Still comparing amps for a minor upgrade. Some amps advertise that they will accept speaker level inputs while most do not. However, all amp specs will list input sensitivity and they range from some millivolt range on up to a couple of volts, five volts, eight volts, twelve volts, etc. Exactly what would be needed to accept speaker level inputs and not use line level converters? Anything peculiar here on the standard Lexus speaker levels (I have a premium package system, not ML). I assume that if you get an amp that will accept full 14.4 volts that you would be safe but I was just wondering if some of these other amps can be used to accept speaker level inputs whether they are advertised for it or not.

 

Ron,

The only way to get an amp to accept non line level voltages is if they have a line level converter built in. They will always list whether or not an amp has this capability. In fact, most of the time, only a mid to low end amp will have this feature. The companies will figure that if you're doing something mid to high end then you'll be using a decent head unit with line level outputs anyways.

DO NOT hook up the stock head unit output (from speaker) to an amp that doesn't have a built in line level converter. You're taking a high level voltage and a good amount of current that will FRY an amp without a LLC (line level converter) built in. The listings that some amps give (4 volt input, etc) is for a low voltage, low current input. Anything higher than 1/2 an amp will fry the amplifier in question.

I think you're mixing up the 14.4 volts with a different figure. The 14.4 volt is used for a power supply from the car batter itself. This is NOT for a signal input, but rather for a battery supply input.

Do it right. Get a Line Level converter module if you're going to use the stock head/stock amp. You can't seperate the two without a lot of hassle (relay IC's are built into the amp).

Percy

 

Thanks Percy. That answered that question. Wasn't confused about the voltage. Never spent much time with audio amps, just wondering if the amp output exceeds power supply voltage which, unless they build it up, would limit at something less than the battery supply (50 or 60% for most op amps I have worked with). When you get to RF and up power amplifiers, typically voltage is not increasing much with power out but they build up considerably from line voltage. Not trying to figure out mobile audio amps, just curious. Is there any rough range on what kind of max voltage/current you do get out of an audio amp (say for a 50W amp) to the speakers? Mac may have placed that announcement about some new amps that will accept line level inputs but I haven't seen one advertised for sale yet. Thanks again.

 

Ron,

Due to the wonderful DC/DC converter that EVERY amp has, exceeding battery supply voltage is no problem. The McIntosh 4000M 1000 watt amp will have a +/- 58 volt rail, that is, 58 volts per swing or 116 volts total. That's for one of the 300 watt channels. A 100 watt channel will have 36 volts per side or 72 volts total swing. Usually with Ohms law, when voltage rises from a known source, current drops. But, there's so much current in a car battery that in most cases (unless you're doing SPL) that it's really a no issue. The alternators are fused for 125 amps and that's plenty of current. The better amps will have better internal circuitry, better filtering, tightly regulated voltage and all the other goodies. Also, the higher end amps will have a fan built in...sure works better than touching a hot heat sink by accident!

The Op Amps (the input/output buffers that every signal sees) are, at least in McIntosh amps, have a +/- 15 volt power supply controlled by a seperate DC/DC converter. The cheaper amps might use a +/- 5 volt supply and this will reduce the dynamic range. 99% of the companies out there will use the NE5532, TL074, Rohm or Motorola equivalent in op amps. Zapco, Alpine, Sony, Xtant and even McIntosh will use them. This is their weak spot! Zapco advertises a 55v/us slew rate but their op amp isn't rated for that speed. I spoke with a design engineer from Zapco and he said it uses TL074's and NE5532's. With TL074's, it's MUCH less than 55v/us, more like 10v/us or less. This is an amps "0-60" in response to an input signal. Depends on where you measure! All the company has to do is switch out the op amps and the amp will sound WORLDS better. That's why high end head units (Sony C90/Sony XESZ50/Pioneer ODR/McIntosh MX406 and MX4000, Clarion DRX9255's) are still known for their sound quality. Reason, better power supply (+/- 15 volt regulated) and their choice of op amps, namely the OP275 Analog Devices. In Mc's and Clarions case, the Burr Brown OP2604. But, most companies would rather pay a nickel a pop for a dual input op amp than 3 bucks a pop.

Prediction...If a company were to use the Burr Brown OP627 op amp (they're single so they need to be doubled up) in a production amp or head unit, and with the properly regulated power supply, I can GUARANTEE that this will blow everything else out of the water in terms of sound quality. Zapco? Not a chance. Stock McIntosh? No go. Genesis amps? Not them either. PPI, Phoenix Gold, and all the others out there? Nope. Only problem...they're 15 bucks each. Well worth the cost though if you're after the ULTIMATE in sound quality.

As for the Mc amps with the built in LLC's, I don't know if they've built them yet. Call McIntosh directly as they've been known to announce a product but not build the product due to lack of demand. Mc amps are built on a production run (they set aside time for certain pieces) so don't be surprised if you're on a waiting list. Mc was also planning on building a Dolby Digital/DTS decoder back in '98 to be the "King of processors" but this hasn't happened yet. Their projected cost was around 3 grand and was meant to blow the KEF processor out of the water. The KEF, IMO, is the top end right now.

Percy

 

Percy,

As always, have to start by saying thanks to you and Mean Gene as well. Fascinating stuff this. Generally, my world starts at around 15 MHz and I have one program working on 3GHz filters now. Last Burr Brown amps we bought were more like $120 apiece but some of that was packaging. Thanks once again for the explanation. Don't know if anyone else here is interested in this level but I am. Keep trying to find the simplest way to improve my stock system (OK, so maybe I am foolish in that expectation, wouldn't be the first time). Trying to collect all the pieces and then have at it (also finishing off the garage so I have a place to play now). I have the Dyns (going to use a Dyn sub as well) and I have pretty well decided to be done with it and use a MCC446 for everything with external LLCs. May not qualify for the exotic end but it will probably far exceed my hearing and the stock system as well. Just don't like the LLCs but I want to stay with the stock head unit so I guess I have no choice. Any recommendations on LLCs would be appreciated.

Just to wind up, so on a 100W speaker at the full 100W there is roughly a little more than an amp going to it, correct? Never really thought about it. I understand the difference between sound quality versus pure SPL but from glancing at the auto sound mags, I wonder how many of those guys appreciate slew rate (TL074, not much less expensive than that) or the impact on sound quality. Heck, I wonder if I appreciate the impact on sound quality. The MCC446 is pricey enough without a few hundred buck adder for higher spec parts. Still, if someone took your challenge and made high quality equipment with high quality components and got the sales.....

Ron

 

Ron,

It's more like 5 amps per speaker if you're going for 100 watts rms. I squared R or current squared times resistance. 5x5=25 for the current. 25x4 (4 ohm resistance) for the speaker. 1 amp is about 4 watts if the speaker is exactly at 4 ohms. This doesn't account for impedance changes and assumes a flat and ideal 4 ohm impedance throughout the speakers working range. Nearly impossible except for ribbon speakers. That's where the Zobel network comes in...smooths out impedance changes.

Try PAC for line level converters. Arguably the best there is. The cheaper ones overheat and smell all over the place of burnt plastic, resin and other components. Forgot their website though....

Percy

 

Percy - IsquaredR works why doesn't VI? If there is something on the order of 75 V PtoP, seemed like an amp or so could work. I am probably getting muddled with the load being a reactance and these simple calculations are just going to lead to heartbreak. But say 5A, that is sort of what I was curious about. Now, unless you think this thread is getting too narrow, how does this relate to speaker wire and the LLCs? Just bigger is better?

Ron

 

Ron,

Keep it simple! Ohms law. Just because a power supply has the ability to produce 75 volts peak to peak doesn't mean that there is a demand for all of it!

Speaker wire and interconnects...buy the best that you can afford. Low level signals are very sensitive to cabling. Some will hear differences between cables, some won't. As for my experience, cabling makes a big difference. If you were to compare a "zip cord" wire versus some of the mid to high end Monster home M series products, the difference is like night and day.

Also applies to LLC's. Get the best that you can afford. Do your homework and RESEARCH!

Just remember that in some cases, what looks great on paper in terms of specs will actually not sound great! Titanium tweeters are an example....but don't get me started on that one!

Percy

 

this is is where im gonna get the correct info me thinks ...

i know you can by-pass the factory amp(but keep it connected)
what i need to know in laymans terms is how!
what cables can i disconnect to put in LLC,I will be fitting FOCAL 165W in the front doors,possibly MB QUART in the rear and 2 KICKER SOLOBARICS in the trunk...im not yet sure on which amps to use or the number of amps(or channels/wattage) i have done BIG system instals before but this Lexus Active system is kinda throwing me.

if some one out there can give me usefull advice then i would greatly appreciate it..

im also gonna be fitting (i already have it from my last car)

Dietz cableing and fuses etc and a Brack 1 farad power cap to help the sub amp keep its juice

 

What are your system goals? Some SPL? Earbleeding SPL? Good SQ? Ultimate SQ?

Percy

 

blownis200 - Percy is going to give you far more definitive help if you give him enough info to help you. The LLCs, line level converters, take speaker level signals and reduce them to levels required by better amps, usually referred to as RCA inputs which describes the connector nothing to do with the signal strength but this is probably getting too confusing. It would be great to grab the signal before the amp in the stock setup because everytime you do anything to an electrical signal, you distort it slightly, but my understanding so far is that the Lexus setup is not friendly to this approach. So you disconnect the wires at the factory speakers and run them through the LLC, assuming you are not using an aftermarket amp that can take the higher level signals directly, and then send them to your amp. After the amp does its magic on the signal you return it to the speaker for that location. Don't know what Percy and MG think about some of the books on car stereo but if you get to a book store take a peek, in the automotive section. At least they cover some of the basics on how the systems are configured and approaches to modifications.

 

well i am in the right place,basically i want good SQ,the solobarics will give me the bass i require,they will be (amp for the solobarics) controlled by a remote so can turn it to my desired level.

so basically i run the signals from the speaker wires,.......so for the rear shealf i would be better using a 4 ch amp so what would be the best point to take a signal to power the KICKERS,take a signal from the 4ch to another amp,and use a 4ch to power the doors,give me the info as technically as you wish i will understand,i have done it all before,just not on these active systems(normally i do everything new,e.g,strip the car and re-wire)

 

blownIS200 - Still figure Percy will give a more detailed answer. The PAC line level converters have two converter channels in each. I am using a Mac six channel amp so I am setting up to use one LLC for left (front and rear) and one for right (front and rear). Then I will use a third for the sub and run two channels together. I am probably not getting the same desired goal as you are so we should see what Percy weighs in with.

 

Blown - Which Lexus R U putting this system in? I ask only because I had major trouble trying to fit the Focal Xpert 7" midbass driver in the front doors of my GS4 ( 2 29/32" mounting depth ) - came too close to the window track for my comfort so I ended up settling on Diamond Audio HEX 6.5's for the front midbass - they have a mounting depth of 2 1/8" & play within 2 Hz of the Focal 7" so it was basically an even swap & I lost little in terms of SQ. FWIW - I squeezed a Diamond HEX 8" driver in the back doors ( depth of 3 3/8" ) & it was VERY tight but so far, so good. As far as BASIC installation instructions, I've found it hard to beat Crutchfield's info. Their advice is easy for the neophyte audiophile to follow & is easy to access either via www.crutchfield.com or by purchasing equipment from them or their installation manuals/videos.
BTW - the link to PAC is www.peripheral-aamp.com
Have fun!!

 

thanks,
this will all be going into an IS200,basicaly the same as the IS300

If your using only one LLC for left and right i assume you have lost your front/rear fade,i want to keep all these functions so in reality i want perfect SQ

As for speaker depth thats a problem i will solve when i get to it,but at the mo im after getting the FOCALS,...........