Just ordered some new 12AX7 valves for my Marshall amp.

Hi Everyone,

I finally decided to "bite the bullet" and order a set of three Russian made Genalex 12AX7 ECC83/B759 Gold Lion Gold Pin valves for my Marshall MA100C guitar amplifier from Evatco, I've decided to pay a bit extra so I can get them delivered via express post, apparently these Genelex Gold Lion 12AX7 valves are supposed to be amongst some of the best 12AX7 valves you can buy, so it'll be interesting to see how they perform in my Marshall amp, going by what I've read on a valve comparison chart that I downloaded from amplifiedparts.com, they have the highest ratings out of all the valves listed on the chart.


Here's a pic so you can see what the Genalex Gold Lion 12AX7 valves look like:

Attachment 17165

"Gold Lion's gonna tell me where the light is."

Keen to see how you go with them. My valves are (probably) long overdue for a replacement, and it sounds like these have some hype behind them. Any chance of a before/after comparison?

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Originally Posted by G-Axe

"Gold Lion's gonna tell me where the light is."

Keen to see how you go with them. My valves are (probably) long overdue for a replacement, and it sounds like these have some hype behind them. Any chance of a before/after comparison?

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Yeah it'll be easy enough for me to record a before/after comparison of my Marshall amp, will do that when the new valves arrive in the post so stay tuned.

Update:


I just got an email notification from Australia Post, apparently the three Genalex 12AX7 Gold Lion Gold Pin valves that I ordered from Evatco are due to be delivered today, so that's only three business days (not including weekends) that it took for the parcel to arrive in Darwin, not bad for express delivery.

Good stuff. I imagine you'll be very excited to have them in your hands sometime about now.

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Originally Posted by G-Axe

Good stuff. I imagine you'll be very excited to have them in your hands sometime about now.

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I just checked my mailbox after getting home from uni (I was at uni all of today), expecting to find a parcel card in it, but there was nothing, hopefully I'll be able to pick them up tomorrow, Australia Post did send me a second email notification, saying that there was a parcel ready to be picked up at the Winnellie Post Office just up the road from where I live, it included a parcel tracking number with it, so, it looks like I might need to either write-down the tracking number on a piece of paper, or do a printout of the email, and then take it with me to the post office tomorrow in the morning, it's very odd that they didn't leave a parcel card in my mailbox, usually they do, oh well, I'll just have to wait and see tomorrow then.

Update:


Finally got the parcel with the new valves in it home from the post office, since my Marshall amp is at uni, I will be taking the parcel with me when I go to uni, along with my laptop computer, Scarlett 2i2 Audio Interface, and etc so I can do the before/after demo recordings, I do need to stop off at Battery world to get them to order in a new rechargeable battery for my laptop computer though, but it can still be powered by the power adapter, once everything is sorted I'll post a link to the before/after demo recording so stay tuned.

Update:

Unfortunately, I didn't get a chance to do the before/after demo recording today because I still need to install my DAW software onto my laptop computer (I had to do a reformat/clean install recently because it had been running very slow lately), which I will be doing tonight, hopefully I'll get a chance to do the recording tomorrow, but, I did manage to get the three new valves installed in the Marshall amp and give them a tryout, first impressions is that the Marshall Amp sounds a lot smoother with the new valves installed, especially the overdrive channel, I can turn the gain up all the way and it doesn't get all flabby in the low end like it did when the old valves were installed, it sounds much more like a Marshall amp now, and the amp definitely seems to like the new valves, anyway, I like the sound of them so they are keepers.

The clean channel sounds really good, especially with some reverb dialed in too, definitely worth the money I paid for them, so I'll be buying more of them in future.

Glad you're happy with the changes. It can be a real let-down when you splash out on some reportedly extra special valves only to find you liked the old one's better. Done it myself several times!

Pre-amp valves last for ages so you won't need to buy any more for the Marshall for many years (except for an early failure). It's the power valves that need replacing, but even they can last for many, many years if the amp isn't used that much and is always driving into the correct load impedance.

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Originally Posted by Simon Barden

Glad you're happy with the changes. It can be a real let-down when you splash out on some reportedly extra special valves only to find you liked the old one's better. Done it myself several times!

Pre-amp valves last for ages so you won't need to buy any more for the Marshall for many years (except for an early failure). It's the power valves that need replacing, but even they can last for many, many years if the amp isn't used that much and is always driving into the correct load impedance.

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Yep, that's because the preamp valves usually only have anything up to a milliamp of current flowing through them, on the other hand, the power valves tend to conduct the most current while the Amplifier is operational, hence the reason why most valve guitar amps have a standby switch which does two things, firstly it enables the valves to properly warm up before the + HT is applied, secondly it prolongs the life of the power valves while the amp is powered up and not actually being used, there's been stories of used preamp valves being still good after 40 years of use.

When I am powering-up my Marshall amp, the first thing I do is make sure the standby switch is set to "Standby", then I set the mains power switch to "On" and then I give the amp time to warm up, then I switch the Standby switch to on so that the + HT gets connected and the amp is fully operational.

When I power down my Marshall amp, I simply set the mains power switch to "Off", leaving the Standby switch on so that the filter caps in the amp's power supply can drain.

I just found an mp3 of a recording I made of my Marshall amp with the two Chinese 12AX7 B preamp valves installed in it, so here's a link to it, this is what the Marshall amp sounded like before I swapped-out the preamp valves for the Gold Lion 12AX7 valves:

https://dl.dropboxusercontent.com/u/...C%20record.mp3

I'll see if I can do a demo recording of the Marshall amp with the new valves installed in it tomorrow, will post a link here once it's sorted, so stay tuned.


And just for interest, here's a demo recording I made of my Marshall amp before it got fixed after blowing fuses at random times, the preamp valves I had in it were the original Marshall brand ECC83 valves that were installed in it when I first bought it, here's what it sounded like:

https://dl.dropboxusercontent.com/u/...C%20Record.mp3

Aha! I'm afraid that the standby switch myth has recently been debunked and you don't need it at all. In fact, it can actually do harm if you leave it on too long as you can get cathode poisoning from just the heaters being on. There are now several YouTube videos about it and it's been mentioned in most of the guitar magazines. My friend Dave McCready (who was an amp designer at Blackstar until recently) confirmed it.

All the stuff about cathode stripping in valves only applies to larger valves using a 1kV+ power supply. Voltages in valve amps only get to about half that.

The first standby switches occurred in some Fender amps because as models increased in output power over time, their standard store of capacitors weren't rated for the higher voltages present on initial switch-on before the tubes started conducting current and the voltages at the capacitors dropped as a result. If they allowed the tubes to pre-heat, then they conducted straight away and so the capacitors never saw the higher no-load voltages.

Marshall basically copied a Bassman circuit and stuck with the standby switch. No '50s or '60s Vox or Gibson amp had a standby switch. They only appeared on modern re-issues where the standby switch had become a marketing tool.

You'll find that a lot of amps are now dropping the standby switch. It was only ever designed to protect the capacitors, not the valves - and only because of Leo Fender's penny-pinching designs where one extra switch cost a lot less than buying uprated capacitors! In a properly specified valve amp, they are simply not required.

Quote:

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Originally Posted by Simon Barden

Aha! I'm afraid that the standby switch myth has recently been debunked and you don't need it at all. In fact, it can actually do harm if you leave it on too long as you can get cathode poisoning from just the heaters being on. There are now several YouTube videos about it and it's been mentioned in most of the guitar magazines. My friend Dave McCready (who was an amp designer at Blackstar until recently) confirmed it.

All the stuff about cathode stripping in valves only applies to larger valves using a 1kV+ power supply. Voltages in valve amps only get to about half that.

The first standby switches occurred in some Fender amps because as models increased in output power over time, their standard store of capacitors weren't rated for the higher voltages present on initial switch-on before the tubes started conducting current and the voltages at the capacitors dropped as a result. If they allowed the tubes to pre-heat, then they conducted straight away and so the capacitors never saw the higher no-load voltages.

Marshall basically copied a Bassman circuit and stuck with the standby switch. No '50s or '60s Vox or Gibson amp had a standby switch. They only appeared on modern re-issues where the standby switch had become a marketing tool.

You'll find that a lot of amps are now dropping the standby switch. It was only ever designed to protect the capacitors, not the valves - and only because of Leo Fender's penny-pinching designs where one extra switch cost a lot less than buying uprated capacitors! In a properly specified valve amp, they are simply not required.

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But still, I reckon it's a good habit me to get into when powering-up my Marshall amp anyway, while trying out the new preamp valves, I noticed that the Marshall amp is pretty quiet on it's own so the problem is not in the amp, but when I plug any of my guitars into it at uni I get a noticeable hum coming through, apparently Room 105 ,where I have my Marshall amp, is a pretty noisy room electrically because of the fluorescent lights, I'm seriously thinking of putting some copper shielding-tape in my Gibson LP Studio guitar, since it seems to be the most hummy out of all my guitars, which is a bit odd cause the pickups are both Humbuckers, I might check to see if the bridge hardware is properly electrically-grounded to the guitar's circuit-ground, I know that it is definitely not an instrument lead issue cause both the leads I was using at the time were a couple of known good ones that I had made myself, so I'm guessing that my LP Studio is picking up some RFI from the fluorescent lights in room 105, hopefully the copper shielding-tape will sort it out.

For short periods, it's not going to do any harm. Just don't leave it in standby for too long. Once it's on, you are better off simply turning the volume down than putting it in standby. After an hour or so in standby, you can get 'cathode poisoning' which will shorten your valve life considerably.

This is all new stuff to me too, and it's hard to unlearn the perceived wisdom of 35 odd years of playing through valve amps.

If your pickups have metal covers, then shielding the pup cavities probably won't give much benefit, but doing the control cavity will do. If you've got open coils, then shielding the cavities will help a bit.

There's only so much you can do to reduce buzzing if it's a really noisy electrical environment. After a certain level, it's going to break through regardless.

Quote:

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Originally Posted by Simon Barden

For short periods, it's not going to do any harm. Just don't leave it in standby for too long. Once it's on, you are better off simply turning the volume down than putting it in standby. After an hour or so in standby, you can get 'cathode poisoning' which will shorten your valve life considerably.

This is all new stuff to me too, and it's hard to unlearn the perceived wisdom of 35 odd years of playing through valve amps.

If your pickups have metal covers, then shielding the pup cavities probably won't give much benefit, but doing the control cavity will do. If you've got open coils, then shielding the cavities will help a bit.

There's only so much you can do to reduce buzzing if it's a really noisy electrical environment. After a certain level, it's going to break through regardless.

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My LP Studio features coil-tapping on both pickups (activated by pulling up the volume controls), I did notice that the hum got worse when the coil-tapping on either or both pickups was activated, so I'm going to try shielding the control cavity when I get the chance to do so.