best upgrade ever....and it was free

[sickicw]

For the last 6 months or so I have been trying different things to get my lsi9 speakers to sound there best. Well I think I just finally found the solution. About 4 months ago, I upgraded my power from an outlaw amp to a Rockford Fosgate T8004 (in bridged mode) + AC/DC power converter. I immediately noticed an increase in bass. I didn’t do any testing, but I will would estimate that the frequency roll off was around 75 - 80hz with the outlaw and around 55hz with the Rockford fosgate. Big change in bass.

I stuck with this setup for a few months until yesterday I read on the forum about people bi-amping there speakers and did a little more research and decided to give it a shot. After demoing it last night, I couldn’t explain how much of a difference it made. HUGE change. Everything was much, much more dynamic. There was tighter bass slam and the mids and highs just jumped out at you (in a good way). The distorted electric guitars from rock/metal music sounded almost like the guitar amp was right in my living room and the guitar solos just threw its self from the speaker. I think the most impressive difference is when I demoed my guns and roses GNR lies CD. The acoustic guitar sounds so real.

Here are my specs from my Rockford fosgate amp….

Old setup (lsi9 left and right)…
200 W x 2 @ 4 Ohms bridged RMS
400 W x 2 @ 2 Ohms bridged RMS

New setup (lsi9 left and right bi-amped) …
50 W x 4 @ 4 Ohms RMS
100 W x 4 @ 2 Ohms RMS
200 W x 4 @ 1 Ohms RMS


Anyway, I just wanted to share my experiment with anyone who is interested. I just goes to show that even though I cut my max power to my speakers in half, I in effect doubled the max current delivered, and now my speakers sound much, much better.

[audiobliss]

That is interesting. That is also some stout amplifier. Even most car amps I've seen won't handle a 2ohm load while bridged. I don't think I've ever seen a 4-channel amp that can handle a 1ohm load on each channel.

Congrats on finding a setup you like.

[sickicw]

[QUOTE=audiobliss]That is interesting. That is also some stout amplifier. Even most car amps I've seen won't handle a 2ohm load while bridged. I don't think I've ever seen a 4-channel amp that can handle a 1ohm load on each channel.QUOTE]


yea, i think rockford is to car amps as krell is to home amps. I cant really afford krell, but I can afford rockford.

[audiobliss]

Well, I'm personally not fond of Rockford Fosgate period, but that is undoubtedly one solid amp.

[sickicw]

yea, i have head people say they didnt like there lower end amps, i am happy with what i have. Why dont you like rockford?

[F1nut]

Bridged amps should never drive speakers rated at less than 8 ohms.

[audiobliss]

I would say that totally depends on the amp. In this case, the amp is stable down to 1 ohm, so it still should have quite a bit of headroom bridged into 4ohms. There just aren't that many HA amps that have that much current. And if they do, then they usually have enough power that bridging isn't a concern.

However, obviously it wasn't a great solution since so much was gained when it was setup for bi-amping instead.

[F1nut]

I've yet to see a stereo amp that when bridged was rated to drive less than 8ohm speakers. As for car amps, I have next to no experience, but I find it hard to believe that a car amp can have more current than a stereo amp. Does anyone know how much current this Rockford amp has?

[audiobliss]

Just as a quick commentary on CA amps, they generally have a lot more power than the typical HA amp, in part, because they have to. There are no 8ohm car speakers. They're 4ohms. And subs can be wired to provide anywhere from a 4ohm load to, if I'm not mistaken, a 1/2 ohm load. In short, CA amps are built to handle low-resistance loads moreso than your typical HA amp is.

I can't find any info on the current, but you can tell it has to be a good bit from some of the specs. I'll keep looking for a few more minutes.

I got this off Rockford Fosgate's website:
Rated Power:
50 W x 4 @ 4 Ohms RMS
100 W x 4 @ 2 Ohms RMS
200 W x 4 @ 1 Ohms RMS
200 W x 2 @ 4 Ohms bridged RMS
400 W x 2 @ 2 Ohms bridged RMS

Total Power:
800 Watts

Bridgeable:
Yes

Circuit Topology Class:
Class A/B

[audiobliss]

There's no mention of current in the owner's manual, but here's a screen shot I took from one page of the specs. It lists the wattage and that they recommend a 150A fuse. I wonder if that would help guesstimate as to the current?

[comer]

From "2005 PowerAmp electrical require" (name of the document retained original :D )
Typical Average Current Draw with music @12.6 VDC -- 75A
MAX Current Draw with sine waves @12.6 VDC -- 150A

I am not sure if link is going to work, but here (http://www.rockfordfosgate.com/scripts/rightnow.cfg/php.exe/enduser/fattach_get.php?p_sid=1WNnDN3i&p_tbl=9&p_id=452&p_created=1115933221) it is.

[sickicw]

yup, very true. That is the reason I am using a car amp instead of a home audio one. Also they are cheaper cuz low impedance is the norm for car equipment. If you want the total current just use ohms law...

amps = sqrt(watts/ohms)
volts = sqrt(watts * ohms)

800 watts at 1 ohm = 28.3 amps at 28.3 volts into constant 1 ohm load
800 watts at 2 ohms = 20 amps at 40 volts into constant 2 ohm load
800 watts at 4 ohms = 14.1 amps at 56.6 volts into constant 4 ohm load

now this is obviously not the actual numbers because the voltage will fluctuate, but it gives you an idea of what happens with a good amp that can draw more current into lower impedances. It might be accurate to think of this example as voltage being how loud the volume is and current is how dynamic the sound is.

Now as far as input to the amp, here are my calculations….

At around 50% efficiency, the amp will need 1600 watts. I use a 14 volt power supply, so that adds up to P = VI, I = P/V, I = 1600/14 = 114 amps (at 14 volts), which means you need a 114 amp AC to DC converter to push the amp to its limit (I use a 55 power converter, and don’t push it all the way to its limit).

Now to convert this to a wall plug, you get I = 1600watts / 120 volts = 13.3 amp max draw from the wall.

[sickicw]

oh yea add in to the equation that the power supply 90% efficency and you will need a bit more than 13 amp max.

[ND13]

So you're running a car amp, with a power converter, on your home speakers???

[sickicw]

So you're running a car amp, with a power converter, on your home speakers???

yup, and it sounds far better than any home audio amp that i could find for the same price.

[EricT43]

Watch out Krell, your house of cards is coming down!

Soon instead of A/V racks, we'll have carpet-covered boards with our components screwed on. Under the couch.

[audiobliss]

Soon instead of A/V racks, we'll have carpet-covered boards with our components screwed on. Under the couch.
ROFL!!! :p

[Early B.]

Let me make sure I understand what's going on here -- you "upgraded" from an Outlaw amp to a CA amp? And the Rockford sounds better on a pair of Lsi9's?

[audiobliss]

I didn't think the thread was that confusing.

[sickicw]

Let me make sure I understand what's going on here -- you "upgraded" from an Outlaw amp to a CA amp? And the Rockford sounds better on a pair of Lsi9's?

yup. at first it only sounded better because it was giving me more bass and i could use a 60hz crossover. Then i decited to bi amp the rockford and not use the bridged outputs (less watts but more current), and now it has the same amount of bass, but everything is much more dynamic, tight, and clear. The music is much more in your face which i like.

[EricT43]

sickicw, can you get yourself a PA amp and a couple more audiophile buddies and do a shoot-out?

[jcaut]

Car amp for home audio. Ugh. I've not tried it though, so I can't really comment. I'm glad you're getting a sound that you like. One thing's for sure: You'd have to have one heck of an AC-DC power supply to run a high powered car amp and have any hope of getting the kind of current you think you're getting.

[sickicw]

im not so sure a PA amp would sound very good. i did look into it for a bit, but noticed most of them were geated toward SPL and not sound quality. Also most are just as low current as home audio amps. They have high power ratings, but i don't really need that much power, just lots of current.

[sickicw]

You'd have to have one heck of an AC-DC power supply to run a high powered car amp and have any hope of getting the kind of current you think you're getting.

I have a used 55amp power supply that i got from ebay. I think i am pushing it close to its max output (i also have a 1 farad capacitor and the voltage reading turns on when it is drawing current) when i turn it up really loud.

[marvda1]

watch the power ratings on car amps as they are not required by the same laws/standards as home equipment as to how they measure their power and come up with their "watts"

[audiobliss]

Never heard that before. But, given you're dealing with a reputable name (which RF is), then CA amps are under rated, and quite often grossly under rated.

[EricT43]

im not so sure a PA amp would sound very good. i did look into it for a bit, but noticed most of them were geated toward SPL and not sound quality. Also most are just as low current as home audio amps. They have high power ratings, but i don't really need that much power, just lots of current.

You may be right, but I know a lot of people are using pro audio amps in their home rigs.

[sickicw]

yea, they included the test documentation with my amp and it gives the efficiency and max watts tested. The output was well beyond the advertised amount and still under 0.05 distortion.

[audiobliss]

You may be right, but I know a lot of people are using pro audio amps in their home rigs.
I would always prefer to use a quality HA amp than anything else, but I'd certainly rather run a CA amp than a PA amp.

[comer]

I am totally clueless in car audio, but don't their amps have a crossover and EQ inside (to correct for specifics of car acoustic and feed the sub) or you can actually run it as a straight amp without any EQ "correction"?

[audiobliss]

The nicer ones do have EQ's and crossovers and such, but they can always be disabled.

[brettw22]

Sorry.....but I have to clarify this...... the RF amp should in no way/shape/form be compared to Krell.........ever.

I'd like to see a picture of this setup........but I'd also warn you that if you blow your speakers by using an amp that is not designed for the purpose in which you're using it, you could very well be blowing your warranty as well as the speakers.

[F1nut]

My home amp has an output current of 96 amps. :p

[EricT43]

Sorry.....but I have to clarify this...... the RF amp should in no way/shape/form be compared to Krell.........ever.


See? They're already gettin' nervous ;)

[audiobliss]

Well, I think I'd agree that you can't compare it to Krell, Bryston, Monarchy, Musical Fidelity, Niles, Parasound, Sunfire, etc. But, it sure beats the stuffing out of PA and pro amps, and I certainly wouldn't be surprised if it hangs with or outdoes some Outlaw, NAD, Rotel, and B&K stuff, dependent of course on the specific amps.

[Chrisssssssss]

Hey there,
I agree. I am thinking on powering some house components with some car stuff. I have a huge collection of both and have large systems in all my cars. I have a abundance of car stuff left over and was thinking on putting them into active duty in the house. One way of powering these things are to use a few car batts wired paralell and then using a large battery charger to keep the current flowing. That way you will have the amperage avail if needed and then the chargers will keep the batts topped off when the current flow is less than being used. A couple of deep cycle batts and a heavy duty batt charger and you're off to the races. That's how places like Best Buy and the like are able to demo car product in the store.

[TroyD]

Eh, pumps your nads.

There are some amps that, bridged, are stable into low impedances. My Classe gives ratings into 2 ohms bridged.

BDT

[Dennis Gardner]

Hey, I've thinkin' that with all this extra home stuff I have I could put a killer 2channel BAT tube amp powered, Clearaudio turntable rig in my Ford Festiva. Anyone know of a particular phono preamp (moving coil of course) that would work best under these conditions? This would definatley kick the ass of any stuff the car audio guys could put into their mega buck cd receiver installs since we all know that under all conditions vinyl rules.

WTB: 100 mile extension cord, preferably 12 gauge.:rolleyes:

[F1nut]

There are some amps that, bridged, are stable into low impedances. My Classe gives ratings into 2 ohms bridged.

BDT

Well, there ya go.....I learned something new today.

[dudeinaroom]

back in the day all I used in my bed room was car audio amps. There's a few car audio amps that can match some of the better home audio amps. If your going to use a car amp in you home setup, make sure you have a desent capacitor, not only does it give you reserve current, but also helps to kill power supply noise. Rf hade some really good amps int late 80's early 90's but kinda went to the birds around 94, but from what I have been seeing, and hearing they are right back on track. If you wanna try this I would recomend rockford fosgate, soundstream(NOT SOUND STORM), some of the upper modles from hifonics(who has also recently bounced back from the cheapper is better designs) ppi, orion, and dei, stay away from class d amps for any thing but a sub.

[audiobliss]

Dennis Gardner - Thanks for your contribution.

[Dennis Gardner]

Dennis Gardner - Thanks for your contribution.

No problem..............I've actually run CA gear as home stereo stuff years ago and agree that the amps are powerful, and if you get lucky in the noise department, can sound pretty good. CA gear is a more reasonable buy when you compare WPC in low impedance loads.

I think that in this situation, and no disrespect intended, but if you can't afford to properly power the LSi series, or any other higher end (low impedance) design, you should find another speaker choice. They deserve it and anything less is a compromise. I guess my motto would be "Buy the most speaker you can afford to drive". I would love to have those B&W 800Ds that I listened to last month, but I would have to drive them with a walkman and "70s Marantz integrated since I would have to sell all my gear to afford the speakers themselves.

With that said, I fully appreciate anyones budget concerns and respect their choices on how to deal with that concern and applaud their workaround solutions, such as tweaks to DVD/universals, DIY, kits etc.

We all enjoy audio and in the future, when we are looking back on our paths to our current systems, I certainly expect each of us to chuckle at the choices we made to get the best sound out of what we had to work with.

Enjoy!! and keep tweakin'...

DG

[audiobliss]

Well, thank you for expounding upon your viewpoint. IMO your argument is a lot more effective, now. :p

[sickicw]

Chrisssss, I would not use car batteries for this for many reasons. First it can be a fire and toxic hazard. Second you won’t be able to find a battery charger to keep up with the batteries. Just look for a good high current AC to DC converter and hook it to a large capacitor. I use cascade audio for my converter. Take a look at there web site. Also I was talking to circuit city on how they power there car audio stuff and they use a high current converter as well, but a different brand than cascade.

[Zen Dragon]

I have a used 55amp power supply that i got from ebay. I think i am pushing it close to its max output (i also have a 1 farad capacitor and the voltage reading turns on when it is drawing current) when i turn it up really loud.

At those current ratings you should also be using 8 or preferably 6 gage wire for the connections from the power supply to the amp. (Assuming 55A max) Ultimately this is what makes such a set-up impracticle for most home users. The amp itself may have been cheaper, however the cash then needs to be laid out for a quality power supply unit. A unit that puts out that kind of current with low ripple and good regulation is relatively expensive. You are also near the point where most manufacturers at that current output set the unit up for 220V input to the power supply.
Large power supplys are not very efficient either as can be attested to by the amount of heat they throw off when operated in high current mode. I would be surprised if you are getting 90% efficiency from a used ebay supply. Check the ratings on the unit as to power and or current usage and make sure you are plugged into an outlet that can handle the current draw. Depending on the efficiency of the unit a power supply pushing 55A could be drawing 20A or more of wall current. Make sure your electrical outlet is rated correctly.

[sickicw]

the converter i am using uses a switching system, UL listed, and is very efficient. i am using 4 gauge wire from the converter and cap through distrubution blocks and then 0/1 gauge wire to the amp. yes, the converter is pretty expensive, but i found a good deal on a used one. I am going to be running new lines from my fuse panel to my living room soon, so i will have more power to play with. When this happends, i might try to demo a krell showcase amp and do a A/B comparision between the two.

[Zen Dragon]

Kudos on the wire gage. More than sufficient. So the Fosgate amp will accept 0/1 gage wire! That must be a pretty impressive connection block on the amp.
Rock on.

[LuSh]

This entire thread boggles my mind.

[AndyGwis]

Enjoy your rigged rig!

[francis1967]

Just need to subscribe to this as I want to get back to this thread later...

[heiney9]

I believe someone asked for pictures...where are the GD pictures? I'm thinking this looks like a science experiment gone mad :) :D .

H9

P.s. Where are the pics!

[sickicw]

yea, I guess I could post some pictures this weekend….

Actually, I am still in the experimental stages of the game, but I have been expanding on my car amp system. About a month ago I got another 55 amp power supply and hooked it up in parallel with my other 55 amp power supply. Of course I also have 12 gauge extension cords running from different parts of the house so as not to drain one entire 15 amp circuit. This addition has made the sound even more dynamic (especially with dolby digital or TDS sources). There is almost no current compression at all with my amp. I can tell that my amp is almost never starved for current because my capacitor voltage display only turns on when the cap is discharging. The only time I can ever get it to temporarily discharge is when I am watching battlestar galactica in high definition on universal hd channel. And let me tell you this show sounds awesome when I turn it up loud with my setup. I wish I could experiment on my system with Dolby truehd or DTS-HD Master, but I will have to wait for that. I am under the impression it will give me even more current compression, and might need to add even more power.

So my next steps in my setup are as follows:
1) Hire electrician to install four 20 amp dedicated lines (two for the power supplies, one for the my velodyne HGS-15, and one for everything else), and to replace my 14 gauge rear speaker cables (in wall) with duel 12 gauge cables. This will let me bi- amp the rear lsi speakers.
2) Buy two more 55 amp power supplies and one more Rockford car amp, along with all the stuff to wire them together. Two channels of the new Rockford amp will go to the center channel speaker, and the other two channels will go to each of the “high frequency” input of the lsi rears speakers. The “low frequency“ inputs of the lsi rear speakers will be powered by my onkyo receiver. My outlaw audio amp gets pulled out of the system.
3) Build a nice looking box for the four power supplies and run them all in parallel along with the capacitor. Also will add some switches and stuff to turn on/off each amp.
4) Buy some “Mondo traps” from real traps website to put behind my front and center speakers. Might end up building these traps myself if I have the time.
5) When I decide on a good 1080p TV, I will buy that along with new salamander furniture to put all my stuff in.
6) I am buying a ps3 in November for 1080p source and next generation audio.
7) Then by the end of the year, I hope to buy a new receiver or preamp that can support the next generation audio formats (either PCM and/or encoded DD DTS HD) over hdmi from the blu-ray player. Denon, and Yamaha already have receivers for this, but I am waiting for Onkyo or some nice pre-amp.
8) Buy some beer and camp out in front of my complete home theater system.

[ohskigod]

I would always prefer to use a quality HA amp than anything else, but I'd certainly rather run a CA amp than a PA amp.


I dont know dude, there are some pretty good pro audio amps out there.

I think for many speakers out there, home theater amps would be far better, but the LSi is kind of a different animal. we all know the power whores they can be. The LSi just might be one of those speakers that having more power is better than having a lesser powerred amp with better sound quality.

I noticed a substantial difference in the LSI15's performance going from the outlaw monoblocks to my Carver 4.0t (basically going from 300 - 500 watts)

the LSi's love gobs of power, this isnt a secret. If the Rockford car amp is the best way to get the most out of your LSi's, then god bless bud. Most car amps I've seen suck, but I am quite familiar with Rochford Fosgates solid rep as being well built car audio amps.

[sickicw]

OK, here are some pics.......

[Holydoc]

That is seriously too much for me. I don't even have a wife, and it would not meet my WAF!

LOL

[sickicw]

Yea, I plan to have all this done before i get married (see step 3 of my 8 step program above). I think when im all done, it should all be hidden pretty good in my salamander tv stand. Hopefully it will all be worth it.

[dudeinaroom]

rock on man. brings back memorys of 15 years ago

[audiobliss]

I dont know dude, there are some pretty good pro audio amps out there.
Perhaps so. I believe when I first posted that I was a little misinformed as to what a pro audio amp actually is. Anyhoo, from what I've read I'd say your argument abotu LSi's being power hungry is probably pretty accurate. I guess such blanket statements as I made can't ever really be safely made, and that each situation must really be assessed individually, and that by the main listener.

[tonyb]

The only thing missing is the lightning rod sticking thru the roof!
That would be a nice set-up......in a motor home.

[heiney9]

I have to give you credit for thinking outside the box (equipment case :p ). It certainly is nothing I would choose to do, but it seems like you're having fun and have turned it into a DIY project. This is what this hobby is all about.....having fun and trying different things. You have a great attitude about it as well.

H9

[del44]

Them pics are sick, sickicw. Thumbs up. Definently something I mighta done back in the day. Pretty clean too.

[HiPerf360]

The only thing missing is the lightning rod sticking thru the roof!
That would be a nice set-up......in a motor home.

Awesome!

[SKsolutions]

If you tuck it under the couch, don't fall asleep with your beer.