Speakers run in Parallel......in series....daisy chaining...help

[AMPEG]

My GB head can operate at 4 or 8ohms depending on what speakers you run it with i.e 8ohm with an 8 ohm speaker or 4ohm with two 8ohm speakers. Can anybody tell me the difference between plugging both speakersdirectly into the two speakon speaker connectors on the back of the head as opposed to plugging one into the back of the head and daisy chaining it to a second speaker.

[barkin]

As far as the load presented to the amp goes, no difference.

[Salt on your Bass?]

If they're daisy chained in parallel (which I believe most cabs are) the load presented daisy chaining will be the same as that plugging into the amp. No difference.

If daisy chained and they're series, the the load would double - i.e. two 8 ohm cabs would present a 16 ohm load. This would result in circa half the power your amp puts out at 8 ohms.

[AMPEG]

[quote name='Salt on your Bass?' timestamp='1343999907' post='1758484']
If they're daisy chained in parallel (which I believe most cabs are) the load presented daisy chaining will be the same as that plugging into the amp. No difference.

If daisy chained and they're series, the the load would double - i.e. two 8 ohm cabs would present a 16 ohm load. This would result in circa half the power your amp puts out at 8 ohms.
[/quote] Thats what im trying to establish....the difference to running them in parallel / series whats the diffence....I thought two 8 ohm cabs produced a 4 ohm load

[AMPEG]

[quote name='AMPEG' timestamp='1344002070' post='1758544']
Thats what im trying to establish....the difference to running them in parallel / series whats the diffence....I thought two 8 ohm cabs produced a 4 ohm load
[/quote]I need to know definitively because i plugged two 8ohm speakers in the back of the head and one blew

[Salt on your Bass?]

It all depends on how they're wired:
Two 8 ohm cabs in parallel = 4 ohms
Two 8 ohm cabs in series = 16 ohms

This is a useful link to calculate total impedance and power from your amp going to each speaker: [url="http://www.duncanamps.com/technical/impedance.html"]http://www.duncanamps.com/technical/impedance.html[/url] It also has basic diagrams showing you how the speakers are wired.

Hope that helps

[obbm]

Cab sockets, whether they be jacks or Speakons, are wired such that as you daisy-chain them the cabs are connected in parallel.

i.e 8-ohm cab linked to another 8-ohm cab presents 4-ohms to the amplifier.


To make the cabs be in series, e.g. 8-ohm + 8-ohm =16-ohm, then you need a special cable.

The confusion occurs because physically the cable appear to link the cabs in series however electrically the internal conductors of the cable are actually connecting them in parallel.

[Salt on your Bass?]

[quote name='AMPEG' timestamp='1344003330' post='1758569']
I need to know definitively because i plugged two 8ohm speakers in the back of the head and one blew
[/quote]

What GB head do you have and what cabs are you using?

If they're definitely 8ohm cabs it wont be an impedance mismatch....

Edited August 3, 2012 by Salt on your Bass?

[flyfisher]

The parallel/series thing is confusing because there's a difference beween the physical cabling arrangement and the actual electrical circuit.

Connecting two cabs into two amp outputs 'looks' physically like a parallel connection and is, in fact, electrically parallel as well. So 2 x 8 ohms in this arrangement will present a 4 ohm load to the amp.

Connecting one cab into the amp and them connecting that cab to another cab 'looks' like a serial connection but is, in fact, still an electrically parallel connection. So 2 x 8 ohm cabs connected this way will also present a 4 ohm load to the amp.

Connecting two cabs in an electrically serial way would involve some special cables. I don't know how common it is to truly use a serial connection for two cabs, but I've never seen it done.


Edit: OBBM beat me to it - drat those phone calls that come in halfway through writing a post!

Edited August 3, 2012 by flyfisher

[Coilte]

[url="http://www.tunemybass.com/bass_amps/how_to_hook_up_heads_and_cabinets.html"]http://www.tunemybass.com/bass_amps/how_to_hook_up_heads_and_cabinets.html[/url]


I usually refer to this link if in doubt.

[AMPEG]

[quote name='Salt on your Bass?' timestamp='1344003539' post='1758576']
What GB head do you have and what cabs are you using?

If they're definitely 8ohm cabs it wont be an impedance mismatch....
[/quote]I have a Shuttle 6.0 which states in the spec 370 to 8ohms and 600 to 4ohms....i plugged 2x 8ohm cabs in and it blew one (sp212 600 watt rms and an Ampeg 200watt rms.....the latter one blew)

[AMPEG]

[quote name='AMPEG' timestamp='1344006330' post='1758633']
I have a Shuttle 6.0 which states in the spec 370 to 8ohms and 600 to 4ohms....i plugged 2x 8ohm cabs in and it blew one (sp212 600 watt rms and an Ampeg 200watt rms.....the latter one blew)
[/quote] Both were plugged into the back of the head so should only have created 4ohms which the amp is designed to power

[Commando Jack]

[quote name='AMPEG' timestamp='1344006330' post='1758633']
I have a Shuttle 6.0 which states in the spec 370 to 8ohms and 600 to 4ohms....i plugged 2x 8ohm cabs in and it blew one (sp212 600 watt rms and an Ampeg 200watt rms.....the latter one blew)
[/quote]

Well if you were running it relatively high the ampeg wouldn't be able to take the ~300W it was getting, which would blow a speaker.

[BassTractor]

AFAIK, mixing cabs is often taking extra risks. The impedance of the cabs wil vary with frequency and load, and that goes for both cabs, so the Ampeg may be blown even earlier than when you cross the nominal 200W.
Also, 200W is not just 200W.
There's enough threads on this stuff here.

BTW, there's two types of blowing up as to which element goes. There's a huge difference between a tweeter blowing (amp hard clipping) and a sub blowing (not tolerating amp's watts). From what you wrote, I gather a large element blew, but just wanted to mention this as well.

YMMV, and I may be wrong.

best,
bert

Edited August 3, 2012 by BassTractor

[dmccombe7]

Sounds like the 200 W cab has gone due to running 300 W into it.

Dave

[flyfisher]

Yep, ohms is important for the amp, watts is important for the cabs.

An 8 ohm / 200W cab + 8ohm / 600ohm cab will present a 4 ohm load to the amp, but the total cab wattage is notcannot be shared across both cabs, i.e. the 200W cab will still only be able to handle 200W.

So, presenting a 4 ohm load to the amp enables the amp to deliver its full power of 600W. Because both cabs are the same ohms, that 600W will be divided equally between the two cabs, i.e. 300W each. This won't trouble the 600W cab but the 200W cab will very likely complain when pushed, as the OP has discovered.

[xgsjx]

The speaker's wattage is how much heat it can deal with. Was you playing at the time & how long at what sort of volume? There's every chance the Ampeg cab wasn't getting 300 watts if you wasn't playing at a pretty high volume.
I suppose it's a good way to get rid of the weak cab. Onwards & upwards

[Musky]

[quote name='xgsjx' timestamp='1344113107' post='1760097']
The speaker's wattage is how much heat it can deal with. Was you playing at the time & how long at what sort of volume? There's every chance the Ampeg cab wasn't getting 300 watts if you wasn't playing at a pretty high volume.
I suppose it's a good way to get rid of the weak cab. Onwards & upwards
[/quote]
I was wondering about this as well - with the two cabs on the go it should have been making an awful lot of noise for what I'm guessing was a domestic situation.

You didn't turn on the amp or plug in the cabs with the volume cranked did you?

[TimR]

You don't necessarily have to be have playing very loudly. If the 200W cab was hitting it's limits of excursion it's distortion could have been masked by the sound from the other cab. I think it's more likely that you just busted the driver by driving it to it's mechanical limits, rather than overpowered/heated it.