The most commonly asked questions about amplifier valves.

Q1: My valve kit comes with a “Balanced” valve, where does that go?

In 99% of amps, the balanced valve goes in the final preamp valve position. So that means it is nearly always the one furthest from your input jack where you plug your guitar in. (There are exceptions but when you look at the valve kit on our website for your amp it will tell you where the balanced valve goes).

The balanced valve is used for the phase splitter so works in a totally different way to the other preamp valves.

So it usually goes furthest from the input jack and closest to the power valve section.

The good news is, if you do accidentally get the preamp valves mixed up it won’t do any harm to the amp.

Note: We are often asked how you will be able identify the balanced valve since they all look the same. We mark the valve box “balanced’ and we also put a small letter “B” on the top of the valve using a black permanent marker.

Q2. My amp is starting to make a bit of noise (crackling, popping, hum etc). Is it likely to be the valves?

It’s always hard to diagnose an amp fault without looking at it but the first sign that your valves are getting worn is a noisy amp. The most typical symptoms are an increase in hum, crackles, popping, and volume issues. Eventually one of the valves will blow and the amp won’t work at all.

It is always advisable to change the valves before they get to this point as other problems can often occur when a valve eventually blows.

Changing the valves is always a good starting point when you start getting “odd” noises as they are usually the culprit.

You can do this yourself very easily and you won’t need to take it to an amp tech if this proves to fix the problem. If it doesn’t solve the problem, at least you have removed one of the most likely causes. You have also saved yourself the labour fees and markup fees on the valves at the same time.

Most of our customers change their valves themselves. The only thing you need to remember is that amplifiers can carry a very high voltage long after they have been switched off. This should not be a problem provided you don’t go poking around but if in any doubt, simply leave the amp unplugged for 2 to 3 days before changing the valves.

Q3. My amp has always been quite noisy, even after fitting new valves, is that a fault?

Many amps are noisy because of noise on the power circuit. A noisy mains feed can easily be checked by trying the amp on the downstairs circuit of your for example instead of a bedroom. Make sure you remove all four-ways, pedals and long guitar leads as they can all add to the back ground noise. Just plug the amp in with its power lead and nothing else to see if that makes a difference.

Long guitar leads, cheap guitar leads and leads that have had a tough life can all add noise to the amp as well. Long ones will often act as an antenna pick up passing taxis.

Another thing you can do is replace the ECC83 (12AX7) preamp valves in your amplifier with Electro Harmonix 7025EH preamp valves instead.

The 7025EH is a high quality low-noise, low-hum, low-microphonic version of the ECC83 and will clean up most amps very nicely.

Fender specify the 7025 in a lot of their amps for this very reason. A 7025 is not expensive and it can be used in any position that has an ECC83 so it will never go to waste. The V1 position has the most benefit but other ECC83 valves may benefit significantly from the upgrade as well.

If you have an ECC83 in the phase inverter position (that’s the last one in the preamp stage that feeds the power valves) use a balanced 7025 for best results.

If you are about to order a set of valves and suffer with a noisy amp, add a 7025EH valve to your order by click on the “Choose your valve” section on the website or alternatively you can find 7025 valves here.

Everyone should have a spare ECC83 or a spare 7025 in their bag.

If you are gigging without one you are taking a big risk. I never understand why guitarists will risk having a gig end prematurely because a preamp valve blows half-way through the evening. Having a spare will also make it very easy for you to check if a preamp valve is playing up if you start to get problems with your amp.

Q4: I have ordered valves but not received my tracking details.

You will first be sent a message from the warehouse to say your valves are being packed and prepared. Later that day, when the valves are collected by the courier, you will be sent your tracking details.

When we dispatch your valves (which is usually next working day unless you have chosen the free 7-day delivery service) we send your tracking details to the email address you gave us when you ordered. If you have not received those tracking details there are three possible reasons:

  • You ordered through Amazon and you ticked the box that says you do not want to receive any communications from sellers. Unfortunately that means you cannot receive your tracking information either.
  • You entered the wrong email address.
  • And thirdly, and most likely, the email has gone to your junk folder.

If you still cannot find your tracking details, drop us an email and we will send them to you again.

Q5: What valves does my amp use?

You can find out exactly what valves your particular amp uses by clicking on the “Choose Your Amp” from the menu on the homepage. We have covered over 700 amps on our web site but if yours does not appear there, just drop us an email. 

Q6: I’ve heard about this “bias” thingy – do I need to bias my valves?

Ideally yes. We will always tell you to bias them every time. That’s because if there is a problem and the valves “red-plate” we could be held liable for not giving you good advice.

However, as you will have seen on the forums, most amp owners don’t bother. When I say “most” I would guess as many as 90% don’t.

To be fair to them, although there is a recommended bias setting specified by the manufacturer, in reality, some guitarists will actually prefer their amps to run hotter or colder than the recommended setting. So we are not dealing with absolute numbers here. If you do decide you would like to bias your amp there are two routes.

You can buy the testing equipment and a bias manual from us (check here to see if we have one for your model) and have a go yourself – or you can take it to an amp technician. If you do go to an amp tech you will have the peace of mind that it is correctly set up and if you need it tweaked to be hotter or colder than the recommended setting this will be done for you.

Biasing is easier with amps that have adjustable trim pots compared with those that have a resistor soldered in place. (Also see our answer below on “What is Bias Exactly?”).

Some amps are Cathode biased which means they do not need to biased. You can see a list of these amps here to see if this applies to you. There aren’t many in this category but you might be lucky – or you bought that amp for that reason.

Q7: What is bias exactly?

A: Good question. It’s like setting the tick-over rate on the car. A power valve “idles” at a certain current. Adjusting the bias sets this current not too high and not too low. The good news is that there is quite a bit of tolerance which is why so many people do not bother to bias. Too hot and your valves will wear out a bit more quickly, but you’ll get a fat sound. Too cool and the valves will last longer but the sound might sound a little thin in extreme settings. This is an important point because when you read on a forum that a particular set of valves, let’s say 6L6 power valves, sound like this on a particular amp, and break up at let’s say volume 7, your set of so-called identical 6L6 valves may be running either hotter or colder and your amp may be biased completely differently.

Remember, “fixed bias” does not mean you don’t have to adjust the bias. It means that it can be adjusted to a fixed value. That’s the opposite of what you would think. You can find out more about fixed bias here.

We have a more detailed blog on this subject here: “Biasing amplifiers – what’s involved?”

We also have a blog dedicated to “Cathode Bias – What is it exactly” that you can read here.

Q8: I live near your warehouse in Reading, can I collect from the warehouse?

A: Unfortunately the warehouse is not geared to accept customers or payment. Nor are they able to pull one order from the hundreds we send out each week. We do have a spare storage facility in Beaconsfield and if you drop us an email BEFORE you place your order we may be able to help with a collection. Once your order has been placed though we usually cannot intercept it.

Q9: I’ve never changed valves on my amplifier before, is it easy?

Yes it really is. To remove a valve, steadily pull it. If it doesn’t come out give a VERY slight circular rocking motion and it will pop out. Note; I use the words “very slight“. If you are too violent with the valve you run the danger of bending the pins.

To replace a valve, make sure the pins are correctly aligned with the socket (they only go in one way) then push it firmly home. The Health and Safety guy will also recommend that you hold the valves with a piece of cloth just in case the valve breaks and cuts your hand.

Warning: Do remember that guitar amplifiers carry very high voltages even after they have been switched off so be sensible and don’t go poking around in places that don’t concern you.

Q10: I’ve heard that brand ‘X’ valves give a superb sound. How do they compare with your valves?

Great question.

If you have visited a few forums you quickly realise that if you ask 5 guitarists which valves are best you get six different answers. There’s a very simple reason for that and it’s called ….. the “variables”.
If you take five identical amps straight off the production line and compare them brand new, they all sound different. That’s because even at that point there are differences in the manufacturing processes. Also, the brand new valves inside vary massively and the setups also vary massively.
Now send those amps out into the market place.

Let five different guitarists plug them in. They all use different strings, they have different settings on both their guitars and their amps, they use leads that cost from £5 to £55, they play differs styles of music, they play at different volumes, in different rooms with massively different acoustics …..  they are even playing different guitars.

Then, of course we are all chasing different sounds in our head. I want to sound like Slash and you want to sound like Mark Knopfler. How can we possibly agree on what guitar, amp or valve sounds “best”?

There’s more but I think you get the idea.

So the answer is it’s a bit like choosing a partner – play around and find out what you like. (Apparently, that’s not the correct PC company line here but it’s the easiest way to explain the concept that we all like different things in life. What is great for you isn’t great for everyone).

We have been in this industry for 30 years and our valve kits are very carefully chosen to ensure great sound from your amp.

Compared with what you will spend on gear, valves are cheap. Experiment – find out what what floats YOUR boat!

Q11: How can I tell if my pre-amp valves are blown?

Before we get into the theory, can I just say that every guitarist (especially a gigging guitarist) should have at least one spare pre-amp valve in their tool kit, carefully wrapped of course. Pre-amp valves are not made of concrete and so you should have at least one spare valve so you can quickly test when you have a problem or keep the band on stage when an amp goes at a gig. The ECC83 valve fits just about every valve amplifier ever made. It would be very naive to not have a couple of brand new spare ones in your drawer.

Right, now on with the techy stuff. If one of your preamp valves is blown there are often a few telltale signs:

  • Visual Clues

Unfortunately, at first glance, a blown preamp tube will often look okay. Sometimes it may be more obvious because the valve is cracked or has a white film on the inside.

  • Microphonic Valves

The easiest way to tell whether a valve is blown is when it goes “microphonic”. When this happens your amp gives off a high-pitched squeal when you turn up the volume. That will happen when the guitar is plugged in but also when it isn’t. You can test which tube has gone microphonic by gently tapping each valve with a pencil. Simply listen as you tap each one and the valve that is blown will sound very different from the others. Note, all valves tend to have some element of microphony sp don’t get too carried away here.

  • Crackling Noises

Crackling, hissing and popping noises coming from your amp are a sign you have a failing or blown preamp valve. However, you need to eliminate the power valves in case they are the culprit. If you are hearing noise or crackling, you can rule out a power valve with this simple test.  Gently tap on the power valves, one at a time using a pencil.  They should not make any noise.  If noise changes when you tap, this could mean you have a failing power valve. Always be ready to switch the amp off quickly in case you have a failing valve and the tapping causes it to short out.

  • Weak Signal 

A blown pre-amp valve can cause your amp to produce a weak signal or lose all sound. A weak signal will diminish the amp’s volume and cause it to emit a low buzzing sound. A weak signal will eventually turn into a complete loss of sound.

  • Lack of EQ Control

You may be surprised to know that the Pre-amp valves also control the EQ. If adjusting the EQ knobs on your guitar does not change the tone of your amp, you may well have a blown pre-amp tube.

  • No Reverb

In older tube amp models, the reverb is also controlled by the pre-amp valves. So if your reverb begins to sound a bit odd, or you lose your reverb altogether, it could be a blown pre-amp valve.

Q12: I’m looking for a certain sound on my amp (more bluesy, more bite, better low end, better top end, more headroom or whatever). Which valves would you recommend?

In our experience, changing valve manufacturer will not significantly alter the sound of your amplifier.

Don’t get me wrong, you will find subtle differences. Trying a different brand in the V1 position is worth the effort and cots little. But if you want your Fender to sound like a Marshall or Vice Versa – forget it.

We also get asked if the power valve scan be changed to a different type of power valve. A very small percentage of amps are designed to cater for this and even have a switch to accommodate the change. Mots don’t!

You also have the problem that the amp was set up to take certain valves and changing to different ones will require an amp tech to make sure it can both cope and deliver the tone you want within the bias settings.

The forums are full of opinions and, as you will see, if you get 30 comments you will get 29 different opinions. The reason there are so many opinions is simple –  there are so many variables.

  • No two amps sound the same.
  • No two guitars sound the same. Even two identical guitars made the same week will sound different.
  • All guitarists play in a different style.
  • We all have a different idea in our head of what sound is “best”.
  • You play rock and I play country.
  • You use different strings to me.
  • Your guitar is set up differently to mine.
  • I have a brand new £60 lead – yours is a tatty free one the shop gave you that is adding more noise than you could ever imagine.
  • You have the tone set low and the volume high. I have the bass dialled in and low volume because of the neighbours.

The list is endless – which is why the discussions are futile. You need to change your amplifier if you’re looking for a different sound – which is the reason I own so many amplifiers.

Q13. My amp is running too hot and sometimes blows a fuse.

My HT fuse blew on my Laney so I’m thinking that I may need a new set of output valves. I know that a blown fuse is the result of a fault not the cause and the replacement fuse hasn’t blown yet – but the amp seems to run very hot.

It’s not red plating but the rear panel is too hot to touch even with no signal. I can’t say whether it has always been like this and I gig virtually every weekend with it but I am a little concerned now. Would you know if they run hot naturally and if I need new ones would I need to re-bias? Any recommendations regarding replacements? ACDC, Sabbath type sound.

A. From what you have described I diagnose that the output valves are pulling too much bias current and that sometimes it just tips over enough to take out the HT fuse. You probably need a new set of output valves as they will have become worn with this excess current, but in this case, you should then get the amp biased to make sure the current is correct. 

Q14. My amp keeps blowing fuses.

There could be many reasons for this but If your amp keeps blowing fuses the starting point is to replace the rectifier valve (if it uses one). Amp owners often change their preamp and power valves but forget about the rectifier valve. The first job is to swap that out.

Q15. Is it easy to change the valves on my amplifier?

Yes, this is a very straightforward job and you can easily do it yourself. There are some tips above on how to remove and replace your valves.

Q16. I want my amp to sound different (see also question 12 above).

As a guitarist myself I will be blunt and honest. You will never get an amp to sound like a different amp simply by changing the valves. Once you have a particular sound in your head you will never be satisfied.

That is why I have a house full of amps.

It is true to say that swapping an ECC83 for an ECC81 will make a difference in the sense that it will reduce the gain and that will impact to some extent on the tone – but your Orange Rockerverb will never sound like a Fender Blues Deville.

Yes, you would also need to rebias if you change the power valves.

Q17. I have one amp that runs at 220 volts and one that runs at 120 volts. Do I need to specify the voltage when I order my valves?

I’m assuming you are talking about MAINS INPUT voltage for your two amps? E.g. one is UK voltage and one is USA voltage. If that is the case then no, you don’t need to make any changes and your valves will work perfectly with either amp. Your amps have different mains transformers to handle the two different input voltages, but they produce identical OUTPUT voltages and so you can use the same valves.

Q18. I have a noisy scratchy volume pot. Will a contact spray solve the problem?

Yes, you can use a contact spray and we estimate you have a 50/50 chance of this curing the problem without removing the chassis. Those are pretty reasonable odds considering the small outlay. The product we recommend is Caig Deoxit D5. We have found this to be the best product available. It is not the cheapest but well worth the extra money. The 40g can is about £13.00 at the time of writing.

Here’s how you do it. Put the amp on its back so the pots are pointing upwards. Remove the knobs on any of the pots you want to clean. Now spray the DeOxit onto the shaft, close to where it enters the chassis. The plan is that enough runs down the shaft and into the pot body. Turn the pot backwards and forwards a few times. We reckon that on average 50% of the time this will work. 50% of the time you have to take the chassis out and try to get the nozzle into the pot.

To find out more about scratchy sounding pots click here

Q19. I have decided to get involved in biasing my power valves myself. How can I work out what the settings should be?

Here is a link that will tell you what the settings for each power valve should be: https://tedweber.com/bias-calc/