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Mini Torii SE Amplifier (Read 59741 times)
Les Lammers
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Re: Mini Torii SE Amplifier
Reply #270 - 04/15/12 at 00:17:12
 
Radushka,

Have you had the gain issue from the time you first received the amp?
Or did it start when you got the AN DAC? I don't inderstand how attenuators could have caused it.
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Raduschka
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Re: Mini Torii SE Amplifier
Reply #271 - 04/15/12 at 00:51:33
 
I had it from the start. I suppose it got worse when I got the dac, but not by a large measure. No wonder, my cd has a tube output stage an is rated at 2V. The dac is arted at 2.5V, but I measure 2.1V. SO btw 2V and 2.1V there sin't a world of difference.

I suppose that even with the atts the volume rises too quickly, but it isn't an issue for me anymore, because I have plenty of useful steps. I would love to know how one can lower the gain of the MT, it must be very easy. I am just curious.

Remember my biggest issue was with how little room I had on those pots and how they wouldn't stay put. Just to remind you, out of 9 steps I could use the first 2, maximum 3. 3 was very loud for an appartment, 2 was acceptable, 1 was my regular listening level. Which is quite low, since I like my music at low volume and the MT delivered detail and clarity at ..step one. It is hard for me to tell if you would have the same issue with it.
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Fireblade
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Re: Mini Torii SE Amplifier
Reply #272 - 04/15/12 at 13:54:41
 
I have the same concern.  I assume you have 12aU7 drivers and even though your DAC's maximum output voltage may be somewhat higher than the 2.1 V you have measured (as it may have peaks depending on the source signal), it probably is still well under the 2.5 V.  For example, my DAC is rated at a 'maximum' of 2.25 V output.

My speakers are also 94 dB (@ 4 Ohms), which means we will share basically the same configuration and probably the same loudness sensitivity issues.  Other than not having so much volume restrictions in my listening room, I'm probably headed for the same problem ...

What puzzles me, is I have not heard other owners complain about the issue.  I remember Rivieraranch stating he did not feel his volume adjustment being over-sensitive, although he could not pass the middle mark on the dial before clipping set up (I hope I'm remembering this right).  Half-dial leeway is not that bad.

Or it could well be your, maybe, extreme low-volume listening style?  Again, I would like to know if the issue is relative or absolute (loudness vs perception of loudness).

Also, there may be some less 'beamy' 6_6 family beam tetrodes to try at the output stage?  I find myself with more questions and doubts now that when this thread started  :o
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Raduschka
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Re: Mini Torii SE Amplifier
Reply #273 - 04/15/12 at 14:17:43
 
doubts and fears are not that bad, sometimes it's a sign of advancing, which means resolution might be underway Smiley
I have the 12au7 indeed. I DO have a low-volume listening style. I wish I could somehow objectively translate the volume behaviour to you, but I am afraid I can't.
My listening room is about 4x8metres, or perhaps 5x10.
I can show you over Skype, but now I have attenuators instead of the old pots. I am now going to my parents' place, it is Easter time in Eastern Europe and surroundings.
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Raduschka
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Re: Mini Torii SE Amplifier
Reply #274 - 04/15/12 at 14:20:56
 
I think Erik has 6y6 in his right now, but coupled with 12at7, which seem to have higher gain?? I tried the 6l6 variety and found it very fuzzy and unfocused, basically nothing to do with the 6v6 in my experience.
I have all gas voltage regulator types and I always end up liking the 0d3 better for punchiness and tightness in the bass. Dynamics seem more lifelike with that one.
skype pseudo is :  raduschkamuschka
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Les Lammers
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Re: Mini Torii SE Amplifier
Reply #275 - 04/15/12 at 14:22:43
 
FB and Radushka,

I agree that there must be an easy way to reduce the gain. I ordered my amp with a stereo pot because I did not want dual volume controls.

Radushka,

Did you order your amp with the dual stepped attenuators?
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Raduschka
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Re: Mini Torii SE Amplifier
Reply #276 - 04/15/12 at 14:26:37
 
I had ordered my MT with the stock volume pots (they are called stepped volume controls) and they are not stepped attenuators. They are now in the back of my MT controlling input signal on one of the two switch positions (the other being direct through).
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Raduschka
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Re: Mini Torii SE Amplifier
Reply #277 - 04/15/12 at 14:28:26
 
my AudioNirvana speakers are fullrange and I just read that they are at least 95db inside cabinets. So who knows, mine could be 98db as far as we know.
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erik2a3
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Re: Mini Torii SE Amplifier
Reply #278 - 04/15/12 at 15:54:07
 
I can't think of any other way to say this, because there in fact IS not just a simple way, but an add-them-to-your-system-with-your-eyes-closed-simple way of curing the problem.  You are doing less "harm" to the precious signal thatnyou would with an impedance buffer like the zbox (of which there are many kinds) or active linestage.

Please see here: http://www.parts-express.com/pe/showdetl.cfm?Partnumber=266-244

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erik
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Fireblade
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Re: Mini Torii SE Amplifier
Reply #279 - 04/15/12 at 16:05:38
 
I think it may be a combination of room dimensions, apartment status, loudness preferences and hyper-sensitive speakers.  Besides, the Mini Torii is supposed to be a 'beamer amp' relative to, say, a SET, with more punch to it.

Ruling out defective volume pots (as you are using them normally again), hopefully that's the case, and the rest of us mortals won't necessarily share the same issues.   Smiley
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« Last Edit: 04/15/12 at 16:07:17 by Fireblade »  

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Fireblade
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Re: Mini Torii SE Amplifier
Reply #280 - 04/15/12 at 16:13:09
 
Good idea, Erik.  Now, what's the correspondence between volts and dBs in this case?  Let's say I want to reduce my DAC outpout signal as it goes to the amp, by 1 Volt.  How many Dbs of attenuation is that?

The only minor problem I see with this idea is the additional pair of cables required.
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« Last Edit: 04/15/12 at 16:13:44 by Fireblade »  

Laptop-Foobar2000-Wasapi Ev//WD 1.5Tb HDD//Audioquest Forest USB cbls//HRT MS II+ USB-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 P. Cord
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Les Lammers
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Re: Mini Torii SE Amplifier
Reply #281 - 04/15/12 at 19:05:15
 
FB,

The attenuators appear to connect to the IC's so you won't be adding a set of cables...just 'extending' them. Looks good to me.
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erik2a3
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Re: Mini Torii SE Amplifier
Reply #282 - 04/15/12 at 19:24:30
 
Fireblade - i know, it always seems there's a compromise some place, doesn't it? As Florida Boy mentioned, there is not (necessarily) a need for another pair of IC.  I've used these several times over the years, and my dad is not using the 12dB attenuatora I sent him to use with a Dynaco ST70 amp I rebuilt and gave him.  His speakers are also very efficient, probably in the range of Raduscha's.  He had hair trigger volume pots, too, and these attenuators solved the issue, leaving the controls still just a bit sensitive but much less so.  What is good is that, at least to me, did nothing in terms of degradation of HF response or anything else.  They just knocked the level down.  I used them straight into the back of my amps, but the Mini Torii's inputs are of course on the top.  This might be a visual or aesthetic concern that Raduscha won't want.  The attenuators aren't that long though.  There is a more high end company that also sells these, but I can't recall their name off hand.  Regarding the math of this: Iused to have it on the tip of my tongue when I was using them before, but I just can't remember.  What's just easier is to just get a a couple of values and try them.  On the IC, thing, though, if one were to build a buffer or line stage for this, another pair of ICs would be mandatory, not to mention the extra circuitry, power supply (hum can be a problem with high efficiency, crossoverless drivers), another power cord, etc.  these attenuatorsmare the first thing I mentioned.  They actually really work quite well, at least in my experience, and like you guys I'm picky about this sort of stuff too.
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erik
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Les Lammers
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Re: Mini Torii SE Amplifier
Reply #283 - 04/15/12 at 19:31:43
 
Erik, thanks for the link.

FB,

The reviews said they did not degrade the sound and they are a lot less $$$ than a buffer etc. I am done with the gain obssession/anxiety. Grin
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« Last Edit: 04/15/12 at 19:32:09 by Les Lammers »  
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erik2a3
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Re: Mini Torii SE Amplifier
Reply #284 - 04/15/12 at 20:13:01
 
Sure!
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erik
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