First bias attempt with 2006 Herbert

A

~Abstract~

New member
I've been running 6 JJ EL34's. I want to change outside pair to SED =C= 6550's.

I've removed the 1+6 fuse.
I've replaced the 1+6 tubes.
Amp is connected to cabinet.
Bias pot fully counter-clockwise.
Ch1, master volume on 0...turn amp on.

Bias around 180ma and climbing.

Not red plating...blue led above the fuse hole comes on if I turn bias pot clockwise. Kinda flickers when I take a bias reading even when bias pot is fully counter clockwise. But stays off if I don't touch anything.


Was ist das problem?

Danke!
 
The EL34 don´t match and meet the 6550 to set
the correct bias. That´s one of the reasons we
don´t recommend this tube.

Best,
Peter
 
Can I change all tubes to 6550 safely? Or is that not recommended either? Thoughts on 6V6's?

I've got 6 of the 6550's and also 6 EL34's...


Danke sehr Herr Diezel!
 
Only 6V6S by JJ would handle the plate volts, but not the screen volts (lim is 450V, your 2006 amp should have 475V on the screens).

I'd either go all 6550 or all EL34.

Diezel recommends EL34.
 
I don't think the Herbert can handle all 6550s. I just retubed a VH4 with 6550s and had to perform a mod to get the bias down to about 45mA a pair which is what you need for this type. After I was done and installed the 6550s I thought they made the amp sound inferior. The customer is experimenting (wants to sound like James Hetfield), but I am certain he will be back next week to install EL34s. Diezel Amps are designed for EL34s and those tubes are what produce the signature Diezel tone.

If you install all 6550s on your Herbert and then turn the bias trimmer all the way to left, if your DMM reads more than 45mA you need a small mod.

Another thing: we really do NOT like any JJ tubes (preamp or power amp). They sound awful and we at Diezel all agree on that. That is why we only install Ruby BHTs or the new BGs. If you you put a Sextet of those in your Herbert you will already hear a big improvement over your JJs.

Jens Kruse
 
Ok...I'm a noob.

I had it set for microamps, not milliamps...so no wonder. :D

I just reinstalled the EL34's...and set bias to mid 60's (63-67mA per pair) Sounded colder and harsher than I was used to...not sure where bias was set initially. Is this where EL34's should be?

I just removed all 3 fuses and adjusted all three on the fly...is this acceptable?


How much are a set of Rubys?
 
No, you must have put the DMM correctly, because 6550s do run very hot on an EL34 bias setting. The current can go up to 180mA which of course is close to a nuclear melt down.

The EL34s should be biased (in the US) to 70-75mA per pair. I bias to 75mA since it goes down over time. This is in accordance with Peter's recommendations.

No, you should NOT pull all 3 fuses and bias your amp ! Pull 1 fuse at a time and bias. Turn amp off in between. Be very careful ! This is all very dangerous play and should only done by a professional.

I will pm you the Ruby set infos.

Kind regards,

Jens Kruse
 
Diezel US Support":eoi8hn2t said:
No, you must have put the DMM correctly, because 6550s do run very hot on an EL34 bias setting. The current can go up to 180mA which of course is close to a nuclear melt down.

The EL34s should be biased (in the US) to 70-75mA per pair. I bias to 75mA since it goes down over time. This is in accordance with Peter's recommendations.

No, you should NOT pull all 3 fuses and bias your amp ! Pull 1 fuse at a time and bias. Turn amp off in between. Be very careful ! This is all very dangerous play and should only done by a professional.

I will pm you the Ruby set infos.

Kind regards,

Jens Kruse
Click to expand...


Oh. No I'm POSITIVE I had the multimeter on the wrong setting.

Ok...I'll bias up hotter, it's darn near unplayable as it is.


Thanks for your help! I referenced the tech section on the Diezel site and didn't see the info on biasing (which I heard about in several other threads)
 
There is no info on biasing as we are not allowed by law to teach non pros how to do this. It's dangerous and Diezel can't be liable.

Throw those JJs out, they will never sound good.

Jens
 
Diezel US Support":1yvr6cxv said:
You don't have to buy anything from me.tubes can be bought from zillions of places.

Kind regards

Jens
Click to expand...


Yup. I just got them from the Valve Queen with cheaper shipping.

Thanks!
 
Diezel US Support":mw3wv4ll said:
Welcome! You will like your new tone.

Jens
Click to expand...


LOL


I've got some matched SED =C= and Sylvania EL34's...would those sound better than my junk JJ's until my Rubys come?
 
JJ's are not junk.... :loco:

I had Winged C EL34's in my Herbert when I got it and ran them for a few months. I was not totally happy with Herbert's tone, channel 3 was so compressed with a guitar that had a hot pickup that it was nearly useless.

I then switched to all JJ KT88's in the amp. Totally woke my Herbert up, it got rid of a noticeable amount of compression causing the tone to sound big and fuller. The bottom end got ultra tight and ice picky just the way I like it. Obviously a big improvement for metal.

I realize that here recently, Peter Diezel has gone to an EL34 only policy, but I can't help not to comment because of the improvements I heard, when I and many others were going to big bottles back when for a while some of the Diezel amps were coming from the factory with 6550's.
 
Diezel US Support":2czxw9n3 said:
I don't think the Herbert can handle all 6550s.
Click to expand...

FWIW - I run my Herbert with a sextett of SED =C= 6550 for over 2 years now without problems.

Before the 6550, I was running JJs...first EL34, than E34L...not a single pair lasted longer than 3 months (1 pair even made the fuse explode after 10 hours). Never will I touch anything from JJ again.
 
RJF":uo5vbp2j said:
...when for a while some of the Diezel amps were coming from the factory with 6550's.
Click to expand...


Yeah, mine shipped from the factory with those non-recommended Winged =C= 6550's.

:doh:

:LOL: :LOL:


How long before the Ruby EL34BHT's are non-recommended and Diezel moves on to another tube?
 
People demanded different tube types some years ago and so Peter tested (lots of threads in this forum) a bunch of brands and types, somehow in the public . . . . This includes JJEL34L, JJEL34, KT77, Svet EL34, Svet 6550 and so on.
The reason was that players were looking for things like more tightness, less of this and more of that. And it was when/after chinese EL34STR supplies were not meeting the standards of Diezel (and other manufacturers). A bit later Ruby (Mr. McNeal if I recall correctly), who has influence on the manufacturing sites in china, came up with the "BHT". After testing and asking customers here Diezel decided to go with this tube and did for quite some time until Ruby came up with a even better and more reliable tube, the BG.

Sure, there may come the time when Diezels are shipped with XY tube and the reason is reliability and sound.

To me thats a much better concept than throwing STRs into the amps, biased to 40% max plate diss to result acceptable failure rates as f.i. Marshall does - and the price the customer has to pay is a cold, sterile sound.
 
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