Need tech advice on using a supplemental power amp

[Biggsy]

Hi guys,

I want to add more beef to my rig by way of extra cabs. To do so, I'd need an amp that can carry a 2ohm load.

I have an Eden WT300 (4ohm) which I couldn't love the sound of more. I've heard of some people using it as a pre-amp, and then going through a power amp for more headroom.

Is it possible to take a 4ohm signal from a pre, feed it into a power amp that converts it to 2 ohms, thereby being able to run 4 8ohm speakers?
If anyone has any reccomendations I'm not adverse to used gear (infact I prefer it) and will be on a pretty limited budget. (probably under the 200 bean mark)

Apologies if I've used the wrong terminology, hopefully I've conveyed what I want to know!

Cheers,
Biggsy

[BOD2]

It's possible to link amps together but not in the way you suggest.

You cannot take a speaker output from one amp and feed it to the input of another amp. The signal from a speaker output is way too big to feed another amp, not to mention possible impedance problems etc. - either way something would get seriously damaged !

What you need to do is take a "line level" output from the first amp, then feed that into the second amp.

If you have a "preamp out" on the first amp, that will do. Alternatively you should be able to take a signal from the "Send" of an FX loop from the first amp. Both of these would be "line level" signals.

For the second amp it depends on if it's a proper bass amp or just a power amp. If it's just a power amp then feed the signal straight into the input. If it's a bass amp look for a "power amp in" or the "Return" of an FX loop might work. You may still be able to use the normal input of a bass amp but you'd need to put the input gain way down as the "line level" signal will be hotter than a normal bass guitar signal.

As always when connecting equipment together, start with all the volume/gain controls way down then slowly bring these up to avoid overloading anything accidentally.

Perhaps someone with experience of the Eden WT300 will post with more specific advice.

[Biggsy]

There's a couple of line level outputs from what I understand, if the DI counts as one.

From how you understood my mail, am I right in thinking that line-level isn't subject to any impendance, or at least that impendance is so (low/high?) it becomes irrelivant?

I guess that would make sense.

[Biggsy]

Thinking about it, are there any other ways to achieve my goal of being able to use my Eden with 2ohms worth of cabs? Perhaps modifying the electronics, some kind of impendance converter or something?

I'm not too bothered about the power aspect, I just want to move more air

[BOD2]

[quote name='Biggsy' post='225107' date='Jun 23 2008, 03:50 PM']There's a couple of line level outputs from what I understand, if the DI counts as one.

From how you understood my mail, am I right in thinking that line-level isn't subject to any impendance, or at least that impendance is so (low/high?) it becomes irrelivant?

I guess that would make sense.[/quote]


Yes - line level doesn't have the same impedance restrictions that a speaker output has. As long as you put a line level output into a line level input you'll be ok (and there is quite a big variation in what constitutes an acceptable "line level" so there's a lot of flexibility there).

Your DI will be line level but check if it's "post" or "pre" EQ. If it's "post-EQ" then that means the tone controls on your Eden will control the sound. If it's "pre-EQ" then the signal is tapped off before it reaches the tone controls which might not give you the sound you want when fed to a power amp.

[MythSte]

Hmm, id say buy an eden pre-amp then buy a poweramp thatl go down to 2 ohms, but the navigator might be a bit overkill :/

[BOD2]

[quote name='Biggsy' post='225113' date='Jun 23 2008, 03:58 PM']Thinking about it, are there any other ways to achieve my goal of being able to use my Eden with 2ohms worth of cabs? Perhaps modifying the electronics, some kind of impendance converter or something?

I'm not too bothered about the power aspect, I just want to move more air [/quote]

Well, if you use two 8 ohm cabs together that would give you a 4 ohm load. So you'd have the same amp, but two cabs.

If this interests you then popular advice is that the best results might be obtained with two cabs with the same speaker sizes rather than going for a different size speaker in the second cab. There's a recent thread on this.

Another alternative is to go for a more efficient speaker cab (e.g. the BFM type). There are threads on this here too.

[Biggsy]

[quote name='ste_m3' post='225116' date='Jun 23 2008, 04:01 PM']Hmm, id say buy an eden pre-amp then buy a poweramp thatl go down to 2 ohms, but the navigator might be a bit overkill :/[/quote]

Yeah, I'm trying to avoid spending much money; would the DI-out (post EQ) not do the same thing? It's a hybrid amp wtith a tube pre section, I feel like I've nailed a sound that I really like..

I suppose another option is simply exchanging for two bigger 8ohm cabs.

Money money money :wacko:

[obbm]

No need to go down to 2-ohms if you get a secondary power amp.

You can run one set of 4-ohm spekers from the Eden. Take a line out to the secondary power amp, and if it's a 2-channel device then you can run a set of 4-ohm speakers from each channel. 6 x 8-ohm cabs in total. Is that enough air movement?

[Biggsy]

[quote name='BOD2' post='225119' date='Jun 23 2008, 04:03 PM']Well, if you use two 8 ohm cabs together that would give you a 4 ohm load. So you'd have the same amp, but two cabs.[/quote]
Ah, you beat me to it! I do currently run 2 8ohm cabs - Aguliar GS112's, just not enough surface area now my musical direction has become heavier.

[quote name='BOD2' post='225119' date='Jun 23 2008, 04:03 PM']If this interests you then popular advice is that the best results might be obtained with two cabs with the same speaker sizes rather than going for a different size speaker in the second cab. There's a recent thread on this.[/quote]
I'd like to read that actually, I imagine it's one of those that could be discussed forever.. I'll 'ave a search

[quote name='BOD2' post='225119' date='Jun 23 2008, 04:03 PM']Another alternative is to go for a more efficient speaker cab (e.g. the BFM type). There are threads on this here too.[/quote]
I don't think cabs get much more efficient than my current ones, but certainly something to look out for if I do want to switch.

It's a toughie - My question has been prompted somewhat by seeing Geester's GS112's for sale. I wondered about switching for a 4x10 and leaving room to upgrade, or even adding another pair of GS112's in the future. I'm so happy with my amp and cabs I didn't really want to risk switching for anything else, and the idea of 4 GS112's instead of two (after hearing the difference between 1 and 2) made me a little moist.

[Biggsy]

[quote name='obbm' post='225128' date='Jun 23 2008, 04:14 PM']No need to go down to 2-ohms if you get a secondary power amp.

You can run one set of 4-ohm spekers from the Eden. Take a line out to the secondary power amp, and if it's a 2-channel device then you can run a set of 4-ohm speakers from each channel. 6 x 8-ohm cabs in total. Is that enough air movement?[/quote]
That sounds perfect! Righto, off to ebay to search for cheap 2 channel power amps. I hear Crown and QSC are good. What should I look out for when considering bass-specific performance?

[Moose]

[quote name='Biggsy' post='225133' date='Jun 23 2008, 04:23 PM']That sounds perfect! Righto, off to ebay to search for cheap 2 channel power amps. I hear Crown and QSC are good. What should I look out for when considering bass-specific performance?[/quote]

I can highly recommend the QSC PLX 1802. I have been using one for about a year and it really does the job. For bass, I think you need to look for a power amp with a high damping factor - at least 300. The QSC has a damping factor > 500.

[Bill Fitzmaurice]

[quote name='Biggsy' post='225130' date='Jun 23 2008, 11:20 AM']I don't think cabs get much more efficient than my current ones[/quote]Possibly not commercial cabs, but no direct radiating cab is particularly efficient. One of the reasons for DIY is not having to live with the inefficiency of direct radiators.

[bass_ferret]

Somebody was selling a 1000 watt job for f*** all but its sold now - shame you did not ask yesterday. It weighed a ton mind.

Sure chop is running 3 or even 4 DB112's from a DB750 or something equally massive. Worth a look.

[Steve Woodcock]

[quote name='Biggsy' post='225133' date='Jun 23 2008, 04:23 PM']Righto, off to ebay to search for cheap 2 channel power amps. I hear Crown and QSC are good. What should I look out for when considering bass-specific performance?[/quote]

I have an excellent power amp for sale [url="http://basschat.co.uk/index.php?showtopic=21866&hl="]here[/url].

[gilmour]

[quote name='Biggsy' post='225097' date='Jun 23 2008, 03:37 PM']I have an Eden WT300 (4ohm) which I couldn't love the sound of more. I've heard of some people using it as a pre-amp, and then going through a power amp for more headroom.[/quote]

I have an Eden Time Traveller WT405 - and it goes down to 2 ohms, not that I've tried, but that's what it says in the manual, you sure yours doesn't?

[quote name='Biggsy' post='225130' date='Jun 23 2008, 04:20 PM']I don't think cabs get much more efficient than my current ones, but certainly something to look out for if I do want to switch.[/quote]
[quote name='Bill Fitzmaurice' post='225239' date='Jun 23 2008, 06:42 PM']Possibly not commercial cabs, but no direct radiating cab is particularly efficient. One of the reasons for DIY is not having to live with the inefficiency of direct radiators.[/quote]

I've built a BFM O15TB and been gigging it for about 3 months now, it's simply awesome and complements the Eden really well. You'll be amazed how much more volume and sensitvity you can get form these cabs compared with commercial ones. My build diary and review are here [url="http://basschat.co.uk/index.php?showtopic=11971"]http://basschat.co.uk/index.php?showtopic=11971[/url]