Pre-amp to increase ohm capacity for a 8 ohm receiver?

 

New member
Username: Srkstan

Kazakhstan

Post Number: 2
Registered: Apr-04
I have been buying a home theatre system piecemeal, and I wanted good speakers. I bought some older B&W 610i speakers, which have had particularly good reviews, but I later found that they are rated for 4 ohms. Most HT receivers are only rated for 8 ohms. If I get a pre-amp and hook it up to the front pre-outs on a 8 ohm receiver, will it drive my 4 ohm speakers? If it is a stereo pre-amp, will it effect my surround sound? Are there any other pitfalls I should know about in getting a pre-amp for this purpose if it will indeed be of help?
 

Silver Member
Username: Kegger

MICHIGAN

Post Number: 163
Registered: Dec-03
i think you generally have the right idea.

but you say to a get "pre-amp" and hook that up.
that is not correct you need a 2 channel AMP.

AND YES YOU CAN USE AN EXTERNAL 2 CHANNEL AMP.
hooked to the front preamp outs of the reciever.

just obviously make sure the new amp supports
at least a 4 ohm load.

also if you pick up a quality 2channel amp you
should in theory have a better music system also.
 

Silver Member
Username: Gman

Mt. Pleasant, SC

Post Number: 450
Registered: Dec-03
The amp drives the speakers, not the pre-amp. The pre-amp just boosts the signal for the amplifier to power the speakers. A stereo pre-amp or stereo receiver is for two-channel listening, just as a stereo amplifier is for two channel listening.

For 5.1 AV surround ( 2 front speakers, 1 center speaker, two surround speakers, and a self-powered subwoofer)listening you need either a 5.1 (or 6.1 or 7.1)AV surround receiver or a separate AV preamp and a separate multi-channel amplifier. Separates are more expensive.

NAD, Arcam (more expensive usually), and Outlaw Audio make AV surround receivers for 4 ohm speakers. This is not to say that a Harman Kardon or Denon can't drive 4 ohm speakers, but they may have a problem at loud listening levels.

That is why it is generally wise to buy 8 ohm speakers, particularly for budget systems. NAD has a T743 model that is their least expensive current model. If you want to spend less you may try the older T742 (either used or possibly leftover stock) or the discontinued Outlaw Audio 1050 (although this model has Dolby Prologic, but not Dolby Prologic II). DBII can matrix the sound of a 2-channel recording (cd, LP, tuner, etc.) for 5.1 listening. But you don't need Dolby Prologic II for listening to surround DVD's and other surround sources.

At Spearit sound one can get a refurbished NAD T742 for $399. It originally listed for $649. The also sell the remaining new T742's at $449. If you need a dvd player too, they have a great deal for the T742 receiver with the NAD 512 DVD player for $599. Of course, if you already have a dvd player, you just need a receiver.

One can get the new NAD T743 (list price-$699) at various places at around 20% off--usually between $525-$575. You might be able to find a used Outlaw Audio 1050 for between $300-$400.

Remember, if you plan on getting at least a 5.1 surround system you need at least 5-channels of amplification (as long as you buy a self-powered subwoofer). It is generally unwise to buy a non-powered subwoofer in a system powered by receivers, as subwoofers require more wattage (than bookshelf speakers) to work well and will "steal" power from your other speakers, making the whole system sound worse.

If the NAD receiver is too expensive for your budget it may be wise to sell your 4 ohm speakers and get fairly efficient 8 ohm speakers--then you can get a less expensive surround receiver.
 

Silver Member
Username: Kegger

MICHIGAN

Post Number: 164
Registered: Dec-03
do you allready have the reciever?

if you do than you can go the route i mentioned.

otherwhise you might be better off "money wise" going
with a reciever that can handle the 4 ohm load
like gregory said.
 

Silver Member
Username: Gman

Mt. Pleasant, SC

Post Number: 451
Registered: Dec-03
Sorry about the multiple posts---when sending it crashed and I didn't know whether it was successfully mailed.

One cheap try may be going to Radio Shack and adding extra impedance to the pre-outs on your receiver to make them 8 ohm. This will be safe for the receiver, but it may adversely effect the speakers performance. You may want to e-mail B&W tech support and ask them if this will compromise the 4 ohm speaker performance.

What receiver do you have?


Ultimately you may have to sell either the speakers or the receiver, depending on which you decide to keep. As always, your budget will likely determine your path.
 

New member
Username: Srkstan

Kazakhstan

Post Number: 4
Registered: Apr-04
Thank you for all of the responses. Right now, I have a Pioneer VSX-D411. It is nice for 5.1, but I doubt it has the power to drive the 4 ohm speakers, since it is a rather low priced receiver. I suppose I might add an itegrated amp (is that what they usually call 2 channel amps?)to this (will that work with 5.1 by only increasing the power of the fronts?), but I am also willing to upgrade my receiver. I have seen some good deals on the NAD T742 and T743, but many forums mention that the T742 has bugs and the T743 has limited options. I would need at least to be able to have one 5.1 input since I have my old desktop set up to play my music collection on mp3s, and I would like to hear them through all 5 speakers--it would also be nice to have my regular TV signal coming out all 5 speakers (plus sub). Another option is the Onkyo 6.1 TX-SR601, which has many options that would be useful, but I am not positive if it will power the 4 ohm speakers. I would hate to sell the speakers since I got a good deal on them - $220 shipped, and forums say they are very nice sounding. Any further advice--again, thanx for the help. I am trying to increase my hi-fi knowledge and improve my equipment, and you guys are helping alot! Oh, by the way, my other speakers are 8 ohm - I have B&W DM302 surrounds, and I am still shopping for good deals on a B&W center (looking 8 ohm this time) and a decent powered subwoofer.
 

Silver Member
Username: Kegger

MICHIGAN

Post Number: 165
Registered: Dec-03
yes it will work the way you are thinking.

but again you have the termonolgy wrong it is
not an integrated amp.

an integrated amp is basicaly the same thing as
a reciever meaning it does other things besides
amplify the signal.

it will have, say a tuner in it plus inputs for other devices.

where just a basic 2 channel amp has nothing but
2 inputs and 2 outputs.this would be what you use
for external amplification of the front channels.

basically an amplifier just takes the signal you
give it and amplifies it.

amplifiers come in many different sizes and shapes.
you have 1 channel amps (mono block)
2 channel amps.(like what we are talking about)
and other various channels maybe as many as 12 or
so.

but they are just called amplifiers.

your reciever has amplifiers in it but also does
other things so it would be called an inegrated
amplifier.with preamp outputs.

a preamp with no amplifiers in it is what you
would connect like tape decks or dvd players and
such to then connect the amplifier to the preamp
outputs.

it is simular to a reciever and integrated amp
but has no amplifier built in. just an adjustable
signal that comes out the preamp outputs a very
low signal that goes up and down with the volume
control than that very low signal that comes out
the preamp outputs connects to an amp that increases
the output (amplify).

 

New member
Username: Srkstan

Kazakhstan

Post Number: 8
Registered: Apr-04
Since I have your attention Kegger, can I ask you another related question. I have decided to get a new receiver that can handle 4 ohms. The ones I am considering (i.e. Onkyo SR601 or SR801) both have the capacity to have 2 music zones. Can I attach my present receiver to a pre out on a new receiver using one of the audio inputs of my old receiver (i.e. cd, tape, md, etc.)? Would this transfer the sound from my new receiver through my old receiver to out put to speakers in a different room?
 

Silver Member
Username: Kegger

MICHIGAN

Post Number: 167
Registered: Dec-03
you could do what you want but not from a preout.

you would need to come from one of the rca outs
like tape out or vcr out or something like that.

so it is not an amplified signal.

if you come out a preamp output it still a low
level amplification and you would not want to put
that into a line level input of your other reciever.

so basically you come from tape out on 1 reciever
and go to tape in on the other.then you would
have volume control on the reciever that has
the 2 rca's going into the tape in.while the
volume control from the one you are coming out
of has no effect.
 

Silver Member
Username: Hawk

Highlands Ranch, CO USA

Post Number: 530
Registered: Dec-03
Sean:

Are you sure the Onkyos can handle a 4 ohm load? I doubt it. Look on the back of the receiver near the output binding posts and it will say what impedence range the receiver will handle. Last time I looked at an Onkyo (6 months ago), it required 8 ohm speakers when running five or more channels.

I have another suggestion. Assuming your Pioneer has pre-outs (not a foregone conclusion), you could get a great Outlaw 7100 7 channel power amp for about $795, or about the same price as the Onkyo 801, and it will have more than twice the power of the Onkyo. It is power that you will be able to hear the improvement in sound. If your Pioneer has pre-outs, you can use it as your pre-pro and the Outlaw will drive the speakers. Since it is a 7 channel amp, you can assign two of the channels to drive another music zone and still have 5.1 sound in your main listening room. Check it out at www.outlawaudio.com
 

New member
Username: Srkstan

Kazakhstan

Post Number: 10
Registered: Apr-04
Actually, I don't think my present Pioneer has pre-outs. Reviews seem to suggest that the Onkyo 901 could definitely handle 4 ohms, but I am not sure about the 801. Uggggh, I am wondering if I will need to sell my speakers,....:-( Now I know why I got such a good deal on them.
 

Silver Member
Username: Kegger

MICHIGAN

Post Number: 168
Registered: Dec-03
sean that is not a problem there are quite a few
recievers that handle a 4 ohm load.

if you just get a good reciever that handles 4
ohm's you will be fine.

harmon kardon does , i know nad does, i think the
outlaw audio reciever does. rotel and many others

i personally love the b&w sound and i would just
find a reciever to accomadate them.

what would your budget be for a reciver?
we can help find you something.

 

Bronze Member
Username: Srkstan

Kazakhstan

Post Number: 12
Registered: Apr-04
Thanx Kegger!
My budget is $400-$700, but I am willing to look for refurb versions or even used from a reliable ebayer. Do you know which models of HK handles 4 ohms?
 

Silver Member
Username: Kegger

MICHIGAN

Post Number: 174
Registered: Dec-03
i just looked quickly and your right it is hard
to find some of the specs of the recievers these days.

as of just recently manufacturers use to list
whether there recievers could handle a 4 ohm load.

i know that nad lists it on there web sight.

hk use to list it but i don't see it anymore.

anyways when i get some more time i will see what
i can come up with but right now i've got some
work to do.
 

Bronze Member
Username: Srkstan

Kazakhstan

Post Number: 15
Registered: Apr-04
Thanx--I really appreciate it! It seems that the Sony ES STR-DA2000ES will handle 4 ohm as long as you are not using A&B fronts (i.e. 9 speakers). Do you know anything about this receiver? It seems very reasonably priced for its features.
 

Bronze Member
Username: Srkstan

Kazakhstan

Post Number: 16
Registered: Apr-04
Another option looks to be JVC RX-8020VBK. Their websites says:
"The JVC RX-8020VBK features premium performance with its high current power supply capable of handling 4 ohm loads, and a new high performance Motorola DSP. The new 24 bit DSP is capable of executing 150 million instructions per second (MIPS). This DSP power enables the RX-8020VBK to provide the highest level of accuracy in decoding Dolby Digital Ex and DTS-ES and Dolby Pro Logic II. It also makes possible All Channel Stereo, and the JVC exclusive DAP soundfield. The RX-8020VBK also allows you to play your MP3 files directly from your PC through a front USB input. This new flexibility allows you to play music recorded on your computer with the greatest fidelity. Finally the RX8020 comes with HD component switching to allow the user to take full advantage of the switching capabilities even with HD signals."
The item, however, is pretty inexpensive. Do you anything about this receiver? Also, the specs don't seem to mention 4 ohm capability--just the item description.
 

Silver Member
Username: Gman

Mt. Pleasant, SC

Post Number: 454
Registered: Dec-03
From what I know about Sony and JVC receivers, driving 4 ohm speakers is not advisable. Don't be misled by marketting hype for actual performance. Most any receiver will have "the capability" to drive 4 ohm speakers. But they mostly aren't able to drive them loud and often will overheat and shutdown after a while, or at worst--destroy your speaker drivers.


Stay away from the Sony's and JVC's, unless you have 8 ohm speakers or want to risk being disappointed.

I would either get the NAD T753 or the Harman Kardon AVR 430. The HK AVR 430 should have no problem driving 4 ohm speakers (it cranks out 40 amps)and is very conservatively rated. The specs say that it supplies 80 watts into 7 channels, but as it can consume up to 940 watts, it must have huge headroom. This means that it probably won't clip up to at least 125 watts--probably 135 watts. Just keep the receiver in a well-ventilated space. I have seen it on sale for $659 at onecall.com (and they are an authorized dealership).

If you want to be 100% sure, send HK an e-mail or send Onecall.com an e-mail about the 4 ohm speakers you have.

The NAD T753 is a very good receiver, but it doesn't have all the features of the HK. If the extra features of the HK aren't important to you, then by all means get the NAD. You won't go wrong with either model.

The Onkyo's aren't designed for 4 ohm speakers either. That doesn't mean they won't drive them--but what is the point in risking it? The downside is too big.
 

Bronze Member
Username: Srkstan

Kazakhstan

Post Number: 20
Registered: Apr-04
Greg,
Thanx for your input. Do you think the HK AVR525 will also drive the 4 ohm speakers? I did send an email to tech support at HK, and they said that their HT receivers are only rated for 8 ohms, but that the receivers may handle 4 ohms without extensive loudness. They also said that the worse thing that would happen would be that the receiver goes into "protect" mode and must be turned off and on again. If you think the 430 handles 4 ohms, I would guess that means the 525 should do even better?
 

Silver Member
Username: Gman

Mt. Pleasant, SC

Post Number: 455
Registered: Dec-03
Sean--

If HK isn't confident about playing the 4 ohm speakers without extensive loudness, then I am not going to go out on a limb and say it will. Although I believe they are saying this to cover their -ss.

I see no reason with the amperage why it shouldn't be fine, but who knows?

The 610i's list in the audiogon blue book at $180--maybe up to $220 shipped and in very good conditiion.

There would be less potential problems with them if used as surround speakers. The front and center speakers get more power.

It seems you are in a budget bind. If you could sell the speakers at the price you paid for them it would erase your potential receiver problems. You could then buy a less expensive receiver and get better 8 ohm speakers. One can always sell and buy used speakers and other equipment at audiogon.com

Axiom, Ascend, and Aperion all sell very good $235-$350/pr speakers online and have a 30 day return policy.

It is all up to you. Either sell the B&W speakers and buy almost whatever receiver you want, or maybe try the HK 525 or get a NAD receiver.
 

Bronze Member
Username: Srkstan

Kazakhstan

Post Number: 27
Registered: Apr-04
I think I can get a refurb NAD T762 for just outside my budget (which is allright since I always leave some headroom to go above). Is this receiver worth the money, or am I spending the extra dough to drive my 4 ohm speakers? In other words, is the T762 a ton better than the Onkyo NR801 or the HK 525 and as good as the Pioneer Elite tx55?
 

Silver Member
Username: Kegger

MICHIGAN

Post Number: 235
Registered: Dec-03
sean the nads are very nice recievers and if your
getting a revferb one you should be getting a good deal.

so if the price right the nad should be fine.
 

Jan Vigne
Unregistered guest
Sorry, Kegger, but your description of recievers, integated amps and power amplifiers has some errors. Try this which is copied from another thread I responded to:
A reciever is made of three components put into one box. A tuner, whose function should be obvious by its name. A pre amplifier, whose function is to do two things; step up and give frequency shaping (RIAA and other curves) to low level signals from the various source components (with buffering between inputs and outputs) such as phono, tuner, tape, etc. and to give you the control over these sources that will send signals in the desired direction (selector switch), give you volume adjustment and whatever other control functions you might need (bass, treble, balance, etc.). In the early days of audio, before turntables (with magnetic cartridges) and tape decks, the function of stepping up signal levels was not part of a "pre amp" and the unit was simply called a control amp. In today's market many preamplifiers, whether in a reciever or separate, do not contain a phono pre amplifier, only high level, line level inputs, and can rightfully be called a control amplifier once again. The last piece of a reciever is the power amplifier which is where wattage is developed. By placing all three in one box a designer has to make certain concessions to the layout which may seriously affect the sound. By separating each component of a "reciever" you achieve (ideally) better performance and the ability to pick which piece actually suits your needs the best. Recievers are meant (usually) to sell for less money than separates and unless you have a good sized budget you will probably need to look at a reciever or used separates. By removing just the tuner from a "reciever" you create an integrated amplifier. It still contains a pre amplifier and a power amplifier. Because this is a somewhat specialized market niche (particularly in the US, much more common in the European market designs) this is often a better built component than a reciever and you can, if you desire, add a separate outboard tuner at any time.
 

Silver Member
Username: Kegger

MICHIGAN

Post Number: 238
Registered: Dec-03
jan i was just trying to show him what he could
use and why.

without trying to get to indepth to loose him.

just giving the basic idea on how they work.


sure i could of written a page on each one and
broke it down completely but i felt that is was
not neccesary.
 

Silver Member
Username: Kegger

MICHIGAN

Post Number: 239
Registered: Dec-03
i was just trying to show him what an amp does to the signal.

and what a reciever or inegrated amp does to the
signal.

and what a preamp does to the signal.


i did not want to try to loose him by explaining
the differences between an integrated amp and
a reciever.just show that they both do the same
thing with a signal.

if he asked what the differences where i would have told him that the integrated amp has no tuner.but i just wanted him to think about both
of them treating the signal the same way.

i was keaping it simple so he could understand it
better as to what he was trying to do.
 

Unregistered guest
Sean

The B&W 610i's are rated at 8 ohms not 4,you will not have a problem driving them.

I am still using these after 10 years,a lot of them as part of a home cinema system-the original Dolby pro-logic surround sound.

If looking for a centre speaker try for the B&W CC6 as it is a good match.It is very important to try and get matching speakers across the front.
Best wishes

Ian Sampson
 

Unregistered guest
Along the same lines as the above -- I am feeling stupid in that I am unable to get the system I just installed to work correctly.

I have a Denon DRA395 receiver and a Niles SI-1230 -- there are 10 sets of speakers hanging off of this.

The problem is that the only way I can get the system to work is to drive the amp from CD out -- which works except that the volume control on the receiver is ineffective. The only volume control that I have is from the remote volume controls in each room. I suppose that there is sufficient volume in total -- but I would like to be able to drive the overall level from the audio cabinet.

If I try to drive the amp from the speaker A or B out on the receiver -- the receiver shuts down almost immediately. Most maddening as this is what I have done with other setups.

So, I was thinking that I could put a pre-amp in the middle --- would that give me the desired outcome of being able to control the volume / output level from the central location?
 

Unregistered guest
i would like to get some help on the following question:
i want to connect a non-amplifier subwoofer to my stereo system how can i do it please thank you
 

Silver Member
Username: Gman

Mt. Pleasant, SC

Post Number: 627
Registered: Dec-03
Duval--

Unless you plan on getting a subwoofer without serious 35Hz and lower capability, or you have a powerful amp or a rather rare and powerful stereo receiver, I advise against getting a passive subwoofer.

You will get much better performance from a self-powered subwoofer.

Of course, for anyone to give you specific advice, you would need to write what your budget is for a subwoofer and what receiver or amp you have.
 

Tiberius13
Unregistered guest
I stumbled across this thread in a web search and found it useful. I'd like to add another question here (probably a stupid one).

If you connect a 2 channel Amp to the pre-outs for the front speakers from a 'receiver' that won't support 4 Ohm speakers... and then drive the 4 Ohm front speakers from the 2 channel Amp...

..... I assume all of the processing (THX, DTS, Pro Logic II, Neo, equalizer settings, volume adjustments to balance the surround speakers, etc.) is passed in the signal to the 2 channel amp, and hence is not lost. Would that be accurate?

Thanks!
 

Gold Member
Username: Kegger

MICHIGAN

Post Number: 2090
Registered: Dec-03
Yes everything that would come out the recievers amps to the speakers
would also come out of the preamp outputs.
 

Bronze Member
Username: 514329

Post Number: 43
Registered: Jun-04
Kegger
would it be possible to use 2 subwoofer ( left and right ) on my B&K Ref 50? it only has 1 LFE output. I'm thinking of using a Y splitter or is there another way. thanks
 

Gold Member
Username: Kegger

MICHIGAN

Post Number: 2256
Registered: Dec-03
A y splitter is fine! I've done that.

Recently I went a little crazy and built these little boxes from partexpress.com

What I did was get these little kit boxes about 1" thick and rectangle in shape.
I took 1 female rca on 1 end of the box and put 3 female rca's along 1 side.
That geve me a 1in and 3out rca box "obviously wired up and solderd"

I put that on my preamp out going into the female input "on the box" and out to 3 amps!
Works great no extra noise or anything.
So yes splitters are fine the better quality you get or make the less chance of noise
or signal degregation! When I use splitters I use the heavy duty monster ones.

Heres links to both male and female.

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=185-276

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=185-278
 

Bronze Member
Username: 514329

Post Number: 44
Registered: Jun-04
thanks a lot. thats the very same splitter that I got. I just purchase 2 supercube I for $775 (msrp 1200.00) each. brand new but I don't know if this is the best price and a good sub. I'm not content w/ the bass output on the Def Tech 2002TL so I purchase this one but I can always return it if u have any other personal suggestion. I heard the Sunfire Ultimate Sub EQ but I can only get it at $ 1200.00( msrp $1600.00) thanks.
 

Unregistered guest
I apologize if this question already has been answered or may seem elementary to you: What type of av receiver should I get to fit my new JBL 8-ohm speakers? I would prefer to stay under $300, and I would like a USB connectivity for my computer. Is there such animal out there? Thanks in advance. JR

Add Your Message Here

Bold text Italics Create a hyperlink Insert a clipart image Add a YouTube Video
Need to Register?
Forgot Password?
Enable HTML code in message
   
Jump to: Home Audio Forum | Home Video Forum | Home Theater Forum | Car Audio Forum