Laney LC50 Power Tube Confusion ??!!

[ryanrobles]

Need some advice regarding power tube replacement.

I currently own an Laney LC50 1x12 combo. Plate voltage measures ~400V. I currentl use 2 SED 6l6GC power tubes - no problems to date.


When bought new (late 90's) the amp was fitted with Sovtek 5881s. The laney service manual specifies "5881 (6L6)" in the power amp positions.

I want to go back to using Sovtek 5881 - however everywehere on the net states that the Sovteks have a max plate voltage of 250v; I dont understand how they ever could of worked in my amp with 400v plate voltage ??

Just to add more confusion - The factroy service manual specifies bias settings for EL34 (as well as 5881) so I assume that, with the proper bias setting, the amp can accept EL34 types ??!!

Would it be safe to fit the Sovtek 5881/6L6wGC??

Any other laney LC50 owners - what tubes are in your amp?????

Any advice / help would be great.


Ry

ps.

Schematic at http://tremolo.elektroda.net/tematykanf.php?adres=Firmowe/LANEY&plik=Firmowe/LANEY

 

[donnievaz]

Re: Laney LC50 Power Tube Confusion ??!!

Need some advice regarding power tube replacement.

I currently own an Laney LC50 1x12 combo. Plate voltage measures ~400V. I currentl use 2 SED 6l6GC power tubes - no problems to date.


When bought new (late 90's) the amp was fitted with Sovtek 5881s. The laney service manual specifies "5881 (6L6)" in the power amp positions.

I want to go back to using Sovtek 5881 - however everywehere on the net states that the Sovteks have a max plate voltage of 250v; I dont understand how they ever could of worked in my amp with 400v plate voltage ??

Just to add more confusion - The factroy service manual specifies bias settings for EL34 (as well as 5881) so I assume that, with the proper bias setting, the amp can accept EL34 types ??!!

Would it be safe to fit the Sovtek 5881/6L6wGC??

Any other laney LC50 owners - what tubes are in your amp?????

Any advice / help would be great.


Ry

ps.

Schematic at http://tremolo.elektroda.net/tematykanf.php?adres=Firmowe/LANEY&plik=Firmowe/LANEY

Not sure where you got that info but this is straight from the Tubestore's website.

Facts you should know before purchasing:
25 Watt tubes such as 6L6, 6L6GB, and 5881 are rated for plate voltage up to 400 volts.
30 Watt tubes such as 6L6GC, 6L6WXT+, and 6L6WGC are rated for plate voltage up to 500 volts.
The KT66 tube type is a 25 Watt tube rated for plate voltage up to 500 volts.

I had a VC50 with 5881's in it with no problem. I eventually swapped them out for JJ 6L6's and the JJ's sounded way better to me.

 

[wixedmords]

Re: Laney LC50 Power Tube Confusion ??!!

Hey Ryan,

Check out this page:

http://thetubestore.com/6l65881types.html

The LC50 is capable of using both EL34 and 6L6 type tubes. I would look around for a slider somewhere that allows you to switch from EL34's to 6L6's and back but if memory serves me correctly there isn't one.

Your plate voltage will change a bit when changing power tubes, so check the plate voltage when you do change power tubes.

If you do eclipse 400v by a little bit I wouldn't worry about as you are likely to only wear your tubes faster. But, as you edge toward 450 volts it may be worth having a tech look at the amp to see if the voltage can be brought down some. This would only apply to 5881's type tubes, as 6L6GC and 6L6 GC tubes and handle more voltage.

Check out the bias equation in my signature if you need.

As always I would start with the bias pot turned down and then check to see that the pot has the range needed for the tube you intend to use.

Good luck.

Wixed

PS. Looks like Donnie beat me to it.

 

[ryanrobles]

Re: Laney LC50 Power Tube Confusion ??!!

Thanks for the replies.

Below are some links that reference the Sovtek Max plate voltage as 250V. However, I also found a post on a different forum which suggests that this is "the result of a common but understandable misreading of the poorly written spec sheet on the Sovtek." And that the actual plate max rating is 550v - which I find more believable.

Can't thank you enough for your posts and putting my mind at rest!! Thought I was going MAD. :smash:

Note your comments on the ability to use EL34 - though there is no switch on the LC50 so assume I would have to bias using the internal pot.

Last question - Given that I can use 25w 5881 types, 30w 6l6 types, can I also use KT66??

Wixed - I'll keep an eye on the plate voltage. I understand that it will differ depending on the bias setting. From memory, the max plate voltage on the LC50 is 414V (at max negative voltage on the grid).


Ry



http://www.activemusician.com/item--MC.58816L6WGCMP
http://muinstrum.com/tubes/8.html
http://www.lpgear.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=LG&Product_Code=S561

 

[jeremy]

Re: Laney LC50 Power Tube Confusion ??!!

the only thing about the kt66 is the current draw but if the amp can handle el34's then it should be fine, so yes.