VTA ST-120 POWER TUBE OPTIONS.

what are the plus and minus of using kt-120's in an st 120 that calls for the kt 88 ? It seems I recall Bob saying he uses the 120's in his. Thx scott

I use the KT120's in my ST120 - quite a few of us do. Them big bottles also had a LOT to do with the custom case design, as I wanted more room for those bad boys to breathe ...

And of course you need a BIG rectifier to stand up amongst the big trees!



I also have a set of Psvane KT88's that are quite nice, but don't have the strong bottom of the KT120's. That's not necessarily a bad thing. I recently switched over to a set of 5963 drivers, which are also strong in the bass. They have a really sweet midrange, but combining those with the KT120's was too much bass, so I'm currently switched back to the KT88's. That killed the boom nicely and I still get the tasty midrange and vocals.

One note on the KT120's - you can run them at 55mA just like the KT88, but they really sing at 60mA. Driving them a bit harder, but they're still just coasting along compared to what they're actually made to do. The ST120 is plenty strong to drive them at those levels.

sKiZo wrote:I use the KT120's in my ST120 - quite a few of us do. Them big bottles also had a LOT to do with the custom case design, as I wanted more room for those bad boys to breathe ...

And of course you need a BIG rectifier to stand up amongst the big trees!



I also have a set of Psvane KT88's that are quite nice, but don't have the strong bottom of the KT120's. That's not necessarily a bad thing. I recently switched over to a set of 5963 drivers, which are also strong in the bass. They have a really sweet midrange, but combining those with the KT120's was too much bass, so I'm currently switched back to the KT88's. That killed the boom nicely and I still get the tasty midrange and vocals.

One note on the KT120's - you can run them at 55mA just like the KT88, but they really sing at 60mA. Driving them a bit harder, but they're still just coasting along compared to what they're actually made to do. The ST120 is plenty strong to drive them at those levels.

whats that rectifier you're running?

That's an actual for real NOS Mullard GZ37 ... getting kinda hard to come by. Plugs right into the ST120 with no mods required. Main difference is it can flow a lot more current than a GZ34 or 5AR4 - the ST120 can be kind of challenging to those as they're operating towards the top of their capabilities.

Been running mine for several months now with nary a hiccup, and I tend to CRANK it ...

The GZ33 is another big bottle option. Flows less power, but works well in the Latino amps.

Set you back around a hundred bucks each for either type, but should last forever.

Another big bottle is the Philips 5R4GYS - but I didn't have any luck with that. Worked fine for maybe a month, then went south. No satisfaction from the seller. We win some, we lose some. Couple other folk here running them with good results.

I'm liking the broken in Tung Sol KT-120s very much in the ST-120.  Their heightened low-end really compliments my system especially with low volume early morning listening.  Vocals good and smooth highs as well.  Sounds good cranked up well.  The KT-120s are very affordable and available everywhere.  Plus I don't worry if tube bias drifts up to 60mA just reset to 55mA every week or so.  Also expecting long life with the KT-120s.  One negative is the KT-120s draw slightly more heater current so your amp will run marginally warmer but the ST-120 handles it effortlessly.

Psvane KT-88s are good as well but over double the price of KT-120s.  Gold Lion KT-88s work very well also.

.I have a quad of Psvane KT-88's but one is not good anyone have just one for sale? thank you Scott.P.S.when I get some KT-120's do I need to change the rectifier tube also? sorry for my ignorance .I am an audiophile that knows what sound's good to me I just don't know why! can I get a hardy rectifier that will go well with the kt120's and not cost a hundred dollars? thank you in advance Scott .

$22 for a WZ68 copper cap is hard to beat. Fairly bulletproof too ...

In fact, I think I'll swap mine in and give it a listen ... got an argument going on another channel about how much rectifier you really need. I tend to go with what works, but I had the copper cap in before I scored the GZ37, and that's been in there long enough that my ears should pick out any real difference immediately one way or the other.

I got as WZ68 coming for m ST120, also have a WZ34 in my ST70 and I have not been able to hear any difference in the sound

Not gonna get into the old "but how could a rectifier possibly influence the sound" argument ... no sir ... not gonna go there.

What I can say is ... the rectifier swap certainly influenced the sound here ...   

Just got done with an extended session of some pieces that I've recently played with the GZ37. The WZ68 certainly had a bit more punch, but along with that came a certain graininess that I had less than fond memories of. As I mentioned, certainly doesn't sound bad - in fact i sounds quite good. But the GZ37 sounds better. On paper, the WZ68 should (and does) provide more current, but there's more to the equation. Not to get too technical, but the bottle rectifier just has much more ... muchness. If anything the WZ68 had TOO much punch when I fired it up, as I have the room tuned using my dbx BoomBox to compensate for any "lack" with the bottle. So, realistically, leaving all the engineering aside, solid state loses once again.

No big rush - I'll leave the copper cap in for a while, but I expect to see the GZ37 shining in all it's glory again fairly soon.

Fun thread over on AK about how the ST120 can't possibly deliver it's rating using ANY bottle rectifier. Using some of the numbers being bandied about, same holds true with the WZ68, which I guess would leave some sort of home brew solid state rectification as your only option.



Lord save us from engineers ...

http://www.audiokarma.org/forums/showthread.php?t=589646

It's a good read with a bottle of beer. You should also read AK on Bybee filters: John Curl vs the engineers. Next try Shannon (AT&T) information theory which states that land lines can support only 1200 bps error free. Finish up with the wonder of mylar caps (Horowitz and Hill) -- it's why so many amps and pre's (Apt Holman, Heath) in the '70s and '80s are full of them.

I've looked at the numbers more than once and the bottle rectifiers don't make much sense with four KT88s.  But I have probably never operated my ST120 at sustained maximum output anyway.  But I like the WZ68s as they are simply more efficient than the bottled rectifiers.  You are saving about 20W by not heating the rectifier cathode so the amp runs cooler.  The tube rectifiers have soft recovery which is good for noise but I have no noise issues with the WZ68.  So I really can't imagine my ST120 sounding any better with a bottle rectifier.  But I have been proven wrong on many occasions so wouldn't be the first time.

Hey ... take it to the other forum!!   

No complaints when I hear that you can't hear the difference. What gets my goat is people who tell me I'm delusional. I'd give good money to find one of them going on about uber macho power cables and interconnects, or funny little doodads that look like reese's peanut butter cups and are the next best thing since the whoopie cushion.

My switch back to the bottle came a lot sooner than expected. I put on some of my favorite Porcupine Tree, and it was just missing something with the copper cap.

Probably all in my head ... it can get kinda crowded in there sometimes. Having paid better than four times as much for the big bottle has something to do with it I suppose.

So, has anyone ever actually tracked B+ under load to see if and when the different bottles start to choke? Maybe a good extra credit project.

sKiZo wrote:Hey ... take it to the other forum!!   

No complaints when I hear that you can't hear the difference. What gets my goat is people who tell me I'm delusional. I'd give good money to find one of them going on about uber macho power cables and interconnects, or funny little doodads that look like reese's peanut butter cups and are the next best thing since the whoopie cushion.

My switch back to the bottle came a lot sooner than expected. I put on some of my favorite Porcupine Tree, and it was just missing something with the copper cap.

Probably all in my head ... it can get kinda crowded in there sometimes. Having paid better than four times as much for the big bottle has something to do with it I suppose.

So, has anyone ever actually tracked B+ under load to see if and when the different bottles start to choke? Maybe a good extra credit project.

mmmmhhhh Reeses!!

Stock up!

http://www.madscientist-audio.com/

I'm waiting in gleeful anticipation to find out it's all a hoax perpetrated by some bored geek with a  twisted sense of humor. Probably selling the address list to lawyers in Liberia and time share realtors ...

black discus???.....sounds a bit fishy to me. Sounds like those magnet thingies in the 70's that were supposed to save on gas usage, you just put them around the incoming fuel line.........

sKiZo wrote:No complaints when I hear that you can't hear the difference. What gets my goat is people who tell me I'm delusional. I'd give good money to find one of them going on about uber macho power cables and interconnects, or funny little doodads that look like reese's peanut butter cups and are the next best thing since the whoopie cushion.

Hearing is very subjective. Not enough research has been in psycho-acoustics to form any guidelines. As you say the critics of this point often wax rhapsodic about cables, magic blocks, and power cords. I've seen this lack of consistency often in print.

Bob wrote:It will probably make its spec also using the larger Mullard GZ37 and GZ33 rectifiers. It may not make its spec with a GZ34 but will probably come close.

I did think that particular post was a slur on the ST-120's documentation. BTW: Recall that the original ST-70 didn't produce 35 watts @ rated distortion

Bob Latino wrote:I did see that post this morning on "that other forum" and I would comment there BUT they kicked me off that forum on a post that I made some time ago clarifying some wrong info about one of the VTA amps. Evidently they though I was trying to "promote" the VTA amps.

We're filling in for ya ...

sKio wrote:I'm waiting in gleeful anticipation to find out it's all a hoax perpetrated by some bored geek with a  twisted sense of humor. Probably selling the address list to lawyers in Liberia and time share realtors ...

Of course it's a hoax; it's a send up of Bybee Quantum Purifiers. I like the Reese's foam cups in particular.

BTW: I believe I can tell the difference between tube and SS rectification in my ST-70. Roy thinks it makes a signifcant difference, e.g., in the GG pre. (Had one of those and agreed on its deficiencies, but not the causes.)

sKiZo wrote:Probably all in my head ...

 Go with what sounds best to you and never mind any one else.  I'm just too cheap to try a tube rectifier again after blowing up my first!!!!

I know how much you like add-ons.

sKiZo wrote:I'm waiting in gleeful anticipation to find out it's all a hoax perpetrated by some bored geek with a  twisted sense of humor. Probably selling the address list to lawyers in Liberia and time share realtors ...

Chock full of snake oil du jour: Good music + snake oil

Priceless. Gotta noisy PC? Critical PC Damping

My Firefox has been hacked. Many links now cycle to Yahoo search. Tryin to fix it.

I'm starting to wonder about Audio Advisor too ... Power cables, regularly $200, for $60 ... kinda reminds me of the old DAK catalog days. Say what you will about those, but they WERE entertaining.

I am tempted to pick up on some of these though ...

http://www.audioadvisor.com/Pangea-Audio-Pico-Small-Sorbothane-Foot/productinfo/PGPICO/#.U1_njlVdXLo