[ProCast99]

Hi there:

I've been doing a bit of research on the power tubes used in these Nightshade amps, and before deciding on a couple of options, I have couple "compatibility" questions, and am interested in other people's experiences.

Here are my compatibility questions -

1) I am told that the KT-66 is basically the same as a 6L6 - can these tubes be dropped in?
2) I'm told that the EL37 is a true power pentode - can the NS-30/40 use it?
3) I've also read that the "cat's meow" is the 350B - I am pretty sure I'll never see one of the original W.E. versions, but wonder if anyone has heard the re-issue? I understand it has pretty well the same specs as a 6L6...

..and as for the 6L6's proper - have folks had especially good experiences with any tube in these amps? I'm hearing that the Svetlana "winged C"s are the best, but also interested in the Valve Art KT66, Tung-Sol re-issue...

I listen to jazz, chamber, folk-world, blues, classic rock - so capturing harmonics of acoustic instruments is much more important to me than slamming bass and super loud electronic signals...

Thanks!

[Niteshade]

About the only thing you have to watch out for is the filament current and you would have to specify whether EL34's or EL37's will be used due to slightly different socket wiring. 6L6's use .9 amps and 350B's are a little more. We have a high current power supply for tubes that require over .9 amps each. (D.C. filament upgrade heavy duty option) The EL37 draws 1.4 amps, not much different than a EL34.

Tube rolling is fun! So you know- All my amps use 5881's/6L6's unless otherwise stated. I chose this tube because it is pretty much the ideal tube for audio use. A good 6L6 is VERY clean sounding, noise free, efficient, fast and cost effective. Doesn't get much better than that! One more perk: The most wattage for the money of any tube made.

[ProCast99]

Thanks so much Blair -

I now know what to look for when I'm reading about exotic tube rolling opportunities!

On that basis, I'm guessing the KT66, often called a "drop in" substitute, or a European 6l6, is also not suitable - as its heater current is about 1.3 A... right?

Is there any wiggle room on that 0.9? If so, how much? Or is it a maximum value ?

I'm checking in with a dealer to see what the heater current for the VA 350B's are, as I have read on the 'net that they use a 6l6 filament, and so may be compatible... I'll let the community know my findings!

Cheers
Stuart

[Guy 13]

About the only thing you have to watch out for is the filament current and you would have to specify whether EL34's or EL37's will be used due to slightly different socket wiring. 6L6's use .9 amps and 350B's are a little more. We have a high current power supply for tubes that require over .9 amps each. (D.C. filament upgrade heavy duty option) The EL37 draws 1.4 amps, not much different than a EL34.

Tube rolling is fun! So you know- All my amps use 5881's/6L6's unless otherwise stated. I chose this tube because it is pretty much the ideal tube for audio use. A good 6L6 is VERY clean sounding, noise free, efficient, fast and cost effective. Doesn't get much better than that! One more perk: The most wattage for the money of any tube made.

Hi Blair and all Audio Circle members.
Would it be too much to ask you to post a list of all the compatible tubes (With no modification) for the 6L6 and in addition, it would be nice if you could post all the variant of the 6L6 and wich sound better and/or is more powerful.
Thanks.
Guy 13

[ProCast99]

Thanks for the "call-out" Guy!

I agree, it would be most helpful to have some impressions of how these 6L6 variants sound in the NS family.

Just to follow up on my earlier post, the dealer mentioned that he was assuming that the "Valve Art" 350Bs are indeed true 350Bs and run at 1.6 A- based on his own use of them (he was not aware of a Valve Art-specific data sheet).

I was originally interested in the KT66, 350B, EL37 types because the i-net commentary suggests they have really good internal detail and a "airy" sensation.
From what I have read, the closest any true 6L6 comes to that is the 7581, which is not made any more, and I'm not keen on spending $400 for a matched quad.

Now my question to the forum is: to what extent do these reviews apply to the NS PP amps - should I be considering upgrading my DC power supply for that extra bit of resolution - or is what I am reading pretty well hype, and with a good set of 6L6's, I can get similar results?

Any and all suggestions welcome!

Thanks!

[Niteshade]

I typically use 5881's and love the 6L6WXT+ tubes in all my 6L6 based gear. These are current production tubes, as is the 6L6GC by JJ/Tesla, which is a strong tube as well.

Present modern tube list:
Russian:
5881 (6P3S-E)
6l6WXT+
JJ/Tesla 6L6GC

Stay away from: Cheap Chinese and Russian 6L6's.
Vintage tubes: Ask first! I have a mod that will make them sing that is inexpensive.
High filament current tubes: High current DC filament upgrade adapter necessary. Examples:
EL34, 6550, KT88, 350B

What to try: My suggestion is 6L6WXT+ tubes. Input/splitter tubes: TungSol 6SN7
That is one of my all time favorite configurations! It's advised that you have the DC filament package for the TungSol 6SN7's since they have poor cathode/filament insulation. That does not reflect on the tube's performance otherwise.

The list of tube choices seems small. I stress that the 6L6WXT+ is a fabulous tube to try. Do NOT forget the + at the end when ordering. These are the workhorses of the modern 6L6 family. The standard 5881 that I use is a workhorse as well and my other favorite.

I design my amplifiers to work perfectly with easily obtained, cost effective modern tubes. Designs which rely on esoteric components to perform well are better off left alone. Have fun purchasing music, sources, speakers, etc... don't worry about putting expensive capacitors, tubes, etc.. in my electronics.

[gcos]

The Valve Art 350B is not a direct copy of the WE350B. It is in fact a 5881..a 25 watter, so it can be used in the NS40. This is the info given by the supplier

[djbnh]

My NS-40 came with 5881s.

[Guy 13]

Hi Blair and all Audio Circle members.

I've looked at Tube Depot web site and found the following:
Sovtek/EH 6L6WXT+ = 30 USD/pair
Sovtek/Tungsol 5881WXT/5881 = 40 USD/pair
GE 5881 = 90 USD/each WOW !
More than double the price, please don't tell me that the sound quality is more than double...
Guy 13

[gcos]

The Valve Art 350B is not a direct copy of the WE350B. It is in fact a 5881..a 25 watter, so it can be used in the NS40. This is the info given by the supplier

further info received from boiaudioworks.com  vendors of the VA350B is as follows : 'Unfortunately, there isn't really an official VA350B spec sheet that we are aware of.     From our actual measurements, VA350B draws a little more filament current (1.2A vs 0.9A for 6L6), and it'll at least handle max voltages and current as 5881 tubes.   We test them the same as 5881 or 6L6GC type tubes  (~450V on plate/screen).'   

[ProCast99]

Hey everyone --

Thanks for the great info - especially of the cautionary kind!

Blair, I wonder if what you advise about Tung Sol 6SN7s is for the NOS or the current production variety?  I have some NOS coming in the mail....

[Niteshade]

Either NOS or new production TungSol's. The new production tubes are fabulous.

BTW: Don't get carried away with these exotic, expensive tubes I see floating around. There is no need for that.

Point of interest: Sino 6SN7's tend to sound great! They are inexpensive, last a long time. I find them to sound allot like vintage RCA & GE 6SN7's.

[ProCast99]

Hi Blair:

Thanks for the helpful info (and tip on Sino 6SN7s) - and no worry, I'm way too cheap to get sucked into the vortex of esoteric audiophilia!

I did, though, get some NOS Russian 6-SP3-Es (or whatever their name is) - and they sound fantastic!

[6L6PPP]

Hi Blair:

Thanks for the helpful info (and tip on Sino 6SN7s) - and no worry, I'm way too cheap to get sucked into the vortex of esoteric audiophilia!

I did, though, get some NOS Russian 6-SP3-Es (or whatever their name is) - and they sound fantastic!

If you really want to experiment with tube rolling get some tube socket adapters. A socket adapter alters the pin out so you can use electrically exact or similar tubes.

http://www.ebay.com/itm/Two-adapters-7N7-6SN7-tubes-amplifier-SUB-/260903937441?pt=Vintage_Electronics_R2&hash=item3cbf1625a1

http://www.ebay.com/itm/6F8G-6SN7-Tube-Adapter-pair-/220901309236?pt=Vintage_Electronics_R2&hash=item336ebe7b34

http://www.ebay.com/itm/6CG7-6FQ7-Tube-6SN7-Tube-Adaptor-pair-/220889318085?pt=Vintage_Electronics_R2&hash=item336e0782c5

For example, for input/ gain tubes I use the 7AF7/7N7 plus adapter to replace the 6SN7 as these tubes are exact electrical equivalents. Same with the 6F8G (6SN7 with plate cap). I also like to use the 6CG7 with adapter again to replace the 6SN7. The 6CG7 is often referred to as a 6SN7 in a 9 pin bottle. You can pick these adapters up on ebay and once you have the adapter every tube you buy saves you money.

Why??? NOS sound quality for much less money. The Sylvania tall bottle 7N7 = Sylvania VT-231/6SN7 for $8-10. 6CG7's can be had for $11-15 and you can use another tube wit the 6CG7 adapter called the 6GU7 ( the 6GU7 is essentially a 6.3 volt 12BH7 and one of my favorite tubes) and they cost all of $5 each.

For power tubes I use the 6AR6WA plus adapter (5881 specs but 1.2 amp heater current draw so be careful), the 6BG6GA plus adapter tht are similar to the early 6L6's spec wise and the 807 plus adapter which is a higher dissipation tube more like the 6L6GC. I also like the 6P3S-E which drops right in without an adapter.

http://www.ebay.com/itm/two-Adapters-6AR6-6384-6L6-5881-tubes-SUB-/250803738959?pt=Vintage_Electronics_R2&hash=item3a6511594f

http://www.ebay.com/itm/TWO-Adapters-6BG6-6L6GC-KT66-tubes-SUB-/250800877845?pt=Vintage_Electronics_R2&hash=item3a64e5b115

http://www.ebay.com/itm/6L6-Tube-Adapter-Use-807-inplace-6L6-PAIR-/220893820413?pt=Vintage_Electronics_R2&hash=item336e4c35fd

[ProCast99]

Wow - very cool - thanks for all the effort you put into that reply. I've heard some VT 231's (not mine) in my system, and the idea of getting an equivalent sound for much less sounds very good. Now I know what I'll be doing for the next few nights....

Thanks again!

[djbnh]

For my NS-40, got rid of the (sierra hotel india tango) non-labelled stock 5881 power tubes, and rolled in matched quad of Sovtek 6L6WXT+ tubes from eBay seller yenaudiostore for $63.75 total including shipping to NH. Perfect sale, fast shipper, highly recommended vendor.

The Sovtek 6L6WXT+ quad has started to amass some hours, I slightly adjusted the bias, and these tubes have transformed my NS-40: 1) soundstage dramatically increased on all three axes and is much more realistic; 2) positively enhanced macro-dynamics; 3) palpably improved imaging / localized instruments and voices; 4) palpably improved micro-detail; 5) increased amp power. These tubes should be stock, esp. considering the very modest outlay of $63.75; the old no-name 5881s are to be relegated to the trash heap. YMMV, but I don't think by much.

[gcos]

Dave, we seem to be thinking alike... I replaced my JJs with the Sovteks last week and my experience has been identical to yours. The NS40 sounds so much more musical, the detail is captivating and there was a noticeable increase in attack in my music (jazz). From a marketing standpoint I can't understand why these are an upgrade option and not the stock tube installed in the NS40 given that they are the same price with the JJs in the Tube Store. I should mention that I also simultaneously replaced the stock no-name 6SN7s with nos RCA coin based 6SN7s so technically the change in sound could be attributed to both changes.

[rklein]

In my NS-60 SE and my Beacon III, I am still running the six "generic" 6SN7's that Blair sent with the units.  Blair never sent me driver tubes(reflected in the pricing of the amp), as I had a matched quad of Genelex Gold Lion KT-88 re-issues from a previous amp that I have been using which I happen to like quite a bit.  I have tried the SED Winged "C" 6L6GC which didn't really "float my boat".  I recently picked up a used quad of the Black Treasure KT-88's and must say that the jury is still out on whether they will live up to all the "hype and love" bestowed upon them in other AC threads...  The Gold Lions more than hold their own(at least in my NS-60).

I am in the midst of ordering either the Tung-Sol re-issue 6SN7's or the Electro Harmonix 6SN7's(gold pin).  I need three 6SN7's for my NS-60 SE and another three for my Beacon III.

Like Dave mentioned...YenAudiostore on Ebay looks to be a very good vendor for these tubes.

Regards,

Randy

[guest1632]

If you really want to experiment with tube rolling get some tube socket adapters. A socket adapter alters the pin out so you can use electrically exact or similar tubes.

http://www.ebay.com/itm/Two-adapters-7N7-6SN7-tubes-amplifier-SUB-/260903937441?pt=Vintage_Electronics_R2&hash=item3cbf1625a1

http://www.ebay.com/itm/6F8G-6SN7-Tube-Adapter-pair-/220901309236?pt=Vintage_Electronics_R2&hash=item336ebe7b34

http://www.ebay.com/itm/6CG7-6FQ7-Tube-6SN7-Tube-Adaptor-pair-/220889318085?pt=Vintage_Electronics_R2&hash=item336e0782c5

For example, for input/ gain tubes I use the 7AF7/7N7 plus adapter to replace the 6SN7 as these tubes are exact electrical equivalents. Same with the 6F8G (6SN7 with plate cap). I also like to use the 6CG7 with adapter again to replace the 6SN7. The 6CG7 is often referred to as a 6SN7 in a 9 pin bottle. You can pick these adapters up on ebay and once you have the adapter every tube you buy saves you money.

Why??? NOS sound quality for much less money. The Sylvania tall bottle 7N7 = Sylvania VT-231/6SN7 for $8-10. 6CG7's can be had for $11-15 and you can use another tube wit the 6CG7 adapter called the 6GU7 ( the 6GU7 is essentially a 6.3 volt 12BH7 and one of my favorite tubes) and they cost all of $5 each.

Hi, so how do the 6CG7 tubes sound versus the 6SN7 tubes. I think there is also another variant of the 6CG7, 6FQ7It doesn't have the Screen like the 6CG7 does. That is the only difference. Once you have the 6cg7 tube, a direct plug in is the 6n1P. I'm told properly biased, and it will bring out the potential of that tube. I think the guy who makes the Audio Mirror stuff told me about the bias issue. Something for you to play with Blair if you are so inclined. Anyway, interested in the differences in the 6SN7 versus the 6CG7 soundwise.

I read somewheres on the net, that the 6SN7 is the most copied tube out there. The 12AU7 was never ment to be used in audio. I don't remember the reason why. I think it's the problem with linearity. If memory serves me right, that is why the 12AX* and the 12AT* were preferred over the 12AU*. Anyhow, so much for info.

Ray Bronk

[Niteshade]

The 6P3S-E (5881) that I get is unlabeled since it's manufacturer direct.


If you want it to be a Sovtek....your wish has come true!

The tube is rugged and good for a starter set. Some people stick with it, others change them out.

The 6L6WXT+ is a FANTASTIC tube! Niteshade amps work well with them due to the way we load them up.

Here is a WXT+


They have a heavy plate structure and possess the drive abilities of an EL34 while maintaining the cleanliness and efficiency of a high grade 6L6.