Tube options? Little Lanilei tweaks...

[kidsmoke]

My Mahaffay Little Lanilei uses two tubes:

 

this is from some of the literature.

 

 

Product Specs:

• One Ecc82 tube
  
• One Ecc83s tube used as a REAL output power tube, built in power soak to a Solid state class "A" booster stage. Big Fat tube tone at ANY volume level
  
• Master volume control, pre amp control, tone control
  
• High gain, low gain, mid gain settings, foot switchable (foot switch not included.)
  
• Head phone out
  
• Line out / channel insert TRS Cable for line level effects WOW!!!
  
• Internal 6 ½ speaker (same custom made version used in all popular Little Lanilei amplifiers)
  
• Floating filament power supply for hum free operation
  
• Star grounding
  
• Two external speaker output jacks - one cuts off the internal speaker; one leaves it on
  
• Hand wired point to point tube socket assemblies
  
• Hand made in the USA
  

the builder states that this tube compliment is optimal for low volume/high gain sound. I'm not one to argue.

here's my question: What tubes could be swapped for the existing, and what sonic results would they produce?

for example - on the same page as the above info he mentions using a 12ua7 tube. I'm assuming that this is identical to the Ecc83s tube due to the context where he mentions it.

What tubes might allow for a cleaner tone? Would I need to be concerned about biasing?

I seem to have knocked the amp somehow and jacked up the gain selector microswitch. So I'm thinking if I'm gonna open it up for that simple repair, it's a good opportunity to mess around.

Thanks in advance for any suggestions!

[kidsmoke]

Oh, and it's 33W output. i assume that matters

[Steiner]

The various 12A_7 labels all denote preamp tubes. The brittish equivalent is the ECC__ tube.

For example:

12AX7 = ECC83

12AU7 = ECC82

12AT7 = ECC81

 

As you travel from the AT to AU to AX, the gain increases. I know the 12AX7 is 100% gain, I don't recall the other two but they are a lesser % gain. So, if you have too much gain, you can try swapping out your 12AX7/ECC83 with a 12AU7/ECC82 or 12AT7/ECC81. It should give you less gain at the same volume level.

 

This is a real fun experiment to do. Quick, easy and obvious results. Enjoy!

[Franke]

Here you go. good information on the various 12A_7/ECC_ tubes and how they effect gain.

 

http://thetubestore.com/gainfactor.html

[kidsmoke]

cool stuff Franke, thanks.

 

I pulled the back off my amp last night to look at the tubes....they're chinese made 12au7 and 12ax7, and at least 4 years old. I'm thinking just getting some RCA's or GE replacements and seeing what the new "baseline" is with NOS quality tubes is.

 

I'm well aware of Eurotubes(JJ's). Does anyone recommend another source for quality tubes?

[plexirocker 68]

kidsmoke,

 

All my old Rca's, GE's etc I have a good source locally for cheap NOS or used- I'll check on some 12Ax7's -I normally grab them for $10

 

PM me with your address and I'll just send you some real deal 12au7's. I'll send you a couple of the "good ones" I believe I have "several"

 

Lots of the newer amps are designed with the new tubes so NOS may or may not always be better, you just have to experiment

 

plexi

[plexirocker 68]

I like Tube Depot for new tubes.

 

plexi

[Blunote]

A lot of folks very much prefer the Chinese tubes.

[212Mavguy]

I like PR 68's solution, FWIW. That same company makes a little lightweight Leslie style speaker that is supposed to sound really good, available also as a kit.

[Blunote]

I'm interested to know how a lower gain 12AY7 or 12AT7 works in that amp. Like you said before, there's not a lot of headroom if you turn it up at all. Also curious that the 12AU7 isn't shown in the replacement chart at http://thetubestore....gainfactor.html as a possible replacement. I'd think it could be used in the 3350LT output since that's what's used for the preamp stage.

[kidsmoke]

I'm interested to know how a lower gain 12AY7 or 12AT7 works in that amp. Like you said before, there's not a lot of headroom if you turn it up at all. Also curious that the 12AU7 isn't shown in the replacement chart at http://thetubestore....gainfactor.html as a possible replacement. I'd think it could be used in the 3350LT output since that's what's used for the preamp stage.

 

Yes I wondered this. Based on that chart, the pre- amp tube is already at the "lowest" gain option. That leaves the power tube.

 

Your comment re: Chinese tubes is the first I've heard that, but it doesn't surprise me. To the informed...I have some nearly new chinese tubes removed from the Bugera almost immediately after buying (did a JJ "kit" for this particular amp)

 

They are designated 12ax7-A and 12ax7-B wha?? can either of them be swapped for the 12ax7 currently installed.

 

Plexi - PM sent

[212Mavguy]

Yes, the Chinese tubes can be subbed no problem. The suffix after the type denotes a style of build, but the overall thang is as the main designation implies, any "12ax7" is supposed to have a gain factor of 100, but the Sovtek 12ax7 short plates test out to only around 70, same as a 5751. Chinese tubes were factory issue in my 90's vintage Mesa Boogie Maverick 2/12 combo. .FWIW, Cninese and Russian pre's are my least favorite of all preamp tubes for the tones produced, with the aforementioned short plate Sovtek 12ax7wa anbd 12ax7wb at the very bottom of my list. Ugh. Have read some nice tone reports about the long plate sovteks, though, in PI positions. Not always, but the old stock tubes tend to go longer before needing replacement. I bet those 4 year old Chinese tubes are not worn out, they might very well sound more mellow on the top end than some shrill new ones.

 

I got nearly all of my tube collection from ebay. Don't be afraid to try a 12at7. Gain factor is 60, and they put out more current than a 12ax7.

[kidsmoke]

First off....Plexi, you rock, man. Thank you.

 

So I had a chance to mess around a bit. Plexi sent me some NOS 12at7's and 12au7's, not even sure of their provenance....KEN RAD? onthe 12AT's and some barely visible old english font on one of the 12au's.

 

I had just taken the amp to a repair guy, as I needed a little microswitch replaced on the back. It's a three step selector switch that started just flopping about. He replaced it with a beefier US made switch and cleaned it up. Called me to recommend a re-tube, saying they were "pretty noisy" and one was starting to get microphonic. I said nope, got that covered.

 

So I pulled the "made in China" tubes that have 4 years of my own use on them, and I bought the amp used. Tris recalls building mine because it came with a one-off ext cab, so figure these are probably 6 years old.

 

I wanted to do an apples/apples swap for starters. I put plexi's NOS 12au7 for the pre, and a 12ax7a, chinese tube that was oem on my Bugera V22. I pulled those tubes almost immediately after buying the amp, so they had very little use. They're Bugera branded "premium" tubes. yah...ok. At least they're new.

 

Immediate impact. The amp is SILENT! I can't remember this amp EVER being silent. So for that reason alone, I'm happy. But, it got better. This is a Plexi voiced amp, so the drive is harsh, not just crunchy, but brittle....if that makes sense. I'm grasping here. Point is there was distinction. some what fuller sound. Blunote may be the only guy with an adequate frame of reference here. This micro combo has a proprietary 6.5" speaker. I hesitate to call it a limitation, because it isn't trying to be a 212, it's trying to be a little high gain tone machine in an 8x8 box, and does that in spades. But it's limited in it's range potential by simple physics. A 6.5" cone just doesn't move enough air to get rounder tones. The tube swap cleaned it up and gave it precision.

 

I did try both of the 12at7's in place of the 12ax7, one gave a SLIGHT bit of hiss from the amp, but otherwise consistant, perhaps a tad less brittle. Tried the other, and it was microphonic. tapping my finger on the top of the cab gave me a nice little bell tone.

 

So the tubes needed replacement. I'm still gonna try to find a NOS 12ax7 for the Bugera that's in there, but this amp sounds much better.

 

Note...when I drive my 212 with scorpions in it, this thing opens up and is a metal machine. HUGE sound. Setting it at it's lowest gain setting possible gives it a nice early seventies crunch, but with the 3 gain stages plus gain knob dimed, you could easily, as GE Smith says, sit in with Korn noooo problem.

[212Mavguy]

Ahhhh... Kidsmoke! You did it right! Plexirocker, awesome job! YaaaaaY!!

[robdean]

An update to this old thread as I recently read it looking for advice and I guess others might:

 

Watford Valves in the UK confirmed that the ECC82 is the lowest gain preamp valve option. They recommended I try a Philips 5814A in that position and I do think it sounds really sweet.

They also suggested I try a 5751 low-gain variant of the ECC83 in the power position to help tame things. I bought a JJ manufactured one but felt it was fizzy and thin sounding. An ECC82 sounded sweet in the poweramp but of course cut the available gain tremendously. I tried a Philips ECC81 in the power position, just for the hell of it, and thought it sounded rather good so have left it there. What I haven't done is try a range of different 82s and 83s in the spec positions!

[Guest HRB853370]

We need a tube factory here in the USA.