Author Topic: SENERGY What really is It ??  (Read 2489 times)

Offline tmazz

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Re: SENERGY What really is It ??
« Reply #15 on: August 14, 2017, 06:55:33 PM »
Quote
His reasoning was that circuit non-linearities are usually expressed in terms of change per octave. The audio band although it is only 2khz wide spans 10 octaves.

I am assuming you meant 20khz. I am going to guess that the professor had studied Olson, Rane etc, as they demonstrated the importance of  bandwidth, and harmonics and bandwidth etc.



yup, 20 khz  :duh :lol:

You are right While human hearing can theoretically detect fundamental tones up to 20khz, music is not made up pure sine wave but rather very complex waveforms that as Dr Fourier taught us contain spectral energy at frequencies far above their fundamental tones. Also it is the harmonic content of an instruments tone that lead to its distinct character. it is the different mix of harmonics that make middle C on a cello sound different from middle C on an oboe even though the notes from both have the same fundamental frequency. So the preservation of the harmonic structure even about the hearing threshold it vital to making recorded music sound similar to a live performance instead of like a reasonable facsimile. which makes designing equipment for high end reproduction even more difficult than the just good enough reproduction of most  mass market audio equipment.
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Offline steve

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Re: SENERGY What really is It ??
« Reply #16 on: August 15, 2017, 07:25:17 AM »
Quote
His reasoning was that circuit non-linearities are usually expressed in terms of change per octave. The audio band although it is only 2khz wide spans 10 octaves.

I am assuming you meant 20khz. I am going to guess that the professor had studied Olson, Rane etc, as they demonstrated the importance of  bandwidth, and harmonics and bandwidth etc.


You are right While human hearing can theoretically detect fundamental tones up to 20khz, music is not made up pure sine wave but rather very complex waveforms that as Dr Fourier taught us contain spectral energy at frequencies far above their fundamental tones. Also it is the harmonic content of an instruments tone that lead to its distinct character. it is the different mix of harmonics that make middle C on a cello sound different from middle C on an oboe even though the notes from both have the same fundamental frequency. So the preservation of the harmonic structure even about the hearing threshold it vital to making recorded music sound similar to a live performance instead of like a reasonable facsimile. which makes designing equipment for high end reproduction even more difficult than the just good enough reproduction of most  mass market audio equipment.

Nice explanation Tom. If I can expand a little from Olson (keeping it simple) there is a weighting factor for harmonics. Higher harmonics are perceived much easier than low harmonics. In otherwards it takes much less change in, say, the 14th harmonic to be perceived VS a change in the 2nd harmonic. Below are just some figures based upon a pentode.

Harmonic               Weighting factor

2nd                               1
3rd                                1.5
4th                                2
5th                                2.5
6th                                3
7th                                3.5
8th                                4
9th                                4.5
10th                              5
etc.
14th                              7

According to Olson's work, higher orders would be even more sensitive to amplitude changes. (Cymbals come to mind.) As such, if the frequency response varies in the highs or lows, such as +/- 0,1db, a variation would occur in several harmonics, thus a instrument or voice change would be perceived. In my testing, I have consistently found, along with others, that altering an ~9k resistor, parallel, across a 4 ohm driver, by less than 0,1 ohms is perceivable. Pretty amazing to me.

Since same model drivers have fairly large spec differences, adjustments will be different for each driver, both electrically and placement wise in the room.

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Steve
« Last Edit: August 15, 2017, 07:35:16 AM by steve »
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Offline rollo

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Re: SENERGY What really is It ??
« Reply #17 on: August 15, 2017, 08:00:50 AM »
   Very informative explanation of the science. Exactly what I look for in a component. Harmonic structure and tonality.  I put this question out there to hear the engineering or scientific reasons for component synergy.
  My subjective synergy combos are just that. You know a tubed pre with SS amp. DCs and tubes and so on. however if I'm choosing a speaker cable should I be aware of the capt ? Inductance, impedance as a guide to select contenders. When matching a Pre to amp output and input impedance of each is important.
  So what I'm looking for is a guide to help select the right stuff to audition.


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Offline Nick B

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Re: SENERGY What really is It ??
« Reply #18 on: August 15, 2017, 08:37:09 AM »
Good posts. More harmonic structure is the missing ingredient  right now. As I've broken in the four receptacles on the Uber, I may plug the dac in soon with that in mind
Nick
ICEpower 1200as2 stereo amp
Audio Hungary APR 204 preamp
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Offline doug s.

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Re: SENERGY What really is It ??
« Reply #19 on: August 15, 2017, 09:00:56 AM »
  ...So what I'm looking for is a guide to help select the right stuff to audition.


charles
charles, it seems my response, (other than the one poking fun at your spelling), is the only one that's non-technical.  but that's the guide i use.  let the engineers figure out the stuff that determines what will appear on my radar for possible use.

and yes, impedance matching between pre and amp is important, as i mentioned.  my first foray into a tube preamp was the arc sp-9mkll.  in a word - it totally sucked.  it was worse than the adcom gfp-1a i was using at the time.  reading this thread, and seeing that tmazz uses an sp-9 in his system made me go and read a lot of articles on it, and what folks thought, good and/or bad.  one thing i gleaned was that the sp9 wants to see an amp w/minimum 60k ohm input impedance.  i knew nothing about that back then.  the amp i was using at the time has an input impedance of 22k ohms.  maybe that was why everything sounded like it had molasses poured over it; the sound was so thick, heavy and lifeless.  even so, i wonder, as the sp-9 mkll's output impedance is 250 ohms, and the standard rule of thumb is the amp's input impedance should be at least 10 times greater.  and tho arc recommends 60k ohm amp input, it also says "min 20k ohms".  but, in any event, preamp-amp impedance matching is definitely something to consider.

ymmv,

doug s.

Offline doug s.

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Re: SENERGY What really is It ??
« Reply #20 on: August 15, 2017, 09:25:04 AM »
hi nick,

in the electrocoompaniet thread, i mentioned the stellar melos ma333r preamp f/s on agon and audiomart; and you said it was too spendy.  but, that's what you need in your system, imo, if you want "more harmonic structure".  you don't have to spend that much.  i saw three melos sha-1's sell recently on ebay, for $325 to $450.  (also one of the best headfone amps ever, according to the headfone freaks.)  this is a simple low-frills unit w/three line inputs.

and, there's one f/a now, w/discolored faceplate; a not uncommon feature of vintage black melos gear:
http://www.ebay.com/itm/253093887794

and another more traditional unit:
http://www.ebay.com/itm/172816881914

yes, i am partial to the melos preamps; mine was fabulous before i upgraded it.  i only had it upgraded because i could!  but, you don't have to get a melos just cuz i like it; there's other preamps out there as well, that garner good reviews.

also, i am curious - you mentioned in the ec thread about wanting to upgrade your speakers, possibly to sp tech.  what speakers do you have now; unless i am missing it, there's none listed in your signature, w/the rest of your stuff.

doug s.
Good posts. More harmonic structure is the missing ingredient  right now. As I've broken in the four receptacles on the Uber, I may plug the dac in soon with that in mind
Nick

Offline Nick B

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Re: SENERGY What really is It ??
« Reply #21 on: August 15, 2017, 10:13:03 AM »
hi nick,

in the electrocoompaniet thread, i mentioned the stellar melos ma333r preamp f/s on agon and audiomart; and you said it was too spendy.  but, that's what you need in your system, imo, if you want "more harmonic structure".  you don't have to spend that much.  i saw three melos sha-1's sell recently on ebay, for $325 to $450.  (also one of the best headfone amps ever, according to the headfone freaks.)  this is a simple low-frills unit w/three line inputs.

and, there's one f/a now, w/discolored faceplate; a not uncommon feature of vintage black melos gear:
http://www.ebay.com/itm/253093887794

and another more traditional unit:
http://www.ebay.com/itm/172816881914

yes, i am partial to the melos preamps; mine was fabulous before i upgraded it.  i only had it upgraded because i could!  but, you don't have to get a melos just cuz i like it; there's other preamps out there as well, that garner good reviews.

also, i am curious - you mentioned in the ec thread about wanting to upgrade your speakers, possibly to sp tech.  what speakers do you have now; unless i am missing it, there's none listed in your signature, w/the rest of your stuff.

doug s.
Good posts. More harmonic structure is the missing ingredient  right now. As I've broken in the four receptacles on the Uber, I may plug the dac in soon with that in mind
Nick

Doug,
Can't believe I left the speakers out  :duh They are SP Tech 2.0 upgraded to 2.1 or 3.0 status. Where is that paperwork from 2008 ??? As I've seen your posts since you came on AN,  I'm comfortable trusting your judgment. But getting a Melos is kinda like shooting in the dark for me. It's also a bit difficult to comprehend that I'd be getting the excellent sq that I'm getting now from an older,  unmodded unit.
I'd be a bit more inclined to try a Tortuga LDR  and my Buddy Gary has one. If I'm extra nice, he may bring it from Vegas. At one time, I had thought of getting a McCormack unit, but the upgrade was more than I wanted to spend. I am going to read up more on the EC though as I've always thought favorably of the company.
Nick
ICEpower 1200as2 stereo amp
Audio Hungary APR 204 preamp
KEF LS 50 speakers
Border Patrol SE dac
Auralic Aries Mini
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Offline doug s.

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Re: SENERGY What really is It ??
« Reply #22 on: August 15, 2017, 10:53:30 AM »
hi nick,

i bet the tortuga ldr is fantastic - ldr attenuators are about as good as it gets for attenuators, imo.  in fact, the melos "photentiometer", used in the ma333r and the sha-gold-r preamps, use this technology. 

i have a much simpler (and less expensive) ldr attenuator - the diyparadise eva-2 - and it is phenomenal in its clarity.
http://diyparadise.com/shop/index.php?main_page=product_info&cPath=18&products_id=113

that said, if you're looking for "more harmonic structure", i am not certain that a passive ldr preamp will get you there.  now, tortuga's tube buffer stage, inserted between a passive ldr preamp, (or between your source(s) and amp); that's another story.   8)  it might be the ticket.  the tortuga seems a bit spendy for a tube buffer; there's a lot of others out there that offer excellent results at far less cost.  i have two ase z-man buffers, and a kailin buffer; i think they're excellent.

in fact, there's one f/s right now, on one of my fave sites!  :mrgreen:  it has gotten good reviews, but i would suggest upgrading its tubes - which would cost more than the asking price of the buffer stage itself - but would still be relatively reasonable:
http://www.audiocircle.com/index.php?topic=151620.0

doug s.
hi nick,

in the electrocoompaniet thread, i mentioned the stellar melos ma333r preamp f/s on agon and audiomart; and you said it was too spendy.  but, that's what you need in your system, imo, if you want "more harmonic structure".  you don't have to spend that much.  i saw three melos sha-1's sell recently on ebay, for $325 to $450.  (also one of the best headfone amps ever, according to the headfone freaks.)  this is a simple low-frills unit w/three line inputs.

and, there's one f/a now, w/discolored faceplate; a not uncommon feature of vintage black melos gear:
http://www.ebay.com/itm/253093887794

and another more traditional unit:
http://www.ebay.com/itm/172816881914

yes, i am partial to the melos preamps; mine was fabulous before i upgraded it.  i only had it upgraded because i could!  but, you don't have to get a melos just cuz i like it; there's other preamps out there as well, that garner good reviews.

also, i am curious - you mentioned in the ec thread about wanting to upgrade your speakers, possibly to sp tech.  what speakers do you have now; unless i am missing it, there's none listed in your signature, w/the rest of your stuff.

doug s.
Good posts. More harmonic structure is the missing ingredient  right now. As I've broken in the four receptacles on the Uber, I may plug the dac in soon with that in mind
Nick

Doug,
Can't believe I left the speakers out  :duh They are SP Tech 2.0 upgraded to 2.1 or 3.0 status. Where is that paperwork from 2008 ??? As I've seen your posts since you came on AN,  I'm comfortable trusting your judgment. But getting a Melos is kinda like shooting in the dark for me. It's also a bit difficult to comprehend that I'd be getting the excellent sq that I'm getting now from an older,  unmodded unit.
I'd be a bit more inclined to try a Tortuga LDR  and my Buddy Gary has one. If I'm extra nice, he may bring it from Vegas. At one time, I had thought of getting a McCormack unit, but the upgrade was more than I wanted to spend. I am going to read up more on the EC though as I've always thought favorably of the company.
Nick

Offline Nick B

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Re: SENERGY What really is It ??
« Reply #23 on: August 15, 2017, 12:06:39 PM »
Hi Doug,
I believe you're right and a tube buffer may be the way to go for what I'm trying to achieve. I was on the Tortuga site and the cost of the buffer is way more than I want to spend right now. I checked out the Zman ASE and part of the description mentions a reduction in noise..lessening the harsh sound of CDs. Well that's fine, but the Uber already does a great job at lowering the noise floor with all the resultant benefits. But I'm trying to reproduce the harmonic structure of violins, guitars etc. or at least what they should sound like imo. All my components are capable of excellent resolution, so why am I not getting that right now and why would a tube buffer be able to do/create that? None of my audio buddies even use one afaik. I haven't checked out the Kaitlin yet. If any of your units are for sale, send me a pm if you'd like.
As a side note, I plugged in my dacs Voltikus power supply into the P and S polished receptacle. It's a fuller, seemingly more accurate sound. Very nice and an apparent improvement in "harmonic structure", but not there yet. More listening tonight in the later hours
Nick
ICEpower 1200as2 stereo amp
Audio Hungary APR 204 preamp
KEF LS 50 speakers
Border Patrol SE dac
Auralic Aries Mini
Roon & Tidal
Don Sachs phono
Basis Ovation turntable
Graham 1.5 T tonearm
AT-ML150 cartridge
PI Audio Uber
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Offline doug s.

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Re: SENERGY What really is It ??
« Reply #24 on: August 15, 2017, 12:59:27 PM »
nick, the kailin mu-1 and the z-man have both been out of production for a long time; good luck finding one used.  mine are keepers; i find them useful in 2nd systems, and sometimes even w/a tubed preamp, in front of particularly dry sounding gear.

i am a firm believer in tubed preamps; they seem to me to provide that "je ne sais quoi" to a system that makes it sound more like real music instead of a recording.  (at least tube preamps that i like anyway!  :D)

a tube buffer (like the yaqin) is an inexpensive way to see what you think.  w/the particular yaqin i linked, i'd recommend some quality nos tubes; you still won't be out a ton of cash, and could always recoup most of the investment if it's not your cuppa.  and, i'd ask that seller if he would consider including the tubes he used in it - he obviously has other tubes or the ones he's including w/it would not be "unused"   8)

doug s.

Hi Doug,
I believe you're right and a tube buffer may be the way to go for what I'm trying to achieve. I was on the Tortuga site and the cost of the buffer is way more than I want to spend right now. I checked out the Zman ASE and part of the description mentions a reduction in noise..lessening the harsh sound of CDs. Well that's fine, but the Uber already does a great job at lowering the noise floor with all the resultant benefits. But I'm trying to reproduce the harmonic structure of violins, guitars etc. or at least what they should sound like imo. All my components are capable of excellent resolution, so why am I not getting that right now and why would a tube buffer be able to do/create that? None of my audio buddies even use one afaik. I haven't checked out the Kaitlin yet. If any of your units are for sale, send me a pm if you'd like.
As a side note, I plugged in my dacs Voltikus power supply into the P and S polished receptacle. It's a fuller, seemingly more accurate sound. Very nice and an apparent improvement in "harmonic structure", but not there yet. More listening tonight in the later hours
Nick

Offline Nick B

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Re: SENERGY What really is It ??
« Reply #25 on: August 15, 2017, 01:06:05 PM »
Ok, Doug. Thanks for the "sound" advice:thumb:
Nick

nick, the kailin mu-1 and the z-man have both been out of production for a long time; good luck finding one used.  mine are keepers; i find them useful in 2nd systems, and sometimes even w/a tubed preamp, in front of particularly dry sounding gear.

i am a firm believer in tubed preamps; they seem to me to provide that "je ne sais quoi" to a system that makes it sound more like real music instead of a recording.  (at least tube preamps that i like anyway!  :D)

a tube buffer (like the yaqin) is an inexpensive way to see what you think.  w/the particular yaqin i linked, i'd recommend some quality nos tubes; you still won't be out a ton of cash, and could always recoup most of the investment if it's not your cuppa.  and, i'd ask that seller if he would consider including the tubes he used in it - he obviously has other tubes or the ones he's including w/it would not be "unused"   8)

doug s.

Hi Doug,
I believe you're right and a tube buffer may be the way to go for what I'm trying to achieve. I was on the Tortuga site and the cost of the buffer is way more than I want to spend right now. I checked out the Zman ASE and part of the description mentions a reduction in noise..lessening the harsh sound of CDs. Well that's fine, but the Uber already does a great job at lowering the noise floor with all the resultant benefits. But I'm trying to reproduce the harmonic structure of violins, guitars etc. or at least what they should sound like imo. All my components are capable of excellent resolution, so why am I not getting that right now and why would a tube buffer be able to do/create that? None of my audio buddies even use one afaik. I haven't checked out the Kaitlin yet. If any of your units are for sale, send me a pm if you'd like.
As a side note, I plugged in my dacs Voltikus power supply into the P and S polished receptacle. It's a fuller, seemingly more accurate sound. Very nice and an apparent improvement in "harmonic structure", but not there yet. More listening tonight in the later hours
Nick
ICEpower 1200as2 stereo amp
Audio Hungary APR 204 preamp
KEF LS 50 speakers
Border Patrol SE dac
Auralic Aries Mini
Roon & Tidal
Don Sachs phono
Basis Ovation turntable
Graham 1.5 T tonearm
AT-ML150 cartridge
PI Audio Uber
All cables by Gary A

Offline doug s.

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Re: SENERGY What really is It ??
« Reply #26 on: August 15, 2017, 01:23:43 PM »
also - if you search the web, you will find quite a bit of info about parts swapping and tube rolling on the yaqin cd-3.

doug s.
Ok, Doug. Thanks for the "sound" advice:thumb:
Nick

nick, the kailin mu-1 and the z-man have both been out of production for a long time; good luck finding one used.  mine are keepers; i find them useful in 2nd systems, and sometimes even w/a tubed preamp, in front of particularly dry sounding gear.

i am a firm believer in tubed preamps; they seem to me to provide that "je ne sais quoi" to a system that makes it sound more like real music instead of a recording.  (at least tube preamps that i like anyway!  :D)

a tube buffer (like the yaqin) is an inexpensive way to see what you think.  w/the particular yaqin i linked, i'd recommend some quality nos tubes; you still won't be out a ton of cash, and could always recoup most of the investment if it's not your cuppa.  and, i'd ask that seller if he would consider including the tubes he used in it - he obviously has other tubes or the ones he's including w/it would not be "unused"   8)

doug s.

Hi Doug,
I believe you're right and a tube buffer may be the way to go for what I'm trying to achieve. I was on the Tortuga site and the cost of the buffer is way more than I want to spend right now. I checked out the Zman ASE and part of the description mentions a reduction in noise..lessening the harsh sound of CDs. Well that's fine, but the Uber already does a great job at lowering the noise floor with all the resultant benefits. But I'm trying to reproduce the harmonic structure of violins, guitars etc. or at least what they should sound like imo. All my components are capable of excellent resolution, so why am I not getting that right now and why would a tube buffer be able to do/create that? None of my audio buddies even use one afaik. I haven't checked out the Kaitlin yet. If any of your units are for sale, send me a pm if you'd like.
As a side note, I plugged in my dacs Voltikus power supply into the P and S polished receptacle. It's a fuller, seemingly more accurate sound. Very nice and an apparent improvement in "harmonic structure", but not there yet. More listening tonight in the later hours
Nick

Offline topround

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Re: SENERGY What really is It ??
« Reply #27 on: August 15, 2017, 02:03:24 PM »
I agree
a good tubed preamp would work wonders, the amp you have is very good I had a DNA 0.5 deluxe and loved it.
Also those speakers might be a little problem, I had the 2.0 for a while and while they play loud very cleanly they do not impart any great amount of love.
They are very neutral and fast, they really benefit from tubes, not trying to knock them just being honest in their sonic signature.

Tmazz has Nola Boxers. you might LOVE those, very musical speakers.

what is your budget for a preamp?
System consists of an amp a preamp, 2 speakers a turntable and a phono preamp, Also some cables and power cords and a really cheap cd player.

Offline steve

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Re: SENERGY What really is It ??
« Reply #28 on: August 15, 2017, 04:05:34 PM »
Things are a little more complicated than what might appear. There are several other factors to consider, this is not exhaustive. For general consumption.

Quote
and yes, impedance matching between pre and amp is important, as i mentioned. 

Not so much as one normally thinks. RCA Radiotron Designers Handbook suggests a 5:1 ratio, amp input Z to preamplifier output Z. I suggest, as you have heard, 10:1 to be safe. But that is normally calculated at midband. What is really important is across the entire audio band.

My Preamplifiers are approximately 1.9k output Z, and works fine to 20k amp input Z. So a buffer stage is not necessary. Why not? What is the scoop.

1) Let's examine high frequency first. Example: we have an IC capacitance of 100pf and amplifier input capacitance of 50pf, so 150pf in parallel with the 100k input resistor (100k input Z at 1khz).

The reactance of 150pf at 20khz is ~53k ohms. So at 20khz, we actually have 100k ohm in paralleled with 53k ohms of capacitive reactance (called "I").

However, the preamplifier output Z is in parallel with "I" and 100K resistor, so not that bad. With 1.9k output Z, the high frequency response exceeds half a mhz (550khz) before -3db. 

Believe it or not, the major limit on high frequency response is the volume control to tube grid input capacitance (including Miller effect). Not only that, the minimum frequency response (FR) occurs at mid resistance setting of the volume control. Using a 100k volume pot limits the HF more than a 50k or 25k pot.

2) Let's examine the low frequency response. Pretty easy as a coupling capacitor and following grid resistor. Here is some data.
Frequency 10hz. Grid resistor 100k ohms.

Coupling Capacitor          -db

1uf                                 .114
.82                                 .162
.68                                 .235
.47                                 .47
.33                                 .883
.22                                1.76
.1                                  5.5 db

With 50k grid resistor.

1uf                                 .38db
.1                                 10.

That is just one stage coupling. With multiple stages, dbs add. By the way, the 1uf coupling capacitor, - 0.116db at 10hz may seem small enough to not be perceived, but when additional stages and/or the OPT are considered, don't be so sure. By the way, bloated bass in tube amps is not so much damping factor, but more likely a power supply design problem.

Quote
my first foray into a tube preamp was the arc sp-9mkll.  in a word - it totally sucked.  it was worse than the adcom gfp-1a i was using at the time.  reading this thread, and seeing that tmazz uses an sp-9 in his system made me go and read a lot of articles on it, and what folks thought, good and/or bad.  one thing i gleaned was that the sp9 wants to see an amp w/minimum 60k ohm input impedance.  i knew nothing about that back then.  the amp i was using at the time has an input impedance of 22k ohms.  maybe that was why everything sounded like it had molasses poured over it; the sound was so thick, heavy and lifeless.

With a smaller 22k ohms, the sound should have been thinner than using 60k ohms minimum, not heavier. This leaves several possibilities.
One, the room is quite bass resonant.
Two, the speakers are not correctly matched for the venue,
Three, the speakers are bass heavy to begin with, due to either their venue or electronic components they used
Four, the other electronic components in your system are not designed properly, thus bass heavy

The proper way I have found is to design the electronics first, since the preamplifier and amplifier can be listening tested for accuracy. After that, then I worked teeter/totter with speaker/venue.

Quote
even so, i wonder, as the sp-9 mkll's output impedance is 250 ohms, and the standard rule of thumb is the amp's input impedance should be at least 10 times greater.  and tho arc recommends 60k ohm amp input, it also says "min 20k ohms".  but, in any event, preamp-amp impedance matching is definitely something to consider.

Although the rule of thumb 10:1 is good, as shown above, the real culprit is the output capacitor size and quality, and also the power supply, which I did not address.
 
There are some weird "rules of thumb", such as concerning the -3db point, way out of line.

Cheers

Steve

« Last Edit: August 15, 2017, 04:25:50 PM by steve »
Steve Sammet (retired, but manufacturing "V" ics again)

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Offline doug s.

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Re: SENERGY What really is It ??
« Reply #29 on: August 15, 2017, 04:57:17 PM »
steve, it could simply be that i think the sp-9 sucks!   :D  i was just trying to figure out a possible reason, as i know others are fond of it.  looking at the sp-9's specs, i suspect it's less likely any impedance mismatch, and more likely that i just don't like that preamp.

regarding the speakers and venue, i seriously doubt either was an issue.  the room was quite huge - ~20x40, w/ceiling vaulted to a 2nd story balcony along the 40' length.  and, tho i don't know the design specifics, i do know, just from my ears, that items 3 & 4 also don't apply.  nothing at all bass heavy was going on.  (and it wasn't bass heavy w/the sp-9 either - just dull lifeless sound.)  speakers were on the short wall, about 4' from the back wall.  there were some short walls in the room splitting it up, but it was basically one big open space.  speakers were thiel 3.5's, (flat to 20hz w/factory eq), amp was original series adcom gfa555 (smooth faceplate w/rack handles.)  the adcom gfp-1a was adequate, the sp-9 was not.  if anything the preamp should have been a good match, due to the sonic characteristics that have been attributed to the speakers and the amp. (at least according to the audio press.)  next preamp was an arcam delta 110 preamp; it was most excellent.  (a bud of mine still uses one; bought after he heard mine.)  that was followed by the electrocompaniet ec-1a; even better.  it was several years later before i tried another tube preamp; the melos ma333r completely thrashed the rogue magnum 99 and the cary spl98 that i was auditioning.  at that point, i stopped investigating preamps; the melos was that good.  (different venue, by then, and various speakers were now being actively crossed over to subs.)  i was really wanting to like the cary because it looked so nice, but it was not to be..

doug s.
« Last Edit: August 15, 2017, 05:01:23 PM by doug s. »