I need more power

[fmw]

One more thing. If you build a switchbox it needs to be silent. Otherwise you will be able to tell whether a change was made in the equipment by the number of clicks you hear. We went through problem in our tests and finally ended up not using a switch. We could unplug and replug components in the same way so as not to tip off the listener what was happening.

 

[Midcow2]

Drive the fronts only with a 2 channel power amp

You only need power for two channels

Here is a very good 2-channel amp for $349.95, Behringer EP2500 Power Amp
http://www.zzounds.com/item--BEHEP2500 ( the blemished amp listed is even a better price at $269.95)

Your sound will be mainly due to you speakers and their quality. However, if your speakers were previously under powered , especially at higher dB levels, then you you might experience a fuller, richer sound with more POWER!

 

[OttoMatic]

1. Level matching needs to be done with a voltmeter and levels should be matched to within .1 volts.

That should be no problem. Any problem with matching at 1Khz?

2. If you can build a switch box or comparator, that's great.

Yes, I'd probably build a simple switch box, no comparator, no volume control.

Remember, you need to level match every time whether you have a switchbox or not unless your switchbox is a comparator with its own volume control. This needs to be done every iteration.

I don't see why I need to set levels every time. If levels are set, and nothing changes, the levels should not change. I want to A/B fast. I would be willing to swap back and forth between components and measure levels repeatedly to ensure that they don't generally change (this would be prior to the "real" test), but I see no reason to repeatedly measure levels during the test.

3. play exactly the same input material for exactly the same amount of time for each iteration.

I would consider this. However, why not allow the listener to listen to "A" or "B" as much as desired, and then pick "X"? I mean, if I can pick which is which, I can pick which is which. Why create this restriction?

 

[avaserfi]

There is one other need with such a test: If there is a statistically significant difference found between both units should be fully analyzed to determine if these differences can be correlated to human perception and/or are malfunctioning.

This must be noted because there have been proper DBTs completed where audible differences were found, but in the end these have all be directly related to colorations induced by design (intentional or not) within one of the test units.

Additionally, it is imperative that you are using these amplifiers are moderate levels such that it is not possible to driver any tested unit to clipping as this will cause audible differences.

 

[OttoMatic]

This must be noted because there have been proper DBTs completed where audible differences were found, but in the end these have all be directly related to colorations induced by design (intentional or not) within one of the test units.

So we're already set up so that if I am able to hear differences, it is due to a malfunction?

Regarding any "coloration induced by design" -- isn't that what happens every day in loudspeaker design? Loudspeakers sound so different from one another. Why not apply this same requirement to them? Why not immediately dismiss any loudspeaker that deviates from whatever measurements with the claim that it's inherently flawed by the fact that it was created the way that it was? I've read some of your articles, and unless I'm mistaken, using the underlying logic, we should be able to pick loudspeakers based on measurements, right? Why does everyone endorse auditioning loudspeakers at all?

 

[OttoMatic]

I want to be sure I'm clear about the unit under test. Basically, I want to compare an old Denon receiver any the combination of a Cary Cinema 11 and a Sunfire Cinema Grand. Yes, I will be replacing two devices with one. As I noted previously, this should test the preamp, DACs and amplifier. I will feed both the Denon and the Cary a digital signal from either a PC or a BluRay player. It may be necessary to feed one with optical, and one with digital coax. If necessary, I can do the full test, then swap which device is receiving the digital signal from the optical connection and which device is receiving the digital signal from the coax connection. I can then repeat the entire test. Both units will be active at the same time, and the switch box will be at the speaker cable level. Therefore, when I do the switch, there should be only a minimal delay in audio coming from the speakers, and there should be no change whatsoever in level or program material.

 

[avaserfi]

So we're already set up so that if I am able to hear differences, it is due to a malfunction?

That is not what I said, but rather, for a proper test to be completed if the case there audible differences arise such possibilities must be tested. The knowledgeable objective argument is that differences in audibility can be measured and correlated directly to perception. If there are audible differences it is a requirement to ensure proper [inaudible] functioning of the equipment. This is in the interest of thorough investigation as that seems to be your goal. In the end, your individual test will do little to nothing to sway the scientific conclusions published in credible journals such as the AES. Rather, your results will, if properly conducted, will result in a reassertion of the findings already published.

More information on previously conducted DBTs can be found in this thread. The situation where audibility of amplifiers is actually discussed as well where an amp with non-linear frequency response (relatively rare) is compared to one with a linear frequency response. This cause of audible difference was only found via proper testing of the equipment.

Regarding any "coloration induced by design" -- isn't that what happens every day in loudspeaker design? Loudspeakers sound so different from one another. Why not apply this same requirement to them? Why not immediately dismiss any loudspeaker that deviates from whatever measurements with the claim that it's inherently flawed by the fact that it was created the way that it was? I've read some of your articles, and unless I'm mistaken, using the underlying logic, we should be able to pick loudspeakers based on measurements, right? Why does everyone endorse auditioning loudspeakers at all?

Not all loudspeakers have coloration by design, but almost all do. That being said there are virtually no loudspeakers DIY or commercial that are are neutral while many components can be neutral. This is due to cost of manufacturing and development. As far as auditioning loudspeakers I personally do not endorse such a method under typical sighted procedures. Rather, with proper knowledge, use of measurements is a far more accurate method of choosing an ideal speaker with optimal sound quality characteristics.

 

[Midcow2]

nice specs ,nice speaker = superb sound!

Higher quality/sensitivity speakers will yield a more audible advantage.

It's a fact.

I agree completely! Get some speakers with really nice specs for superb sound!
Specs
Enclosure Type Woofer: Front Ported
Enclosure Type Midrange: Rear Ported
Enclosure Type Tweeter: Sealed
Woofers: One - 13 inch (33.0 cm)
One - 15 inch (38.2 cm)
Midrange: Two - 6 ¾ (17.78 cm)
Tweeter: One - 1 inch inverted dome (2.54 cm)
Super Tweeter: One - 1 inch rear firing (2.54 cm)
Sensitivity: 95 db @ 1 watt (2.83V at one meter)
Nominal Impedance: 4 ohms, 3 ohms minimal
Minimum Amplifier Power: 7 watts per channel
Frequency Rexponse: +0, -3 dB 19.5 Hz - 22.5 kHz
Average in-room response

 

[fmw]

That should be no problem. Any problem with matching at 1Khz?

2. If you can build a switch box or comparator, that's great.

Yes, I'd probably build a simple switch box, no comparator, no volume control.

Remember, you need to level match every time whether you have a switchbox or not unless your switchbox is a comparator with its own volume control. This needs to be done every iteration.

I don't see why I need to set levels every time. If levels are set, and nothing changes, the levels should not change. I want to A/B fast. I would be willing to swap back and forth between components and measure levels repeatedly to ensure that they don't generally change (this would be prior to the "real" test), but I see no reason to repeatedly measure levels during the test.



I would consider this. However, why not allow the listener to listen to "A" or "B" as much as desired, and then pick "X"? I mean, if I can pick which is which, I can pick which is which. Why create this restriction?

Yes, you're right. The units themselves have volume controls. I was thinking of something else. Once they are level matched they will stay that way.

The reason you want some results as I suggested is that you want to be in line with other bias controlled tests using the same procedures. Otherwise someone will criticize your results. If the music and time frame aren't the same then some people, including me, would consider the results invalid. If you want to run other tests in addition to that then, by all means, do it. The results might be the same or might be different. It would be interesting to find out.

 

[MatthewB.]

Here's my view using seperate average joe amps. In my master bedroom system I have a Denon 3808 and a Kenwood five channel amp (driving the rears and center)and my Mains being driven by the Denon. There was no difference in sound whatsoever by adding the outboard amp I just took the strain off the 3808 and gave more breathing room to drive the mains, but again no difference in Audio (BTW Kenwood was only 100wpc while 3808 was 130 wpc.

Part One (cause my computer is on work air and won't let me type long posts.

 

[MatthewB.]

Part Two
On my main system I used to have a Denon 4802 and that was 125 wpc and for my rear channels I added a simple 60wpc Adcom stereo amp and noticed an immediate inprovement in sound from the lil Adcom. The sound was cleaerer and more precise compared to the Denon (and this was with a smaller watt amp. I now have an Onkyo 805 (preamp) and a H/K Citation amp driving the mains, H/K 2200 biamped driving the Center, a B&K amp driving the sides and that lil old Adcom driving my rears and although that Onkyo is a powerhouse, I noticed very small improvements by using the amps. I had em so why not us em. Best thing to do is use the amp money and buy room acoustics to get the bigger audio improvements than a simple amp can add.

 

[OttoMatic]

That is not what I said, but rather, for a proper test to be completed if the case there audible differences arise such possibilities must be tested. The knowledgeable objective argument...

Well, perhaps you didn't say exactly that any perceived difference will be directly related to a malfunction, but you do continue here in asserting that any difference that might be heard should be measurable. That may or may not be -- I really don't know. I do understand many of the measurements and specs, but I also leave open the possibilty that there are other "things" that we might not know to measure.

Supposing I can hear a difference, I would love to try to be able to resolve it to a measured difference. I am a EE by trade and a skeptic by nature, so I have no desire to try to do any hand waving or attribute differences to any type of woo-woo nonsense. However, I probably won't have the ability to measure much of anything in an effort to try to figure from where the difference has originated. I have some tools and some expertise, but probably not enough of either to perform measurement with the required level of resolution. In that event, I won't be trying to hide anything, and I will be forced to admit that it could be called something of a malfunction (or whatever other term may be applied -- coloration by design, poor design, poor components, whatever).

Now, that said, I will also submit that all of these devices have been with me for more than a year (some rather longer) and I'm familiar with each of them. There is no reason for me to believe that there is any problem with any of the devices -- from cables on up, I truly believe that all components are operating as designed and intended. I will also not run anything outside of its limits, to clipping, etc. Eveything will be done as nominally as possible and at a reasonable volume.

It is reasonable to believe that a competently designed and constructed amp should sound the same as any other. And it's reasonable to relate most (all?) measurements to audible changes. But I also believe that it's possible for devices to have an ever so slightly sonic difference, even though they measure generally the same. I've never done a DBT, though, so we'll see if it makes any difference.

I also happily admit that I might buy something just because it looks cool or because I just like it. But I think we all agree that there's nothing wrong with that.

 

[fmw]

One thing we know for sure is that there is always a measurable difference. While it might be of interest to know where the measurable difference is, it will take some fancy gear to determine that. If you can do it that's great but it isn't as important as the audible difference itself. After all, measurable differences aren't always audible.

Don't get hung up on qualitative judgments. Just get down to ID'ing the components. This is A or this is B. Anything else is interesting but fairly immaterial. Good luck.

 

[OttoMatic]

One thing we know for sure is that there is always a measurable difference. While it might be of interest to know where the measurable difference is, it will take some fancy gear to determine that. If you can do it that's great but it isn't as important as the audible difference itself. After all, measurable differences aren't always audible.

Don't get hung up on qualitative judgments. Just get down to ID'ing the components. This is A or this is B. Anything else is interesting but fairly immaterial. Good luck.

Agreed, I'm just trying to see if I can hear a difference at all; if I get into which one is "better" that's OK, but it's definitely not my goal.

The discussion is nice, but I probably won't get to this for a while. Actually, I've been talking about doing something like this for a couple years! However, my previous idea involved someone else's amp. I have all these components at my house right now, so you never know.

Thanks!

 

[zumbo]

I am going to say here, probably with much criticism, that the test itself is not along the lines of what I was stating in this thread.

This particular thread is about adding an amp to the 3808.

So the 3808 will be the pre-pro in any situation.

With the 3808 as the pre-pro, in the same room, with the same speakers.

Any amp added will not have any audible difference, unless a tube amp is used.

This is my position.

A speaker change will yield the most audible difference in every aspect.

 

[ParadigmDawg]

I just tested this out using my 3808 and MPS1 and you are wrong Zumbo!

The sound going from the 3808 and amp was just outstanding. I then disconnected the amp and not only did it not sound as good, it had no sound at all.

Crap....scratch that... I never hooked the speakers to the AVR...

I am going to say here, probably with much criticism, that the test itself is not along the lines of what I was stating in this thread.

This particular thread is about adding an amp to the 3808.

So the 3808 will be the pre-pro in any situation.

With the 3808 as the pre-pro, in the same room, with the same speakers.

Any amp added will not have any audible difference, unless a tube amp is used.

This is my position.

A speaker change will yield the most audible difference in every aspect.

 

[davidtwotrees]

............I have no desire to try to do any hand waving or attribute differences to any type of woo-woo nonsense.......

Whew. We like to keep the woo woo to a minimum around here!

 

[mtrycrafts]

OK, OK, so I know all the arguments. I've never participated in a DBT, but I might like to do something like that in my own home. I would like to compare two systems, and I would like to be able to rather instantly switch between the two. Suppose two systems:

DMP-BD30-> old Denon 170x receiver->Vandersteen
DMP-BD30->Cary Cinema 11->Sunfine Cinema Grand->Vandersteen

So we'll basically be comparing DACs, preamps and amps all in one shot. Those are all things that are generally considered to sound the same, assuming that they're all competently engineered, and operating within their limits, right?

I want to create a speaker cable switch that I can control from my chair. I can use relays, or I could run the speaker wires all the way to the chair and use a mechanical switch (yeah, relays are mechanical, but I'm talking something like a big blade switch that I would physically operate).

I can level match.

I can have my wife do the hookup of the cables so that I won't know what's what. She won't hang around, and she couldn't care less about which is which, as long as she hooks them up correctly.

I can do the math for the statistics, but I'll be happy to hear opinions from the people here on how many trials will be needed.

From there, what do I need to do to ensure that I have a proper test? I don't have any desire to cheat, or to have my more expensive gear come out the "winner". I also don't want to be accused of doing something wrong in the event that I can statistically differentiate the two.

Thanks.

You will need two switching places, at the output of the bd30 and the two amps or at the speakers from the two amps.

I think that .1V mentioned may be too high, I think you need to do no more than 1% voltage variation.
It would be a good idea to check he levels at 100Hz and 10kHz too, just to be sure. Even if your volt meter cannot do 1kHz or 10kHz, it will read something and both systems needs to be withing that 1% at the speaker terminals.

Not sure if I follow you that the wife will not be in the room? After she makes a switch so you can compare one and the other? That may work but she certainly needs to keep proper track which one is connected for each trial. Then you write down your guess and compare at the end.

 

[mtrycrafts]

There is one other need with such a test: If there is a statistically significant difference found between both units should be fully analyzed to determine if these differences can be correlated to human perception and/or are malfunctioning.

This must be noted because there have been proper DBTs completed where audible differences were found, but in the end these have all be directly related to colorations induced by design (intentional or not) within one of the test units.

Additionally, it is imperative that you are using these amplifiers are moderate levels such that it is not possible to driver any tested unit to clipping as this will cause audible differences.

If he gets a positive outcome, then further investigation is warranted why. Maybe one component was out of specs, or broken or as you said, by design.

If he cannot level match at other frequencies as I suggested, that would indicate a frequency response that is not flat enough.

 

[mtrycrafts]

Yeah, if you guys have any plans to be in the Denver/front range area, we could set this up.

I'm all ears for other opinions on protocols. I have ideas of how to do it, but I need input from here so that my results could be respected.

Thanks!

One more thought for you. Contact Tom Nousaine and see if he might be in your area. He certainly has the volt meter, the switch box and maybe whatever else needed? I think he still has nousaine@aol.com