Page 1 of 2
Goto page 1, 2  Next
Author Message

<  Music Gear  ~  Re-Tubing Amps

distantsundave
Posted: Mon Apr 16, 2012 6:20 pm Reply with quote
Joined: 07 Jun 2005 Posts: 2010 Location: Hell
Anyone ever done this? I've to replace the tubes in my ENGL Fireball and this'll be the first time I've had to do it.

Simple process? Should I buy the stock tubes that came with the amp when i bought it or go for something different?

Any advice would be appreciated.

I'm off to Google to find out more!
View user's profile Send private message Visit poster's website
chewy
Posted: Mon Apr 16, 2012 9:25 pm Reply with quote
Joined: 19 May 2009 Posts: 279 Location: Shoetown
Presume you mean power amp tubes? If so you'd need to get a matched set e.g.

http://www.hotroxuk.com/matched-valves-links-page-12ax7-6l6-909-0/jj-computer-matched-valves-ecc83s-6l6-el34-2188-0/jj-valve-6l6gc.html

JJ are supposed to be good and aren't just rebadged from other manufacturers.

The instructions for ENGL recommend you get a professional to replace them since the bias needs to be adjusted and since these amps have high voltage its risky if you don't know what you are doing.

If you just mean pre-amp tubes (e.g. 12AX7/ECC83) then this can be done yourself.
View user's profile Send private message
evil crawling i
Posted: Mon Apr 16, 2012 9:31 pm Reply with quote
Joined: 07 Jun 2005 Posts: 407 Location: Amity Island
Hey Dave,

Firing them in is the easy enough done. Although even using exactly the same valves require you have you amp rebiased. I've never done this, but it's essential to have your amp running at optimum level. A local amp tech should be able to do this no sweat.

As for the type of valves, that's up to you. 6L6's and EL34s are the most used power valves for metal. 6L6s have a warmer sound with slightly more low end, and EL34s have more crunch and mids and a tighter sound.

Hope this helps

Ian
View user's profile Send private message Visit poster's website
fonniewhelan
Posted: Tue Apr 17, 2012 4:00 pm Reply with quote
Joined: 02 Mar 2009 Posts: 153
Fuck sake...just wrote a huge reply and i hadn't logged in. Lost it all. Basically my advice is to learn to do it yourself as you won't believe how simple the process is.

Start by going to www.eurotubes.com and read up a bit about biasing and specifically biasing for your amp. They have advice up there. What you need to get is a bias probe, which I bought from this website. I also bought their cheap multimeter.

You should really try do it yourself. You will not regret it and you'll never have to worry about it again, and I can't stress enough how simple it really is, especially for the more modern amps. I bias my Peavey JSX head all the time and have re-tubed it myself. If you have any specific question let me know and I'll respond.
View user's profile Send private message
fonniewhelan
Posted: Tue Apr 17, 2012 4:16 pm Reply with quote
Joined: 02 Mar 2009 Posts: 153
Oh ya, obviously you will need a new set of power amp tubes. For this you really should get a matched quad of whatever make you are getting. A lot is spoken about various different tubes and to be honest I think most of it is a load of nonsense. Any reputable make is worth putting in your amp really.

I use JJ Electronic 6L6GCs in my JSX. I bought them from www.jjtubes.eu. Got a matched quad. The reason I bought JJ was due to the www.eurotubes.com website that I mentioned above. Went on their recommendation. Plus the JSX came stock with JJ EL34s. To my ears they sound superb. Really keep their low end thump at high volumes and tighten up really nicely. Lovely compression too. The cleans from a JSX wouldn't be great but the 6L6GCs make a big difference. They are so much nicer than the EL34s, which I found quite sterile and harsh in this amp. Switched them out and never looked back.
View user's profile Send private message
StoutAndAle
Posted: Fri May 04, 2012 10:06 am Reply with quote
Joined: 19 Apr 2012 Posts: 34 Location: Cork City
How's it going lads?

I have a Laney TF200 which has an ECC83 (12AX7) tube in it which needs to be changed.

Is it just a case of popping out the old one and putting in a fresh tube?

The manual says to take it to a Laney dealer but the place I bought the amp has long closed. Also the tube is about 15 quid so if it can done done easily then I'll just do it myself.
View user's profile Send private message
chewy
Posted: Fri May 04, 2012 10:31 am Reply with quote
Joined: 19 May 2009 Posts: 279 Location: Shoetown
Yes there should just be a retainer to hold it in place. Don't hold it by the glass.

I couldn't see a picture where it showed where the tube was (although I should imagine it is behind the grill).
View user's profile Send private message
StoutAndAle
Posted: Fri May 04, 2012 11:07 am Reply with quote
Joined: 19 Apr 2012 Posts: 34 Location: Cork City
Cheers man.

I'll do that.

Sound.
View user's profile Send private message
chewy
Posted: Fri May 04, 2012 11:25 am Reply with quote
Joined: 19 May 2009 Posts: 279 Location: Shoetown
If you can't see the tube then don't open the casing though. JJ and Tung Sol tubes come recommended (although I use TAD myself).
View user's profile Send private message
StoutAndAle
Posted: Fri May 04, 2012 1:21 pm Reply with quote
Joined: 19 Apr 2012 Posts: 34 Location: Cork City
chewy wrote:
If you can't see the tube then don't open the casing though. JJ and Tung Sol tubes come recommended (although I use TAD myself).


The tube is clearly visable if you undo the screws on the back mounting. It's sat in the middle of the PCB.
View user's profile Send private message
chewy
Posted: Fri May 04, 2012 1:29 pm Reply with quote
Joined: 19 May 2009 Posts: 279 Location: Shoetown
That should be fine - my Peavey has the pre-amp tubes mounted to the PCB and requires a hatch to be removed to access them. Really it was just a warning due to the voltages involved.
View user's profile Send private message
kranog
Posted: Wed May 09, 2012 3:10 pm Reply with quote
Joined: 17 Jun 2010 Posts: 129
It's very simple - you don't actually need a bias probe (you should have one if you plan on doing this quite a bit - I don't have one as I only change my tubes every year maybe!)
But you will require a multimeter.

Don't wear any metal bracelets while working on the amp.

Important points to remember;

Change the tubes when the amp is switched off
Make sure the speaker is plugged into the amp when you turn it on
Turn it on and leave the tubes heat up for about 15 minutes or so
Use the black multimeter pin on the centre bias pole and red pin on both the red and left bias poles
6L6 tubes recommend about 90-100 mA per side - so a trick is to start with the right side and go up to about 110 mA - give it about 10 seconds (the left side will try to balance in accordance to the higher output of the right) - then set the left side to the desired mA level and then adjust the right side to match.

I just bought a set of JJ KT77's - I'm really looking forward to hearing what they can do in my Marshall! Smile
View user's profile Send private message
Nanoman
Posted: Thu May 10, 2012 10:50 am Reply with quote
Joined: 18 Jun 2006 Posts: 113 Location: Galway
While replacing and biasing tubes is a simple procedure I felt I should add a note regards safety considering the voltages that these things run off.

A few safety tips:

* Keep your LEFT HAND IN YOUR LEFT POCKET AT ALL TIMES! If you do get a shock this reduces the risk of current traveling directly through your heart.

* Making sure the amp chassis is grounded to something is a good extra safety precaution - not necessary though.

* HIGH FUCKING DC VOLTAGE - Be bloody careful, a shock of this is worse than the mains AC. If you touch a charged power supply capacitor you may not even know about it (that is you are dead).
View user's profile Send private message
Mazzy Maz
Posted: Thu May 10, 2012 11:13 am Reply with quote
Joined: 03 Sep 2008 Posts: 1661 Location: http://bit.ly/QahY0C
kranog wrote:
I just bought a set of JJ KT77's - I'm really looking forward to hearing what they can do in my Marshall! Smile


Nice. My JCM800 came stock with 6550's which I replaced a while back with JJ KT88's. Very happy with the sound out of it.
View user's profile Send private message Visit poster's website
StoutAndAle
Posted: Fri May 11, 2012 1:56 pm Reply with quote
Joined: 19 Apr 2012 Posts: 34 Location: Cork City
Shit lads, I thought it was just a case of popping one tube out and putting the other in.

Confused

EDIT: After looking in another thread it seems that I don't need to bias anything seeing as it's a pre-amp tube.

Thanks be to fuck.
View user's profile Send private message

Display posts from previous:  

All times are GMT + 1 Hour
Page 1 of 2
Goto page 1, 2  Next

Jump to:  

Post new topic
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum