GZ34 lying about idle

[Alf]

Hi,

I have a Philips NOS GZ34 lying about. I know it has the least voltagedrop of all tube rectifiers. So the question is ; is there any advantage tonewise between using this tube or just go for solid state diodes ?
I mean I like the sag a tube rectifier intoduces but would it be noticable with this tube ? Are there any other advantages ?

Regards, Alf

[Bruce / Mission Amps]

Although the solid state diodes will only net you about 12-17vdc higher B+, the GZ34/5AR4 is still is a reactive componenent in the B+ rail and the amp will have a very slightly different feel to it over the solid state diodes.
Also, the tube is a slow startup which gives the other tubes a chance to start heating up before being smacked with full Hi-VDC!
The SS diodes could push your filter caps harder because they are instant on too.
The main filter caps will get hit faster and charge up to a higher peak VDC too, so you could have a problem if they are already at their limit with a tube recitifier.
You'd just have to check this...

[MWJB]

You will still hear the difference between a GZ34 (warmer) & SS rectifiers (harder), of course, whether this is an advantage or not depends on what you are trying to get. Sag with a GZ34 is not as pronounced as with 5Y3/5R4/5U4.

The GZ34 also has a slow warm up, meaning that it is kinder to your tubes than solid state/5U4/5Y3, which is why you sometimes see it used in amps without a standby.

[ScottW]

Hi,

I have a Philips NOS GZ34 lying about. I know it has the least voltagedrop of all tube rectifiers. So the question is ; is there any advantage tonewise between using this tube or just go for solid state diodes ?
I mean I like the sag a tube rectifier intoduces but would it be noticable with this tube ? Are there any other advantages ?

Regards, Alf

You might not notice the difference. I have a JTM45 clone with a GZ34, set up with EL34s (like a JTM50) with switchable split cathodes. Also have a '74 50W with EL34s and a ss rectifier. When I A/B them with a Switchbone switcher, I can barely hear the difference, they are THAT close. No obvious sag with the GZ34, that's for sure. They both sound fantastic, btw.

[Alf]

Thanks guys for the replies , I guess I'll have to find out for myself.
Bruce and MWJB the argument for using a tube rectifier because of the slower voltage startup is certainly important.

Regards, Alf

[TD_Madden]

of course, a Weber GZ34 CopperCap replacement gets you the best of both worlds...slow start-up, slight sag, and solid-state durability. I use 'em and they work quite well (in a Mission Amps 5F4, a modified Mission Tweedy Deluxe, and a Kendrick Lion 7).

[Alf]

TD ,

That's a very good alternative indeed.
What model would you use for a 2 x EL 34 amp ?
And IIRC there are also solid state diodes in the copper cap ??

Alf

[TD_Madden]

Take a look at the CopperCap page for a better explanation:

http://www.webervst.com/ccap.html

I've used the 5Y3, 5V4, 5U4, and GZ34 equivalents....all perform satisfactorily. BTW, Bruce Collins assisted in the testing of several of these models...

Think there's a chart in there that helps you detemine what your needs are as well.

[Alf]

Thanks TD for all the useful information.

Alf

[R.G.]

Also, the tube is a slow startup which gives the other tubes a chance to start heating up before being smacked with full Hi-VDC!
The SS diodes could push your filter caps harder because they are instant on too.

Inrush prevention thermistors, anyone?

[Alf]

Inrush prevention thermistors

I use these in an amp with a Toroidal PT in the primary because otherwise the fuse blows.
Would it be possible to use these in the heater winding too to get a slower startup and consequently longer tubelife ?
I've been wondering about this for some time now as I bought a number of NOS ecc83 tubes (Philips anmd good readings) but 50 % of them flash during a cold startup. Wouldn't it be beneficial to slowstart them this way ??

Alf

[Alf]

Inrush prevention thermistors

I use these in an amp with a Toroidal PT in the primary because otherwise the fuse blows.
Would it be possible to use these in the heater winding too to get a slower startup and consequently longer tubelife ?
I've been wondering about this for some time now as I bought a number of NOS ecc83 tubes (Philips anmd good readings) but 50 % of them flash during a cold startup. Wouldn't it be beneficial to slowstart them this way ??

[Steve Conner]

I see quite a lot of preamp tubes that flash like that. I don't think it's much of a problem. In fact, I was kind of under the impression that the tube designers made the little bit at the bottom of the heater flash on purpose, since it ended up reducing the inrush current and protecting the rest of the heater overall. Could be wrong though.

[Bruce / Mission Amps]

>>tube designers made the little bit at the bottom of the heater flash on purpose,<<

I don't know about doing it on purpose but I heard so many of the old 12AX7s did (do) it that customers were getting too worried a particluar brand was defective so the manufactures changed the filaments so they would not "glow up" in a little flash.

[R.G.]

I use these in an amp with a Toroidal PT in the primary because otherwise the fuse blows.
Would it be possible to use these in the heater winding too to get a slower startup and consequently longer tubelife ?
I've been wondering about this for some time now as I bought a number of NOS ecc83 tubes (Philips anmd good readings) but 50 % of them flash during a cold startup. Wouldn't it be beneficial to slowstart them this way ??

Alf

It would. I know of one commercial amp that does exactly this, and for exactly that reason. However, a primary-side thermistor does much the same thing by limiting the total power into the transformer. It certainly helps.