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Tube selection (Read 19336 times)
ob2
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Tube selection
03/17/10 at 15:13:04
 
If we swap tubes to improve sound, which pair of tubes you will change first? Any suggested tubes?

I want to improve the high-low frequency extension and resolution. It roll-off too early for the set of tubes come with the shipment.

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Steve Deckert
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Re: Tube selection
Reply #1 - 03/17/10 at 16:36:48
 
Couple comments;  Rolling tubes in the mini torii doesn't make it sound better, just different.  The difference you may like better.

The high low frequency extension is excellent no matter what tubes you choose.  Make sure the treble control is turned off for max high freq extension.

Steve
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ob2
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Re: Tube selection
Reply #2 - 03/17/10 at 17:28:09
 
Thanks, may be I better re-phase my question. I'm still going through run-in process of mini-torii and ERR. The micro-details, dynamic and micro-dynamics are not as good as I expected yet. I'm not sure whether it is due to the amp and ERR not run-in yet. Or I better use better quality tubes to achieve the sound quality I want.

Also, I turn my DAC to highest volume (or turn it to fixed output) and the mini-torii volume control to 12 O'clock position to get just the sound level for the music I play. In fact, I want to make it louder in some cases. But worry about turning it more than 12 O'clock will start distortion. In fact, I feel the bass is not well controlled beyond 12 O'clock position.

Sorry, it becomes a much longer question now. Should I go for 12AX7 to have higher gain?  Should I roll tubes to get the micro-details or be more patient with run-in?

It is my first time using tube amp. I used to have SS amp. Need advice to go through learning curve and get good sound out of this set-up.
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Lon
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Re: Tube selection
Reply #3 - 03/17/10 at 17:34:10
 
Try backing the volume on your DAC down to 2/3 or so and the volume on the amp up a bit and play around.  Also try speaker positioning. The Radial speakers that I have can have very different frequency responses in different positions in the listening room.
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ob2
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Re: Tube selection
Reply #4 - 03/17/10 at 18:01:16
 
For the DAC volume, I switched to fixed volume now and let mini-torii to control the volume. For ERR, difficult to change positioning in my home environment. However, I'm adding 4 little fat glider to support ERR and make it easier to move around. Still, I can only move it sideway but difficult to move it back and forth in my environment.
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Lon
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Re: Tube selection
Reply #5 - 03/17/10 at 20:16:39
 
I fear that with the DAC fixed out you're compressing the sound a bit and you may not like the results of that compression.  If you can back the input volume down and play with the amp volume, you may find a sort of sound that you're missing.

Radial design speakers really benefit from being moved way into a room.  Yes that does make them a bit harder to live around, but the benefits are huge imo.

So the Herbie Audio feet WILL help but I do encourage you to keep trying speaker positions.
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ob2
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Re: Tube selection
Reply #6 - 03/18/10 at 14:24:31
 
Thanks, with the Herbie Audio Feet, will be much easier to move around and will try different position to get good sound out of it. Thanks!
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hifitubes
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Re: Tube selection
Reply #7 - 07/06/10 at 15:54:23
 
Lon,

Could you elaborate some more on your comment about compression using max volume of the DAC.

I have two DACs that output about 2vrms at max volume but I don't use a preamp anymore. Although, I do have a tubed pre inbound in a few weeks.

Aren't the DACs just mimicking a standard disc transport which has fixed gain of about 2vmrs?

If I add a preamp, should I drop the DAC down to say 1vrms and let the pre "take it from there" ( I don't think it has a fixed output, only variable).

thanks!

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Lon
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Re: Tube selection
Reply #8 - 07/06/10 at 23:50:35
 
ob2 didn't specify what outupt voltage his DAC was putting out.  My experience with components with higher inputs than 2V is that they can sometimes "be too much" for the input of an amp or preamp. I hear this as "compression" though I'm not certain that that is correct. I've heard in this situation sounds that seemed to be compressed dynamically and perhaps obscuring a bit of detail.

It's been my experience that if you have any component with controllable output going into a preamp or integrated amplifier its worth playing around with the variable output of the source component. I find that there's one "zone" between the two variable outputs that sounds best--to me. Play around and see what happens. That may not be the same for others. Stereo reproduction is one of the most subjective things I seem to experience.
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hifitubes
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Re: Tube selection
Reply #9 - 07/07/10 at 14:04:19
 
Mine kicks out 2v.

Do preamps act as attenuators?

Couldn't one lower the output to 1vrms (w/ 0dbfs sine wave for example, or maybe 0dbfs pink noise track) and then you'd be letting the preamp "take over"; avoid "compression" and impart it's own gain to the signal?

thanks!
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hifitubes
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Re: Tube selection
Reply #10 - 07/07/10 at 14:11:53
 
Wondering if the Mini-Torii has its signal ground and chassis ground tied together?

If I float the ground pin on its power cord, it becomes much quieter. I also had to reverse the + and - wiring at my subwoofer for it not to short out.

I read this about a DAC:

There is a floating ground inside your dac. If it did not hum prior to being upgraded, it is easily fixable.
Inside the dac, a 10 - 47 ohm resistor between signal ground and electrical ground will usually solve ground loops. This is a much better way than fancy ground loop isolators. The modder may have disconnected whatever the grounding scheme inside was originally.


I have 2 DACs, one of which is very quite, and the more expensive DAC is very noisy. Everything is connected to an Exactpower EP15, only 3 components in the chain.

Just curious why floating the Torii grounded drops the noise floor by almost 10db !!!
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Lon
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Re: Tube selection
Reply #11 - 07/07/10 at 15:00:22
 
Regarding the dropping the voltage of the DAC:  I don't have any specific training or knowledge in these things, just what I've found through experimenting with gear.  Try it and see!
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Raduschka
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Re: Tube selection
Reply #12 - 05/10/11 at 02:06:11
 
Hi, I am functioning with nos NEC 6v6 tubes right now. I wonder if I should get a pair of RCA 6v6, black plate, grey glass, yadda yadda

for 130$

I wonder if there will be a marked sonic improvement, in terms of 3d and bass at least.
ANyone know those tubes? What is sooo special about them?

Raduschka
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KimKman
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Re: Tube selection
Reply #13 - 11/01/11 at 18:18:03
 
In my experinces so far the most satisfying tubes have been the  Russian 6V6 tubes the amp came with.
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Raduschka
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Re: Tube selection
Reply #14 - 11/01/11 at 18:30:48
 
I ordered 3 of those Russian 6v6 tubes from Bulgaria on ebay. They were made in the 70's. My amp was number 50 something if I recall correctly, so I missed out on them as stock tubing.
I am waiting for a pair of NOS sylvania 6v6 (14$ at an ebay auction). It has been 2 weeks, they should get here soon.
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KimKman
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Re: Tube selection
Reply #15 - 11/01/11 at 18:57:31
 
Raduschka eager to hear what you think when you get your tubes.
SN: 012 here , used in my office system.
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Raduschka
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Re: Tube selection
Reply #16 - 11/01/11 at 19:00:25
 
KimKman, have you had any difficulties with certain brands/types/specimens of 6x4s whistling loudly in your mini torii?
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Raduschka
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Re: Tube selection
Reply #17 - 11/01/11 at 19:14:35
 
Both packages have just arrived!
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KimKman
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Re: Tube selection
Reply #18 - 11/01/11 at 22:19:27
 
"KimKman, have you had any difficulties with certain brands/types/specimens of 6x4s whistling loudly in your mini torii?"

No issues at all here testing 4 different pairs.
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Rivieraranch
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Re: Tube selection
Reply #19 - 11/02/11 at 02:12:27
 
I would be happy to test the whistling 6X4's out.
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Raduschka
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Re: Tube selection
Reply #20 - 11/02/11 at 02:16:43
 
hello , just pm me your address please and i will mail them to you. Based on your findings I will send my mini torii back to steve for repair or consult a psychologist. Thank you
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Raduschka
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Re: Tube selection
Reply #21 - 11/02/11 at 23:47:51
 
can you please suggest a place to buy a 9 to 7 pin adapter. I just cannot find any! Thank you
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