advice needed on valve amp...

[andytoad]

Hi all,
I need some advice..

I have just bought my first valve amp, its a trace elliot quatra valve. as you probably know, it runs at 4 or 8 ohms.

I like the sound of SWR cabs, so...

to go with this I have an SWR son of bertha (1x15 + horn @ 8 ohm) and a modded 2x10 SWR cab running at 2 ohm.

Is this ok to run the amp at 4 ohm like this? or will i soon be looking for new valves??!!

I would link the 1x15 through the 2x10. should i rewire the 2x10 to 8 ohm?

thanking you all kindly in advance... im now on the all valve dream, yay!!

[TankJon]

Id rewire the 2x10 back to 8 ohms. Assuming the head has two 8 ohm outs, the two cabs in parallel will run at 4 ohms. If you run the 2x10 into the 1x15 then thats running in series and if you leave as is you will get 6 ohms which the head should be ok with but I wouldn't run two 8 ohm cabs in series though as you will be putting an excessive strain on the amp, although not life threatening, it will shorten the life of the valves and output transformer.

Edited May 17, 2010 by TankJon

[andytoad]

[quote name='TankJon' post='840269' date='May 17 2010, 10:02 PM']Id rewire the 2x10 back to 8 ohms. The two cabs in parallel will run at 4 ohms then.[/quote]

So, If I take the line output of the 2x10 (rather than the amp as it only has one output), that would be in parallel?

[TankJon]

In that case then leave the 2x10 at 2ohms and go: Head -> 2x10 -> 1x15. The total ohms would equate to 6ohms which will be fine with the head.

Does the 2x10 have an out on it then?

Edited May 17, 2010 by TankJon

[andytoad]

[quote name='TankJon' post='840281' date='May 17 2010, 10:08 PM']In that case then leave the 2x10 at 2ohms and go: Head -> 2x10 -> 1x15. The total ohms would equate to 6ohms which will be fine with the head.

Does the 2x10 have an out on it then?[/quote]


yes, both cabs have outputs, im presuming that the SWRs are wired in paraellel, not series?

[TankJon]

[quote name='andytoad' post='840293' date='May 17 2010, 10:15 PM']yes, both cabs have outputs, im presuming that the SWRs are wired in paraellel, not series?[/quote]

Ok. Found this on the SWR website.

Q: I have a mono amplifier*. Should I use the speaker outputs on the rear panel of my amplifier to connect my speaker enclosures, or connect a speaker cable from the head to cab #1 and then a speaker cable from cab #1 to cab #2?
A: There is no advantage one way or the other, as both methods produce the same result—a parallel connection that delivers the same amount of power to each speaker enclosure (given that your enclosures have the same impedance). For the sake of simplicity, we generally recommend connecting each enclosure directly to the speaker outputs on the amplifier.

Right, if the above is correct then if you rewire the 2ohm as 8ohm and run: HEAD into 2x10 into 1x15. Going on the assumption the info is right, the two cabs will be running in parallel so the cabs total load will be 4ohms.

[andytoad]

[quote name='TankJon' post='840305' date='May 17 2010, 10:23 PM']Ok. Found this on the SWR website.

Q: I have a mono amplifier*. Should I use the speaker outputs on the rear panel of my amplifier to connect my speaker enclosures, or connect a speaker cable from the head to cab #1 and then a speaker cable from cab #1 to cab #2?
A: There is no advantage one way or the other, as both methods produce the same result—a parallel connection that delivers the same amount of power to each speaker enclosure (given that your enclosures have the same impedance). For the sake of simplicity, we generally recommend connecting each enclosure directly to the speaker outputs on the amplifier.

Right, if the above is correct then if you rewire the 2ohm as 8ohm and run: HEAD into 2x10 into 1x15. Going on the assumption the info is right, the two cabs will be running in parallel so the cabs total load will be 4ohms.[/quote]


I best get the soldering iron out!! thanks for the advice, I will give it a shot!

[Mr. Foxen]

I'd get a meter and check the resistance (to estimate impedance) at the jack you are going to plug into the amp once you've wired it all up, just to make sure. All sorts of potential complication there.

[Mr Rabble]

IMHO SWR cabs don't sound good with tube amps

[umph]

[quote name='andytoad' post='840256' date='May 17 2010, 09:53 PM']Hi all,
I need some advice..

I have just bought my first valve amp, its a trace elliot quatra valve. as you probably know, it runs at 4 or 8 ohms.

I like the sound of SWR cabs, so...

to go with this I have an SWR son of bertha (1x15 + horn @ 8 ohm) and a modded 2x10 SWR cab running at 2 ohm.

Is this ok to run the amp at 4 ohm like this? or will i soon be looking for new valves??!!

I would link the 1x15 through the 2x10. should i rewire the 2x10 to 8 ohm?

thanking you all kindly in advance... im now on the all valve dream, yay!![/quote]
nice buy, i'd rewire both the cabs to the same impedence for a whole hoast of reasons.

[Ancient Mariner]

Absolutely. If you use the 2 ohm and 8 ohm in parallel that will give about 1.6 ohms (or something similarly daft - too lazy to calculate properly). Valve amps do not behave like SS amps, and need correct impedance matching.