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05-11-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 1
Post ID: 10498
Reply to: 10498
Why the tubes shall be the same?
fiogf49gjkf0d

I kind of in a way used these techniques with my playback during past years.  When I used 3-channel Melquiades and had a dedicated ½ 6C33C for MF driver of Macondo I usually tended drive my rights MF channel at slightly higher current then left channel. My rational was that the 1st violin section is always on left. If the 2st violin section sits right with 1st violin and the violas and Chellos are on right with bright copper way behind then to have an extra half or one dB within right MF does not heart and it gives some compensation to generally HF-attention deficient right channel.  It did not rely EQ it but rather shaped the imaging curve in more proper way.  If the 2st violin section sits on opposite side of 1st violins then it does not truly hurt as 2st violins do not care main melody but rather the filler of melody and usually stay in background.

When I moved to single stage amp for MF then I was mach less flexible with those tricks as I had no spare gain and very little spare current on the single stage plate.

Now, finding myself with DHT, having plenty of extra gain, having ability to use different loading (anodes of 2.5V vs. 4V tubes) and having an opportunity to use deferent brands and vintages of tubes at right and left channel I think it would be a wonderful opportunity to shape the sound at very kinky fashion.

Truly, why the tubes shall be matched by gain or my other characteristics? My upperbass channels have deferent gain; my bass channels have different gain. If my DHT project for MF goes down successfully (as it appears it will) then I do see myself running different DHT tubes for right and left channels…

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
05-22-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 2
Post ID: 10553
Reply to: 10498
It is kind of strange
fiogf49gjkf0d

While I am proposing the to use different MF tubes between right and left channels might not be such a bad idea I have to admit that now I have different MF channels on the right and left  and I am not sure that it is the problem but something is definitely wrong. I have to point out the I not juts have different MF channels but different topologies between the MF channels and one of them was not tested by me in full-range (I am talking about DC-coupling).

It is not that the sound is bad; in fact it is good it has some strange sense of imaging inflexibility and unfriendliness that I never had. I do not over estimate the values of the imaging but there are no other problems that I can complain in the sound I am getting. I wonder if the problem that I am complaining about comes from the fact that I use very different amps on my right and left channel and by doing it I too much violate the indispensable rule of multi-amping – to use the same type amplification for each channel.

I play a lot of LP lately as it is imposable to say anything about FM – everything that comes from live FM is too frigging wonderful imaging-wise. LPs are more capriccios imaging-wise. So, I play vinyl and in a way I do not get what is going on. Sometimes the channels just do not talk to each other and do not talks to room in the way they shall and I have no idea where it comes from. It is very small but it is there and I am kind of “concerned”…

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
05-22-2009 Post does not mapped to Knowledge Tree
drdna
San Francisco, California
Posts 488
Joined on 10-29-2005

Post #: 3
Post ID: 10554
Reply to: 10553
Both sides now
fiogf49gjkf0d
Since both sides use different amplifiers, I think there may be incomplete correlation between the two sides in terms of coincidence of frequency response. Small changes in frequency response that vary with frequency and amplitude between the two sides may impact the image stability, focus, dynamics, etc.  or have more subtle difficult to define effects. I would be interested to see if there are any detectable differences between the frequency response  at different loudness levels of the two sides where different amplification is used.
Adrian
05-22-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 4
Post ID: 10556
Reply to: 10554
Not in terms of frequency response....
fiogf49gjkf0d

 drdna wrote:
Since both sides use different amplifiers, I think there may be incomplete correlation between the two sides in terms of coincidence of frequency response. Small changes in frequency response that vary with frequency and amplitude between the two sides may impact the image stability, focus, dynamics, etc.  or have more subtle difficult to define effects. I would be interested to see if there are any detectable differences between the frequency response  at different loudness levels of the two sides where different amplification is used.
Adrian

Well,

The incomplete correlation between the two sides in terms of frequency response is not a problem at all. It is easy to monitor and easy to take care. Furthermore I feel that minor misbalance between frequency response and left channel is not a big deal. The rooms are asymmetrical and we always have right/left frequency response misbalance, even at HF. What I afraid it might be is something deeper, something that is not on surface, like some vibrant harmonic discrepancies between the single-stage high Mu IDHT and DC-coupled DHT, or some kind ULF wobbling of my DC-coupled solution. I think it is something more fine then frequency response, as the sound generally is quite good but the  it feels that something is keep drifting in music while is plays. It is not firm and sound is not locked firmly in its presentation manner.

Paul proposed that it might be my caps are still burning in. Possibly but from what I recall it was different before with my new Nichicon caps. What is very amasses me is that the extreme latitude ends of what they call “soundstage” are not the curbed toward to me but curbed in opposite direction. This is very bizarre. I know how to deal with it by positioning of my speaker but why shall I move speaker if I juts change the MF amp that presumably (?) does the very same as the old amp did?

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
05-23-2009 Post does not mapped to Knowledge Tree
drdna
San Francisco, California
Posts 488
Joined on 10-29-2005

Post #: 5
Post ID: 10558
Reply to: 10556
Dht and harmonics
fiogf49gjkf0d
 Romy the Cat wrote:
I afraid it might be some vibrant harmonic discrepancies between the single-stage high Mu IDHT and DC-coupled DHT, or some kind ULF wobbling of my DC-coupled solution. I think it is something more fine then frequency response, as the sound generally is quite good but the  it feels that something is keep drifting in music while is plays. It is not firm and sound is not locked firmly in its presentation manner.
Well, I experienced the same exact phenomena with using different 2A3 tubes as you remember, which I do believe has to do with the mechanical harmonics in part.  At some point it would be interesting to explore the possibility of removing tube dampers or adjsting them to see the effect.
I still think it is worthwhile to see the frequency distribution, or ideally make a waterfall graph to see the decay of harmonics between the sides just to see if there is a difference.  At least if it is identical, it narrows down the possibilities.
Adrian
05-23-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 6
Post ID: 10564
Reply to: 10558
So, the non-paired tubes are the bitch?
fiogf49gjkf0d

 drdna wrote:

Well, I experienced the same exact phenomena with using different 2A3 tubes as you remember, which I do believe has to do with the mechanical harmonics in part.

I do not remember that, it you wrote it then I most likely did not pay attention to this experience. You are saying that you had imaging problems using different type of 2A3 tubes on right and left channel, giving to the fact that the gain of the right and left channels were balanced and that those different type of 2A3 tube sounded similar when they drove the same channel? If so, then it is VERY interesting fact. Can you provide me with more adjectives and more descriptions what exactly you recognize was differently-wrong in the sound of playback with use of non-paired tubes?

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
05-23-2009 Post does not mapped to Knowledge Tree
drdna
San Francisco, California
Posts 488
Joined on 10-29-2005

Post #: 7
Post ID: 10565
Reply to: 10564
Soundstage and tube mismatch
fiogf49gjkf0d
 Romy the Cat wrote:
Can you provide me with more adjectives and more descriptions what exactly you recognize was differently-wrong in the sound of playback with use of non-paired tubes?
The results I found were similar to what you had found with different amplifiers.  And after all what is an amplifier but really a way of expressing the characteristics of the tube?  
Anyway, in the center, I was surprised to find that I could mix and match the tubes on either side and it seemed to have an effect like I was adding ingredients to a soup and mixing them in.  It affected the presence, tonality, focus, dynamics, etc. but as far as I could detect had an effect overall on the music quite evenly.  It was at the edges of the soundstage that I saw the differential effects.  I can compare this to using different optical lenses, like a telephoto lens or a fisheye lens.  All the same information is there, but for example with the fisheye lens it is all compressed at the edge. Here is where there was discontinuity with mismatched tubes. There can be with different tubes I observed a standard soundstage, a change in the dimensions of depth and width, or an elimination entirely of the soundstage, with musical presentation simply extending outwards in natural space with no regard for the dimensions of any artificial soundstage. The mismatch created an alteration of the curvature of space like the distortion you can get with funhouse mirrors.
Adrian
05-23-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 8
Post ID: 10568
Reply to: 10565
Not optional anymore?
fiogf49gjkf0d
Well, Adrian,
 
if you are right (and I do not see why you would not be, as you described the aberrations at soundstage’s edge very perfectly) then it is a very strong message to me that I need to convert my second Milq from single-stage to DHT. That sucks and I thought to keep it with single-stage over summer and considered this conversion was optional.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
Page 1 of 1 (8 items) Select Pages: 
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  DHT driver & input..  Effects of radiation...  Melquiades Amplifier  Forum     25  160753  02-01-2007
  »  New  Amplification and Consciousness...  Freedom of expression vs. something to say...  Playback Listening  Forum     15  72868  01-07-2008
  »  New  All Active! A DSET and multi-way acoustic system...  Hahaha...  Audio Discussions  Forum     14  78226  01-31-2008
  »  New  Single-stage Melquiades vs. DHT amps..  A hallucination?...  Melquiades Amplifier  Forum     397  2499626  11-22-2008
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