TL;DR Has anyone heard the Tung-Sol 7581-A or compared it with the Tung-Sol 6L6GC STR?
To pass the time while waiting for my Mogwai SE I’ve enjoyed reading about various tubes. A shootout by TheTubeStore between several 6L6 tubes named the Tung-Sol 7581-A as their favorite new production tube of the lot. Unfortunately, the Tung-Sol 6L6GC STR, which I think this is the stock power tube shipped with the Mogwai SE, was not included in the shootout.
I have not.
One approach is to compare the different tube types such as 6L6GC, 6384, EL34, 6550, KT88, and then interaction with 5U4G vs 5AR4. 12AU7 was my choice input tube for headphones.
The positive feedback online site reviews of the Nautilus and Big Ben have a good discussion of A&S tube rolling.
I have a Bigger Ben, but I think it uses the same tube compliment.
I spent a lot of time and money trying different “NOS” tubes and buying adapters. I found a few I liked, but was never really satisfied.
I decided to take a step back and looked at what was available for tubes that were new.
I’m using a Grant Fidelity 6SN7 Treasure Globe and KR Audio KT88s. The rectifier is a NOS Cossor GZ37 “fat bottle”. The tubes were expensive, but they took this amp next level. I’m done with tube rolling, I’m going to buy backups for these, but they’re better than anything vintage I ran through it
I love my GZ37 in my Stratus with the added 5ar4/gz37 rectifier switch option.
How does the KR KT-88’s compare to your Tung Sol 6550’s?
@Earmuffs I’d say that the modern tubes together are tighter, slightly more resolving and enhance the A&S house sound vs. trying to “tune” it to something it’s not.
Adding the spring 3 and these tubes, I feel like I took this amp next level.
The GZ37 knocked my socks off when I added that to the amp. I was lucky someone had an extra to sell 
This is a great group. I’m sure Justin is a regular!
With that, my MO is beyond my hearing ability to appreciate. No slam on A&S whatsoever. I’ve spent hours rolling across 2 tube set, 6 headphones and 2 amps. It’s gotta be my age. Certainly not for lack of interest.
LMK if you are interested in buying a 6-month old MO (caps upgrade). Twin Cities Minnesota would be great.
I had to reread that one as I thought you meant the Mogwai had no Slam to it which I find as one of its amazing qualities. Have you tried some 6550’s or Kt-88’s with a 5ar4 rectifier?
I like that combo a lot.
Anyone tried Mogwai with LCD-5?
If so what are your thoughts on synergy?
I’ve tried the LCD-5 on the Kenzie another Nautilis and both were amazingly good combinations. Such a wonderful sounding headphone. I’d imagine insanely good results with the Mogwai se. Likely 32 or 8ohm.
Couldn’t agree more - the LCD-5 is an amazing match to my Kenzie Ovation. Just gorgeous.
I just purchased one today. Getting it around Jan 12th, I plan on using my LCD5’s, HE6se v2, fostex th900 with the Mogwai
Special order Mogwai owner here. Jupiter caps 32/300 with a gorgous walnut wood that Justin had from ZMF. Absolutely love it.
Just ordered an LCD-5. I have a Mogwai og upgraded to jupiter caps, I’ll report back! I’ll also tube roll a bit.
What are everyone’s thoughts on rolling the rectifier? How does it affect sound compared to the other tubes? Been rolling them from stock 5u4gb to 5ar4 and I think I can hear a bigger difference in sound than rolling the input/output tubes. Is this normal?
Normal and very pleasing to me.
Have you got a preferred rectifier tube and why?
With dynamic driver headphones I really love the sound of the TungSol 6SL7GT because it is very clean and drives without efforts high impedance headphones.
With planars and expecially with the DCA Noire I prefer the 6SN7: in particular I’ve found an old RCA one with black base that is really great to my ears. It is very clean, reduced the noise a lot and gives a good amount of current.
I hope this answers your question.
What if your using a low impedance dynamic HP like a Focal
Would you choose 6sl7 orver 6sn7?
I was specifically asking about the rectifier tube not the input tube but it is nice to get peoples thoughts on how all tubes change the sound and why they choose one over the other.
The Mogwai SE gives me a thicker and slamier bass over solid state amps and I really enjoy this a lot. Definetely made the right choice getting Mogwai.
I find changing the tubes only slightly changes the general sound of the amp or in the case of inputs tubes changes the gain.
Rolling the stock 5u4gb rectifier to a 5AR4 seem to make it less thicker/slamier . (that I didnt personally like)
Rolling the stock 6l6gc output tubes to KT88 sounds slammy and great but can also introduce blowtiness to some tracks.
Is this what you and others have experienced?
First of all I ask you pardon for my mistake. I drove all night the ambulance and I’ve replied you when I was almost sleeping. My fault.
I won’t use the 6SN7 with dynamic driver headphones: I love it with low impedance and low sensitivity planars. Focals are low impedance but have a high sensitivity and work better with the 6SL7 to my ears.
About rectifier tubes I really don’t like the sound of KT88: they give you power but at the price of losing control in difficult/busy passages.
As far as my experience goes I prefer EL34 or 6L6 STR.
The EL34 with headphones like the Focals are particularly good IMO: you have a very controlled sound with a pleasing coloration that never becomes distorted.
If for Sennheisers I prefer using 6L6 with lower impedance headphones I suggest you to give a try to the EL34.
In particular if you find a couple to a reasonable price I suggest you to try the EL34 B STR. They sound fantastic to my ears.
