retrodrive

In the middle of my install I decided to go with 2 IDMAX subs powered by 2 ARC Audio 1500dr amps. That is about 1000wrms for each sub. Now I have to soundproof the whole car (including the roof). I just thought that 1 sub install would be too boring for me. Talk about the install that never gets done.

Anyway just decided to let you guys know

amlin423

Retro, How are your subs going to be mounted? Free Air? Sealed? Ported? What's the max current draw on the 1500d? I have the 2100 bridged and it's "just right" (w/ the gain a pinch over minimum)

retrodrive

Subs will be mounted about 6 inches below rear deck firing upwards. I am going with a 3/4 plexi sealed box (/www.gatelyaudio.com).

I am not sure about the 1500dr draw but its a class D (class T actually). My friend runs 2 of them and 2 4150s off a 120 amps alt and has no dimming at all.

I was thinking on going with 1 2100 since it has a little better SQ (like any a/b amp) even for subs. However 2 1500's put out more power and draw much less then 1200.

amlin423

your friend meaning Rick right? I never used my Arc for my Dyns but if he's traded his Mac amps for the Arc, I'm guessing he has his reasons...
You're using Arc parametric EQ right? Using any tools or are you doing everything by ear?

retrodrive

Yeah, that would be Rick. He actually likes ARC much better then Macintosh. You know how it is with amps though. If you are so sure there is a difference, take up Richard Clark's challange.

As far as tuning goes, I tune everything by ear and then let some music major friends of mine listen to it and make some sugesstions...worked so far

Percy

What was RC's challenge?

Percy

retrodrive

Basically he says that watts are watts and if you can see a difference between any 2 amps that are identically rated then he will give you $10k

Lemmi see if I can find the link...

I will post it later; however ,here is something about it.:

http://www.carsound.com/cgi-bin/ubbc...c&f=1&t=014100

amlin423

Very interesting..Retro, do you have any idea if anyone actually won anything?
I often wonder about the "vast" differences between amplifiers.
I once replaced my Alpine Amp with an Xtant and I thought the differences were quite noticeble...much "smoother"
However, one time..I borrowed a Jeff Rowland integrated amp (5K-6K) and compared it with my 400 dollar receiver with my MartinLogan Electrostatic speaker and let me tell you the difference was NOT night and day...in fact...I can barely tell the difference...

I bought my Mcintosh because frankly it's really not THAT much more than PPIs and RFs. It looks and the built is great. If there really is not that much difference (i've never heard the PPIs or any other amp with my system), I'm not bothered by it because I'll look at it like I bought a Mont Blanc pen...it'll write just as well as a Bic but it looks and feels better....

Also, I don't claim to have a great ear...I don't have a LOT of experience with various gears and stuff so I can't compare. But I tend to still believe there are subtle difference between various gears even if I can't hear them. Why? Because I think it's kinda like wine tasting...for me...I hate alcohol and I can't tell the difference between different vodkas, or different cognacs, or whatever..to me, it's no different than taking a gas pump and pumping fuel into my mouth...but a lot of people love wine tasting and can taste the little subtle qualities of a certain drink...those people have more exp than the avg person so I believe even if I can't taste it, someone else with a trained taste bud might. Same goes with sound..someone with a lot of experience should be able to hear minute differences between various equipment...just because I don't hear it doesn't mean the difference doesn't exist...ugghh too much babbling....just my 2cents...

retrodrive

That is what the challange is all about. I think there is some difference between amps; however it iwould be hard to hear since speaker has much greater distortion then an amp. Also the amps tested must be the same power and maybe parameters (dont remember) but different brand. If the power is different or an amp goes into cliping, then difference is obvious. Here are the rules...

THE $10,000 AMPLIFIER CHALLENGE RULES {April 21, 2000}
By Richard Clark
There is no question that all amps are not the same. It is very easy to measure large differences in the performance of amplifiers. This is true in nearly every known specification, including power, noise, distortion, etc. My experience has led me to believe that even though these differences can be easily measured, hearing those differences may not be so easy. Given the relatively small magnitude of performance differences, there is a giant step between amplifier performance and our ability to hear performance differences.
It is claimed by designers, manufacturers and especially salespersons that differences in amplifiers are clearly audible. Reasons include "obvious" advantages of one type of circuit topology over another. For example, it is claimed that certain designs have a smoother midrange response whereas other amplifiers exhibit tighter bass. Tube fanatics claim that tube amplifiers have that "warm" sound we all need in our systems.
Such descriptive terms are certainly subject to personal interpretation. It is not my intention to determine if one particular amplifier is better than another amplifier. Differences in the quality of the discrete components and constructions are more appropriate for settling the issue of "good - better - best." The sole purpose of my amplifier challenge is to determine if the differences in amplifiers are audible.

What differences are Audible?

I believe the perceived differences in amplifiers are all due to various factors that can be explained with basic physics and elementary psyco-acoustics. For instance, if two amplifiers are not carefully matched in volume, and one amp is slightly louder than the other, then it would be a simple matter to detect such a difference. In such an example it is important to understand that it is not the circuit topology, quality of the component, design excellence, or superb marketing and packaging that caused the noticeable difference - it was an error in the test setup! It is my present belief that as long as a modern amplifier is operated within its linear range (below overload), the differences between amps are inaudible to the human ear.

Comparing Amps

The idea here is for a test subject to scientifically demonstrate his/her ability to hear differences in amplifiers. It is our job to carefully match the amps so that we are comparing "apples to apples" instead of "oranges to frogs." This means that we sure wouldn't want to compare one amplifier that had + 12 dB of high frequency boost against another amplifier that was adjusted for + 12 dB of bass boost. Such a test would be easy to pass - even on identical amplifiers with consecutive serial numbers.
For our comparison test, we aren't concerned with which amplifier sounds best to the test subject. We only require that the listener be able to identify each amplifier when it is powering the speakers. Since many folks seem to believe that amplifiers have some kind of distinctive sonic character, this test should be easy to pass. Right? After all, we're talking about comparing those harsh sounding, high distortion, squeaky "widget As" to those warm sounding, smooth, bass hog "widget Bs."
Now pay particular attention to the following sections. Since we're looking for differences in amplifiers, and we already know that those differences are probably going to be very, very small, it is important that the parameters under our control be carefully adjusted so as to be equal as possible. This means that we must be cognizant of differences we might unknowingly introduce between amp A and amp B. They must be adjusted as identical as possible. We already mentioned the importance of volume. The same goes for the L and R balance. It sure would be easy to choose an amplifier that exhibited left side bias over a balanced amp. Right?
Well, in order to keep this amplifier comparison test fair, there are a few other parameters that must be considered. I'll list them all in the following section.


Amplifier Comparison Test Conditions

1. Amplifier gain controls - of both channels - are matched to within +- .05 dB.

2. Speaker wires on both amps are properly wired with respect to polarity. (+ and -)

3. That neither amp has signal phase inversion. If so correction will be made in #2 above.

4. That neither amp is loaded beyond its rated impedance.

5. That all amplifiers with signal processors have those circuits bypassed. This includes bass boost circuits, filters, etc. If frequency tailoring circuits cannot be completely bypassed an equalizer will be inserted in the signal path of one (only one and the listener can decide which) of the amps to compensate for the difference. Compensation will also be made for input and output loading that affects frequency response. Since we are only listening for differences in the sonic signature of circuit topology, the addition of an EQ in one signal path only should make the test even easier.

6. That neither amp exhibits excessive noise (including RFI).

7. That each amp can be properly driven by the test setup. Not normally a problem but it is theoretically a problem.

8. That the L and R channels are not reversed in one amp.

9. That neither amp has excessive physical noise or other indicators that can be observed by the listener.

10. That neither amp has DC OFFSET that causes audible pops when its output is switched.

11. That the channel separation of all amps in the test is at least 30 dB from 20Hz to 20kHz.

Page 1 of 2


In addition to these requirements the test will be conducted according to the following rules.

Amplifier Test Comparison Rules

1. To make things easy we would prefer to use high quality home type loudspeakers for the test. If our speakers are not acceptable, the listener can provide any commercially available speaker system as long as it uses dynamic drivers. The actual measured impedance cannot exceed the rated load impedance of the amplifiers tested. If, however, the tester would like to perform the test in a car, we will use a car, however, it will have to be provided by the test subject. For practicality we will have to limit the number of amplifier channels to four or less.

2. Amplifiers will be powered from the same power supply at a nominal 14 volts DC. (any voltage is OK as long as it is the same for both amps)

3. The test can be conducted at any volume desired; however, the amps will not be allowed to clip. In other words, listening volume can not exceed the power capacity of the smallest amp of the pair being tested. (power capacity will be defined as clipping or 2%THD 20Hz to 10kHz, whichever is less)

4. No test signals can be used - only commercially available music.

5. The listener can compare two amps at a time for as long as desired. For practical reasons we would like to keep this at least no more than a few hours. A test session will consist of 12 A/B sequences. Passing the test will require a positive identification of each amp for all 12 sequences. Remember, guessing will get you about 6 out of 12. If the differences are so great, and a subject can really hear the difference, then he/she should be able to do so for all 12 sequences.

6. To win the $10,000.00, the listener must pass two complete sessions of 12 comparisons. Passing the test means 24 correct responses.* The amp of choice can be compared to the same or a different amp in each session - challengers choice. We have many amplifiers in our demo inventory such as, but not limited to, Alpine, Rockford, Kicker, Phoenix Gold, Precision Power, MTX, Adcom, Kenwood, Pioneer, Sony, etc. You can pick any of them or bring your own.

7. All amps must be brand name, standard production, linear voltage amplifiers. This does not exclude high current amps. Amps can not be modified and must meet factory specs. They must be "car audio amplifiers designed to be powered from a car's electrical system."

8. Failure of an amp (this includes thermal shutdown) during the test will require that the test be repeated after repair or replacement or cooling of the amp. This means that the entire test session will have to be repeated.

9. The amps will not be overloaded during the session from either a voltage or current requirement.

10. To save time the listener will have to pass a quick 8 trial session to qualify for the extended 2 session test for the money prize. Any 2 amps can be used for this test. Passing this qualifying test will require at least 6 out of 8 correct answers.

11. The amplifier power up and/or power down sequence will not be acceptable for comparison. (The turn on/off noises of some amplifiers would give it away.)

12. Although anyone is welcome to take the test, only subjects employed in the car audio industry or Car Sound subscribers are eligible for the $10,000.00 prize.

13. Cost to take the test is $100.00. $300.00 for people representing companies. Payable in advance, scheduled appointments only. Done correctly the test takes several hours and I don't have the time if you aren't serious.

* Twelve correct responses in a row is certainly a lot of correct listening but $10,000 is also a lot of money for a few hours of easy listening. The way people describe the differences is that they are like night and day. I would certainly not have any trouble choosing between an apple and an orange 12 times in a row. When compared fairly I believe the differences in amps are much too small to audibly detect and certainly too small to pay large sums of extra money for. If I am wrong someone should be able to carefully take this test and win my money. Even if I am right, if enough people take the test eventually someone will take my money due to random chance. This is the reason for the large sample requirement. If you feel that you can easily pass this test but 12 sequences will give you "listening fatigue" I am willing to modify the requirements. Since the way it is being offered is a challenge and only my money is at risk I am willing to let a confident challenger "put his money where his ears are". If we are willing to make this a bet instead of a challenge, I am willing to drop 1 sequence for every thousand dollars put up by the challenger against my money. This would mean:


____My___________ _ _Your________Trails Required to win__
$10,000 to $0 = 12 Tries
$9,000 to $1,000 = 11 Tries
$8,000 to $2,000 = 10 Tries
$7,000 to $3,000 = 9 Tries
$6,000 to $4,000 = 8 Tries
$5,000 to $5,000 = 7 Tries
$4,000 to $6,000 = 6 Tries

I will not do the test with less than 6 trails. It would be statistically meaningless and reduce the challenge to mere gambling.

Kyle Harty

iTrader: (17)

Retro, very nice.

RC has the amp challenge set up so no one wins, the tests eliminate all differences between amps such as power, clipping; all that stuff. I just heard something a little while back about his changing the rules to allow some clipping. He said he'd tested a JL and Jensen amp at different levels, put them both into clipping and still didn't hear a difference. Maybe the new rules will give someone a chance since clipping seems to be one of the main theories as to where we hear a difference between amps. Who knows, I guess I figure if it sounds better to you, use it regardless of what Richard says, you're the one who has to listen to it.

retrodrive

You can always get Pyramid build a custom amp to match the power of one of the brax amps and see how they sound. I am pretty sure they will sound differently due to the components used in both amps. Its just no one cares to really put some time and money into it.

Kove has their own challange on subs too. I think they clame to be the best sub out there (yeah right) so they use their "no one wins challange" for advertising.

Percy

For RC's comparison rules...

#1. Use Dynaudio (of course) Confidence 3's, 5's or the studio monitor series. If the Evidence speakers are available, then use them. They're extremely revealing.

#4. Use a HDCD encoded disc with a source that will handle HDCD. I've found that the better HDCD recordings can exercise a system quite thoroughly, especially with female vocals. "City of Angels" soundtrack, track 6 (Angel by Sarah McLachlin) is an excellent choice.

#7. This blows away my entry piece. Modded McIntosh MC4000M and MC440M. Auto disqualification. Grumble...

#12...hmmm...I'm not in the industry and I rarely read Car Sound.

Now as for his test conditions...

Speaker wires that I would specify...Transparent Audio Reference XL's. Nothing else. These are 7000 dollar USD cables. Same with interconnects...also Transparent Audio Ref XL. Extreme high end. For the source unit I would use either a Mark Levinson No. 39 cd player/transport or the Linn or even the Krell KPS25. The ML is the cheapest of the bunch at 6k$. The other two are 20k$ units. Or if RC will allow it, I'll use my highly modded Krell as a source unit. The only thing he's asking for are the amps not to be modded. You can take a cheapo Jensen amp versus a high end Brax Platinum or McIntosh. Guess what...you'll have to train your ears and be familiar with the source material and the acoustics of the room. Notice that he didn't want headphones being used. Headphones are NOT room dependent and often times you can pick out very small dynamics, thus this is probably why he isn't allowing this.

Also notice that his rules don't allow for ANY amp being compared to each other, for example, a Krell Full Power Balanced monoblock for home use compared with a Brax Platinum amp for car audio use. Guess what...EVERYBODY would win. The Krell FPB would beat up a Brax Platinum and McIntosh with one hand tied behind it's back...so to speak. His "watt is a watt" attitude doesn't hold water, especially if he's not willing to compare a "home watt" with a "car watt". Scientifically, they're the same. But in reality.... Thus his rule #7. His "save his a$$" rule.

It's literally a rigged challenge. You don't know what type of interconnects he's using, what type of speaker wire, which source unit (crappy in, crappy out...might not be able to tell the difference), and why he isn't willing to use a "home watt" versus a "car watt". Plus he wants to use speakers instead of some nice Sennheiser HD600's or electrostatic headphones. Loosen up the rules just a touch and guess what...he'd lose 10 grand a lot more than he wants to admit.

Percy

spykedawg

wassup pete, just wondering what you were going to do about your rear deck. if you are still cutting it, what are you going to do about the trunk lid bars (sorry i dont know the real term for them) that run across the bottom of the deck. ive only been able to enlarge the stock opening a little bit before running into them (i tried mounting my cmp on the deck, but couldn't get the opening big enough). let me know, cant wait to see/hear your ls when its done.

retrodrive

Actually the bars will stay. I have been to Streetnoyz (very pro audio store) and La Jolla Audio (60$ an hour very high end) and they both worked with LS400 cars before. They told me that the best position for the subs would be 6-8 inches below the read deck (wave developement before hitting the rear window). I will cut all the metal around the support bars and cover the holes. That would be more then enough for bass to come through.

P.S. Check out my post on ECA concerning my experements with Rainbow Pro's

Percy...RC is kind of clever about his challange since he actually made up rooles to seem fair. As far as Kove goes their challange is pure BS. Someone sent them a DD Beast and they simply said that the Kove was better. The guy didn't win anything. What a bunch of monkey sh|ts!