Pre-out for power amp, but already used by sub?

[Condi]

Following some fantastic advice and information from people on here about Ohms, a power amp was recommended as my amp is 8ohm and speakers are 4 ohm.

Anyway, progressing down this road and it appears most amps have 1 pre-out, which is what feeds into the power-amp, and this then connects into the speakers, which all make sense, except that my pre-out is already used by the sub. Is it possible, or sensible, to split the pre-out and connect both sub and power amp, or is there another way round this problem?

The alternative would be to just buy some 8ohm speakers, but 4ohm is apparently better, and as I already own the speakers buying new ones doesn't seem very logical.

[JimbobVFR]

What sub is it?

Some of them also have high level speaker level inputs to connect to a stereo amp without using pre-outs

[hman]

4 ohm speakers on an 8 ohm amp will work fine, just it will get loud very quickly.

As for the "pre-out" if you mean that either your pre-amp or actual amp have phono connections for you to connect to other amps at a signal level then yes you can buy a splitter cables (you'll need two for left and right). most times you will want a 1 x male to 2 x female - then you can connect a standard phono cable between the splitter and the next amp / sub this is an example :-

https://www.ebay.co.uk/itm/330680409808?hash=item4...

[Lucid_AV]

Condi said:

Following some fantastic advice and information from people on here about Ohms, a power amp was recommended as my amp is 8ohm and speakers are 4 ohm.

Anyway, progressing down this road and it appears most amps have 1 pre-out, which is what feeds into the power-amp, and this then connects into the speakers, which all make sense, except that my pre-out is already used by the sub. Is it possible, or sensible, to split the pre-out and connect both sub and power amp, or is there another way round this problem?

The alternative would be to just buy some 8ohm speakers, but 4ohm is apparently better, and as I already own the speakers buying new ones doesn't seem very logical.

For those of us who haven't seen your other thread (?, or were you just reading advice in posts from other OPs?), what is it exactly you're trying to do?

The pre-out used for a subwoofer connection on an AV receiver is frequency filtered so that it carries just bass and sub-bass audio. If there's just one pre-out on your AV R then its mono as well.

You talk about speakers - plural. Are you trying to make and run multiple 4 Ohm subwoofer drivers, or are you trying to drive a full set of surround speakers that happen to be 4 Ohm? If it's the latter, then you're trying to do something that the sub pre-out won't allow. It doesn't carry the channel info for the main channel surround speakers. That's a different kind of pre-out connection. It's a pre-out connection with 5 or 7 RCA connections; one per channel. Front L, FR, Centre, Surround L, SR, Rear Left, RR.

Incidentally, there's no "better" or "worse" with 4 Ohm versus 8 Ohm. There's what's suitable for the supporting gear and what isn't. Then the rest is about the design and manufactured quality of the item. A crap 4 Ohm speaker running on an under-powered amp that's going to overheat because it's designed for an 8 Ohm load isn't a great combo just as much as running a crap 8 Ohm speaker with the exception that the 8 Ohm speaker might sound dire but is less likely to kill the amp too.

[Crackie]

Lucid_AV said:

Condi said:

Following some fantastic advice and information from people on here about Ohms, a power amp was recommended as my amp is 8ohm and speakers are 4 ohm.

Anyway, progressing down this road and it appears most amps have 1 pre-out, which is what feeds into the power-amp, and this then connects into the speakers, which all make sense, except that my pre-out is already used by the sub. Is it possible, or sensible, to split the pre-out and connect both sub and power amp, or is there another way round this problem?

The alternative would be to just buy some 8ohm speakers, but 4ohm is apparently better, and as I already own the speakers buying new ones doesn't seem very logical.

For those of us who haven't seen your other thread

Here's the other thread.......... Denon amp specs are near the start.

[Lucid_AV]

Crackie said:

Here's the other thread.......... Denon amp specs are near the start.

Is my Internet broken, or is what I'm seeing right and you've just quoted my post without a link to Condi's original thread or any text from it? LOL

Here's how your post appears to me in my browser, Crackie

[Lucid_AV]

Lucid_AV said:

Is my Internet broken, or is what I'm seeing right and you've just quoted my post without a link to Condi's original thread or any text from it? LOL

Here's how your post appears to me in my browser, Crackie

ETA: I think I found Condi's thread on my own. Is this it? Amp overheating

If so, then Condi's plan to add a power amp has already hit the rocks. The Denon amp would appear to be something quite basic such as the AVR-X550. There are no main channel pre-outs on that AV receiver. Adding a power amp then is not going to be an option.

Put the money towards changing to a better amp; a different brand, one that has more power on tap and doesn't run hot like the Denons. That, or change the speakers to something more forgiving.

Whilst at it, I'd give the speaker cable and connections a once-over too.

If it's a bare wire connection either the amp or speaker end (or both) then look for stray filaments bridging between the speaker terminals. The amp will appear to run okay with that at low volumes; but as soon as the volume increases then it'll have the effect of shorting out the amp and making it overheat and cut out. Have a think about switching to banana plug connections to avoid the possibility of bad wiring.

Also look at the speaker cable gauge. Thin stuff such as bell wire is okay for relatively short runs, but it does sap power, and the amount of power it robs from the system increases with distance.

[Crackie]

Lucid_AV said:

Is my Internet broken, or is what I'm seeing right and you've just quoted my post without a link to Condi's original thread or any text from it? LOL

Here's how your post appears to me in my browser, Crackie

Oops........sorry about that.....Clearly wasn't functioning on any cylinders just there. Bit too early.

[Condi]

Lucid_AV said:

If so, then Condi's plan to add a power amp has already hit the rocks. The Denon amp would appear to be something quite basic such as the AVR-X550. There are no main channel pre-outs on that AV receiver. Adding a power amp then is not going to be an option.

Put the money towards changing to a better amp; a different brand, one that has more power on tap and doesn't run hot like the Denons. That, or change the speakers to something more forgiving.

Whilst at it, I'd give the speaker cable and connections a once-over too.

If it's a bare wire connection either the amp or speaker end (or both) then look for stray filaments bridging between the speaker terminals. The amp will appear to run okay with that at low volumes; but as soon as the volume increases then it'll have the effect of shorting out the amp and making it overheat and cut out. Have a think about switching to banana plug connections to avoid the possibility of bad wiring.

Also look at the speaker cable gauge. Thin stuff such as bell wire is okay for relatively short runs, but it does sap power, and the amount of power it robs from the system increases with distance.

Interesting, thanks. The cables already have banana clips on the end and are pretty tidy. Speaker wire is just normal speaker wire.... not especially thin but it is not super expensive either. Whatever Richer Sounds sold me years ago!

Seems like the plan isn't going to work that well, and new speakers or new amp would be the way to go, which is a bit annoying and more costly that I had hoped!

As for 4ohm and 8ohm speakers, this bloke designs speakers and he seems to say 4ohm (lower resistance) is best.
https://www.youtube.com/watch?v=tMAO9LPsups&t=...

[Lucid_AV]

Condi said:

Interesting, thanks. The cables already have banana clips on the end and are pretty tidy. Speaker wire is just normal speaker wire.... not especially thin but it is not super expensive either. Whatever Richer Sounds sold me years ago!

Seems like the plan isn't going to work that well, and new speakers or new amp would be the way to go, which is a bit annoying and more costly that I had hoped!

[b]As for 4ohm and 8ohm speakers, this bloke designs speakers and he seems to say 4ohm (lower resistance) is best.
https://www.youtube.com/watch?v=tMAO9LPsups&t=...

A 4 Ohm load is the most likely reason why your Denon amp is overheating and cutting out. Now you've got to buy a more powerful amp or higher-Ohm speakers.

Do you still think 4 Ohms is the best?

I'll leave that hanging.


I stand by what I wrote in a previous post. There is no best between 4 Ohm and 8 Ohm. There's only the quality of the product and what matches the ancillary equipment.

To put it in car terms, take the gearbox from an F1 car and stick it in an average family car. Do you think the family car would be great to drive or a dog because the gearing doesn't suit a lower-revving slower vehicle? The F1 gearbox alone would cost several times the value of the family car, and yet the family car is made worse because it's a bad match.

The world of custom speaker designs mated to custom-designed amps is a world away from the mass-market. You have to remember the context when watching these YouTube videos.

Edited by Lucid_AV on Friday 16th July 18:25