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08/22/14 at 08:56:45


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7062 Tube  (replaces a 12au7 in Mini Torii (Read 702 times)
P K
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7062 Tube  (replaces a 12au7 in Mini Torii
03/03/14 at 22:12:47
 
FS:
 AMPEREX NEW STOCK, LOW HOURS 7062, PAIR, $30.00 OBO

USE A 7062 TO REPLACE THE 12AU7 IN A MINI TORII. SEE DISCUSSION IN THE MNI TORII FORUM AT THE DECWARE WEBSITE ("TUBE ROLLING")

TESTED IN MY MINI TORII.
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grinnell
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Re:  7062 Tube  (replaces a 12au7 in Mini Torii
Reply #1 - 03/04/14 at 01:43:21
 
i just put in a pair of IEC Mullard 7025's

more gain is noticable  but it might be a tad too much

i may try some other 12ax tubes i have some Genelex, Groove Tube, Tungsram etc to see what i get
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MT w/ 1940's RCA 6v6g st
Ref 3A de Capos
VPI HW-19 mk iv
Mac Tuna MR-67
MH 25.2 CDP
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Fireblade
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Re:  7062 Tube  (replaces a 12au7 in Mini Torii
Reply #2 - 03/04/14 at 13:55:02
 
In my limited experience, the 12AY7-12AV7 family works best in my setup, a nice balance between the warmth of the 12AU7 and the more open but 'edgy' 12AT7.

Personally, I would not expect the 12AX7 family to bring that middle-of-the-ground combination that pleases me, due to the excessive gain involved (100 Mu). The tougher/darker 6V6 I have is the Russian Black Plate, and its the only one not overcome by the higher gain of the 12AT7's (only 60 Mu, which is as high as I would go to pair with this Russian tough 'oyster').

I guess you may have experienced some edginess and some ringing in the high-pitch passages with the 7025, along with a less warm/smooth sound overall? Too analytical and forward sounding maybe?

I would contend that in order to identify the specific group to later on fine-tune through quality design differences, one needs first to find the right spec configuration in the driver. Chances would  be much higher for success.

Right now I'm curious about the 6072 (44 Mu) and 5965 (47-48 Mu), which go between the 6414 and the 7062.

Keep us posted on your 12AX7 findings,

Thanks

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« Last Edit: 03/04/14 at 14:08:49 by Fireblade »  

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grinnell
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Re:  7062 Tube  (replaces a 12au7 in Mini Torii
Reply #3 - 03/04/14 at 14:47:24
 
I have only been listening to the tuner but yes there is a bit of edginess there

more experiments to follow
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MT w/ 1940's RCA 6v6g st
Ref 3A de Capos
VPI HW-19 mk iv
Mac Tuna MR-67
MH 25.2 CDP
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jorgen
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Re:  7062 Tube  (replaces a 12au7 in Mini Torii
Reply #4 - 03/05/14 at 20:34:06
 
I re-read the design notes Steve has published for the MT; Power of this amp is somewhere between 3 and 6 watts depending on the tubes used and the speakers you connect it to.  (Quote)
Which tubes gives this amp more or less power?
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« Last Edit: 03/06/14 at 08:35:04 by jorgen »  
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Fireblade
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Knowledge comes, but
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A.L.Tennyson

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Re:  7062 Tube  (replaces a 12au7 in Mini Torii
Reply #5 - 03/05/14 at 22:26:44
 
IMO, by far the only real difference comes with speaker impedance, whether it is 4, 8 or 16 Ohms. Tube amps, as opposed to SS, increase voltage (rather than current) when facing higher impedances, so in the long run it runs smoother and safer at 4 Ohms (lower voltage surges), with less power (3.3 Watts).

If I'm not mistaken, the trick is matching the impedance function (real, not nominal) of the speaker to its sensitivity to achieve a healthy enough SPL in each amp combination scenario.

I'm sure some people in this forum know way more than I do about this subject though.

I'm of the opinion tubes may help but just marginally, and essentially involves a good beam tetrode (Mini-Torii case) paired with higher gain than typical drivers for the particular amp (but one must consider the sound quality effects as more apparent loudness combinations are not necessarily the best sounding.)

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« Last Edit: 03/05/14 at 22:51:06 by Fireblade »  

Laptop-Foobar2K-ASIO Direct//WD 2.0Tb HDD//Audio Gd USB cable//Audio Gd NFB 3 (2014) DAC//Decware Silver Ref IC's//Decware Mini Torii SE//Kimber Kable spkr cbls//Decware DM945's//Velodyne DLS 3500//BJC SUB Cbls//Tripp Lite 500 Isolation Trnsf.//Jellyfish Pwr Cord
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grinnell
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Posts: 64
Re:  7062 Tube  (replaces a 12au7 in Mini Torii
Reply #6 - 03/05/14 at 23:27:40
 
I have a had several dealers tell me with my tube amps to try both the 4 ohm and 8ohm taps and see which sounds better and use that.
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MT w/ 1940's RCA 6v6g st
Ref 3A de Capos
VPI HW-19 mk iv
Mac Tuna MR-67
MH 25.2 CDP
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