Peach competition

[Coytee]

I put a different preamp into my system last night. I split my cd player output into each pre and put the second pre into my "HT" bypass of the Peach. Set the levels as close as I could (and indeed, the levels sounded identical). The pre's are then connected to my McIntosh MC-2102. I used the HT bypass as my a/b switch.

Just curious if anyone can give me some heads up as to what to try to listen to, any specific program source or source type. my main listening is to classic rock.

What might be a more revealing test, two pre's on a tube amp or two pre's on a solid state amp?

Given my experience last night, they both sounded great but I was also reserving my thoughts because I wondered if the 2102 was smoothing both of them out.

Was a very interesting experience so far. (for me anyway)

[tillmbil]

So what did you think?

[Coytee]

I'm reserving thoughts right now... on a preliminary, they sound identical. I mean identical, which is why I was inquiring for some thoughts on what I might look for. Since my history is more cranked up rock/roll, I'm sure I'm not accustomed to listening for some of the more nuanced details that others here experience.

Knowing I don't have the ear that some here might have, I was hoping that some might give me guidance on some subtle things to listen for. For example, might a difference be more telling if I a/b both pre's on solid state or tube amps... Right now, using the Mcintosh MC-2102, they both sound as identical as I can ascertain and both sound VERY nice.

[NOSValves]

IMHO AB switching is worthless. It takes days with one then switch days then switch.

[meagain]

Coytee - since you brought it up... I'll chime in...

I did the same exact test. The preamps sounded identical. Hubby sat on the floor in front of the Peach to toggle the HT switch. I sat in the listening position. I kept saying "why don't you switch it?" He said "I have been". We switched positions with each other - same result. Zero difference.

Then we tried this test using the preamp in my HK AVR. No difference. Even had a couple visit us that night (a fine drummer & his wife who's formally trained in piano, etc) and they had the same result.

In my mind, it's hard to fathom that the HK AVR, Peach, and my TAD-150 could sound identical - but they do. 4 People here say so (adamantly). The amp was VRDs.

Hence, I still think something's amiss with the science behind this test. On paper, it should be a pure test, but......

Anyway, if you can figure this out - LMK... but we had the same result you did so you're not crazy and neither are we and the 2 others that heard it here.

[meagain]

IMHO AB switching is worthless. It takes days with one then switch days then switch.

Craig - if you were here, trust me... you'd say the same thing. Please be willing to believe what you find incredulous. I find it unfathomable also, but I can't deny the truth. Of all the various listening/testing we've done - of this one we are sure.

I can only surmise there must be something about the HT bypass that mingles things somehow.

[mikebse2a3]

IMHO AB switching is worthless. It takes days with one then switch days then switch.

Craig - if you were here, trust me... you'd say the same thing. Please be willing to believe what you find incredulous. I find it unfathomable also, but I can't deny the truth. Of all the various listening/testing we've done - of this one we are sure.

I can only surmise there must be something about the HT bypass that mingles things somehow.

I believe there is another important factor with this type of testing. when you are doing A/B Testing you are listening in a different mode (ie: you are using different parts of the Brain to Analyze what you are hearing versus when listening in a more normal and relaxed state of mind). A/B testing can get very fatiguing after a short period of time versus in a more normal listening situation of just relaxing and enjoying the music. IMHO A/B testing can show up large differences but the real test is to listen for the subtle but very important differences in details that comes from listening in a more natural state of mind.

mike[]

[meagain]

Mike - I totally agree with you on this in general. But not in this particular case with this particular test. []

[Coytee]

Mike (anyone?)...

Any thoughts on a/b'ing (either instant or over a couple days as per Craig) pre's on solid state verses tubes?

In other words, might one amp help reveal any differences moreso than the other? Thusfar, I've only listened to them on my MC-2102. I might swap to the MC-30's today.

[NOSValves]

Lisa,

I'm not saying you did not hear what you heard. I'm saying AB testing is flawed by nature.

Simply stated the differences come to surface when your NOT trying so hard. A note starts and stops more realistically, a single note sounds oh so real and so on. Audio is just not that cut and dry. You will never get instant gratification. A/B testing is a waste IMHO.

Much of what you hear in this type of setup is what your mind will tell you to hear. I literally quit telling customers what something may sound like! Why.....I got sick of everyone of them coming back with what ever I told them it would sound like. The mind is a very powerful and uncontrollable force.

I have a story for you.

A well seasoned amplifier/preamp audio designer back in the 70's took 10 well seasoned audiophiles and placed them in a room with 2 preamps of identical electrical wiring and circuit. These were both proto types. One he place all kinds of extra chokes, transformers and tubes on the top of the naked chassis but in reality they were disconnected underneath the extra tubes were strictly running heaters only so the lit up. They did a 100% AB blind test and all 10 audiophile reported the preamp with the extra components had more weight and control to the sound!!! These preamps were dead nuts electrically identical. The mind can really screw you up.

Craig

[NOSValves]

Mike (anyone?)...

Any thoughts on a/b'ing (either instant or over a couple days as per Craig) pre's on solid state verses tubes?

In other words, might one amp help reveal any differences moreso than the other? Thusfar, I've only listened to them on my MC-2102. I might swap to the MC-30's today.

I don't think the amp type is going to be better or worse for the AB testing unless one has a flaw that will translate obviously into both equations making both sound bad no matter what you do. I think instant AB testing is flawed no matter what.

Craig

[mikebse2a3]

Mike - I totally agree with you on this in general. But not in this particular case with this particular test. []

I'm not sure we are disagreeing. I believe you and the other people heard things exactly as you described. My point is unless there are large differences between equipment then listening in an Analytical Mode to the more subtle but sometimes very important musical details will not usually lead to why over time you might prefer the musical presentation of two different pre-amp designs(or any other type of equipment) and there is always the posibility that there wasn't any real differences at least in your particular system/room situation.

mike[]

[sfogg]

" Set the levels as close as I could (and indeed, the levels sounded identical)."

This is a key step. If you really want to get them matched hook a

multi-meter to your amplifiers outputs. Play a 1kHz test tone through

each pre-amp and measure the voltage at the speakers outputs. Get them

matched to within 1% and that will match levels to 0.1dB which is below

the level of audibility.

Don't be suprised if often (not always of course) a lot of differences shrink (or even disappear) when level matched.

Very few people level match when comparing different equipment. As such

in many comparisons level differences throw of comparisons. Take a room

full of audiophiles and let them A/B the exact same piece of equipment

against itself 0.3-0.5dB louder and you will get people talking about

the better focus or clarity or body (etc..etc..) of the louder of the

two. Few will recognize that amount of level difference as simply being

a volume difference.

Until someone has actually heard this is action they simply can't understand how subtle and tricky this is.

As far as preferring long auditions vs. short that is up to the user.

There is no reason you can't keep up the A/B for days or weeks if you

desired.

For some verifiable differences though being able to quickly switch

back and forth makes it dramatically easier to tell the difference.

When given weeks between comparisons ones imagination has weeks to do

its thing....

Shawn

[mikebse2a3]

Mike (anyone?)...

Any thoughts on a/b'ing (either instant or over a couple days as per Craig) pre's on solid state verses tubes?

In other words, might one amp help reveal any differences moreso than the other? Thusfar, I've only listened to them on my MC-2102. I might swap to the MC-30's today.

One thing to keep in mind when trying different pieces of equipment together is interaction between the output and input characteristics(impedance being the main one) of each piece of equipment. For example Some Solid State Amplifiers are designed with low input impedance values (ie: 10K to 20K being on the low side and many are around 47K) and if you try to drive that with some Tube Pre-Amps Designs(Especially if they don't use a cathode follower output stage or other circuit Designs to bring down their Output Circuit Impedance and thus Increase their Ability to Drive Low Impedance Loads Like Some Solid State Amps) which like to see 100K ohm input impedances or higher you can cause the Tube Pre-Amp to create higher distortion and an uneven frequency response. I believe your Peach has Two Output Options to deal with this type of impedance situation I've described, so if thats the case you will need to try both when using it with a Solid State Amp to see which works best in your situation.

mike[]

[sfogg]

Mark,

"if you are playing the same selection through A, then repeating that

selection through B, you have a better chance of obtaining useful

results."

Agreed, that way you are comparing the same thing against itself. This

is how I listen when A/B/X tested either listening to a whole song or

setting up an A-B repeat and switching at the repeat. Though the

listener is free to do it however they want.

"In a great many short-term A/B/X experiments "no statistical difference" is the most common result."

That isn't true. A/B/X testing has shown differences in many things. It

is also what has been used to determine common limits of hearing level

differences, distortions, FR differences and so on.

And there is no reason an A/B/X test has to be short term. Using an

A/B/X comparator the test can be run over days or even weeks if

desired. You want to run an A/B/X test over two weeks (or whatever)

comparing your amps or pre-amps let me know and I'll lend you my A/B/X

box.

But for some tests short term comparisons results in dramatically higher accuracy.

There is a PCABX program out there that can be interesting to play

with. A good test to use to see why switching quickly can increase

accuracy is simple level differences. Load two files that have 1dB or

less of a difference between them and set the program to have no delay

between switching. Most here should be able to pass the 1dB difference

test easily. Now set the delay to 10 seconds (meaning 10 seconds of

'dead air' switching between A, B or X) and the results are going to

drop. Set it to 1 minute and the failure rate will increase again. And

that is when the listener knows exactly what the difference is and what

to listen for.

". Now, taken as fact, that leads to the conclusion that "all good

equipment sounds the same." And, from that, all anyone needs is a $200

receiver and we are all done. Clearly then, there is something

"unuseful" about short term A/B/X testing."

Clearly that is a generalization. A/B/X testing has show differences in

equipment. And anyone that really understands what A/B/X testing does

knows that it can't prove a negative. IOW, it isn't possible to say

that there is no difference. The possibility exists that someone

somewhere may not be able to hear the differences between A and B. All

A/B/X can be used for is to prove a positive.... IOW... that xyz did

hear hear the differences between A and B.

If one person can hear the difference it proves that it is possible,

even if only one person can do it. If one person fails it does not mean

that everyone will fail.

Shawn

(P.S... not directed at Mark) JOOC... how many here have actually done

level matched (to 0.1dB) comparisons? How many have actually taken true

double blind A/B/X tests?

It has been my experience that that number is small in comparison to

those complaining about them, without really understanding what they

can and can not do and have no experience with them. They just tend to

repeat claims made by others that don't understand it either and who

also have little or no experience with it. Blind leading the blind....

[sfogg]

Mark,

Forgot to comment on this....

"This will often expose difference, but rarely expose preference. This

is because the brain process for detecting difference becomes

overwhelmed with that task.

"

A/B/X tests are all about difference testing. They are not intended to

be preference tests at all. The whole point of the test is

determining if there is an audible difference between A and B such that

the listener can identify X.

Shawn

[Coytee]

Mark, I agree with you about the passing of time/music as you try to compare. That foible entered my mind as I was doing it so one thing I tried to do, in my noobieness of trying to listen critically, was make the changeover on extended/held notes. Perhaps still not the right way of doing it but maybe my mind was thinking in right direction. (btw, did I just make up noobieness?)

Shawn, to get a test tone so you can measure the output of the amp... where does one pick up a test tone? It's not like I have four of them laying around [] Would a pink noise generator work?

[jpm]

I'm not surprised at the results.

[sfogg]

Coytee,

" It's not like I have four of them laying around "

You probably do. Have any of the Stereophile test CDs? They all have

1kHz test tones on them. Ditto many of the other pretty common 'test'

CDs that are out there.

1kHz is better then pink noise for this as it is more consistent.

Mark,

I was disagreeing with the 'great many' comment. Now you are saying many do while many don't. I agree with that.

Shawn

[meagain]

We did the test every which way we could think of. Played music that had repetitive duplicate parts, switched on various long/sustained electronic notes, and even ran a loop so the same exact music is repeated. Then also listened for long periods of time to one then the other. All I know is there's 4 people here who claimed zero difference.

When I do other a/b tests like switch the VRDs from Triode to Ultra Linear, I can tell an instant, dramatic difference between the 2. Not sure if others find this subtle or dramatic (like me)... but it sort of tells me I'm not deaf?

I don't understand why we got these results and I question the setup. I'd be very interested in doing this a/b test with an amp switcher to avoid the HT setup aspect.

Coytee - you have an a/b switcher... Can you somehow duplicate this test with that to avoid using the HT bypass?