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SUPPORT FORUMS FOR CURRENT DECWARE GEAR >> MINI TORII   >> Tube Rolling Results for Current MT
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Message started by P K on 12/15/13 at 22:07:41

Title: Tube Rolling Results for Current MT
Post by P K on 12/15/13 at 22:07:41

MY FAVORITES BELOW,

Any Comments?

Amperex NOS 7062 Made in USA (RCA NOS 12au7 from Decware, that came with amp and Siemens 12au7 from Upscale Audio, both a close second).

EZ 80 (NOS Tungsram), per other posts, to go with the Amperex NOS 7062 (a NOS EZ 81 Mullard a tie or a close second (stock JJ EZ 81 do not last very long)

New Tung-Sol 6V6GT from Decware, came with amp OR for a warmer, full bodied sound, along with a more relaxed upper-end sound (but with less detail), a New- Tube Amp Doctor 6V6GT-STR from Cyroset.

The TAD 6V6GT-STR is preferred for long listening sessions as it is less fatiguing.

Title: Re: Tube Rolling Results for Current MT
Post by grinnell on 12/16/13 at 20:22:49

I have had some great results from some 40's RCA 6v6g st.  got some bass punch and nice extended range.  I agree about the Amperex 7062 good tubes.

I tried some Art Valve 350's, very nice sound sweet airy but light on the bass.

got some OC3's b/c i liked the blue glow  not much tone change from the stock OA3's

Title: Re: Tube Rolling Results for Current MT
Post by P K on 12/17/13 at 03:34:21

The Valve Art 350B may be the next tube I try.

I notice that Tung Sol has a 6L6-G or the 6L6-GC-STR reissue.

I wonder how they compare to the 350B?

Also I have seen a lot of new production 6L6 tubes from various russian and chinese tube companies, do any stand out?

Title: Re: Tube Rolling Results for Current MT
Post by Fireblade on 12/17/13 at 17:12:21

I've been very happy with my preferred driver tube these days, Philips SQ 7062. These have the ideal combination of openness, warmth and intermediate gain which do not  drive fast and sensitive output tubes (like the current production Tung-Sols), into sibilance on very high frequency passages. As opposed to 12AT7's, these drivers need an open, big sounding output tube to sound their best though.

So far my first choice combo for the M-T is the Phillips SQ 7062 paired with the excellent RCA 6V6 G ST (1940's production, big, coke shape).

The next preferred pairing is Brimar 12AT7 along with said G ST's.

On third place, the Brimars with the Russian Reflektor Plant black glass 6V6's. The usually dark but sweet sounding Russians need to be opened by a powerful, commanding driver, and the Brimars are just the ticket.

The Tung-Sol 6V6's are good tubes but can be ridden to far on high frequency passages by 12AT7's in the M-T. My Phillips SQ 7062's do not show special synergy with these (like with my G ST's), although the combination sounds fine nevertheless.

In all the above suggested combos, I use the RFT EZ80 rectifier rather than the stock JJ EZ81 (not only due to reliability issues).

Some time ago, I decided to skip any output tube outside the 6V6 family due to potentially excessive stress on the circuit and because IMO the original voicing enhances the 6V6. YMMV.

My next test will be a pair of 6414's paired with my tour de force RCA's G ST's. I've heard good things about these drivers and according to the literature, these are very similar to the 7062's.

In general, I prefer to go for drivers offering an intermediate gain between 12 AU7's and 12AT7's, as the former are somewhat dull-sounding in the M-T, whereas the latter tend to be edgy in the high frequency ranges.

The 6V6 G ST's sound big, with wider soundstage, PRAT and transparency, and as has been mentioned here, its bass is better than the rest of my other combos with the ubiquitous OA3's in place. My OD3's, on the other hand, flatten that sound, killing some of the presentation depth.

Yet, the biggest sound improvement from my system came from the installation of 7 DIY absorption pannels, critically placed in the room. There's no question reflections kill the soundstage and naturalness of the sound, and increases listening fatigue. Today, at close to near field, my system behaves neatly and timbres and imaging are again in focus, while bass lines are deeper and well defined (as opposed to boomy).

My system uses an active subwoofer with a crossover at 65Hz and thanks to the absorption pannels now the bass really enhances the nice low-mids, mids and highs of the DM945's when placed on monitor stands and away from walls.

Interested in anyone's experiences with 6414's and the corresponding best output tube pairing.

Title: Re: Tube Rolling Results for Current MT
Post by P K on 12/21/13 at 16:05:37

I can currently recommend three low cost, but big upgrades.

New Valve Art 350b to replace the 6V6GT

A NOS 12AU7  to replace the stock JJ 12AU7 (I was lucky that my Mini Torii stock tube was a NOS RCA 12AU7 (I did obtained a stock JJ 12AU7 for a comparison). Cost from $20.00 per pair to $100.00+ per pair).

Try to replace the stock JJ EZ81 for a NOS EFT, Mullard or Amperex (you may just wait for the JJ EZ81 to fail, it will not take very long).  NOS EFT EZ81 on ebay for $25.00 per pair

Title: Re: Tube Rolling Results for Current MT
Post by Rivieraranch on 12/21/13 at 22:09:26

Jim McShane sells the RFT EZ81.

Title: Re: Tube Rolling Results for Current MT
Post by P K on 12/22/13 at 02:46:11

An Alternative to upgrading the 12AU7 and the EZ81 is to switch to:

7062 (for the 12AU7)  and an

EZ80 (for the EZ81).

I have been using a pair of Amperex NOS 7062  and a pair of NOS Tungsram EZ80's (until I cracked one of the EZ80's).

I switch back to the NOS RCA 12AU7 and the NOS Mullard EZ81 (the quality from this combination is close to the 7062/EZ80).

Title: Re: Tube Rolling Results for Current MT
Post by Fireblade on 12/22/13 at 14:09:34

From Brent Jessee's summary on the 350 B tube:

"For most applications calling for a 7581, KT66, or 6L6GC these tubes will work fine and sound great. They do have different filament current draw specs and other slight differences, so you should always check with the amp manufacturer, dealer, or a tech before subbing these tubes in place of the stock tubes."

The 350's (A & B) seem to be considered the best sounding in this tube family. I just wonder if we can use the KT66's safely in the Mini Torii and if the amp's voicing is consistent with their characteristics ... I assume the latter holds as per the recommendations.

Individual good tubes may or may not be special, depending on the accompanying complement set. SQ 7062's are not that special if paired with Tung-Sol, JJ or Reflektor Plant 6V6's, in my experience. YMMV.

Title: Re: Tube Rolling Results for Current MT
Post by P K on 12/22/13 at 18:01:27

When using the Valve Art 350b,

Which combo is best?

12AU7/EZ81

or

7062/EZ80

Let me know your opinions

Title: Re: Tube Rolling Results for Current MT
Post by seikosha on 12/23/13 at 12:02:58

Hi PK,

Can you describe the sound differences you get with the substitutions that you recommended?

Thanks,

Pete

Title: Re: Tube Rolling Results for Current MT
Post by P K on 12/23/13 at 15:00:33

The Valve Art 350b provides:

A deep soundstage, airy sound, this is the first time i was able to hear this type of detail.

A wide soundstage with music coming from the far left and far right beyond the placement of the speakers,

and most important the high or upper end of the sound range is much more mellow, yet offers a high level of detail.

Others report  "a very nice sound sweet airy but light on the bass".

"Light on the Bass" has not been an issue for me.

Title: Re: Tube Rolling Results for Current MT
Post by grinnell on 12/23/13 at 15:52:55

Hi Others here :)

I found the difference btw the RCA 6v6g st and the VA350's to mainly one of bass.  Your description of the 350's is right on, we differ only the lower end.  The 6v6g's just seem to have more punch in relationship to the 350's

It may be that i'm new to low watt and more used to bigger pumpier tubes like kt88's and el34's

Title: Re: Tube Rolling Results for Current MT
Post by P K on 12/23/13 at 16:37:10

I forgot to mentioned that the RCA NOS 12AU7 sounds better than the new production JJ's.

The overall sound is just better.  It can be argued that a NOS 12AU7 tube will typically sound better then new production (due to better materials and more skilled workers (glass blowing is an art?).

The sound is more open and smoother, or a sweeter sound, with the NOS RCA 12AU7 (since it was supplied to me as a stock M-T  tube by Decware, maybe Steve D. would like to comment).

The JJ 12AU7 is a more sterile, dryer, one dimensional sound in my system.

Title: Re: Tube Rolling Results for Current MT
Post by P K on 12/23/13 at 16:40:09

Grinnell,

Can you tell me where to find the 1940's RCA 6V6G ST coke bottle tubes and how much should the cost be.

Thanks,

PK

Title: Re: Tube Rolling Results for Current MT
Post by Fireblade on 12/24/13 at 01:41:45

In case you are interested, I bought the RCA G ST's from Brent Jesse ($50.00 matched pair). When later I asked him for an additional pair as back-up, he said he was out of them. He said he will make a buying trip early January and he'll probably get them, so I'm holding my order of those plus the 6414's which seem to be another good driver alternative.

I absolutely agree with Grinnel's description of the G ST's and so far the 7062's seem to make the best out of them. Although there could be 12AU7's with some special synergy, I have not been lucky with reasonably priced 12AU7's in the Mini Torii.

Good 12AT7's paired with darker (warm) sounding 6V6's are another good combination IMHO.

Title: Re: Tube Rolling Results for Current MT
Post by grinnell on 12/24/13 at 02:41:05

I got lucky on ebay and got them for about 30.00  
$50.00 is more like it although if labeled cunningham they could be cheaper  RCA made

Jessie brent is probably the best source for the best price i have bought a number of tubes from them

Title: Re: Tube Rolling Results for Current MT
Post by grinnell on 12/24/13 at 02:42:23

ps nice thing about the mini is you dont have to pay for matched tubes  buy them one at a time and save  lol

Title: Re: Tube Rolling Results for Current MT
Post by Fireblade on 12/24/13 at 12:16:46

It is true that we can profit from the self-biasing feature, but I prefer to be on the safe side, as there's less chance of getting a weaker tube that way and the price difference (in relation to, in my case, customs, logistics and all) is not that significant.

Any experiences with 6414's on the driver seat?

Title: Re: Tube Rolling Results for Current MT
Post by grinnell on 12/24/13 at 19:07:07

But we dont need match tubes b/c of the dual mono feature

i scored a quad of Rayethon Blackplate 6414 for 35.00

they sound pretty good but i had some Amprex/philips 7062's that sounded very good also so not a huge difference btw them

Title: Re: Tube Rolling Results for Current MT
Post by Fireblade on 12/24/13 at 20:12:20

Well, I still think when they go about the matching process they have to discard the weaker ones which you will get in a singles purchase (weaker=more probable of early failures). Plus, replacing a tube is a logistics hazzle for me, so it is cheaper to be more on the safe side in the long run. These may still fail but at least there's that first screening on my side.

I'm hoping the 6414's are similar to the 7062's, that's why I would like to try them. I liked the Phillips SQ 7062's so much when paired with the G ST's.

The price is very good BTW. Store?

Happy holidays to all!



Title: Re: Tube Rolling Results for Current MT
Post by P K on 12/24/13 at 23:29:33

Will Fireblade and Grinnell tell me some details about their 6V6G ST

Are they clear coated or grey coated glass.

Do the clearly say RCA on the tube?

Are the plates black or grey, smooth or ribbed.

Round Halo?

Thanks,

Peter

Title: Re: Tube Rolling Results for Current MT
Post by Fireblade on 12/25/13 at 00:08:05

Mine are Radiotron labelled and gray glass, with a round halo getter. RCA made.

Title: Re: Tube Rolling Results for Current MT
Post by P K on 12/25/13 at 14:57:31

Does anyone know if

Match pairs for either EZ81 or EZ80 tubes matter?

Can you mix brands or does a specific brand have a distinct sound?

Do RFT EZ80 or EZ81 tubes sound better or are they just affordable?

Thanks,

Peter

Title: Re: Tube Rolling Results for Current MT
Post by Rivieraranch on 12/25/13 at 17:26:45

You shouldn't mix brands. The RFT sounds better than the JJ's.

Title: Re: Tube Rolling Results for Current MT
Post by Fireblade on 12/25/13 at 18:24:01

In my limited experience, RFT rectifiers are quite reliable and sound good. Either spec preference is based on complement synergies and personal assessment.

In general, same spec tube brands have their distinct sound, stemming from slightly different structural and/or manufacturing details, so unless there's a temporary emergency situation (no spares) one should stick to same specs/brands.


Title: Re: Tube Rolling Results for Current MT
Post by P K on 12/25/13 at 22:21:34

Anyone try a 6F6 output tube in the Mini Torii?

Title: Re: Tube Rolling Results for Current MT
Post by P K on 12/26/13 at 13:59:22

I am enjoying the Valve Art 350b tubes (to replace the stock Tung Sol 6V6 GT).

Others have stated that:

I have had some great results from some 40's RCA 6v6g st.  got some bass punch and nice extended range.  

I tried some Art Valve 350's, very nice sound sweet airy but light on the bass.

My Emerald Physics speakers are bi-amped and I am using the Mini Torii for the Mid/Tweeter at above 1000 hz.

I am now considering searching for 40's RCA 6v6g st., but wonder if it is worth the effort as the 350b  may sound similar (or better?) above 1000 hz.

Any comments,

Thanks,

P K

Title: Re: Tube Rolling Results for Current MT
Post by grinnell on 12/26/13 at 20:48:48

PK,

One is labeled Radiotron the other Cunningham  both identical, grey glass, not sure about the getter (not expert enough to tell)

Title: Re: Tube Rolling Results for Current MT
Post by P K on 01/10/14 at 19:27:44

FINAL RESULTS AFTER TRYING OUT A BRENT JESSE RCA 6V6G ST, COKE BOTTLE:

Valve Art 350B-coke  bottle,blows away the RCA 6V6G ST in my system (mini Torii driving a mid/tweeter at 1000 hz and above)

Amperex NOS  EZ80 from Brent Jesse (white lettering with a cartoon of a tube playing a flute)

RCA NOS Long Black Plates, Old Style White lettering, 12au7 from Brent Jesse.

This is a great combo, 3d deep sound stage, not too hot or bright, airy sound, great definition of instruments, sound stage that is wider than my speakers, balance natural sound.

Any further comments?

P K


Title: Re: Tube Rolling Results for Current MT
Post by marky on 01/10/14 at 22:46:02

"(white lettering with a cartoon of a tube playing a flute)"
Ah, ze famous `Bugle Boy`brand.

Title: Re: Tube Rolling Results for Current MT
Post by P K on 01/11/14 at 00:57:20

Please note I also evaluated the RCA 6V6g ST with a Amperex 7062 tube along with at the EZ80, the VA 350B was still much better

Title: Re: Tube Rolling Results for Current MT
Post by grinnell on 01/11/14 at 18:29:23

Well maybe i will drop in my VA 350's and give it another try

probably need some burn in

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