Battle of the 6L6's !

[beans-on-toast]

Originally Posted by Bassmec

As they used to say "Don't be a dullard, fit a Mullard".

Always brings a smile to my face. Too bad they couldn't get John Lennon to come up with a ditty like Isadora Ducan worked for Telefunken.

Although they are expensive, somehow I play better when I know that NOS tubes are fitted in my amps.

[beans-on-toast]

Originally Posted by Chef

one thing to keep in mind, here, is that the MM runs very high plate voltage.
This needs to be accounted for in your tube selection.

Yes. I believe that the originals were Sylvania 6L6GC's (also called STR-387's).

[nashvillebill]

Quite true, I did not realize this was a MM amp. 700 volts on the plates...yikes!

I'd recommend the Sovteks or EH's, they are pretty rugged and can probably take the plate voltage. The Sovtek 5881's would have lower output but they are very robust.

[Randyt]

I dont have experience with 6L6's in bass heads only 6550's...but in my Fender Vibro King I run NOS Jan Phillips 7581A's (two) and they are the best tubes to date I have ever used or heard...hands down...I have had them for 6 years with out issue...and I run the bias hot at 80%
Creamy vintage tone that just cuts when pushed...(sorry guitar ref)
I bought them here:
http://www.kcanostubes.com/
Good luck

**I actually have a pair in storage...just in case..but never have had to use them

[stanger503]

I went with the 6ca7's in my hd130. Definitely a rounder fatter tone than the el34's someone had put in. But those tubes had more mids I thought and to me, even though everyone says this amp overdriven sounds bad, I thought it sounded pretty decent. With the 6ca7's it didn't sound as nice imo, but still not terrible. Sounds excellent with a guitar too. Big loud clean tone that their known for though

[derridiandrift]

I had the privilege of being able to roll power tubes through V4BH and have them biased up in order to try out different brands. I tried Sovtek, JJ, TAD, and Winged C.

My findings:
Sovtek - good sounding tube but not great. In comparison to the others, the Sovtek has slightly thinner bass and quite harsh top end.
EH - similar to the Sovteks but a bit of midrange hash going on. Both of these strike me as better suited to a guitar amp, or a bass amp where you're going to use a bit of distortion.
JJ - full sounding, nice bottom for bass, top was more clear than the Sovteks and EH.
TAD - similar to the JJ. Pretty hard for me to tell them apart, actually.
Winged C - the nicest of the lot, and by a good amount. Robust tone from top to bottom. All of the fullness of the JJ and TAD (and then some) but even clearer in the top end.

As a result of that experiment I balanced my cash against what my ears heard and went up the middle. I put a quartet of JJ 6L6GC in my V4BH about 18 months ago, using it for anywhere from 3 to 15 times a month on gigs and maybe 5 times a week as my practice amp. The amp runs strong and sounds fantastic. HOWEVER, I ran into a problem with reliability...

Problem #1... one tube developed a crackle after about two or three months. My tech was able to get the supplier to replace it.
Problem #2... another one developed a crackle about after just over a year of use. When I gently wiggled the tube to be sure it was seated properly in the socket, the base and the tube came apart leaving the base in the tube socket of the amp. Apparently the base had been poorly soldered to the pins that come out of the glass bottle. It's possible that the first problem tube had the same issue: the solder connection between the pins and the base had broken.

Because I'd already invested in a quartet of tubes that still tested strong, I bought a replacement for the broken one that was spec'd the same as the others so they would match.

Hindsight recommendation:
If I had a chance for a do-over I would buy the Winged C set of 6L6GC for my V4BH. I've had a set of Winged C 6550s in my SVT-VR for a few years, and I used that set in my SVT-CL before that. They still sound great and they appear to be pretty tough.

Finally, a warning about 5881 tubes. The V4BH can run 5881 or 6L6GC tubes, so you might be able to do that with your amp too. They are probably the cheapest option for retubing. When I bought mine, it had a set of 5881 tubes in it. The 5881 has slightly lower power and is very bass-shy in comparison to any of the 6L6 tubes I rolled through my amp. I still have them because they tested strong when they were taken out of my amp, but they're not suitable for my bass tone, and so therefore I wouldn't recommend you consider these. They break up earlier than any of the 6L6 tubes I tried, so my guess is that I'll find a guitar player who might like them.

[edit: I forgot to mention that I was given a set of Mesa 6L6 from a guy who was going to throw them away. They're still strong. They sound alot like the EH set.]

[nashvillebill]

Caution, don't try to sub EL34's or 6CA7's in the amp if it was designed for the 6L6's, different pinouts. And higher heater current draw than the 6L6.

[jnewmark]

Thanks for all the replies. Yes, the MM HD150 runs at 700pV !. All the MM guys are telling me to bite the bullet and get the military issue Phillips 7581A tubes if I can find a quad matched set. Man, they are quite expensive, but, from what I can gather, probably won't have to be replaced in my lifetime !

[jnewmark]

Originally Posted by nashvillebill

Caution, don't try to sub EL34's or 6CA7's in the amp if it was designed for the 6L6's, different pinouts. And higher heater current draw than the 6L6.

yup, I've read that alot, on the MM site, to stick with the 6L6GC tubes or the miltary version 7581A tubes. Most of the reviews of these tubes seem to be more geared for the guitar player though, not so much info for bass players who just want some nice clean bass tones with headroom.

[jnewmark]

Originally Posted by Randyt

I dont have experience with 6L6's in bass heads only 6550's...but in my Fender Vibro King I run NOS Jan Phillips 7581A's (two) and they are the best tubes to date I have ever used or heard...hands down...I have had them for 6 years with out issue...and I run the bias hot at 80%
Creamy vintage tone that just cuts when pushed...(sorry guitar ref)
I bought them here:
http://www.kcanostubes.com/
Good luck

**I actually have a pair in storage...just in case..but never have had to use them

$490 for a quad ! That's more than I paid for the amp !

[stanger503]

Originally Posted by nashvillebill

Caution, don't try to sub EL34's or 6CA7's in the amp if it was designed for the 6L6's, different pinouts. And higher heater current draw than the 6L6.

I'm guessing this was aimed towards me. I'm not sure what the difference is between the 150 and 130, I know there is some, but the 130 came with 6ca7 big bottles originally. Yes the voltage is very high on these. I think eh makes the only 6ca7's available now beside nos that are iirc in the 3-400 dollar a piece range...no thanks. Sorry I got off topic, just didn't want someone reading that and assuming ya know

[jnewmark]

Originally Posted by stanger503

I'm guessing this was aimed towards me. I'm not sure what the difference is between the 150 and 130, I know there is some, but the 130 came with 6ca7 big bottles originally. Yes the voltage is very high on these. I think eh makes the only 6ca7's available now beside nos that are iirc in the 3-400 dollar a piece range...no thanks. Sorry I got off topic, just didn't want someone reading that and assuming ya know

Yup, the HD 150 head came with 6L6Gs power tubes, not the 6CA7 tubes.

[nashvillebill]

Ultimately though the question may be: pay big bucks for NOS tubes, or buy current production?

There seems to be a belief that NOS tubes are automatically "better" than any current production tube. I'm not sure if that means better specs or better sound, just somehow "better". So folks are willing to fork over the big bucks. Certainly, there are some NOS tubes that have achieved legendary status--RCA blackplate 6L6's for example (whether that legendary status is justified is another debate). However, I would contend that there are some NOS tubes that are no better, and in fact may be inferior, to some modern tubes. So should someone pay $250 for a set of NOS tubes when a set of $60 new production tubes will likely work and sound about the same?

Especially in a gigging amp that may get mishandled, despite the best of intentions. Accidentally break a tube out of a $60 set, not a great loss. Break a RCA blackplate, that will really hurt!!

One other factor: NOS tubes don't last forever, even sitting on the shelf unused. I pulled out a set of NOS GE 6L6GC, still in their original boxes, a month ago and put them in a perfectly-functioning amp. One of the tubes was dead on startup--gas short when I put it in my tester (I knew I should've tested it first!). Tubes can and do lose vacuum and go soft.

So for a gigging amp, I'm in favor of new production tubes. Incidentally, I've got well over a thousand old tubes sitting around here, both NOS and pulls, so I'm not biased against old tubes (pardon the pun), rather that's just my opinion.

[jnewmark]

^ Thanks for your opinion. I'm mainly hitting the Music Man " fan sites," and most of the bass players who play the HD150, are really praising those old military versions of the 6L6, namely the Phillips 7581A, as lasting forever, and being able to take that high plate voltage of 700. Second favorite ( and alot less expensive ) is the SED winged C tubes, which seems to get great reviews from guitar players and bass players alike. Mixed reviews on the newer tubes like the JJ, Electro-Harmonix, some Sovtek's, Ruby and Groove tubes. But, those two previously mentioned 6L6's never seem to get a bad review, wherever I look.

[beans-on-toast]

Originally Posted by nashvillebill

One other factor: NOS tubes don't last forever, even sitting on the shelf unused. I pulled out a set of NOS GE 6L6GC, still in their original boxes, a month ago and put them in a perfectly-functioning amp. One of the tubes was dead on startup--gas short when I put it in my tester (I knew I should've tested it first!). Tubes can and do lose vacuum and go soft.

So for a gigging amp, I'm in favor of new production tubes.

All good advice in your post Bill.

It is true that NOS tube can have issues. Some of them may have had issues long ago and were set aside.

I think that it is important to buy tubes from a reputable dealer that thoroughly checks out the tubes, burns them in for 24 or 48 hours, matches them with an attention to detail, and offers at guaranty. This type of service contributes to the high cost of NOS tubes. Less reputable sellers see what the good guys are charging and match their prices without the service. So it pays to deal with a good seller.

I also find that there are good modern tubes out there. Some consistently better than others in terms of reliability and performance. I've also found that some products are in a state of flux. For example, at one time JJ's were not that bad. Then they changed their quality control, the manufacturing process or the plant, and the quality of the tube dips. If I buy some today, they may not be the same tube that I bought last year. I'll be the first to agree that NOS prices are excessive. In general, I feel that they come out ahead when it comes to service life. They had better QC in the past. The bad tubes were destroyed. Now the bad tubes get relabeled as something else or go out the back door and find their way to less than honest sellers.

[nashvillebill]

Well, it sounds like you've decided on the old Phillips; hopefully they will meet your expectations, considering their high cost.

This amp is biased by a pair of transistors Q3 and Q4. If this bias circuit is not operating properly, you will promptly cook your tubes. Probably the service manual, if you can find one, will show the voltage that should be present on the resistors R39 and R40 that tie Q3 and Q4 to ground--unfortunately the schematic does not show that voltage.

I'll repeat this for those that are unfamiliar with this design: unlike conventional power amps, the biasing is done by a transistor circuit that delivers a constant current to the bias the tubes. Completely unlike any cathode bias or fixed bias scheme; this design is also found in the Peavey Classic VTX amp and their kin.

[jnewmark]

Originally Posted by nashvillebill

Well, it sounds like you've decided on the old Phillips; hopefully they will meet your expectations, considering their high cost.

This amp is biased by a pair of transistors Q3 and Q4. If this bias circuit is not operating properly, you will promptly cook your tubes. Probably the service manual, if you can find one, will show the voltage that should be present on the resistors R39 and R40 that tie Q3 and Q4 to ground--unfortunately the schematic does not show that voltage.

I'll repeat this for those that are unfamiliar with this design: unlike conventional power amps, the biasing is done by a transistor circuit that delivers a constant current to the bias the tubes. Completely unlike any cathode bias or fixed bias scheme; this design is also found in the Peavey Classic VTX amp and their kin.

So, if it's working correctly now, ( which I assume it is since I have'nt cooked any tubes ), if I change tubes, it might not work properly ?

[GlennW]

Originally Posted by jnewmark

Recently got a Music man HD150 head which uses 4 6L6GS tubes...So give me some alternatives and why !

Alternative: sell that thing and let someone else enjoy pouring time and $$$ into it.

Ime for 6L6GC's the old Sylvania STR-387s sound better than =C='s and RCA BP's, but that's for guitar in the amps I tested them in.

It appears your new jewel is going to be a major PITA; so I'd move it along and get something else.

It's ok, you have tube fever right now, but in a few days you'll be able to think straight again.

[nashvillebill]

Originally Posted by jnewmark

So, if it's working correctly now, ( which I assume it is since I have'nt cooked any tubes ), if I change tubes, it might not work properly ?

Well, it might be working--sound might come out--but is it really working properly?

Before dumping hundreds of dollars of tubes into it, it would be prudent IMO to have it recapped and have that bias circuit checked. There's several electrolytics in the driver/bias circuit that--again IMHO--it would be wise to change out. 30 year old electrolytics are living on borrowed time.

GlennW's post is only partly written in jest.

[MAMMOTHvolume]

Originally Posted by Chef

one thing to keep in mind, here, is that the MM runs very high plate voltage.
This needs to be accounted for in your tube selection.

Low grid voltage though so it's alot nicer on your valves