New Production EL34/KT77 questions

I also love the Gold Lion KT-77 it's the best EL34 variant I've heard though I've not heard the JJ KT-77 so cannot compare. It's beat a half dozen EL34 types in my amp handily.

 

Yeah, that's the thing about EL34's. They have that great midrange thing, but to me, the bottom end is the shy point, and as a bassist, I can't have that, lol. Plus I tend to listen to a huge variety of music from Appalachian Bluegrass to Trap Hop, so I need a good all around tube.

As recently as two weeks ago, I re-tubed my entire system including the preamp and amp with Gold Lions. The amp has GL KT77s in the output and it originally came with EL34s. Also, I currently have a set of GL 12 AX7s to replace the new production Mullards that were the amps input tubes.

The Gold Lions are replacing the JJs I had, also in the amp and preamp. Now, I loved the JJs. They did everything right and I never felt a need to change or upgrade them, but after 4 years, they wore out and one of the output tubes was starting to red plate. They were also noisy, but I can't recall if they have always been noisy and I just attributed that slight hiss as the price of entry into tubes or what. I don't know that this constitutes a reliability issue, but 4 years seems a long time in modern tube years.

The differences I'm hearing with the GLs is that the system is dead quiet. Like I can't tell that it's on even when I crank the volume knob. Also the tone isn't quite as rich/burnished, but it's not significantly different. The GL's are more precise sounding, but my speakers are known for having excellent midrange, so I'd say the GLs have more upper mid presence. They are not bright at all and the treble response seems the same. The bottom end is fuller. So in all I'm very happy with them.

The Mullards I'm replacing sound fine, but they are old too, so I figured I'd replace everything as a set. But if money was a factor, at close to half the price I'd buy the JJs again in a heart beat. Are the GLs twice the price better than JJs? Probably not, but it's early yet. I'm unclear of the effect of burn-in time with tubes, so maybe the GLs will get even better, or maybe not. They sound good now regardless.

 

Dunno if anyone is following this thread, but I put the GL's in my amps input stage and they were not good at all. They were kinda strident so I put the Mullards back in after a couple days and the music just sounded more "real". So as I suspected, the input stage seems to have a huge impact on the overall character of an amp. I may send the GL's back, but I don't know if they have that kind of return policy. I may try one in my bass head, but I don't think it will be a good fit. Can't hurt to try. The GL's in the output stage sound fine, but they don't work well in the input for me.

Another thing is that the Mullards had been cryogeniclly treated, so there's another unknown factor to consider.

 

If your GL KT77s are only two weeks old, the bass should continue to improve over the next couple weeks. After they are fully broken in, they do have a warm, rich sound. I was surprised by how long it took for the KT77s to break in and specifically how much the bass changed. But it’s wirth the wait!

 

I did not find that the sound of these tubes changed all that significantly during my testing. I still greatly prefer the sound of the JJ KT77s over ever other EL34 equivalent that I have tried in my system, and I have tried quite a few different makes and models of EL34s (and equivalents).

 

Thinking of picking up GL KT 77's soon. Still enjoying my JJ KT77's very much. Great bargain tube.

 

@Spin Doctor ive read the same thing as what Salectric stayed above. That they take a while to reach potential.

Note this from Upscale Audio’s page:
A quick note on this tube: These tubes seem to take a bit longer to break in than some other power tubes, so if they sound a little lightweight in the bass, you have to give them time. Some guys are reporting at least 100 hours before the fully come into their own.

 

I've been running the GL KT77s in my CJ MV-45 for a few years now and to my ears they've been best sounding tubes I've run in it yet - that after three decades of running most of what is available, including some really nice NOS. The MV-45 works them pretty hard and I had Sovteks and such die after a few months. GL KT77s have had excellent life span and consistent wear across a matched set as well.

 

Generally speaking the input tubes of an amp often have a greater affect on sound than power tubes. Sorry the GL 12ax7's didn't suit I will say I've never heard any of their tubes but the KT-77's. It's possible they could break in but they may also be a good fit. None of my gear uses 12ax7's so I can't recommend any tubes I've tried.

 

The GL KT77's sounded awesome right out of the gate, so if they get better, I'm all for it. The GL 12AX7's didn't sound too good and I don't know that I want to wait for them to "wake up".

 

Did you get the Russian or the Chinese GL 12AX7s? These two tubes sound quite different.

 

Ahhh. Didn’t realize that. I was contemplating getting GL 12ax7 amongst others. Curious which ones you have?

I’ve seen two—ones that have the gold lion on them and others that just say Genalex.

 

Both sets of tubes are Russian

 

I would not let his experience dissuade you from trying that tube unless you are using the same amp. The Russian GL 12AX7 is one of the only new-stock 12AX7s which can begin to do justice inside of my Audio Research SP-8E. His description sounds nearly the opposite of how these have sounded inside of my preamp.

 

Sure I guess it can't hurt. How do they sound in your rig?

 

Mate what you want is either the JJ or EH big bottle 6CA7... still sounds like an EL34 in the midrange and gives you better extension at either end... 77s 88s 6550 etc sound good but not like EL34... the 6CA7 does

 

Beautiful lower midrange, slightly recessed upper midrange, authoritative bass and a slightly dark, yet still detailed, top-end.

 

I had JJ's in it for 4 years. They were fine but the were old and starting to fail. The GL KT77s are better. It's the GL 12AX tubes I had a problem with. They just don't work in my system. It's fine. I put the Millard's back in and it's all good.

 

I don't really thing tubes get better with use. They just start breaking down, like a light bulb -- over time they only go out of spec, pairs will become less well matched, transconductance will drop, maybe the tubes will begin to get noisy, etc. After new tubes have been played in at voltage to weed out early failures and after a few minutes after turn-on when they reach thermal and bias stability, they're going to sound as good as they're ever going to sound when they're new (presuming they're up to spec in the first place).

 

@Spin Doctor
Im sure they do sound great mate... just the OP seemed keen on retaining the EL34 lush midrange which i find the 77 to stray from a bit but i do admit ive only used JJ77s... i definitely think the 6CA7 does a better job at retaining the lushness of an EL34 while giving quite a bit more bass and a small extension and smoothness to the highs... IMO the KT77 does this aswell but darkens the mids a bit and is a bit looser in the low end... its a fabulous tube no doubt and i admit ive not spent a huge amount of time with them (in hifi, lots in guitar amps) but if you want the best compromise of EL34 tone plus a bit more the 6CA7 is a bit truer to the original sound.

 

The thing is, the EH 6CA7, like the KT77, is a beam tetrode, not a pentode. An EL34 is a pentode. Maybe New Sensor voices its tubes differently somehow so that the EH 6CA7 doesn't sound the same as the GL KT77 (they both come out of the same factory) as beam tetrodes, not pentodes, in some ways with respect to design, they're more similar to one another they are to a true EL34.

I haven't heard the EH big bottle 6CA7. I've heard with the big wings on the side of the plates that they can dissipate heat better than other similar tubes, so I'd like to try them out at some point, and they're cheap enough so that I will.

But I wonder, with all these various beam tetrode EL34 subs, how much the tonal differences are down to tube voicing, and how much the differences are down to circuit voicing.

 

One of the strengths of my speakers is its great midrange, so I've never really had to search for a tube that made a point of it. But, I didn't know about the 6CA7 being an option for EL34s. I may give them a shot just for giggles. Thanks for the heads up!

 

My old input tubes aren't noisy and sound great, so it may have been a fools errand replacing them when I replaced all the others in the amp and preamp. Do input tubes go bad? I imagine they don't have to work that hard, but I know nothing of amp circuit design.

 

I've changed from Valve Art (generic Chinese, I hear) EL34 to JJ KT77, and the JJ just reach into the bass much better whilst maintaining the EL34 mid range.

 

I used the EH 6CA7 big bottles in my amp and thought they were fine tubes but they were totally outclassed by the GL KT77. And in terms of the midrange I guess rather that lush I would describe it as more dimensional, the sound had more depth and much improved tonal color and saturation with the KT77. Perhaps this is coloration but it sound real, and good, to me.