Ahhh yes! Only two hours in on these headroom little monster's. I love the ZMA!

....50 hrs needed....of course/for full bloom....but what a steal & cryogenic too.

Running with:
https://www.upscaleaudio.com/collections/vacuum-tubes/products/mullard-e188cc-73...
input tubes
https://www.upscaleaudio.com/collections/vacuum-tubes/products/telefunken-e88cc-...
inverter tubes

RCA NOS 0A3's.

Hi Norm.

Yup, The 7581A's are pinned the same as 6L6's.

I have them biased like the 6P's = 48~50 mA.

I will bring them up to 56 mA (after some hours on them)....they can do it/I will see/hear.

To heck with waiting to bring up the bias....these 7581A's wanted 55~56 mA in their initial rise on the bias/balance meter's. I just put them their at 83db SPL to 91db SPL peaks and they are loving it. (Yes, everyone should have an SPL meter).

Caveat Emptor though....:
the headroom up there....you need speaker's overall & tweeter's to handle it (to appreciate them=no rolled off full range and/or with tweeter's x-over, way to high) + cabling MATTER's.
...input & inverter's too  :-*


..........fun Sunday morning...then heading out....to nice to be inside!


Norm, from Cryoset. Ron is the best.

You know it.

Thanks.  I did not go back far enough and the recommendations on this post change a lot....heh...

Note from Ron:  Sorry but I have only 1 pair of these available at this time.

Guess I am out of luck for now.  A guy on eBay has them so I may pursue that route.

Ron said he should have more in a month. In the meantime, I ordered a matched quad on eBay.

Stone:

Have you been able to compare similar tubes that have been cryogenically treated vs. untreated?  I have not, so I cannot comment on the effects, but I am leery about the cryo process impact on tube life and integrity. The pins are metal and the tube envelope is glass and they each have different coefficients of expansion and contraction. Just using tubes inherently tests this metal-to-glass interface as they heat up and cool. My thinking is that the cryo process has an even more dramatic impact on that interface due to the differences in expansion and contraction. My preference has been to avoid cryo tubes for that reason. Just my opinion.

Norm

I will most likely do Steve’s 25th anniversary (or ZMA2) upgrade. What else are you thinking?

I had some time to enjoy more of the 7581A's yesterday. I am enjoying these tubes immensely. I don't think I'm changing my ZMA. I'm not, I bet.

I will look in, now and again.....to see what other stuff Steve might have cookin.

Yes, I got them at 55-56 Norm. Great bass, in these too!

KT77's? It can happen. Did you try them?

I read ya Jeff. I own $1500 of input NOS plat' grade from uncle Kevy.... And all are in tip top shape for three years now. Knock on wood.

Putting in A QUIET PLACE movie right now on my big Polks.....with  a Surly cold one...

Happy Friday!

I read ya Jeff (those are the 34's I want). I only have 20 hours or so on my 7581A's...nice tubes. However, I glanced over at my Gold Lion KT88's cryo....put them in this morning...it has been awhile for these!

.....the big landscape picture man....like melted butter on lobster...with your best girl, that can't get enough of you!

Love my 6P's for what they do in detail, midrange/imaging and shimmer up top (and the 7581A's have potential).  The KT88's, though...a whole other ball game of MAJESTY.................  

...it is 9 am now....Sue know's...I have to enjoy this till 1 pm...then, we have the whole rest of this beautiful Sunday to get out there!

https://www.amazon.com/Dot-Com-Blues-Jimmy-Smith/dp/B000050J47
Jimmy Smith on that sweet tone of his....only done by a Decware Class A Amp!

...sticking with new production power tubes:
7027A quad in August
PSvane EL34PH quad in October.

NOS input tubes...still a few more pairs to get...  ;)

Jeff, It is a blissful dilemma...having distinct differences in output tubes. + NOS Platinum, input tubes...my Mullard's are diff' from my Ediswans, 6n23p ....my two Pair of Tungsrams distinctly different too. I have not decided yet, which of the Tung's' I like best in my Audio Research LS-2B MK II.

.....the bad Ass Telefunken's as my inverter's, continue to amaze in their purity of getting out of the way!

Norm, did you keep the GL KT77's? I'm curious to someday try a quad of those too.

......grabing my 2nd mug of MAJOR DICKASON's BLEND....heading up to fire up ....my ZMA/KS6063/Acoustic Zen Adagio heaven....7:36 am CST....till Noon.... Then down to BAD WEATHER BREWING outside, for a Pint or two of HOPCROMANCER.........

This mornings tube compliment:

Gold Lion Cryoset KT88 Quad

https://www.upscaleaudio.com/collections/vacuum-tubes/products/mullard-e188cc-73....
input tubes
https://www.upscaleaudio.com/collections/vacuum-tubes/products/telefunken-e88cc-....
inverter tubes

RCA NOS 0A3's.

No Pre in-line.....today.

Tonight...9 to 1 am ....same above ~ except ~ :
T-Sol 7581A Quad will be in ...Cryoset.

INPUT VOLUME of ZDSD from Transport/Illuminati D-60:
0.0, -0.5 or -1.0 dB, only...wonderful TOOL
With Steve's output stage = indespensable.

Stone:

I did not try the KT77's as they were not mine but an error by the seller.  I am still wait for delivery of my 7581A Tung-Sol's.  But the TAD KT66's will be hard to beat.

Stone:  The KT88’s sound intruiging. I am curious as to why such a high bias. Steve recommends no more than 60ma in the ZMA manual. Could you run them at 50ma? 60ma?

Anyone else with experience running KT88’s?  Want bias are you running?

https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1524266800

Check this out Norm....the Thread dives right in on the subject J of A then Steve responding in reply #11.

I have no worries running GL KT88's! (6 or 7 hours max at a time).
Yeah, the bias of 74 to 76 mA is no worry either.  

I would not and will not be, without this KT88 QUAD! It is a whole other side of the ZMA. Then, back to 6P's & 7581A's + EL34's......doing their ZMA magic.

Yes! I did not want to over sell them. I am enjoying them very much too.

6P's, KT88's and now these 7581A's.

Hope my luck continue's with the 7027A's. Might be close to the 7581A's (or not)...but need to find out..... .

The balsey 7027 Steve described it as.....somewhere in this thread or an other, is compatible. He wired this 8 pin tube to work. It is also listed ....tubes the ZMA can run ....in the ZMA site listing.

Now Steve was speaking of an NOS quad. However, I have high hopes for the TSOL 7027A's. TAD makes them too....but I'm going for the TSOL's.

JofA's running a NOS quad too.

Will do on the 7027A's Norm. I'm not getting those in here for another 2 or 3 weeks....but they will get in here!

Enjoying the clarity of tone and treble extension of the 7581A's right now....love these tubes! .....they might be my new favorites too..... .

What's the scoop on your KT88's? Which did you get? I might prefer the smaller envelope 7581A's & 6P's over the 88's. But, like I said previously, I would not be without what the KT88 Gold Lions bring to the ZMA, when I want it!

I am loving these tubes Archie! Yes, they are different than the 6P's. Does not make them better than the 6P/5881**. Let's just say I'm not taking these 7581A's out for awhile...as described. Awesome fair cost too.

**6P's, are a 5881 clone....very good...as we know...and will still make my rotation.

Strange....Ron's site, does not list as a quad....he usually does?

When I purchased mine...
the site and my receipt reads:
1 x Tung Sol 7581A Matched + Cryo Treated Quad  - 4
89.99 + 8.99 shipping.

This quad is like....(if we could see sound) I was a decent drawer with lead on a canvas. Then all the sudden I jumped to an exceptional canvas drawer....shading every detail in beauty and light unetched!
Ohhh, and the mid-bass & bass.......wow deep tone beauty....took 30+ hrs...but worth the wait!

I bought both the Gold Lion KT88’s and the Tung Sol 7581’s from the guy guy on eBay who sells matched quads with 24-hour burn-in. I really love both, but I came back to the 7581’s and I going to stick there for a while. I cannot put my finger on it, but I think then 7581’s have more clarity in the midrange with a strong bass and incredible clarity in the highs. The KT88’s are also amazing, but I think the 7851’s are my favorite. Plus, a part of me like to bias within the ZMA recommended range which the 7851’s do and the KT88’s don’t. I just realized that I am considering buying a backup quad of the 7581’s but not the KT88’s. Interesting.

Archie, cool, go for them. You have a couple opinions in Norm and I. I hope you like them.

I got the 6P's a few days after Christmas.
Then, my KT88's in May.
7581A Quad, three weeks ago.

Next month:
7027A Quad.
September:
EL34 Quad.

My sites on a couple pair of 6922 variants in Oct/November.
Then, bed down for the loooong winter's nap with the glow and warmth of my ZMA.  :)





.............I shut down the SS rig....and came up to the ZMA. This quad of TSol 7581A's....are something special. I will have all I can do to shut the ZMA down at Noon....and head outside on this beautiful summer day!

I have them biased/balanced @ 50mA...dead nuts....so in the pocket!

Norm, I think you're right! I need to shelve another quad of these too. Yeah, I'm to nice some saaaaay.......blabbing about these...cause it crosses on the www ....but, Karma is real man.....share!

No little black boxes or preamp needed here Archie. I have owned the black box(s) yes, I have owned two of the boxes, Monolith 947's and a CSP3/Jup'd..............due to my cabling and quality of driver's and tweeter's & x-over modification..............not necessary for full dense music from my Listening Room.


Full credit too...to the ZMA and Steve's output stage from my ZDSD.... .


These T-Sol 7581A's are blowing my mind tonight!   Cheer's!







Listening Room:

Room Treatments from Michael Green & my Home Brew

Sony as Transport (DVP-NS57P)
Illuminati D-60 Digital Coax IC ~.5 meter

Shunyata Research Zitron Alpha Digital Power Cord to ZDSD {Significant}

Decware ZDSD DAC / Recorder
***************************************************************
W/Steve's Output Transformer's/kicking to the Curb quite a few superb DAC'S
***************************************************************
(@ -20 Ref Level ~ @ 16/192)
.....0.0, -0.5 or -1.0dB/Input Volume

WBT-0102Ag RCA Kimber Select KS1030 ~.75 meter

Decware Zen Mystery Amplifier
~BIASED at *56* mA~
NOS/Platinum/Mullard E188CC/7308's in my A12 an B12 Input positions Cryogenic~NOS/Platinum/Telefunken E88CC for Inverter Tubes~NOS RCA 0A3's & matched Quad/Tung-Sol Cryo'd 7581A's, Reflector Cryo'd 6P's or Gold Lion KT88's Cryo'd

***************************************************
Kimber Select KS6063 Speaker Cable 8ft WBT-0681-Ag Spades
***************************************************

Acoustic Zen Adagio - Black Pearl (Modified)
.....enjoying from 8 ohm ZMA Taps

Caintuck Audio Eminence Alpha 15" OB BASS Unit
Auralex Subdude



Acoustic Zen Adagio's x-over's Modified/Full Range with Mundorf MCap Supremes-single Cap to each Tweeter/4.5k cross
(Gutted: 3kHz/18dB/Octave, Linkwitz/Riley Crossovers....with all crappy parts = gone)


XLO Pro Power Cord to ZMA
PS Audio P3 Power Plant / Pangea AC-9SE from wall to P3
(Transport & ZDSD, Regenerated/*120*~ Multiwave off...ZMA on High Current Output)
System configured/on floor/Townshend CD Seismic Sink deployed & other isolation devices.


~NOS Platinum Tubes from Upscale Audio/Kevin:

(Great Britain) Mullard 7308/E188CC ~  2 pair (both pair Cryogenic)
(Germany) Telefunken 6922/E88CC ~ 1 pair (painfully expensive/worth it)
(US/Great Britain) Ediswan CV2492/6922 ~ 2 pair (one pair Cryogenic)
(Hungary) Tungsram 6922/E88CC ~ 1 pair
(Hungary) Tungsram PCC88/7DJ8 ~ 1 pair.


(Russia) 6N23P's ~ 2 pair/came with ZMA.    

Good points Archie. The 6P's are special....and I need to compare the two, too...before I shelve the additional quad of 7581A's.

For now I am settling on the following:
Sonica DAC (Ric Schultz upgrade) via XLR or ZP3/ZSTAGE into my
ZTPre with Russian 6N5P's into my
ZMA via XLR with Telefunken E88CC's in the Inputs and Inverter and the 7581's.  The entire spectrum of sound in incredible with transparent highs and strong fast bass.

I may go back to the Ediswan's on the ZMA inputs and try the 6P3S's, but I am so pleased with the current sound,I am going to stick to what I have and focus on cables. I am finding that some very inexpensive XLR cables are blowing away some very expensive ones. I have settled on the STYX speaker cables as being the fastest highs, most transparent mids and strongest bass, but I have a vendor who is trying to convince me his are better.

So for now I just want to listen...