Vintage Mullard GZ34 for my Vibrolux

[H]

Bought a vintage Mullard GZ34 for my Vibrolux a few days ago. It was made in Blackburn, England (around 50km from where I grew up) when I was just a few years old. It arrived today and I loaded it up. You would not BELIEVE the difference it makes!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Nothing. Zip. Nada.

 

 

It's just the same as it was with the JJ GZ34: awesome! Don't buy into the hype

[Vanschoyck]

That's intriguing. I have only one question. What's a Mullard? (Yes I can google it, but it's not that weird hair cut, is it?)

[H]

It's that weird haircut. My granny had one for years.

[H]

I lied. It's an expensive old British rectifier tube.

 

Like this: http://tctubes.com/Mullard-GZ34-5AR4.aspx

[peterbright]

The JJ's have all been great tubes for me.

[Spectrum13]

It's that weird haircut. My granny had one for years.

I thought it was a duck.

[schundog]

.....waiting for Kuz's head to explode......

[TalismanRich]

I wouldn't expect there to be much difference. You should get a difference going from tube to solid state, as there will be less voltage drop, less sag during high current draw. As long as you are not to the point where you are stressing the power supply, the rectifier should just be converting AC to pulsed DC. Once properly filtered, DC is DC.

 

The issue of sag comes into play when you max out the power supply. The voltage from the tube can't keep up with demand, and drops. That give the feel of compression or limiting which softens the attack a little bit.

[slider313]

The difference would be the Mullard should last four or five times longer than the JJ.

 

H, is the B+ the same with either tube?

[Kuz]

.....waiting for Kuz's head to explode......

 

Nope, I have different rectifier tubes (ie GZ34, 5VR4, ect) for different voltages, but for the same model tube I can't tell the difference from a Chinese GZ34 & a JJ GZ34.

[DetroitBlues]

So does a rectifier tube really make a difference if you're a OD or otherwise pedal user?

[TalismanRich]

Its shouldn't matter if you are using the OD pedal. Its all about current draw and voltage demand, which means VOLUME! As long as you keep the volume knob down, it doesn't matter how distorted it is in the preamp stage or pedal stage. The rectifier should be able to keep up.

 

Changing from a GZ34 to something like the 5U4 will change the voltage capability of the circuit and cut headroom and response.

[H]

.....waiting for Kuz's head to explode......

Brian, I think you were the only poster here that 'got it'

 

Just to be clear, this wasn't directed at Kuz.

[H]

The difference would be the Mullard should last four or five times longer than the JJ.

 

H, is the B+ the same with either tube?

Yes, it's an old tube that has had a fairly easy life. I expect that I'll never need to replace it in this amp.

 

I don't have any B+ measurements yet. I'm getting into the chassis today with the meter. I've got a spreadsheet of all the useful voltages I measured previously through the circuit that I can compare and contrast between the JJ and the Mullard.

 

A question for you, Slider313: Inside the filter cap 'doghouse' roof, I've seen a kind of spongy strip in videos of AB763 type amp dissections - do you know exactly what kind of material that is? I want to suppress vibration in there (which I believe this is for) but I don't want to use the wrong stuff.

[H]

I thought it was a duck.

Yes, with a green head............just like my granny.

[58super]

Yes, it's an old tube that has had a fairly easy life. I expect that I'll never need to replace it in this amp.

I don't have any B+ measurements yet. I'm getting into the chassis today with the meter. I've got a spreadsheet of all the useful voltages I measured previously through the circuit that I can compare and contrast between the JJ and the Mullard.

A question for you, Slider313: Inside the filter cap 'doghouse' roof, I've seen a kind of spongy strip in videos of AB763 type amp dissections - do you know exactly what kind of material that is? I want to suppress vibration in there (which I believe this is for) but I don't want to use the wrong stuff.

Fender used weatherstripping. I don't know what brand or if was a high temperature variant. I generally run a bead of GE electronics silicone between the caps. It's easy to cut if you need to change a cap.

[Kuz]

Brian, I think you were the only poster here that 'got it'

Just to be clear, this wasn't directed at Kuz.

For the record, and just my opinion since my name was brought into this, if the the Rectifer tube is working and is correct for the voltage, I would never pay extra for one. What ever works, works (if the voltage is correct) for a Rectifer tube. I would not recommend any boutique or NOS tube. Other than possibly the longer life span as TAW (The Amp Whisperer) stated.

[Spectrum13]

So does a rectifier tube really make a difference if you're a OD or otherwise pedal user?

Makes a big difference if you are OCD.

[H]

Fender used weatherstripping. I don't know what brand or if was a high temperature variant. I generally run a bead of GE electronics silicone between the caps. It's easy to cut if you need to change a cap.

Thanks

[H]

 

H, is the B+ the same with either tube?

Got the meter on it today; the JJ gives me 468V, the Mullard 469V. Honours even