Tube AMps: Tone and Care

[Wild Bill]

I've been running and servicing tube amps since the mid '60's. Power tubes can last many years as many have expressed before me. Preamp section can last even longer.

Even more importantly the quality of current tube manufacturer is on the rise. SED/Svetlana 6L6's aree amongst the best of the type ever made. JJ Tesla EL Series (34 and 84) really sing . Groove Tubes is now manufacturing their own 12AX7/ECC83 that is almost identical in sound to the old Mullen "golden refereneces", with JJ Tesla and Electro Harmonics puting out very good Telefunken type ECC83's from the original Eastern European factories.

The story about all the best tubes having been made in the past is quickly becoming "an old wives tale".

Some good sources:

Lord Valve
The Tube Store
Euro Tubes
Triode Electronics

My favorite is Triode, but only beacuse I am lucky enough to be able to walk oevr there and talk face to face with the owner (who has been there over 30 years). No internet lag, just instantaneous parts.

If you tell any of these guys (and probably others) the make/model of your amp (tube cdong if it has any) they will match you up with a tube that is (very) close to the tolerances of the ones you presently have, ensuring a very close tonal match without re-biasing.

(editing to correct spelling)

[antilog]

mmmmm i like my yellowjackets in my hot rod deluxe, which allows it to use el84's instead of 6L6's. the el84's distort at a lower volume....creamy

[ladewd]

I also use yellow jackets in my old Ampeg Reverberocket. The EL84's sound much better than the 7591A's.

[antilog]

great thread, this may be "best of" material...

[RefD]

what Wild Bill said... SED/Svetlana make some of the best tubes currently. if i had to retube, i'd buy tubes made by them.

and what soundy said, as well... EL84s and 6V6s both have a very nice sound to them.

the type of rectifier for the power supply has a large impact on sound, as well. the 5AU4 (i think that's the one) in my dearly departed blackface Fender Princeton made for a very different sound from an '83 Fender Deluxe Reverb II with 6V6s and a diode rectifier. Mesa/Boogie made a very popular product line based on this difference.

btw, i liked the Rivera-designed Fender tube amps from the early 80s.
Except the Twin Reverb II, it had problems.
the Super Champ was fun, tho!

[Meriphew]

what Wild Bill said... SED/Svetlana make some of the best tubes currently. if i had to retube, i'd buy tubes made by them.

I bought a set of NOS Svetlana EL34's last year for my Music Man Sixty Five Reverb head. It's still running fine on the original Sylvania's that are in it (the amp must have been made in the 70's), but I figured I'd get a set before prices started to climb.

[hardLeft]

Couldn't agree more: tubes last a long long time, new old stock is not hard to find, and new stock is getting better and better. Everyone's favorite fence sitter Walter Sear has a great set of articles about tube gear at

http://members.aol.com/searsound/articles2.html

[Paul Fury 161]

Hiya. As you've probably realised from the replies so far, your amp could support not only different makes but also different models of tubes. Oldertubes are often prized because they were manufactured when tube technology was at it's peak.In the 80's and 90's most of these companies and their expert staff closed down orwere decomissioned or retired. In the mid 90's when more companies started making tubes in the fareast in earnest, the quality was often poor because alot of know how had been lost. Things are, i'm glad to say, alot better now. so anyways, here are a few things that might getcha straightened out....

There is NO way to predict how long valves are going to last- they are made by hand, and therefore have slight variances.Even within the same brand/NOS etc.

Not alll new tubes are crap - if you need to re tube, get a matched quartet of powertubes from a reputable tube reseller and get them installed and the amp rebiased by a good tech and you'll be fine. The amp sound may change slightly, but I wouldn't worry about it too much, it should still sound like your amp. In my opinion NOSpower tubes are not necessary, the preamp tubes make amore drastic impact on the amp (although faulty power tubes will DEFINITELY have an effect!). You should also get your pre tubes from a reseller - they bvuy many thousands of these modern chinese orrussian tubes and test them, unlike guitar stores that just get them straight in. A reseller should be able to sell you a set matched roughly for high gain and low microphony. Soundy is also right, many people swap out the 12ax7 (ecc83) tubes from the V1 and V2 positions (as these are involved in the preamp gain of the whole amp) for lowergain models like 12at7 or 12au7 for a smoother, less harsh sound, although this is a lesser consideration for your amp.

Always turn the amp on with an approapriate loadconnected to the speaker jacks...ifthe amp is setfor 8 ohms you can drive a bigger load like 16 ohms no problem, you just lose a bit of efficiency (some people even like this!), you MUST NOT drive a lower load like 4 or 2 ohms. Doing this stresses the outout transformer and may well lead to it's eventual failure. Companies like Magic Parts in the US do stock new replacement transformers for quite cheap but a replacement output tranny will probably change your amp tone a whole lot more than new tubes ;-p. Use the standby when turning the amp on to preserve tube life and when turning off to preserve the life of the big filtercaps that smooth the mains supply and also occasionaly might need a replacement.

If the time comes when you DO need to repair/retube your amp, go to a good tech and spend the money. Don'ttry and do it yourself unless you're really hot with DIY tube electronics. These things can kill ya, no fooloing. With vintage amps, if a good tech goes through the amp and does whatever works is necessary you'll have a nice amp that you can gig with no fear of failure. In my experience that's the best way to go.

When you replace your output tubes, you could install 6L6's (which should be what you have now) orthe military spec version, the 5881.Might be worth checking out- theydo sound a bit different, notbetter or worse, just different - some early tweed fenders only really sound right with this tube, so it's worth considering.You can change your power tubes without changing your preamp tubes, or vice versa - just make sure thatifyou change you pre tubes you get a good one for the phase inverter (this one drives the powertubes).Preamp tubes of thesort found throughout your amp have two gain stages (two halves of the tube), if they are a bit uneven, half of your power tubes will bw working harder than the other half.This can blow tubes or fuses and appear like an output transformer fault (another good reason for getting new tubes from a decent reseller!).

Whew! Sorry, didn't mean to post this long.Hope this all helps. For more info check out the message boards at www.plexipalace.com those guys have answered all these sorts of questions much better than I can.

Take it easy,

Paul Fury 161

[Paul Fury 161]

Whoops, wrote my last reply yesterday but couldn't post it from home, just posted from work and realised most of my points had already been made
;-p that'll teach me to not read the new posts;-p

Hope it's of some interest anyways,

Paul Fury 161

[spankenstein]

Funny thread, my Hot Rod Deluxe started sounding like complete butt last night. I had some other 6L6s sitting around and swapped them in and bam, back in all it's glory. This amp is only around a year old.

Alot of people who buy the newer entry level Fender amps swap the tubes asap. I think Fender uses fairly crappy ones to save $.

they also use ridiculous high gain tubes in the pre, at least in the hot rod line. tap the volume to get a decent volume, 1 is loud, 2 and up is just silly crappy loud. think they do it for the retail showrooms. swap those pre tubes out with some lower gain tubes, ahhhhh. i enjoy 5751, 12au7, 12ay7 in the pre to lower the gain going into the power section, so you can crank up the master a bit, driving the 6l6's.

Also, i advise you to have the new power tubes biased properly for optimal life, or optimal tone, and you might not get as much life out of it. If you don't know what biasing means, you should have a tech do it, or read up and be SUPER careful if you do it yourself.

I took out the sovtek5881's and installed some svetlana 6L6GC, biased them, and I noticed an improvement in tone, especially when the distort. I didn't know the joys of power tube saturation until I got an apt in which I could be loud (silly loud), and experimented with different tubes.

The volume pots on the hot rods are linear taper instead of audio taper. It's annoying.

[0xeneye]

One thing you will notice with New amps - the manufacturers send them out with tubes that have a good probability of NOT going bad in their first year. (A new amp in the field sent back just beecause a tube went bad is very costly.) Manufacturers oftentimes cold bias so the tubes don't get fussy.

This USUALLY means that the longest lasting tube is not the BEST tube. Marshall and Fender both know this, but they don't do anything about it.

So, if you buy a new amp, plan on getting a new set of tubes (the shipped ones are sub-par sometimes) for it and having it biased to taste. Another thing, you don't have to bias HOT to get the AMP to sound GOOD necessarily. People that are happy with their 30 year old tubes know this already.

Only boutique amps ship with really good tubes, in my opinion.

When I walk into a guitar center, I would guess that about 60 % of the amps have sub-par tubes, and of the remaining 40%, about another 50% have a cold bias. And of the remaining 20%, about 50% are boutique, or low wattage amps. That's my guess.

[object88]

the type of rectifier for the power supply has a large impact on sound, as well. the 5AU4 (i think that's the one) in my dearly departed blackface Fender Princeton made for a very different sound from an '83 Fender Deluxe Reverb II with 6V6s and a diode rectifier.

This is true, to a point, if I understand correctly. The type of rectifier makes a difference when the power amp is class-AB. A class-A power amp is not effected by sag in a tube rectifier, whereas a class-AB is. There is little to no difference between a tube and solid-state rectifier in a class-A amp, sound-wise-- so your smaller or older amps (original Fender Champ, etc.) won't care what kind of rectification is used.

Reference: http://www.aikenamps.com/Sag.html.

[jmligt]

I've bought a Fender Hot Rod Deville about 4 years ago and I've replaced both the output tubes and the preamp tubes. I had to replace the output tubes about a year after I bought it, but haven't touched them since. I just replaced the preamp tubes a few months ago. I have the same problem with the volume knob being very touchy. Also my #1 input jack has fallen apart three times. Every time I take it back to the local fender dealer/repair shop they just give me a lot of shit because I didn't buy it off of them. Part of the reason I bought a fender amp was because it could be serviced at any fender dealer/repair shop. fucking bastards

[antilog]

Funny thread, my Hot Rod Deluxe started sounding like complete butt last night. I had some other 6L6s sitting around and swapped them in and bam, back in all it's glory. This amp is only around a year old.

Alot of people who buy the newer entry level Fender amps swap the tubes asap. I think Fender uses fairly crappy ones to save $.

they also use ridiculous high gain tubes in the pre, at least in the hot rod line. tap the volume to get a decent volume, 1 is loud, 2 and up is just silly crappy loud. think they do it for the retail showrooms. swap those pre tubes out with some lower gain tubes, ahhhhh. i enjoy 5751, 12au7, 12ay7 in the pre to lower the gain going into the power section, so you can crank up the master a bit, driving the 6l6's.

Also, i advise you to have the new power tubes biased properly for optimal life, or optimal tone, and you might not get as much life out of it. If you don't know what biasing means, you should have a tech do it, or read up and be SUPER careful if you do it yourself.

I took out the sovtek5881's and installed some svetlana 6L6GC, biased them, and I noticed an improvement in tone, especially when the distort. I didn't know the joys of power tube saturation until I got an apt in which I could be loud (silly loud), and experimented with different tubes.

The volume pots on the hot rods are linear taper instead of audio taper. It's annoying.

Yes, that would also affect the volume...