using tubes to voice your amp

[JamesHealey]

Just been trying to get my amp to have a different 'character' not really change the fundamental idealogy of the amp because it's pretty simple and it makes sense electrically/theoretically.

Anyway the amp sounded rather good as stands to I pulled out my tube draw and did some swapping and round the effects rather much more radical than expected eventually settled on a tube combo which really made the amp sing.


I think this is a lost art, anyone else had a similar experience?

[Structo]

Sure.
Tubes can make a tremendous difference in tone and character of a tube amp.

I remember learning long ago that just because a tube may have the same designation and brand name stamped on it, doesn't mean it is going to sound the same as the next one.

It's called tube rolling.

[Jana]

I hand pick tubes for all my amps. It is a long process to find the right tubes for the various sockets--a tube that sounds great in V1 might sound like used Charmin in V2, etc.

[selloutrr]

For the most part the correct tubes can correct any issue without having to modify the tonal circuit of an amp. i.e. more bass less bass, smoother highs, more break up, less breakup, over all feel, ....

each tube has it's own character. there are differences in even the same batches which is why matched tubes are not always easy to find. and are worth more $$.

brands and models help weed out and get you closer to the tone you are after or help you avoid curtain quality control issues or tonal dislikes you may have. but it's no guarentee just because it's labeled a curtain way it'll sound great!

as an example... martin guitars, by name are amazing and sought after. but as a whole they are hit and miss and some of them sound down right dissapointing. while others in the same model are the "IT".

Groove tubes, Ruby, DR Tube, Mesa Boogie,etc. have all made a living off of this hit and miss, by buying in bulk and offering a graded tube giving you the opertunity to buy a pre voiced tube. If you like the way number "6" sounds buy more number "6". Don't be fooled, the tubes are russian and chinese resilk screened with the sellers logo. you are paying more then double the cost for a picked tube.

If you really want to get a great tube hand sellected for you. call eurotube and discuss what you want and for a very small $ they will hand select tubes to voice your amp. It's a lot cheaper then buying 100 preamp tubes and doing the swap and play swap and play.

[passfan]

I will sometimes swap out 12au's 12at's and 12ay's in V1 in order to tone down the gain for cleaner playing with the Tele. With the express I swap between el34's, 6l6's and 6v6's depending on what I'm playing as well.

[David Root]

In my own amps I only use NOS or UOS (Used Old Stock). Since I am building nothing but Dumble circuits right now, the following is what I find in D-circuits.

In the pre amp 12AX7s I find I prefer 7025s to 12AX7s most of the time, and black plate RCA to gray plate.

I have a few used Amperex 7025s, some labelled both 7025 and 12AX7, from about '67 to '70, which I find have a warmth to them , that while still a very clean and balanced tube, is not ruler flat like a '60s Telefunken smooth long plate.

I have some '62 Tungsols which are also very good, but I keep coming back to the Amperex and the Telefunkens.

In my 50W '70s ODS I currently have V1 Telefunken long smooth plate, V2 Amperex 7025, V3 (FX loop buffer) '85 Mullard M1862 12AT7, and in V4, the PI, an '83 Mullard 12AT7.

I need to try some older Mullard 12AX7s, some older Amperex 12AX7s and I will also try a T'funk ribbed plate in V1 as I saw somewhere that they have a little warmth in the mid range compared to the long smooth plate, and might not be as microphonic as the long plate could be in a combo.

In my #124 I have Amperex 7025s in V1 and V2, and I just put a GE long gray plate in V3 (PI), but have not cranked it up yet. I think Brandon likes those in the PI, and I would certainly trust his judgement.

Power tubes in these? RCA blackplate 6L6GC (UOS), none other! NOS if I could afford it.

[passfan]

In my own amps I only use NOS or UOS (Used Old Stock). Since I am building nothing but Dumble circuits right now, the following is what I find in D-circuits.

In the pre amp 12AX7s I find I prefer 7025s to 12AX7s most of the time, and black plate RCA to gray plate.

I have a few used Amperex 7025s, some labelled both 7025 and 12AX7, from about '67 to '70, which I find have a warmth to them , that while still a very clean and balanced tube, is not ruler flat like a '60s Telefunken smooth long plate.

I have some '62 Tungsols which are also very good, but I keep coming back to the Amperex and the Telefunkens.

In my 50W '70s ODS I currently have V1 Telefunken long smooth plate, V2 Amperex 7025, V3 (FX loop buffer) '85 Mullard M1862 12AT7, and in V4, the PI, an '83 Mullard 12AT7.

I need to try some older Mullard 12AX7s, some older Amperex 12AX7s and I will also try a T'funk ribbed plate in V1 as I saw somewhere that they have a little warmth in the mid range compared to the long smooth plate, and might not be as microphonic as the long plate could be in a combo.

In my #124 I have Amperex 7025s in V1 and V2, and I just put a GE long gray plate in V3 (PI), but have not cranked it up yet. I think Brandon likes those in the PI, and I would certainly trust his judgement.

Power tubes in these? RCA blackplate 6L6GC (UOS), none other! NOS if I could afford it.

I just found three more of those masquerading as rca's and am running them throughout my rocket. They sound really nice.

[Alexo]

I used to roll my tubes around and around, but as the pile of builds has grown, I just don't have the patience for it, or maybe I've just come to know which to choose for the sound I want. ..nah, mostly just lack of patience.

I always start my amps off with easily replaceable tubes, i.e. MIC or JJ, and then once I know all is good in the circuit, I'll dig into my stash of salvages. I used to scavenge ebay, yard sales, surplus stores, etc., I was a tube maniac worthy of any support group. Once I picked up an old Fisher stereo at a yard sale for $15 and found it loaded with 60's Telefunken and Mullard ECC83's! But it's a double-edged sword, I've got a few hundred pounds worth of oscilloscopes, radios, test equipment, etc., that I bought in hopes of striking gold but just turned up a bunch of 6AL5's, 35C5's and 12AU7's (although one old scope ($20) had TWENTY-SIX Amperex 6DJ8's!)...but alas, marriage has a way of taking the edge off of that addiction.

I was also once a serious tube snob in this regard, but after starting my amps up with cheap tubes enough times, I realized that a good circuit will still sound darn good even with "crap" tubes ...although with the right tubes, it may sound downright amazing.

Gotta say, the old Amperexes are my favorite with their milky sweet sounds. The long plate Tele's sound the most 3-D to my ears, and I actually really love old Japanese tubes for a very "musical" tone that sits between the aforementioned. Mullard AX7's do sound great, but they never hit me over the head the way some other old stocks can. New JJ preamp tubes just sound horrible to me, sometimes unusably noisy too, even though I keep trying to give them a fair shake. New Chinese-made tubes can actually sound really, really good, they test impeccably, and sometimes I'll happily take one over some funky old pull that may or may not have developed issues over the past 50 years, and frankly, MIC's, maybe EI's or Tung Sol's often win out over my OS GE's or Syl's (jmho).

...just speaking about preamp tubes here. When it comes to power tubes, there is *nothing* like good old stock! A year ago, I responded to a craigslist ad for an old Bogen 50 watt PA for 50 bucks. I showed up and the guy threw in a set of replacement tubes he had purchased at the time he had bought the amp - a couple of Mullard and RCA preamp tubes and a set of new-in-box GE 6L6GC's (which happen to be matched).

[David Root]

NOS Mazda or RFT 12AX7s intrigue me, either the '50s grayplates or the '60s chrome plates, but they are serious $$$.

Alleged to sound like Mullards on steroids, especially the chrome plates, higher gain and in-your-face dynamics.

Anyone try these?

[PlinytheWelder]

I really like a 12AT7 in the typical LTP phase inverter slot. Unlike the AX7, there are still a lot of good NOS ones around for relatively cheap... I like the Mullards in particular.

FWIW, I was over at another forum and found an interesting site for NOS tubes... http://www.hitestguitars.com/

I haven't tried them, but I see a lot of screaming deals...

[Cliff Schecht]

I love the small stash of Amperex 7025's I have. I only use them in V1 in my Express builds.

I've also had fantastic luck with NOS GE 12AX7s. The short squat plate version is great as V1 if you find a good one and the long plate ones sound good in V2 and V3 in an Express. RCA's always work as well, but you gotta go through quite a few to find a low microphonic guy.

[David Root]

That makes three of us that love the Amperex 7025/12AX7!

I ordered some tubes y'day from Gregg Levy, Hi Test Guitars. We discussed Amperex 7025s, he likes them too, and he told me if you get a chance to buy a '66 Amperex 7025, to do so. He asked me what mine were and I said '67 and '70, but I'm going to check 'em again!.

I did order the NOS Mazda chrome plate 12AX7, and a pair of NOS RCA blackplate 6L6GCs, good price, $250. He also asked how hard or soft I wanted the blackplates, so I picked 8 on a 1-10 scale, fairly stiff.

Gregg asked me if I ever tried Sylvania 6L6GCs, I haven't. He said they are well worth a try in a Dumble circuit, as many of the older Dumbles he has seen came originally with Sylvanias.

He also said that 35 mA cathode current on a Dumble 6L6GC is too much, and to try 30 mA. Anyone have opinions/info on that? All in all a very interesting conversation, he sure knows a lot about how tubes sound and which amps/positions they sound best in.

Also Mullard 12AT7 in the PI. I have that in my 50W because it's designed for the 12AT7. In my 100W I use the long plate GE 12AX7 because that circuit (#124) is designed for a 12AX7.

[orrong65]

Another way to change the character of your amp without altering the fundamentals of the sound is to change types of capacitor in the pre-amp (not the value) especially right at the front end.

Silver micas for small coupling caps or treble tone stack cap can sharpen the tone up a lot, and high quality foil caps (Mallory, sprague) for the other tone stack caps and other coupling caps can really clean a tone up. Or you can muddy it down - if you want. NOS ceramic caps are great if you want to back off the sharpness a bit.

Probably not as dramatic as changing tubes or speaker, but it still has an audible effect.

[Cliff Schecht]

How do you date the Amperex's?

Also, for coupling caps, I try to use PIO and polystyrene whenever possible. Mica when I dont have polystyrene and more generic film whenever I don't have PIO available. Most of my builds are dictated by the parts I have on hand anyways though. I'm excited to see how well this works out when I start selling amps back at school (got a few people interested already).

[David Root]

www.audiotubes.com/mullcode.htm. If that doesn't work, www.audiotubes.com. Click on Eurotube Codes. A wealth of information!