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Discussion Starter · #1 · (Edited)
Afternoon, guys.

My Laney Ironheart 60H is acting up. Truth is, it's been headed this way for a month or two, now.

Every so often, I'll get a really decent hum or buzz going - usually after the head has been on a while. Then, it'll suddenly start feeding back a little. I can reproduce the hiss/buzz with or without the effects loop connected. The feedback issue - not a scream or squeal, but rather more of a groan that gets increasingly louder until you flip the amp into standby - really only happens when I have an overdrive going.

It's not consistent, though. Sometimes, I can turn it on for a short time and have no issues.

Choice of guitar doesn't matter, choice of cable doesn't matter, etc.

I'm thinking tubes.

So, also open for testing suggestions, I'd like recommendations for tubes: brands, etc.

I'm considering switching from 6L6 to EL34 power valves.

The others are 12AX7.

Thanks -
 

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Discussion Starter · #3 ·
EL34B. Do it.
Thanks -

Any real difference in brand or manufacture point? I see a lot of chatter about differences in JJ or Ruby or Tung Sol or Sovtek, etc. Is that all internet bullshit or is there something to it?
 

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Bork!
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Thanks -

Any real difference in brand or manufacture point? I see a lot of chatter about differences in JJ or Ruby or Tung Sol or Sovtek, etc. Is that all internet bullshit or is there something to it?
Not all tubes are equal, that's for sure. I've always had great experiences with JJ and Tung Sol. Tung Sol EL34Bs are the fucking goods, man.
 

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HEAVY HACKJOB RIFFER
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I personally like to replace EL34 tubes with KT88, and 6L6 replaced with 6550. Essentially in either case it opens up the tone, in my opinion at least, and gives more headroom to push more lows while staying tight.

If you like the power amps tube compression, stick to EL34/6L6, or E34L if you want some sort of thicker EL34.

As for brands, I usually stick to JJ, I have never had any bad experiences with them (although obviously don't take that for granted, tubes can fail no matter what the brand is) but more importantly: to me they sound better than other tubes of the same range.
 

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Discussion Starter · #7 · (Edited)
Tube set shipped this morning. I suspect that once I install them and flip the bias switch to EL34, one of three things will happen.

  1. My Laney will purr like a big cat and there will be pussy for all.
  2. The amplifier will explode, sending slugs of my fat ass flying through walls and windows.
  3. The amp will rise up and slay me.

I'm hoping for some combination of 1st and 3rd.
 

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Discussion Starter · #11 · (Edited)
The switch just swaps some resistors, the amp will likely still need to be biased using the internal trim pot.
I'm told by Laney CS that the bias is fixed. I hope it doesn't have to be adjusted. I'm not sure how to do that.

UPDATE: I decided to ask Laney on their Facebook page. I know there is a bias pot, I'm just hoping there won't be any need to adjust it.
 

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Mod Britannia
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It's always a good idea to bias an amp when you change the tubes, even just replacing like-for-like as there's variations in tubes, and it's not a difficult procedure. HOWEVER, the insides of a tube amp are full of high voltages that WILL kill you if you touch the wrong thing, so you need to know what you're doing first and be careful. Google "biasing a tube amp" and you'll find tons of into on how to do it.

If you do decide to go for it, and I'd recommend it, here's some stuff to help:

Bias probe or this one has an option for a version that reads the plate voltage too

Tube bias calculator
 

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It's always a good idea to bias an amp when you change the tubes, even just replacing like-for-like as there's variations in tubes, and it's not a difficult procedure. HOWEVER, the insides of a tube amp are full of high voltages that WILL kill you if you touch the wrong thing, so you need to know what you're doing first and be careful. Google "biasing a tube amp" and you'll find tons of into on how to do it.

If you do decide to go for it, and I'd recommend it, here's some stuff to help:

Bias probe or this one has an option for a version that reads the plate voltage too

Tube bias calculator
The first time I biased my amp I did it by probing the 1ohm resistor the designers had kindly left... As soon as I got it within spec I shut that death machine off, bias probes look a lot safer!
 

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I'm told by Laney CS that the bias is fixed. I hope it doesn't have to be adjusted. I'm not sure how to do that.

UPDATE: I decided to ask Laney on their Facebook page. I know there is a bias pot, I'm just hoping there won't be any need to adjust it.
"Fixed Bias" is a strange term, IMO: www.thetubestore.com - Different Types of Amp Bias

When I swapped the stock tubes in my IRT to a pair of "Winged-C" 6L6s the bias was a little bit off. When I swapped the 6L6s in my old GH50L to EL34s, using the similar switch the IRT has, the bias was wayyy too hot.

+1 to James' post, BTW.
 

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Discussion Starter · #15 · (Edited)
Thanks, guys. Yeah, and thanks James. I'm going to look into it.

If I find I'm not comfortable, I'm going to haul it in to my amp guy and ask him to bias it.

As I understand, though, the preamp tubes are just plug in and go, yes? I'm going to replace them first and see if that cures my initial problem.
 

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HEAVY HACKJOB RIFFER
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Also as for tubes in general, pre-amp tubes should not be touched with bare fingers, since the grease from your fingers might stick to the tube and cause some overheating, therefore adding the possibility of altering the lifespan of the tube. I've actually been ignoring that rule for years though :lol:
 

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Discussion Starter · #19 ·
Also as for tubes in general, pre-amp tubes should not be touched with bare fingers, since the grease from your fingers might stick to the tube and create so overheating, therefore adding the possibility of altering the lifespan of the tube. I've actually been ignoring that rule for years though :lol:
I'll remember that, thanks. I'll just use the latex gloves I keep around for... well, whatever.
 

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HEAVY HACKJOB RIFFER
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You got it, latex gloves are the safest way.

Well, safest way to hold one while you insert it. Into the socket. I mean when you insert the tube in. Wait... :squint:
 
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