found some NOS tubes this weekend

[kmanick]

I was cleaning out the attic at my parents house this past weekend adn found a taped up box marked tubes on it.

My dad passed away way back in 1986, he was an electrical engineer so I figured sooner or later I'd find something cool.

Well I found a pair of slightly burned in orginal Tung Sol 5881 (matching pair)

a pair of ........gulp brand new Mullard 12Ax7s

and a pair of brand new Tungsram 12Ax7's

All of these are from the 1960's

The Mullards may even be from the 50's (they have the old "Badge" logo on them.

I don't know whether I should just throw them into my Mark IV or sell them

any NOS tube junkies here that know what these are worth?

 

[212Mavguy]

Hell yes toss them in your amp! The Mullards will give your dirty channel some added girth and smoothness, and the Tungsrams will deliver some of the sweetest, most articulate cleans you can imagine! Keep your dad around...in your amp! That would honor him as well as give you your own special tones!

Don't sell them!

 

[kmanick]

Hell yes toss them in your amp! The Mullards will give your dirty channel some added girth and smoothness, and the Tungsrams will deliver some of the sweetest, most articulate cleans you can imagine! Keep your dad around...in your amp! That would honor him as well as give you your own special tones!

Don't sell them!

Ya I have decided that I'm definitely keeping them.
so which slots should I put the Mullards in and which slots should I put the tungsrams in?

 

[dodger916]

Hell yes toss them in your amp! The Mullards will give your dirty channel some added girth and smoothness, and the Tungsrams will deliver some of the sweetest, most articulate cleans you can imagine! Keep your dad around...in your amp! That would honor him as well as give you your own special tones!

Don't sell them!

Ya I have decided that I'm definitely keeping them.
so which slots should I put the Mullards in and which slots should I put the tungsrams in?

It depends on the sound you're after. V1 and the driver/phase inverter (V5) have the most global influence on tone, with each successive tube having less global influence. Per page 20 of my Mark IVb manual:

V1A: Input Stage
V1B: Tone Recovery Stage (post tone controls)

V2A: 3rd gain stage (Rhy mode) and 5th Lead Gain Stage
V2B: FX Return Stage

V3A: First Lead Gain Stage
V3B: Reverb Return

V4A: Second Lead High Gain Stage
V4B: Reverb Send

V5: Phase Inverter

The 12AX7 is a dual triode tube; hence the two stages per tube (except V5). If you want a more girthy, midrangy/Marshally voice, stick a Mullard in V1 (and maybe V5 also). If you prefer a more articulate/Fendery voice, use the Tungsram. When you found what you prefer, start "rolling" successive tube slots. So you could voice the amp to be articulate, and then put a Mullard in V3 and V4 for a different flavoring in the lead stage. Lotsa fun, and you have some great tubes to play with!

To be safe, before using the 5881's, I'd try to get their idle current draw. Only certain tube testers will give you that info. And it's OK to mix 5881's with 6L6s, but ONLY with the 5881s in the outside tube sockets (or 5881s in all four slots).

 

[kmanick]

thanks for the info.
I thought 5881's were direct replacements for 6L6's? Not true?
what will the 5881's (especially these old tung sols give me tonally ? anyone know?)
I'm thinking the Mullards in V1 and V5 and the tungsrams in V3 and V4 (to start ) and then try them in different
positions from there ?
I'd like to get a thicker tone out of this amp. I have all JJ's in there now and all 6L6's and my lead tone
is to die for, but rhythm wise it could be a littler thicker.
I don't really notice it until i turn on my 5150 II and I see how much thicker that sounds compared to the mark IV.

 

[Ken j]

...I thought 5881's were direct replacements for 6L6's? Not true?
...

5881 is the industrial version of a 6L6. They are interchangable.
If you want to find values, watch tube sales on ebay and audiogon.

 

[dodger916]

...I thought 5881's were direct replacements for 6L6's? Not true?
...

5881 is the industrial version of a 6L6. They are interchangable.
If you want to find values, watch tube sales on ebay and audiogon.

Per page 20 of the Mark IVb manual (Tube Task Chart): "5881's in all 4 or Class A sockets"

 

[kmanick]

thanks dodger !
I'm going to try them in the "A" slots. *since I only have 2)

 

[212Mavguy]

Vintage 5881's differ from currently produced 5881's. One exception is the new TungSol Reissue 5881, I'm pretty sure it is made to vintage specs.

Pinout is the same, but the vintage ones are designed for lower plate and screen voltages than used in nearly all modern production designs currently made that use 5881's made to modern 6l6gc specs. Boutique amps that use lower output voltages for screen and plate circuits are an emerging trend and an exception.

 

[stokes]

Dont put those 5881's in your MKIV.As Mavguy says,they are rated for lower plate and screen volts and less output watts.I once put a pair in a MKIIC+ and they lasted 7 hours before they cooked.I had 6 pairs at the time and just wanted to see how long they would last.As someone else here said,"5881 is the industrial version of a 6L6. They are interchangable."That is the 6L6 not the 6L6GC which is what pretty much all modern amps are designed for,except,as Mavguy pointed out,some boutique amps,but pretty much all the Boogies are designed for the GC or when they mention 5881,they are talking about modern 5881's which are not 5881's at all.

 

[Ken j]

Dont put those 5881's in your MKIV.As Mavguy says,they are rated for lower plate and screen volts and less output watts.I once put a pair in a MKIIC+ and they lasted 7 hours before they cooked.I had 6 pairs at the time and just wanted to see how long they would last.As someone else here said,"5881 is the industrial version of a 6L6. They are interchangable."That is the 6L6 not the 6L6GC which is what pretty much all modern amps are designed for,except,as Mavguy pointed out,some boutique amps,but pretty much all the Boogies are designed for the GC or when they mention 5881,they are talking about modern 5881's which are not 5881's at all.

I was referring to the modern 5881 tubes. The suffix GC on 6L6's means "glass container". Originally 6l6's had a metal container. The metal container tubes haven't been produced in over 50 years as far as I know. These are not recommended for guitar amps.
Another vintage tube to watch out for are older EL34's as some had a different pin out. The pin outs were changed sometime in the '60s. I had a set of Mullards, that I took out of a vintage amp, that I sold to a friend. They were the new style but had a ninth pin to prevent them from being used in amps designed for the other pin out. The 9th pin was used only as a lock out. He had to cut it off to fit it in his amp.

 

[stokes]

Dont put those 5881's in your MKIV.As Mavguy says,they are rated for lower plate and screen volts and less output watts.I once put a pair in a MKIIC+ and they lasted 7 hours before they cooked.I had 6 pairs at the time and just wanted to see how long they would last.As someone else here said,"5881 is the industrial version of a 6L6. They are interchangable."That is the 6L6 not the 6L6GC which is what pretty much all modern amps are designed for,except,as Mavguy pointed out,some boutique amps,but pretty much all the Boogies are designed for the GC or when they mention 5881,they are talking about modern 5881's which are not 5881's at all.

I was referring to the modern 5881 tubes. The suffix GC on 6L6's means "glass container". Originally 6l6's had a metal container. The metal container tubes haven't been produced in over 50 years as far as I know. These are not recommended for guitar amps.
Another vintage tube to watch out for are older EL34's as some had a different pin out. The pin outs were changed sometime in the '60s. I had a set of Mullards, that I took out of a vintage amp, that I sold to a friend. They were the new style but had a ninth pin to prevent them from being used in amps designed for the other pin out. The 9th pin was used only as a lock out. He had to cut it off to fit it in his amp.

The original poster is talking about NOS 5881's.You're close on that GC designation,and here is where problems arise.The "GC" doesnt mean "galss container".The "G" designation does mean glass,but that was started when they went from the metal envelope to the glass.The first was the 6L6G,which specwise,was the same as the metal envelope,but with glass,then came the GA,GB then finally the GC,so they are all "G"s or glass,but there are A,B and C versions.A metal envelope tube can be used in any 6L6 circuit not designed for the GC,and any of them can be substituted for each other except in a GC circuit,the GC is a 30 watt tube with higher plate and screen voltages than the 19 watt G,GA and GB which had 360 volt plate and about 270 v screen limits.The GC is 500 v's for both.So you are saying you had an EL34 meant to be used in a nine pin socket?And someone "cut the ninth pin off to fit in an octal socket"?No,you did not.

 

[Ken j]

...So you are saying you had an EL34 meant to be used in a nine pin socket?And someone "cut the ninth pin off to fit in an octal socket"?No,you did not.

Correct. It was the same pattern as an octal socket with one addtional pin. He found which pin to clip from an old timer tube expert who expained why the 9th pin was added and that it was only there to prevent one from using the tube in a wrong circuit (if I recall correctly). The tubes are functioning fine for over a year now in my friend's stereo. I never looked that close at the tubes but did have them tested. I was unaware that the tubes had ever changed. Just when you think you have seen it all something like this pops up. I removed the Mullard EL34's (rebranded CMI, Chicago Musical Instrument, the legal parent of Gibson) from a Gibson Kalamazoo Bass 50 amp. I believe these amps date between '65 to '67. I have no pics but if I get chance I will get some. One friend has the tubes another has the amp.

 

[stokes]

No,the Kalamazoo Bass 50 used EL34's with an ordinary octal socket.You are repeating some myth you heard.The EL34 was always an octal tube,there are no nine pin octal sockets,there are no and never was a nine pin octal tube.Think about what you are saying,the tube was made with nine pins to keep it from being used in the "wrong circuit"?And some magician told your friend how to remove a pin so he could use it in the wrong circuit?So tell me,exactly what did you replace these nine pin tubes with in the amp you took them out of?You're killin' me.

 

[kmanick]

Well I know for a fact that my dad used these tung sols 5881's that I found to power his old stereo power amps (as in Hi-fi power amps) so i'm thinking that 212mavguy may be right and
these are lower voltage, so I've decided to just hold on to them for now adn not put thm in my IV.
I did put a Mullard into V1 and a tungsram into V3 and I really like what I'm hearing. it makes the amp sound a little fatter and darker (which I like) and a bit smoother. I need to do some more swapping and see what else it gets me
thanks for all the info guys!

 

[Ken j]

No,the Kalamazoo Bass 50 used EL34's with an ordinary octal socket.You are repeating some myth you heard.The EL34 was always an octal tube,there are no nine pin octal sockets,there are no and never was a nine pin octal tube.Think about what you are saying,the tube was made with nine pins to keep it from being used in the "wrong circuit"?And some magician told your friend how to remove a pin so he could use it in the wrong circuit?So tell me,exactly what did you replace these nine pin tubes with in the amp you took them out of?You're killin' me.

I am going on what my friend told me. I will try and get a pic and have him refresh my memory on why it was different. I have had some health issues this last year and have not seen the tubes since they left my possesion. The amp has gone in another direction. He has no reason to lie to me. I will try to get a pic of the sockets also.

 

[stokes]

Oh,so now its based on "what my friend told me",in your original post you "took them out of an amp and sold them to your friend...." this is how disinformation and myths get started and run rampant on the 'net.Look,there were never "nine pin" EL34's,period.Or any nine pin tube that could have one pin removed to make it fit in an octal socket.Sometimes a little knowledge.....

 

[dodger916]

The original poster is talking about NOS 5881's.You're close on that GC designation,and here is where problems arise.The "GC" doesnt mean "galss container".The "G" designation does mean glass,but that was started when they went from the metal envelope to the glass.The first was the 6L6G,which specwise,was the same as the metal envelope,but with glass,then came the GA,GB then finally the GC,so they are all "G"s or glass,but there are A,B and C versions.A metal envelope tube can be used in any 6L6 circuit not designed for the GC,and any of them can be substituted for each other except in a GC circuit,the GC is a 30 watt tube with higher plate and screen voltages than the 19 watt G,GA and GB which had 360 volt plate and about 270 v screen limits.The GC is 500 v's for both.So you are saying you had an EL34 meant to be used in a nine pin socket?And someone "cut the ninth pin off to fit in an octal socket"?No,you did not.

That's for this explanation, stokes. I've often wondered what the differences were.

 

[212Mavguy]

coulda been el84's instead of el34's, that makes more sense. I have some el84's where somebody snipped off one of the pins, they work fine in the amps I've tried them in. They are Mullards too.

 

[94Tremoverb]

That doesn't make them fit in 8-pin sockets though... it's usually because some (wrongly designed) amps use pin 1 of the socket as a tie point, and some EL84s including some vintage types have this internally connected (often to the control grid), so if there is a positive voltage on pin 1 of the socket (which can be up to the plate voltage if the tie point is used to feed the screen resistor...) it's instant tube death - at best, it can also fry the bias circuit in a fixed-bias amp. This is a problem with the amp not the tube really, because the original tube spec lists pin 1 as *Internal Connection* not *No Connection*, so technically it must not be used. Still, if your amp is one of these and you put an old EL84 in without realising, it can get very expensive very quickly... cutting off the tube pin is a bodge that will avoid this.

But an EL34 is an Octal tube, which is an equally spaced 8-pin fitting. Although there *are* large 9-pin tubes too, cutting one pin off could not possibly make one fit an octal socket, even if the pin sequence was correct - that would be like saying you can fit a 5-stud wheel to a 4-stud hub if you leave one of the bolts out .