High-end tubes replacement for high-end gears

[GYang]

Many times I heard that replacing stock tubes in modern high-end compressors, mic-pres etc. (as rule, new production Dragons, Sovteks or cheaper Philips, RCA etc.) with proven originals from New Old Stocks (Telefunken, Miniwatt, Amperex etc.) can add that desired 'vintage' character and sonically improve it the quite significantly.
Can anyone share experience with 12AX7 and 12AU7?
Any drawbacks (excluding prices for NOS that elevated to over 800$/pair for excellent NIB Telefunkens)?

GYang

[jackinthebox]

Originally Posted by GYang

Many times I heard that replacing stock tubes in modern high-end compressors, mic-pres etc. (as rule, new production Dragons, Sovteks or cheaper Philips, RCA etc.) with proven originals from New Old Stocks (Telefunken, Miniwatt, Amperex etc.) can add that desired 'vintage' character and sonically improve it the quite significantly.
Can anyone share experience with 12AX7 and 12AU7?
Any drawbacks (excluding prices for NOS that elevated to over 800$/pair for excellent NIB Telefunkens)?

GYang

I've had great success with RCA 5751's in microphones. They have a softer character and are lower gain generally than a 12ax7 and i've found them to be really good at softening any harsher pieces of valve gear.
thumbsup

[stagefright13]

Absolutley tubes make a difference! It all depends on the device. All tubes sound different. Check out tubeworld.com they have a decent description of the different sounds of different 12ax7's etc.
I retubed everything I own. Now it's time for IC's...

But always see what is inside your gear first. Some manufacturers use some decent stuff to start with.

[intolerance]

N.O.S. Triple micah, black plate, 5751's by either RCA or Sylvania. 70% gain of a 12AX7. TIP: Check the bins at an old Army Surplus store, really. If you wanted new, check out www.tubestore.com. Electro Harmonics or Ei have the best new tubes in that form factor IMHO.

[rob99]

Originally Posted by GYang

Many times I heard that replacing stock tubes in modern high-end compressors, mic-pres etc. (as rule, new production Dragons, Sovteks or cheaper Philips, RCA etc.) with proven originals from New Old Stocks (Telefunken, Miniwatt, Amperex etc.) can add that desired 'vintage' character and sonically improve it the quite significantly.
Can anyone share experience with 12AX7 and 12AU7?
Any drawbacks (excluding prices for NOS that elevated to over 800$/pair for excellent NIB Telefunkens)?

GYang

A big difference.
I have a micpre that uses 6072 / 12ax7 for the input and 5687 for the output.

I ended up buying several Telefunken ECC83, the European number for 12ax7.
These specific Telefunken are a special, select low noise, NOS tube.
They were tested by Telefunken for low noise to use in medical equipment
and each has its own low noise test print out. Each is also identified with a blue and yellow dot applied by Telefunken. These were made in the Berlin factory.

Before I knew how long these tubes would last, it turns out I bought toooo many for my needs.

These are very rare because of the extra low noise testing and I have seen them only at the one supplier. They have ran out and I haven't seen them elsewhere.

If you are interested, I can sell a matched pair for $250. I can put them on ebay if you like, but I will have to charge more for the ebay commission.

I bought them from Europe and I am in Canada.

This pair is the last I will sell. I will be keeping the rest as I can't buy them anymore.

Pictures are available.

Tubes were measured on a TV-7 where minimal good is 32.

They are 52/52 on each tube.

These are very strong tubes.

For your own search of tubes, here are tube numbers that will work in place of 12ax7's ...

12ax7a, Ecc83, E83cc, 7025, 6072(a), 12AY7 (for a softer sound) CV4004, M8137, 10M, 5751, Ecc803, b759, 7729, 5965, 12av7 (softer sound), 6829.

These are all the subsitiute numbers I could find. Within each number there is also a range of quality so the selection grows even larger.


thanks
rob

[Tubefreak]

There are no current production tubes that I really like. They lack the simple quality in clarity, attack, depth and durability. I still have to check the new Groove Tubes Mullard replica. But the price is so high I wonder why I would even bother trying, for that money you can buy amazing NOS tubes. Somehow I really like the sound of NOS European preamp tubes more then USA brands.

Brands, types and manufacturing years really make differences in sound. And of course… the tube needs to be tested. Many NOS tubes on the market where rejected in the production years, be aware of this when buying NOS!

In general I like Telefunken/Tesla/AEG (smooth and lots of detail), Mullard/Philips/RFT (larger then life mids), Siemens (clarity). Do play around with different types (i.e. 12AU7 instead of a 12AX7) to see what gives the best results.

Maarten

[kats]

My only advice would be to keep an open mind. I've got a great collection of tubes and always swap tubes to see what it gives me. Having said that on two occasions I can think of - the stock $10 tubes sounded better with the circuit, than some of the "classy" tubes I have.

For EG: My 18watt Marshall HW sounded better (whatever better means...you know) with the stock JJ's than my NOS Mullards.

I have a Tube 87 that when I swapped in a nice Amperex Holland, really brought out the mid detail in the mic - but on many applications the stock EH6922, with a smoother mid and beefier bottom is preffered.

OTOH, I find NOS 12ax7 always sound better on Fender amps.

So you know, just don't assume a $100 tube is going to be better - the opnly guarrantee is that they are going to sound different.

[Zep Dude]

This really depends on the circuit design. A guitar amp will definitely demonstrate the differences between tubes -in the pre amp and power amp positions -make sure you know which tube socket is the pre amp and not the vibrato/reverb or other sockets or you will be wasting an expensive tube where it's not helping.

Some modern gear like compressors/eq's may show very little difference depending on how the tube is used in the circuit, if there's neg feedback etc. Once again YMMV. In some cases a very expensive rare 12ax7 or whatever might end up making only a 5% difference or it might make a noticable improvement.

A big problem with old stock tubes is noise. Unless you find some actual NOS never used tubes that haven't leaked over the years, or some used ones that are still in very good condition you may find whatever improvement in tone to be negated by an unusable noise level. While you might get away with this in a guitar amp -which is going to make noise anyway when cranked, this may not fly with a high end compressor/EQ.

Also, some people have pointed out the differences between different gain tubes of the same family -5751 vs 12ax7 vs 12at7 etc. Improvements in the gain structure of gear can be made with certain tradeoffs (more headroom, less bite etc) by these changes, but that doesn't speak to the differences between new vs old, simply different types of tubes.