5881's in MK IV?

[ursinus]

Any one try these tubes in their MK IV? I'm thinking of experimenting with 2-EL34's and 2-5881"3 in my MK IV. Would like to hear from you all. Thanks

 

[Russ]

From what I understand the STR420 was closer to a 5881 than a true 6L6. I have the 420's in my amp and I dig em. If the 420 is more like a 5881 than a true 6L6 then I would suggest getting a properly matched pair within the bias and plate voltage requirements and have at them. All I know is that the 420 rocks...

 

[Antoine]

Russ, the STR 420 are 6L6's Chinese tubes, the 5881 Mesa Tubes are the STR 425, they are Russian Tubes, Sovtek ones i think.
According to the MarkIV manual, the 5881 are more dark sounding than 6L6's, it might be a good choice if you find your amp to be too bright,
the manual says all 6L6's are the better match for the amp too, i would suggest the 6L6's STR 454, which are the Svetlana ones, the best choice actually, or the 6L6's STR 430 which are Sovtek ones.

 

[Russ]

Yes, Antoine, the 420 was a 6L6 and the 425 is a 5881. Also good point, it is in the Mark IV manual that you may substitute 5881's for your 6L6's if you find things to be too bright. Read carefully here as I was making a comparison as a particular 6L6 being close to a 5881 not that a 6L6 was a 5881. According to the Tube Sales Reference Guide from Mesa, you can use their 5881 (STR425) in the Mark IV. Again, I suggested getting a proper matched pair of 5881's suitable for use in the Mark IV if so desired. This was implying the use of other than STR425 5881's with an understanding that ursinus probably already knows about the STR425. Mesa tubes are not the only tubes out there. In fact, Mesa buys a lot of tubes from Ruby who buys them from the manufacturer. This creates some middleman markup. It might behoove the consumer to buy comparably selected tubes that are properly matched for their amps and save a few $'s.

 

[Antoine]

Russ, i'm very sorry for the misunderstanding of your post, i didn't want to offense you at all. I respect everyone and enjoy readind the posts. Plus members like You, Shep, Boogiebabies, Nick, Jamme61... (sorry if i forgot names) are the members which make this forum so unique and attractive, so, Much Respect, and hope everything is fine :wink:

 

[screengrid]

Hi all,

since some years already, I use Mesa's 5881's with my MK IV combo. For my personal taste, the amp sounds less bright as with 6L6's but also with good warms, defination and punch in all 3 channels, al long as playing at moderate volumes.
I also tried a pair of Svets from Mesa. IMO, clean sound at it's best, very warm and crisp sounding with a lot of bottom end. But I didn't like the Svets so much with the lead channel.
I like to play bluesy and jazzy stuff.

regards
Arno

 

[Russ]

No problem Antoine. It is sometimes difficult to get exactly what people are saying here. The internet forums at times can be difficult to get the feeling or intent that the person is trying to get across just because it is solely typed. I too appreciate the input from everyone here. Unless seriously provoked, it would be senseless to have anything but a positive experience here. BTW you have some nice clips. I dig your tone.

 

[ursinus]

Thanks to you all. I ordered some Mesa 5881's to try first. If I like them, I may experiment with other brands that are matches for the voltage. Man, how I love my MK IV, let me count the ways........................

 

[Russ]

I don't think we have enough fingers for that... :wink:

 

[Aart]

Is it possible to put KT88's or 6550's in a bias modded Mark IV?

And what will they do to the sound?

Will it be tighter, looser, brighter, darker?

 

[Russ]

I see that as possible but you have to find ones that physically fit due to the socket spacing. I found 6550s and KT88s to be really in your face sounding. The KT88 especially so. This has been my experience with them in Marshalls anyway. A quick feeling analogy would be like think of getting swatted in the face with a towel as an EL34, mild chest pounding. Then make it heavy leather jacket with a 6550, heavier chest pounding. Then imagine running face first into a brick wall with the KT88, an absolute full body thrashing. Tighter... yes definietly. More headroom comes too. Brightness or darkness depends upon the tube design.

 

[Shep]

the El34 and 5881 would be a cool mix of dark chunk mixed with top end sizzle..that would be cool..i might be getting a Mk III blue with el34's and str425 which are the miltary grade Russain 6L6 ( 5881).. would plp agree with me that a 5881 is the less trebley brother of the 6L6?..

 

[Nick_cor]

Russ, i'm very sorry for the misunderstanding of your post, i didn't want to offense you at all. I respect everyone and enjoy readind the posts. Plus members like You, Shep, Boogiebabies, Nick, Jamme61... (sorry if i forgot names) are the members which make this forum so unique and attractive, so, Much Respect, and hope everything is fine :wink:

Thanks !

 

[Boogiebabies]

A true 5881 is a 25 watt tube. The Sovtek 5881 and 5881 WXT are 30 watt tubes and basically a 6L6 is a small bottle. They may be darker in tone by design. The 5881 when it all comes down to it is a really good sounding tube. The STR-420 was the Shuguang/Sino 6L6 as you guys mentioned. I hate to say this, but it was and awsome sounding tube. It sucked as far as lifespan, but it was awesome. I still have 4 NOS 420's.
Two straight and two coke bottles. For me, in the MK IV the 420's are incredible in all four sockets. I found the best tone and balance in using the GT 6L6GE American Made and the GT 6CA7GE American Made. They combine to give me a huge simul class tone. I also run these in the IIC+ Simul Head with great results. The other C's have a combo of old production Svetlana 6L6GC's and EL34's. These are very well balaced as well, but are a bit brighter with the EL34's over a true 6CA7. The 6CA7's also blend well with Mesa STR-415's and Phillips 7581A's. They are an EL34 basically with a huge bottom and smooth top. My favorite tube for EL-34's in Simul's is a NOS Tesla ( Pre JJ) EL-34. I would give a kidney to get a hold of two more. The JJ E34L is it's modern couter part, but they make it wrong. It's closest duplicate is made by JJ on the GT tooling as the original has huge heat wings. Sadly, they do not sound as fat as the old Tesla's.

Have Fun !!! This can go on forever.

 

[Russ]

I used to love the Tesla EL34 too in my Marshalls. So how would you describe the 7581?

 

[Boogiebabies]

A 6L6GC on steroids. It's a full spectrum 35 watt tube with all the right harmonics. Superior cleans and headroom for days.

I like the Tesla's better than Siemens, especially in Marshalls.
My 2555 Silver Jubilee came with 4 Siemens that are all running within 2ma of each other. The amp was just never used and even the tolex is bright silver. If I could, or would pay the bucks, i would use Tesla's or XF4 Mullards. i am such a big puss when it comes to using my NOS stuff. I still have not used my new STR-415's or Mesa Siemend STR-450's. i also hoard RFT 12AX7's. God I love them.

 

[Shep]

i have a pair of brand NEW 1970's RCA 7025'A (they have been just sitting in a box for the last 30 somthing year's,they were my dad's.. )


i have read that Ampeg used them but apart from that i have never seen them before..

does anyone know of these tube's..they are pretty much the size of a 6l6 but have a full set of pin's ( pentode wiring ?)

 

[Russ]

RFT's.... sniff sniff...

Man.... that's ok, I have 3 1961 Mullard Blackburn Ecc83's that I am sitting on.

I wouldn't mind having 1 RFT to juggle around though. That would make for some interesting combinations with the other 60's GE and RCA's that I have.

I actually dig Siemens EL34's too.

Why is it that you like the XF4? Isn't the XF2 the thing that dreams are made of?

I read an article not to long ago that talked about care of NOS tubes and it was saying something about not sitting on your NOS too long unless you cryotreated? them. It was saying something about how in regular storage conditions that even though you keep them unused that they will degrade slowly. I forgot where I read that. It may have been a bunch of hype over cryotreatment? or just a way for someone to get people to use up their NOS stock.

 

[stokes]

Shep,7025's are a 12AX7 sub,not 6L6.If you mean 7027A's,these are similar to a 6L6GC but have extra pin connections,if you use them in a 6L6 amp you must make sure that there is nothing connected on the "empty" 6L6 socket connections,as in some Fenders,but they are useable in a 6L6 amp.They are very good tubes,I got 2 of them in my MKIIC+ and 2 extra pair in reserve,I love them in the Boogie.The extra pin connections are pin 1&4 are your screen and pin 5&6 are your grid1.

 

[Russ]

I have a matched pair of GE 6L6GC's from 1960 that were premium selected for organ use that I was wondering if it would be safe to run them in my MarkIV. Any ideas?

I could go get them tested to see where they are as far as plate dissipation and mA go but I already tested them for life expectancy, shorts and leakage. They tested great so far.