one guy said I need to replace the last pretube also if I add the two EL34's.
 
I found out which pin is no 1. It's just to the left of the alignment notch finger.
 
Platy and Joey,

My tech here said you need to connect pin 1 to pin 8 to use the El34's. then you can use 67L6's or the 34's.

But hes aid the bias won't be right as the grid voltage for the 6L6 is much higher.
 
RocketRick said:
Platy and Joey,

My tech here said you need to connect pin 1 to pin 8 to use the El34's. then you can use 67L6's or the 34's.

But hes aid the bias won't be right as the grid voltage for the 6L6 is much higher.

Your tech is correct, you need to connect pin 8 and 1 together. However, the amp is made to handle EL34s in the outer sockets, the resistor values are different in these sockets to accommodate EL34s.
 
What about the biasing situation..IOW, the EL34's run at lower grid voltage abt 35 vs 50 for the 6l6's

Also, what bout the sound you get by doing this. I mean wldn't a JCM 800 be the thing if you wanted that EL34 sound?
 
RocketRick said:
What about the biasing situation..IOW, the EL34's run at lower grid voltage abt 35 vs 50 for the 6l6's

Also, what bout the sound you get by doing this. I mean wldn't a JCM 800 be the thing if you wanted that EL34 sound?

Mesa amps are fixed-bias... you have one of the most sought after amps on the planet, you should read some information about it :)

EL34s are just another color to paint with.. bit more crunch and sizzle in the upper midrange, compliments the amp well.
 
RocketRick said:
So do I need to rewire the Mesa to do this or?


Just connect pin #1 to ground, no bias adjustment needed for EL-34/6CA7 tubes (outer sockets) in the MESA current draw range. :D

With an all 6L6 lineup, the outer tubes run much hotter than the inners (simulclass models only). When you change the outers for STR-416 6CA7 type tubes, all four will idle at close to the same current draw.
 
Ok Platy and Joey...I'm convinced. Take the chasis out and point to point it. I took electronics so i can solder it no probs.

Platy said:

you should read some information about it

Love to..tell me where.. :)
 
Joey,

Already read that. I meant info on the modification.

Also, wonder if Mesa can provide the

A. schematic

B. maintenance/tech manual if there is one.
 
There is no need for a schematic. Pull the chassis, look at the outer sockets. Take a small piece of wire, and solder it to the pins on either side of the tube socket keyway. :D To the left of the keyway is pin #1, to the right of the keyway is pin #8. It takes as long to remove the chassis as it does to complete the mod. Easy cheese. :D
 
Joey,

I've been reading about the amp most of the morning. Actually looking for the mod. I haven't found the mod yet but did find some neat sites and understand it's history better etc.

I saw one site that does that mod for ard $120.

Here's a real good site..http://homepage.mac.com/mesaboogie/welcome.html

The amp has the + over the power chord and MB initials below that.

Well I haven't removed the chassis on it. Ever. Is it pretty obvious. Lossen the top bolts and pull out backwards?

Do you stink the mod adversely affects the value?

Thanks
 
If the amp has ever been back to MESA for a tune-up, it may already be done. It is standard practice for any Simulclass C+, and will not affect the amp when running all 6L6's, as the 6L6GC tube has no pin #1. Mike Bendinelli is the person that told me to do it!
The value of your amp will not change one bit. :D
 
Platy & Joey,

Lets get this done.

Tell me exactly what to do per taking the chassis out. I can do the PTP per pins 1 & 8.

thanks

Rick
 
Thanks gts that sounds easy enough.

questions:

1. I have one of these gun type soldering guns..I fear it may be too powerful.

What amperage pen iron shld I use?

2. I guess 14 gauge wire aught to be ok huh?

3. Any other thing I aught to look at or do or write down since will have the chassis out? I'll take pics of course. :)
Like I read someone did this ""The only thing I've done to mine is change the bias caps
and stiffen up the power supply just a tad bit.""

Glad I tuned into this board. Learned a lot..!

thanks again all. :wink:
 
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