[PFKMan23]

Quote:

Originally Posted by purk /img/forum/go_quote.gif What I meant to say was can I use the 6SN7 & 6BL7 in high voltage mode? Can the 6BL7 be used in a driver position? Purk

Yes you can use the 6BL7s as drivers, however, I wouldn't run the 6sn7gts at the higher voltages as they can only handle 300V at the plate.

 

[purk]

What's the real different b/w the 6414 and 5687? I only have one 6414 but have several of the 5687.

 

[Frihed89]

What are the better brands of 6414 and where can you buy them?

 

[tkam]

The 6414 has a little more than twice the gain of the 5687 and nowhere near the output power of the 5687.

 

[Hirsch]

Quote:

Originally Posted by tkam /img/forum/go_quote.gif The 6414 has a little more than twice the gain of the 5687 and nowhere near the output power of the 5687.

Incidentally, this is why I like the 5687 as a driver in front of the 6BL7. It produces some serious voltage swings, that can make use of the increase power output of the 6BL7.

The 6414 is not compatible with all SinglePower amps, so you need to be sure that it will work with your particular voltage/bias combination.

Purk, do not try too much by way of serious tuberolling with new BlackGates in your amp. BlackGates can go through some serious changes before the sound finally settles in. They've got a long burn-in period that some report as up to 400-500 hours. Impressions formed during that period might change drastically once the caps are settled in.

 

[sacd lover]

Quote:

Originally Posted by purk /img/forum/go_quote.gif What's the real different b/w the 6414 and 5687? I only have one 6414 but have several of the 5687.

Lots of questions here ....

The 6414 is much higher gain while still providing good current drive. The 5687 is a low gain tube with high current drive. I find the 5687 as a gain tube is more mellow compared to the 6414 and doesnt have the soundstage size of the 6414. The 5687 is a good sounding tube even used for gain so experimentation is fine. But also, be aware, the 5687 can be microphonic in the gain position.

The high voltage setting was developed for the 6bl7gt. The 6bl7gt/a and 6bx7gt can take up to 500 volts on the plate and require more bias current regardless. Looking at your question I think you might be asking about a 6sn7 driving two 6bl7gt's @ high voltage. You dont need to worry about the gain position as the high voltage setting is ONLY for the OUTPUT tubes. You can use any of the tubes you would normally use for gain.

You can use the 6bl7gt as the gain tube. But I find this tube is best as an output tube and is only a mediocre gain tube. This is probably because he leaves the gain position voltage/ bias settings optimized for the typical gain tubes (6sn7/6cg7/6414 etc... we normally use. These operating parameters of the circuit do not provide enough voltage and/ or current bias to make the 6bl7 tube operate in the tubes sweet spot and sound their best.

 

[purk]

Hirsch,
What would you recommend as a good 5687 tube for the 6BL7 for an R10?


Earl,
Thanks again man....I will try those 12AV7 tubes soon.

 

[augustwest]

"Yes you can use the 6BL7s as drivers, however, I wouldn't run the 6sn7gts at the higher voltages as they can only handle 300V at the plate."

It is my understanding that the 6sn7gt and the other earlier versions of the 6sn7 should not be run at voltages exceed 300-325 volts. However, that one of the advantages of the "gtb" series, in addition to a quicker warm up time, is that the 6sn7gtb's can be run up to 425 volts.

Please correct me if I am wrong?

- augustwest

 

[PFKMan23]

Quote:

Originally Posted by augustwest /img/forum/go_quote.gif "Yes you can use the 6BL7s as drivers, however, I wouldn't run the 6sn7gts at the higher voltages as they can only handle 300V at the plate." It is my understanding that the 6sn7gt and the other earlier versions of the 6sn7 should not be run at voltages exceed 300-325 volts. However, that one of the advantages of the "gtb" series, in addition to a quicker warm up time, is that the 6sn7gtb's can be run up to 425 volts. Please correct me if I am wrong? - augustwest

The issue of 425V vs. 300V applies to both the gta and gtb , as they both handle up to 425V as opposed to only 300V for the GTs. And yes, the gtb's were made to handle a quick warm up time (originally made to be used as TV tubes). That being said the only tubes that I would readily run at the higher voltage would be the gta or gtb tubes.

 

[Hirsch]

Quote:

Originally Posted by purk /img/forum/go_quote.gif Hirsch, What would you recommend as a good 5687 tube for the 6BL7 for an R10?

I like the Tung Sol D-getters.

Earl is right, the 6414 does spread the sound stage better than the 5687. However, I would need to rebias my amp to use it, while the 5687 just drops into its adapter and into the amp.

I've posted this before, but voltage is not the limiting factor on what you can run through the tubes. Plate dissipation is the real limiter, and it's a function of both voltage and amperage. As long as you compensate for increased voltage by decreasing current, you can push some tubes at much higher voltages than their rating, with no risk. Something like the Berning MicroZOTL can put as much as 800 v on the plates of a 6SN7, and won't hurt it.

 

[PFKMan23]

Quote:

Originally Posted by Hirsch /img/forum/go_quote.gif I've posted this before, but voltage is not the limiting factor on what you can run through the tubes. Plate dissipation is the real limiter, and it's a function of both voltage and amperage. As long as you compensate for increased voltage by decreasing current, you can push some tubes at much higher voltages than their rating, with no risk. Something like the Berning MicroZOTL can put as much as 800 v on the plates of a 6SN7, and won't hurt it.

While that's true, in the case of high voltage, in the cases of the SP amps you're also going most likely going to be running a fairly high bias as well. And in the case of plate dissappation you'd have to have almost no current running through them to be pushing them that hard (voltage wise). And even so, just looking at the cost of the sought after 6sn7s these days I don't know why you'd risk it unless you either have a stockpile or do have that much disposable income to throw around.

 

[purk]

I've been pleased with the result of the GE6414 as the driver position and the GE 6BL7s as output tubes. The 6414 really impress me with its amazing soundstage. I will give the 5687 D getter more time, but so far the 6414 is a better match for my R10s.

 

[Inter]

I've read almost all of this thread now and it's just way over my head.

I purchased an mpx3 slam quite some months ago now but have yet to tuberoll at all, so I am currently just using the 6SN7EH that came with it and the two 5687's in the output positions.

You guys clearly know everything there is to know about tubes and I've tried to understand post after post but it's so daunting. I have no idea where to start.

Could somebody recommend me somewhere to actually start? Like for instance, recommend me a few combos of tubes which doesn't cost much but should be fun to try?

I'm sorry for being such a newbie.

I'd be really grateful if someone could give me a few (simple) pointers to get started.

 

[guzziguy]

My advice, which I originally got from Earl and now whole heartedly agree with, is to order a loctal adaptor (7n7) from SP and get a Sylvania tall bottle 7n7 to replace the EH6sn7 tube currently in the gain position. The improvement is very large.

Next, tell us about the 5687's in the outputs. SP sent mine with two Tung Sol D-gettors. I haven't felt the need yet to try something else. Depending on what you have it may or may not be worthwhile to roll something else in.

My main advice is, don't worry too much about it and enjoy the music with your amp.

 

[Etrius]

Quick question about the 6414's. Can you run these in the gain position on a regular MPX3 SLAM or do you need to have the 12 volt option?