OT - Tubes

[mozz]

5755 at amplified parts on sale $5, like a 5751/12ax7. They sell adapters at amazon. Tubes I often use are 6gk6 (el84 ish) and 6bg6 (6l6). Preamp tubes list is hundreds. I have a 6aw8 preamp that needs finishing and a 6cl6 output stage. Others also in the wings, 6au6, 12b4, many more. I have a quad 6aq5 output stage that grinds unbelievable.

[ThermionicScott]

But really if you are going through tubes like crazy then your amp isn't designed right.

On a minimum touring amps for big bands every 3 years and that's only because they are moving the stuff around like crazy.

Most of my amps last for a minimum of 10K hours of use with a set of tubes. I have had users use my amps for decades before changing tubes.

This!  It was already semi-irresponsible to design amps that ran the output tubes extra-hot and required frequent replacements back in the 1960s, now doing so is just going to push more people into modelers.

I really appreciated that 65amps was willing to go out on a limb and do lower-voltage designs so that modern-production tubes would have a better lifespan, but things seem not to have gone well for them anyway.   

[AtomicRob]

...but there are tons of tubes made in China, and JJs are made in the Czech Republic I think.

The main tube manufacturer in China was Shuguang, responsible for almost all of the common relabeled brands coming from China. They had a small fire at or near their factory in August, 2019 and depending which sources you believe they had to move the factory for one reason or another and it's not back online yet, and nobody knows when or if it will be. There are a couple other small tube factories in China, like psvane, which sells expensive but apparently decent tubes aimed at the audiophool crowd more than guitarists, at almost-NOS prices.

JJ is based in Slovakia and is apparently not able to keep up with demand but at least that hopefully means they'll have no trouble staying in business for the foreseeable future.

[amptramp]

Go to page 123 here:

https://worldradiohistory.com/Archive-Radio-TV-Experimenter/Radio-TV-Experimenter-1960-Fall.pdf

for a 75 watt amplifier called the Leasebreaker using a pair of 6146 tubes.  They use a 12BH7 as a series regulator for the screens and you may note that they got the tube circles wrong - the 5R4 rectifier is shown as two tubes and the 5N015 time delay relay is not shown as a tube at all.  Screen regulation is from a 0B2 gas regulator tube but is is not able to control a screen supply without amplification and the 12BH7 supplies that.  And you have to admit - plate caps on an amplifier look butch.  One thing the article makes clear is that any rise in response at either end of the passband is a sign of potential instability and having looked at some of the designs out there, there isn't much stability margin in a lot of designs.  I suggest you read the entire article because it goes into the design criteria they used and why the circuit topology looks like it does.

I have a Muzak 920B P.A. amp that has an interesting design.  It uses 6L6 tubes in push-pull to get 15 watts.  There is a resistor in series with the centre tap of the power transformer HV that you can short out to get 20 watts.  These amps were designed to operate 24/7 and this particular one has a relay so they can interrupt the music on channel 1 with a microphone so you can put out a message like "Cleanup on aisle 6" and then go back to the music.  The neat thing here is that the relay is a plug-in device - take it out of the socket and you have a nice two-channel mixer for instrument and microphone.  It is in my lineup for amplifier reassignment surgery into a guitar amp.

[GGBB]

The tube store is back online - viewer discretion advised - contains disturbing scenes of shocking prices:

https://www.thetubestore.com/preamp-tubes/12ax7-ecc83-tube-types

[PRR]

price of gasoline 1969: $0.34
price of tubes, Allied, 1969
12AX7: RCA/GE (no choice): $1.35 
" " " " Mullard 'Lab Tested' = $2.10

FWIW: the current "Western Electric" is considering making non-300B types.

[davent]

price of gasoline 1969: $0.34
price of tubes, Allied, 1969
12AX7: RCA/GE (no choice): $1.35 
Mullard 'Lab Tested' = $2.10

FWIW: the current "Western Electric" is considering making non-300B types.

Apparently they already have equipment that was purchased from Philips and Mullard. Audioxpress has sent out an informative piece from their editor to, i imagine subscribers, on the current tube issues, haven't found it on line yet but found a reprint at wattkins.com, have to be registered...

https://www.westernelectric.com/expand

[aron]

I noticed the lead times for components are like 52 weeks now! Here we go!

[ElectricDruid]

I've been dealing with lead times of 12 to 18 months in the semiconductor world for a good while now, so tubes are only just catching up. In practice, the semiconductor supply situation hasn't been as bad as the dreadful delivery estimates, but it makes it very hard to plan ahead. And the consequence of that is that people order twice what they need, just to make sure thy've got supplies in case they can't get more, which of course makes the situation worse. The classic "tragedy of the commons", played out in the techno-era.

Not at all impressed with EHX though - their message seems pretty much *designed* to cause panic buying, which is irresponsible at best and downright immoral if they know they're sitting on a good stock of tubes at the point they just quadrupled the price.

Scarcity is mostly caused by everyone deciding they want everything at the same time, rather than there being any actual shortage. Unless you actually need tubes right now, my advice is to NOT PANIC and to sit tight. Tubes aren't going anywhere. What you're seeing is a spike in the price of gold or oil.