A Tube Question

[Frank1938]

Just now experimenting with tube amplifiers and have a question. Is there really any difference in tubes from different manufacturers, ie. Telefunken, Mullard, Genalex, etc.? My guess is that an EL34 tube must be manufactured to certain specifications to operate in an amp designed for that class of tube. Hoping some of you experienced tube afficionados will be able to explain why someone would pay large amounts of money for a certain tube. Thanks in advance to all who choose to respond.

Frank

[sebrof]

Frank - I don't have a lot of experience, but I'll comment on what I can.

At one point I had a Jolida JD1000 amp that used 12AT7s 12AX7s input and splitter, and EL34 power tubes. I swapped all the stock tubes and did get a lot of improvement. I got a bigger improvement rolling the small tubes than when I rolled the EL34s, but I bought more expensive NOS tubes for the small tubes and only decent Svetlanas for the power tubes. It used 8 EL34s, so to go NOS with those it could have cost more than the amp cost.

I also have an 807-based amp that uses 6922 input tubes. I rolled the 6922s and the difference is huge, BUT - I don't know the history of the original tubes so I'm not sure if the originals were getting stale. One of these days I'll get another cheap set and roll them just for kicks.

My conclusion from this was - Yes, absolutely.

Hope this helps.

[Edgar]

Vacuum tubes are like tires -- two tires may be designed to fit the same rim, and may have the same overall diameter, tread width, aspect ratio, etc. But they'll perform differently, depending upon how they're made and what they're made of.

[DanO55]

Yes.

[gartenman]

Generally speaking, pretty much any NOS or used tube made around 20 years ago or more will sound better than any current production tubes that you can buy. The reasons for this are varied, but most are due to the fact that tubes just aren't in demand anymore.

Manufacturers can't afford to make the metals used in construction of the tube as pure, and the vacuum in the tubes isn't as tight because tighter vacuums cost more time and therefore money. That's why you will often find complaints today of certain manufacturers' tubes being unreliable (eg. power tubes 'red plating' soon after they've been installed).

Certain chemicals can't be used for tube production because they are toxic, and the ones that are still allowed to be used today tend to be only legal in countries where workers have less rights, and they don't cost as much to employ either (eg. China, countries formerly in the Soviet Union). That's why old factories in those countries are mostly the only ones still making tubes today, as opposed to old factories in England or USA.

Why go for old tubes?

Old tubes were made so well that they last much longer than current production tubes. Preamp tubes have been known to last around 30 years, or around 20,000 hours. That's practically a lifetime for a tube amp.

In most cases, vintage tubes sound better than their modern counterparts. The quality in manufacture of these tubes has a large effect on the sound, particularly in preamp valves. You really have to try some vintage tubes instead of modern production ones to experience just how better they sound, they make your amp come to life. The more gain your amp uses the less noticeable this effect may be, as in some high gain amps, transistors or diodes are used to get more gain instead of tubes, so the tubes will be less important.

Get them while you can - since these tubes are obviously no longer being made, once they're gone they're gone - and prices are always going up.

Different manufactures produced tubes which sound different - a tube made in a different plant or by a different manufacturer will probably sound different.

Many tubes were relabelled, so they may not necessarily sound like you'd expect by looking at the manufacturer name. The best way to know who made your tube or where it was made is to learn how to recognise the internal construction of tubes, and learn how to interpret the codes printed or moulded on the tube. For example, today from eBay I received a Tungsram 12AX7 that I won for $10, yet the valve said "Made In England". Tungsram 12AX7's were made in Hungary, and by looking at the location of manufacture, the date codes and the internal construction, I know that this was a tube actually manufactured in Britain by Mullard in their Blackburn factory. Buy this same tube from an online vendor and you're talking a good sum of money.

How much will they cost?

Not all vintage tubes cost a lot of money compared to modern production. You can get slightly used tubes from eBay or garage sales for less than you'd pay for modern tubes. I've managed to get lots of them that sound far better than modern produced, new tubes. Getting most types of tube on eBay for cheap is easy, you just have to be patient and know what to look for. I bought 2 Brimar 6060's for $40 that go for $320 ... if you can find them. Slightly used ones are fantastic, as old tubes last so long, the difference between them and NOS tubes is insignificant. I think they actually sound better after being "burned in" a bit.

The really expensive NOS tubes are EL34's/KT66's/KT77's/KT88's, as they don't last as long as preamp tubes and are harder to come across. Fortunately, they don't affect tone anywhere near as much as preamp tubes, and the modern equivalents aren't that much behind in terms of sound. For power tubes, reliability is the big problem with the modern ones.