6V6

Talk about tubes and their effect on your tone

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Anomaly
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6V6

Post by Anomaly » Fri May 04, 2012 1:10 pm

Novice question here. How do you find out if an amp would work with 6v6 tubes?
I heard JJ's could handle high voltage the EL34 & 6L6's do?

mark2boogie
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Re: 6V6

Post by mark2boogie » Fri May 04, 2012 3:18 pm

Anomaly wrote:Novice question here. How do you find out if an amp would work with 6v6 tubes?
I heard JJ's could handle high voltage the EL34 & 6L6's do?
Lies indeed ! You will burn them... Try to find the official datasheets of the 6L6GC, EL34/6CA7, 6V6GTA and compare the specs : even if you are novice, you will understand quickly that the 6V6 is a "kind of downsized" 6L6, as the EL84/6BQ5 is a "kind of downsized" EL34/6CA7.

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stokes
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Re: 6V6

Post by stokes » Fri May 04, 2012 4:41 pm

I read about "6V6 kits" for using in a MKIV and it makes me laugh.A 6v6 isnt made to take the voltage a Mesa amp puts on the plates.Will it work?Maybe for a while,but those tubes will die a premature death.Even if JJ's could take it,I would not use them.I've yet to see/hear a JJ of any kind that sounds good.

212Mavguy
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Re: 6V6

Post by 212Mavguy » Mon May 07, 2012 8:12 am

Hey, it's all right to buy a new amp to run those 6v6's...




I did that once to hear what the Bluesbreaker tone was all about. KT66's in this case, I bought a top end boutique, a Siegmund Midnight Blues Breaker head and got a couple pairs of old stock Brit kt66's. Old stock pre tubes and it sounds glorious. But since then I swapped out the kt's and run some 40's vintage RT 6f6g's in it. Have run similar vintage 6v6g's in it too, what godly tubes those are. That amp could be purchased for the right price, "tailor tubed" for the buyer. ;) Aaaaaaaand... there are a LOT of great choices to run 6v6's outside the Mesa fold FWIW.
212Mavguy

Anomaly
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Re: 6V6

Post by Anomaly » Tue May 08, 2012 1:25 am

stokes wrote:I read about "6V6 kits" for using in a MKIV and it makes me laugh.A 6v6 isnt made to take the voltage a Mesa amp puts on the plates.Will it work?Maybe for a while,but those tubes will die a premature death.Even if JJ's could take it,I would not use them.I've yet to see/hear a JJ of any kind that sounds good.

So it will work but not have a long life like the big glass 6L6/EL34's? but what if adjust the bias & run them cold?

94Tremoverb
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Re: 6V6

Post by 94Tremoverb » Tue May 08, 2012 4:11 pm

mark2boogie wrote:Lies indeed ! You will burn them... Try to find the official datasheets of the 6L6GC, EL34/6CA7, 6V6GTA and compare the specs
The specs aren't a true reflection of what the tubes will take in reality. Most tubes will take more than the original design spec voltage safely, particularly if you operate them with some precautions - like keeping the screen voltage significantly below the plate voltage. You can easily run 6V6s at over 400V safely even if you don't do this - Fender's BF/SF Princetons and Deluxes have been doing for almost fifty years and they aren't particularly hard on tubes. (Plate voltages of typically 420V.)
stokes wrote:I read about "6V6 kits" for using in a MKIV and it makes me laugh.A 6v6 isnt made to take the voltage a Mesa amp puts on the plates.Will it work?Maybe for a while,but those tubes will die a premature death.
Maybe you didn't read the MkIV manual properly then :). You can use 6V6s completely safely if you set the amp to 'Tweed' power, which is equivalent to cutting the supply voltage from 120V to about 100V and drops the plate voltages to under 400V.

You can also do the same with a Dual Rectifier - the Spongy mode is the same as the MkIV's Tweed. Typical plate voltages are 450V in Bold/Diode, 420V in Bold/Tube, 370V in Spongy/Diode and 355V in Spongy/Tube. Only Bold/Diode is a risk for 6V6s. I've had 6V6s in my Tremoverb with no trouble - usefully they also require about the same bias voltage as EL34s so just set the switch to that.

JJs are also tougher than most other 6V6s and will probably survive at 450. Liking the tone of them is a different issue - personally I don't much either.

Also remember that if you do this, 6V6 has roughly double the plate resistance of 6L6s or EL34s, so you should connect the speaker to the next tap lower than the speaker impedance. (eg the 4-ohm tap for an 8-ohm speaker.) If you don't you will stress the tubes a bit more heavily, which can give a nice fat compressed tone if that's what you want, but will wear them out faster.

stokes
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Re: 6V6

Post by stokes » Wed May 09, 2012 10:29 am

Dont own a MKIV or the manual,but I really wouldnt recommend putting tubes in an amp that can only be used on one setting.It totally defeats any versatility the amp has and if you or someone else switches it back to full power.....poof.I had a bass player once who was a pain in the ass,would always complain about and try to adjust everybodies amp settings,well,you get the idea.How many times have you played a gig and between sets found some inquisitive idiot getting too close to your gear.To me,its never a good idea to put your amp in a condition where it can be compromised.There are a lot of old stock 6V6's that will take the overvoltage,but sooner than later they will give up and die a possibly catastrophic death.

94Tremoverb
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Re: 6V6

Post by 94Tremoverb » Wed May 09, 2012 12:36 pm

I'm not saying it's a great idea to do that in a gigging amp either - I wouldn't, for the same reason - but that doesn't cover all situations or uses, and the sort of statements that you and mark2boogie posted are plain, flat-out wrong. You *can* run 6V6s in many of these amps, totally safely and with no compromise on life expectancy, if you set them correctly. (Even if you take the tube specs as gospel.) If you'd bothered to find out a little more before laughing at it regarding an amp you don't know much about, you might know that. No offense intended.

stokes
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Re: 6V6

Post by stokes » Wed May 09, 2012 2:21 pm

I do have a bit of knowledge about these amps,I've had quite a few on my workbench over the years.They are not designed to use 6V6's.Its like the argument in another thread,of course you can use a 30watt speaker in this amp,as long as you keep the volume control below 4.Does that mean you should do it?I wouldnt recommend it.So,you can use a 6V6 in this amp as long as you only use it in tweed mode.If a customer asked me if its safe to do so,I would have to say no,period.To me,doing so is just plain wrong.I wouldnt do it for him or even give/sell him the tubes to do it.Maybe its just me,but I try to answer things here and on other forums as I would if someone walked into my shop.A gigging amp?Would you call a MKIV a bedroom amp?Most people I know dont use a MKIV as a practice or bedroom amp,they gig with them,or play in some sort of band situation.

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