Dying Rectifier?

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simon
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#16 Re: Dying Rectifier?

Post by simon »

Mmm yes, good points.

A separate transformer would be better anyway...
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#17 Re: Dying Rectifier?

Post by simon »

£35 for a Hammond 6.3V 3A transformer. Either I'm getting tighter as I get older or this game's getting too expensive for my liking.

Toroidy might be cheaper, but delivery will probably even it up compared to Mouser.

Are toroids a bad idea for rectifiers? They're supposed to pass more noise than an EI, but does that matter if it's a separate transformer?

Edit - or at least emit noise from where the leads come out?
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#18 Re: Dying Rectifier?

Post by Mike H »

Morgan Jones wrote: Fri May 17, 2024 4:41 pm Looks like the GZ33 was the guilty party.
Incredible but true! :shock:
I've just looked up GZ37 prices. Blimus! And I looked up the GZ33 data sheet. Mea culpa. Yes, a GZ37 is actually less hungry in heater current than a GZ37.
I've just looked at eBay. 2 x NOS Mullard GZ33, original boxes, 'never used', £1,000 :shock:
 
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#19 Re: Dying Rectifier?

Post by simon »

Great, I'll have 2 please...
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#20 Re: Dying Rectifier?

Post by pre65 »

If U19 were to get to that price level I would be pleased. :wink:
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#21 Re: Dying Rectifier?

Post by Nick »

Mike H wrote: Fri May 17, 2024 7:40 pm
Morgan Jones wrote: Fri May 17, 2024 4:41 pm Looks like the GZ33 was the guilty party.
Incredible but true! :shock:
I've just looked up GZ37 prices. Blimus! And I looked up the GZ33 data sheet. Mea culpa. Yes, a GZ37 is actually less hungry in heater current than a GZ37.
I've just looked at eBay. 2 x NOS Mullard GZ33, original boxes, 'never used', £1,000 :shock:
Cant find 2 off for 1k, but there is 9 off for 1k, still a bit optimistic. Looking a the ones that have actually sold £30-£35 seems more normal. But its just supply and demand in action. I think "Mullard" carries a lot of the weigh.
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#22 Re: Dying Rectifier?

Post by Paul Barker »

A pair of tv damper diodes is an option remember though the b pluss out (cathode)is the base pin not the top cap (anode). The heater to cathode can take a lot of voltage difference usually.

For sound in centre tapped full wave valve rectifier set up potato mashers are great if they are still cheap enough. The 5u4 has a hungry heater but a better sound but the potato masher is ok sounding and tolerates more voltage so in my supplies I can never use the nicer sounding 5u4.

Thse are strange times for valve prices. Very strange times. The supply and demand supposed values are false. It is a joke when korean made PX4’s are more likely made in China and badged and if real px4’s Ill eat my hat, worth more than nos osram.

No!

What will probably happen is demand will collapse and the generation that valued valves will dwindle to nothing. The concept a rectifier is worth those prices wont stand the test of time.
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#23 Re: Dying Rectifier?

Post by simon »

I've never used 5U4(G). They look to be in current production so there are cheaper options though NOS aren't too far behind GZ37s. Brimar has one at £55 which it describes as "modestly priced".
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#24 Re: Dying Rectifier?

Post by Morgan Jones »

Current valve prices are ridiculous. It's got so that I can no longer afford NOS valves, so it's just as well I have a decent stock. As mentioned, damper diodes (US) or efficiency diodes (UK) are an option. I use 6CL3 and 12CL3 (no top caps, but you need the right base and it isn't Magnoval). They can still be had cheaply, but the postage (if from the US) is crippling. £55 for a rectifier? Last Sunday a 7 digit Solartron DMM was being offered for £125. That's the price of two rectifiers and a bottle of whisky (needed to cope with the shock of paying for the rectifiers). And I haggled on the DMM price.
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#25 Re: Dying Rectifier?

Post by steve s »

I have a few 37's simon.. I can test your 33 but I'd guess that would only confirm what you already know.
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#26 Re: Dying Rectifier?

Post by simon »

Thanks Steve, I've sent you a WhatsApp
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#27 Re: Dying Rectifier?

Post by simon »

I bought a few 6AX4s from the US some years ago at a dollar a piece. I've used them successfully with a low voltage GM70 amp. Handily they're octals, but the 6.3V heaters are a pain. I could get some 6V transformers (they'd need to be good for the HT) but the cost will be approaching a 5V rectifier anyway.
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#28 Re: Dying Rectifier?

Post by Mike H »

simon wrote: Sat May 18, 2024 9:47 am I've never used 5U4(G). They look to be in current production so there are cheaper options though NOS aren't too far behind GZ37s. Brimar has one at £55 which it describes as "modestly priced".
I've used used a modern 5U4, it was OK. It's directly heated cathodes.
 
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#29 Re: Dying Rectifier?

Post by Mike H »

Nick wrote: Fri May 17, 2024 10:18 pm Cant find 2 off for 1k, but there is 9 off for 1k, still a bit optimistic. Looking a the ones that have actually sold £30-£35 seems more normal. But its just supply and demand in action. I think "Mullard" carries a lot of the weigh.
Must have been taken down. But I agree, wishful thinking. :D
 
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