Topic: Richard Clark Amplifier Pick-out Challenge

[jlester87]

You can use calibration mic and RTA para makuha yung frequency response ng amp with the speaker that you will be using. Then use minidsp for automatic equalization, para ma-adjust na maging pare-parehas yung frequency response ng mga amp-speaker pair. Just change the preset settings sa minidsp pag magpapalit ng amp.

Maganda sana kung ang speaker na gagamitin ay 3 way or more with complicated crossovers para mahirapan mag drive yung mga amp, dun magkaka talo hehe...

[tony]

Lester, the object of the challenge is to find out if anyone can pick out his amp from among amps...
a common speaker is needed, if can be a full range and still be okey....

[jlester87]

Yes agree, kaya gagawing parehas yung frequency response sa room na gagamitin.
All contending amps should produce the same freq response in the speaker measured by calibration mic at room's sweet spot.

No need for dummy load and oscilloscope, the load will be the speaker. The freq response should be measured at the speaker / room by a microphone connected to RTA software.

Using difficult load might show the differences in sound, even if different amps were equalized to produce the same response in a room.

[tony]

Suddenly crossed my (simple) mind why Richard wanted the sound equalized. Baka kasi may magdala ng amp na personally tweaked to sound differently, like boosted or tapered bass/treble (yes it's doable and quite easy for a knowledgeable tech/DIYer). Kung hindi stipulated yun sa rules nya, a lot can beat the challenge and get away $10k richer. 

this is true, a loudness circuit can be included and does not show any bypass at the front panel...
pwede mangyari yan......

[tony]

there is a raging debate over at diyaudio about CFA v.s VFA amps and the thread proponents claim that CFA is superior to VFA...we can also test this claim as an aside....

example of a VFA amp is the Sansui AUD-907A, example of a CFA is a NAD 3020...
i believe both amps are well liked....
would be nice to find out if the claim is true....both are classAB amps..

if anyone would like to volunteer their units for testing, you can post model number of your amps
and we can classify them as to CFA or VFA.....

[markcrenz]

Yes agree, kaya gagawing parehas yung frequency response sa room na gagamitin.
All contending amps should produce the same freq response in the speaker measured by calibration mic at room's sweet spot.

No need for dummy load and oscilloscope, the load will be the speaker. The freq response should be measured at the speaker / room by a microphone connected to RTA software.

Using difficult load might show the differences in sound, even if different amps were equalized to produce the same response in a room.

disregard na clipping?

[jjohnc]

Pa lista na po kayo

[jlester87]

disregard na clipping?

Hindi naman, I just assumed that all amplifiers will be set to a "conservative" or "normal listening" reference SPL level so that clipping will not be an issue. Magiging less complicated ang pag setup pag ganun.

Unless isasali yung mga 5 watter amp (with low sensitivity test speakers), you have to do elaborate measurements just to get the reference SPL level that will make sure that each amp has dynamic headroom to avoid clipping at music peaks.

[dts-HD 3D]

Isn't it that the real challenge here is: how to set-up and calibrate the amps . . . according to Richard Clark's conditions? In other words, how to make the amps sound the same. And not the part of picking-out in the end?

Shootout na lang kaya as suggested by jjohnc? According to class or price bracket. Pass labs, Plinius, Mcintosh, krell, Dan d' Agostino, Sansui, Nad, emotiva, diy amp, etc.

[qguy]

Would be interesting to see an uber expensive pre/power amp vs an equalized budget integrated amp and see if the listeners can pick out which is which.  Another interesting matchup is Tube vs Solidstate

A similar challenge has been done before by Stereophile and Bob Carver, The challenge was for Bob Carver to redesign his amp to sound like one of the expensive amplifier. If I remember correctly Bob Carver was able to make his amp sound like the uber expensive amp. Sadly the models of the amplifiers were not divulge

[tony]

Isn't it that the real challenge here is: how to set-up and calibrate the amps . . . according to Richard Clark's conditions? In other words, how to make the amps sound the same. And not the part of picking-out in the end?

Shootout na lang kaya as suggested by jjohnc? According to class or price bracket. Pass labs, Plinius, Mcintosh, krell, Dan d' Agostino, Sansui, Nad, emotiva, diy amp, etc.

the idea behind the set up is to calibrate all amps under test
to produce the same SPL, same frequency response,
and not clip under testing...
while these seem to make the amps sound the same,
the question still remains, will they sound the same?
and will anyone be able to successfully pick out each amp
under blind or unsighted conditions?

[tony]

disregard na clipping?

clipping is very audible naman.....

[tony]

Would be interesting to see an uber expensive pre/power amp vs an equalized budget integrated amp and see if the listeners can pick out which is which.  Another interesting matchup is Tube vs Solidstate

A similar challenge has been done before by Stereophile and Bob Carver, The challenge was for Bob Carver to redesign his amp to sound like one of the expensive amplifier. If I remember correctly Bob Carver was able to make his amp sound like the uber expensive amp. Sadly the models of the amplifiers were not divulge

yes, but what Carver did was quite different from the Richard Clark challenge...http://www.stereophile.com/content/carver-challenge

Another interesting matchup is Tube vs Solidstate

my bias, SS wins....

[markcrenz]

Hindi naman, I just assumed that all amplifiers will be set to a "conservative" or "normal listening" reference SPL level so that clipping will not be an issue. Magiging less complicated ang pag setup pag ganun.

Unless isasali yung mga 5 watter amp (with low sensitivity test speakers), you have to do elaborate measurements just to get the reference SPL level that will make sure that each amp has dynamic headroom to avoid clipping at music peaks.

[Elliott]

There are some differences that cannot be readily explained. An amp that is deemed "identical" to another in a test situation, may sound completely different in a normal listening environment. It is these differences that are the hardest to deal with, since we do not always measure some of the things that can have a big influence on the sound.

For example: It is rare that testing is done on an amplifier's clipping performance - how the amp recovers from a brief transient overload. I have stated that a hi-fi amplifier should never clip in normal usage - nice try, but it IS going to happen, and it is more common than we might think. Use a good clipping indicator on the amp, and this can be eliminated, but at what cost? It might be necessary to reduce the volume (and SPL) to a level that is much lower than you are used to, to eliminate a problem that you were unaware existed.

Different amplifiers react in different ways to these momentary overloads, where their overall performance is otherwise almost identical. I have tested IC power amps, and was dismayed by the overload recovery waveform. My faithful old 60W design measures about the same as the IC in some areas, a little better in some, a little worse in others (as one would expect).

Were these two amps compared in a double blind test (avoiding clipping), it is probable that no one would be able to tell the difference. Advance the level so that transients started clipping, and a fence post would be able to hear the difference between them. What terms would describe the sound? I have no idea. The sound might be "smeared" due to the loss of detail during the recovery time of the IC amp. Imaging might suffer as well, since much of the signal that provides directional cues would be lost for periods of time.

Q: How much CLEAN power (no clipping) does the average listener need to get a typical 80dB SPL with 100dB peaks during transients at a typical distance of 3m with a typical 89dB/W/m speaker?
A: 113 watts

So the average listener probably listens to music from a clipping amplifier most of the time.

Q: Can he notice the difference from a 200W (no more clipping!) amp?
A: Maybe. But probably not if he turns down the volume a bit to eliminate clipping.

One thing is certain: No one has yet beaten Clark's challenge!

[tony]

So the average listener probably listens to music from a clipping amplifier most of the time.

for this test SPL will be adjusted so that no amplifier under test clips...

this test will take time to organize, the amplifiers are still unknown at this time,
if members are interested to volunteer their amps....
that can be a start....

[dana]

Keyword here is nonlinear. Minimum goal of an amp is to have an almost ruler flat response across the audio band. As mentioned by tony earlier, tube amps may not exhibit a flat response.


Bale all of the above plus the following will be required to simulate this challenge:
1. RTA
2. Pink noise generator
3. Oscilloscope
4. Dummy load
5. Switching mechanism
6. Setup and calibration team
7. ? ? ?

Makumpleto kaya?

mga kelan kaya eto?

i can bring the ff:
1. National Dummy resistive load (adjustable from 4, 8, 16 ohms load), external speaker connection capable
2. Tektronix Oscilloscope with test cables
3. Analog audio sweep generator (say 20Hz~20Khz)...

hanapin ko muna  sa taguan ko, medyo matagal tagal na di nagamit.

the way i  understand it:
set all amp to have (almost?) identical same f-response from 20Hz to 20Khz, tone defeat off, same loudness level at certain listening volume level before clipping level ...
mahirap/matagal  siguro calibration neto.

ganito ba?
common source > switcher 1  >  EQ/bypass > switcher 2>  amps 1,2,3...n > speaker switcher(corrected)> common speaker

[markcrenz]

Fill up nyo na 'to pdvd peeps!

Atendees:                                Amp:
1. Nelson de Leon                     Pivetta Opera One
2. Don King Markcrenz              Yamaha A760
3. Qguy
4. Ninjababes
5. tony
6. geriboy
7. darkangel69
8.
9.
10.

[tony]

 Pivetta Opera One. sigurado ka?

sana me magdala ng Sansui AUD907

[dts-HD 3D]

Would be interesting to see an uber expensive pre/power amp vs an equalized budget integrated amp and see if the listeners can pick out which is which.

Ah yes a different but a more interesting experiment. It's the other way around isn't it?
With R. Clark's test kasi the lower, less capable amp gets to be the reference. Yung linear range nya ang magiging basehan for the SPL and FR and the rest of the participating amps will follow. Para maging pantay ang playing field.

clipping is very audible naman.....

Q: How much CLEAN power (no clipping) does the average listener need to get a typical 80dB SPL with 100dB peaks during transients at a typical distance of 3m with a typical 89dB/W/m speaker?
A: 113 watts

Rooms at LIS are quite big. Dapat at least 100w. nga mga amps.

[markcrenz]

hindi pwede ikabit multiple amps sa common speaker, saka pwede na rin splitter na lang from preamp to amps.

common source > preamp > splitter > amps 1 and 2 > switcher > high sensitivity 3 or 4 way speaker

two amps at a time lang capable ang amp switcher na available sa pdvd.

[markcrenz]

Rooms at LIS are quite big. Dapat at least 100w. nga mga amps.

im sure naman don john c can provide high sensitivity speakers for this endeavor. o kaya bring your martin logans! 

[dts-HD 3D]

heheh pass muna master tsaka marami naman dun.

[jjohnc]

im sure naman don john c can provide high sensitivity speakers for this endeavor. o kaya bring your martin logans! 

Master, hehehe...Monitor/Full range 2/3 way?

[audiojunkie]

the idea behind the set up is to calibrate all amps under test
to produce the same SPL, same frequency response,
and not clip under testing...
while these seem to make the amps sound the same,
the question still remains, will they sound the same?
and will anyone be able to successfully pick out each amp
under blind or unsighted conditions?

With this uniform amp's configuration/setting, it's possible amps will differ with their own sonic signature....

[tony]

Ah yes a different but a more interesting experiment. It's the other way around isn't it?
With R. Clark's test kasi the lower, less capable amp gets to be the reference. Yung linear range nya ang magiging basehan for the SPL and FR and the rest of the participating amps will follow. Para maging pantay ang playing field.

Rooms at LIS are quite big. Dapat at least 100w. nga mga amps.

a low powered amp will be at a disadvantage when it comes to transients...

[tony]

With this uniform amp's configuration/setting, it's possible amps will differ with their own sonic signature....

that is why we want to see if you can pick them up or not....

[tony]

hindi pwede ikabit multiple amps sa common speaker, saka pwede na rin splitter na lang from preamp to amps.

common source > preamp > splitter > amps 1 and 2 > switcher > high sensitivity 3 or 4 way speaker

two amps at a time lang capable ang amp switcher na available sa pdvd.

we can make the switcher to depend on the number of amps entered on the tests...

[Nelson de Leon]

hindi pwede ikabit multiple amps sa common speaker, saka pwede na rin splitter na lang from preamp to amps.

common source > preamp > splitter > amps 1 and 2 > switcher > high sensitivity 3 or 4 way speaker

two amps at a time lang capable ang amp switcher na available sa pdvd.

Agree ako dito. Sana if possible, single speaker na mga 92db man lang.

Isa lang ang source, preamp and speaker. Sana ang amp is at least 75 watts.

@Don King Markcrenz: gawa ka na lang siguro ng powered switcher para pwedeng para pwedeng single source pero multiple preamp output. And baka din after the test, maging interested din si jjohnc sa gawa mo kung wala pa siyang switcher. For those who is willing to lend their power amp (or integrated pero may bypass sa likod ng preamp), they should come early kasi para ma-check kung pare-parehas ang frequency response nila. And question, sino ang mag-EQ kung hindi parehas? Maganda din kung PC source sana para digital EQing na lang, naka-preset na siya para paglipat ng amp, mabilis lang.

[Tempter]

Pivetta Opera One. sigurado ka?

sana me magdala ng Sansui AUD907

Panget yan, Pivetta Opera Only na lang...

[markcrenz]

Agree ako dito. Sana if possible, single speaker na mga 92db man lang.

Isa lang ang source, preamp and speaker. Sana ang amp is at least 75 watts.

@Don King Markcrenz: gawa ka na lang siguro ng powered switcher para pwedeng para pwedeng single source pero multiple preamp output. And baka din after the test, maging interested din si jjohnc sa gawa mo kung wala pa siyang switcher. For those who is willing to lend their power amp (or integrated pero may bypass sa likod ng preamp), they should come early kasi para ma-check kung pare-parehas ang frequency response nila. And question, sino ang mag-EQ kung hindi parehas? Maganda din kung PC source sana para digital EQing na lang, naka-preset na siya para paglipat ng amp, mabilis lang.

another question, who will come in early to check the freq resp? as previously mentioned we need a team to setup/calibrate, two volunteers can't handle all those activities.