Anyone taken a 'bias-reading' on their Electradyne?

[Charles Reeder]

Greetings Electradyners, Electradynoids, whatever!

Has anyone with a 'bias-probe' and 'multimeter' taken a reading to see what the bias is set at?

If not; could someone take a reading and post that info; along with the Mesa color-code of the tubes?

It has occurrerd to me that with all the rave revues the amp has gotten (very-very few negatives)...with a new designer at the helm for the Electradyne....that perhaps they are shipping this amp with the bias set hotter than usual (for them).

Unquestionably a good amp is much more than just the result of the bias setting! But, it might be that the bias is set closer to optimum than usual and that may be helping the amp along.

If on the otherhand the amp is being shipped with the usual disregard for using tubes in the 'warm-to-hot' range...and the amp still sounds as good as it does...I imagine that getting some tubes that sit in the 'warm' to 'hot' bias range would make this thing take off like a rocket! Something to consider.

I know getting adjustable bias for my Lonestar and Stiletto helped both amps tremendously (especially the Stiletto).

Just curiosity on my part...but I'd like to know...and perhaps some others might as well...as they (like me) ponder 'taking the plunge' into the Electradyne realm.

Thanks, Charles

 

[Gordybaby]

Charles,

I just tried out by new bias probe that I built from old parts from work. First of all I started with my stiletto, it read 24 mv. I installed my new bias pot from John Mansfield and I got my JJ EL34's running maxed out at 36 mv. I than tried it on my ED and it was at 34 mv. I think you just may be on to something here. I think Mesa may be missing the boat on the fixed bias amps. All I'm going to say at this time is the distortion that came out of the stiletto was... well I'm stunned! More on that later. By the way my ED is running 6l6 red #10 Mesa tubes.


Gord

 

[Charles Reeder]

Gordybaby! V-e-e-er-y intersting!

34mv is in the 'warm' range. The 'Red' #10's would read about 27-28mv in my Lonestars (too cool). The 'Greys' would read in low 30's and the 'Yellows' in the 34 to 36mv range (the same approximate reading you are getting with 'Reds' in the Electra Dyne.)
It could well be that placing 'Greys' or 'Yellows' in the Electra Dyne could result in readings in the high 30's and low 40's! At any rate...it does appear as if the Electra Dyne is deliberately set to bias somewhat warmer than either the Lonestar or the Stiletto (right from the 'get-go' from the factory).
The results you obtained with the unmodded Stiletto (24mv) were right in line with the results I had obtained. The highest bias reading I could ever get through trying different tubes was 28mv.
Now...if I set my Stiletto at about 39mv (at 50-watts) I get about 35-36mv when set to 100 watts. I experimented with a setting of 42mv (at 50-watts) which resulted in a reading of 38mv on the 100 watt setting.
All of these are in a useable range and the amp sounds like 'serious-business' now.
The exact bias reading we settle on will be the result of many variables; the guitar and pickups used, the speaker(s) used, the brand of pre-amp and power tubes, cabinet style and configuration...and of course not least...personal musical and tone taste and preferences

Keep us updated on your findings with your newly biased Stiletto. Consider posting your results in several places (including the Stiletto bias-mod thread). I'm intrigued...and want to hear more.

Thanks, Charles.

 

[Riff Blister]

Me too I'm all ears! Eyes?
On Monday I dropped my Stiletto off with a guy I know who is a respected amp tech here in the Twin Cities. He is going to install the Mansfield adj. bias mod for me.
I'll have to wait a little while as he is going to be out west for a few days.
Needless to say I'm very anxious to get it back and all of this Boogie Board talk is just fueling the fire of desire :lol:

Interesting about the ED too.

 

[YellowJacket]

This is interesting. I find that Mesa tends to favour dark or 'cold' tones even with their speaker enclosures. The setting for the hardwired bias are intentional, definitely set in a way that creates these sorts of tones. Seeing that I am attracted to a much more 'warm' or 'brown' tone, perhaps this is something worthwhile for me to look into as well.

 

[Gordybaby]

The thing is my ED new had yellows in it but after several tube issues Mesa replaced all 4 tubes with reds. I didn't notice a big difference in tone but I would be curious to know what my meter would read before I swapped the yellows for reds.

Gord

 

[JOEY B.]

The readidgs that I got are with MESA EL-34 tubes.

Plate voltage is 450-ish.

Inner sockets "Green color code STR-442's" 33 mA

Outer sockets "Blue color code STR-442's" 40 mA

I guess this is why I really like the 45 watt mode(outer sockets) for the Vintage Low setting. 8)

Keep in mind that this is a Simul-class power section and the outer sockets are biased a little warmer than inner ones. I could balance the current draw by doing some tube juggling, but it sounds good like it is. Don't fix what's not broken. :wink:

 

[Charles Reeder]

Thanks everyone for the info about the stock bias reading on your Electra-Dyne!

It seems pretty obvious that the Electra-Dyne is set up to bias warmer than is usual for other Mesa amps using the same type of output tubes. This is a step forward (in my opinion) for them...even if they still won't factory install a bias adjustment.

Getting your Lonestar or Stiletto into the same bias range (by way of the bias mod) WILL improve those amps significantly. (I know I have both of them.)

I'm hoping more Electra-Dyne users will post their readings...and I hope that every Boogie-Boarder who is waiting on a bias-mod-kit; or the installation of one on their Lonestar or Stiletto will promptly share the results with everyone else.

It doesn't seem as if the Electra-dyne NEEDS a bias-mod-kit! But, the Lonestar and Stiletto sure do!

Cheers, Charles

 

[dodger916]

It doesn't seem as if the Electra-dyne NEEDS a bias-mod-kit! But, the Lonestar and Stiletto sure do!

How would a bias-mod kit be installed on a Simul-class amp? Or put another way, would it be possible (or necessary) to bias each socket pair separately? BTW, I think the ED is totally a kick-*** amp.

 

[Charles Reeder]

About installing a 'bias-kit' on a 'symul-class' amp such as the Electra-Dyne...

Well; from the few sample 'bias-readings' thus far received from Electra-Dyne owners; I rather doubt that the amp would reap any great benefit from adjustable bias....except for the possibility of receiving some really 'hard/cold' tubes which need adjustment to warm up.

If it is both feasable and beneficial; the moderate cost of the unit would probably encourage me to install one; (just in case)...but it's definitely not the necessity that it is in the Lonestars and particularly the Stilettos.

I don't know how it wiould affect the 'symul-class'(class A) pair of tubes. It is possible that the amp would require the installation of 2-units (one for the 'symul-class' (class A) pair...and another for the A/B pair...or maybe just a unit for the A/B pair. I think all your questions about the feasability of this mod on this amp could be answered by contacting John Mansfield at Mansfield Guitars.

He WILL NEED a Mesa schematic for the amp to answer your questions however. According to John, Mesa will NOT freely share those with anyone but their authorized service centers AND Mesa amp owners...so you will probably need to 'wrangle' a schematic out of Mesa and forward it to John.

If you find out...please let us know.

Charles

 

[screamingdaisy]

For what it's worth...

It's quite possible to tune the bias of the amp via hotter running tubes. I don't know about other vendors, but the one I deal with (www.thetubestore.com) will select a different grade of tube upon request.

 

[Charles Reeder]

screamingdaisey:

You are correct about getting hotter runnung tubes from various suppliers. I have used the 'tubestore' and found their matched pairs to be pretty consistant. Their #22 rated 6l6 read in the high 30's (38 if I remember correctly) in my Lonestar.

However I didn't always get consitent results with all tubes with all suppliers. I experimented with using 6V6's in a Lonestar. I found a tube which would bias at about 22mv in my Lonestar. I recommended this supplier, this tube and the proper number to another boarder. When he installed them and took a reading...the tubes he received were much colder.

The bias mod allows me to 'take charge' and now I can use ANY tubes I have lying around which before were useless to me because they biased so cold. Someone gave me several pairs of coveted RCA 6L6's but they were reading in at about 18mv in my Lonestar. (FRIGID).
I haven't reinstalled them since getting the bias kit installed...but one day I will...and I'll be able to set them where I want. Somewhere in the 35-42mv range.

As for the Electra-Dyne...well it doesn't sound like it needs an adjustable bias kit installed. But knowing me...if I had an Electra-Dyne...I'd probably end up installing one sooner or later!

Charles