Retubing a Fixed Bias ENGL amp..

[ukwan]

Just lost a power tube and wanting to retube obviously.

With this amp being fixed bias, that means i cannot adjust the bias trim.. so what's the current draw ladies and gents for a Screamer 50 Combo..

cheers,

Also anyone with any knowledge on how to mod this amp to have an adjustable bias would be GREATLY welcome.. as my friend is into modding amps and is capable of doing this for me with the schematics etc.

[Paul Secondino]

I think that getting touch with Bob at www.eurotubes.com will be your best bet.

I bias my own amps right now but the Mesa 290 power amp I have is fixed bias.So I simply have to buy very hot power tubes for it to ensure that it will be in the optimal bias range.

I'll see if I can find more specific info to your amp.

[ukwan]

38mA Draw.. is the optimal bias, thanks to Bob at EuroTubes for the info.

Im going to order some JJ's from him.

[DerekB]

Originally Posted by ukwan

Just lost a power tube and wanting to retube obviously.

With this amp being fixed bias, that means i cannot adjust the bias trim.. so what's the current draw ladies and gents for a Screamer 50 Combo..

cheers,

Also anyone with any knowledge on how to mod this amp to have an adjustable bias would be GREATLY welcome.. as my friend is into modding amps and is capable of doing this for me with the schematics etc.

I didnt know the Screamer was a non adjustable fixed bias? You sure about that?Anyway if you need a Schematic for it I can send send it your way just send me an email rocksolidamps@bellsouth.net

Derek

[vai n maiden]

The ENGLs are fixed bias, yeah, when I first lost a valve in my Thunder 50 i was a bit as I had no clue where to get the ENGL 5881s from... I ended up just getting some harma 6L6GCs and hoping for the best, it hasn't blown up yet Had a little more headroom, which at the beginning I wasn't quite sure whether I liked but I think i do now. Wish they did have bias trim pots but I'll survive without


So.... with you being in the UK (or at least the name suggest so) Get to www.watfordvalves.com and get some great priced Harmas your way!

[DerekB]

Originally Posted by vai n maiden

The ENGLs are fixed bias, yeah, when I first lost a valve in my Thunder 50 i was a bit as I had no clue where to get the ENGL 5881s from... I ended up just getting some harma 6L6GCs and hoping for the best, it hasn't blown up yet Had a little more headroom, which at the beginning I wasn't quite sure whether I liked but I think i do now. Wish they did have bias trim pots but I'll survive without


So.... with you being in the UK (or at least the name suggest so) Get to www.watfordvalves.com and get some great priced Harmas your way!

No the Engl's usually have an adjustable fixed bias (Trim Pot) but you are talking about the Screamer and Thunder and I'm not sure about those model's if they have a bias pot or not but I am most certain they do. I am going to verify this info and report later.

Derek

[vai n maiden]

That'd be great, Derek , there isn't one in external view anyway, I don't trust myself not to touch some charged capacitor if it involves taking the casing off

[DerekB]

I finally did find out for sure that the Screamer and Thunders do have trim pot's that are locate inside of the amp. I havent looked for it's exact position but verified this info from Engl in Germany. If you guy's need a schematic shoot me an email at rocksolidamps@bellsouth.net . Hope this helps.

Derek

[vai n maiden]

Ahh brilliant, I'd like to see how much it'd cost to get them wired outside of the casing for easier access, shall search around for techs near me

[power freak]

Originally Posted by vai n maiden

Ahh brilliant, I'd like to see how much it'd cost to get them wired outside of the casing for easier access, shall search around for techs near me

Its free well about £1 for a pot

Its simple to do, so I woul;dn't think it would cost that much. Bewarned it WILL VOID ANY WARRANTY if its inside the 3 year (I am unsure how long ENGL say?) You would also have to install the probe locations on the outside because you would still need some way to measure, so the case ould still come off with the pot.

[vai n maiden]

It's not free if i don't trust myself with high voltage electricity though is it