TC classic 450 mixed cabs at 2.67

[wayneward]

Ive got a TC classic 450 head which states in the back minimum 4ohms although it says you can connect 3 of there 8ohm cabs which is 2.67 ohms

now i have a 2x10 eden cab and 1x15 eden cab
the 2x10 is 4 ohms and the 1x15 is 8ohms
this would give you 2.67 ohms

question is would this be safe as they say 4ohms but they can take 2.67 with three of there cabs
and the other question will there be a mismatch - will the 2x10 be louder and putting out more than the 1x15 noticeably ?

if so im thinking the easiest and cheapest solution without spending to much cash is to keep the 2x10 as 4 ohms being able to run this as single cab sometimes running the TC at the optimal 4ohms therefore getting plenty of welly with one cab
and change the 8 ohm driver in the eden cab for a better 4 ohm speaker and then make a series cable if possible giving me 8 ohms but allowing me to run both cabs with the same ohm,age and safely at 8ohms?

or shall i just bite it and run it as it is not pushing the hell out of it at 2.67?!

other things to consider which could change ohms...
the eden 2x10 has a horn and the 1x15 has a horn if this makes any odds

[drpepper]

"4 ohm" and "8 ohm" cabinets are not necessarily 4 or 8 ohms. They are in the range to be labeled "4 ohms" or "8 ohms" as nominal ratings, not as measurements. RS cabinets are ~10.5 ohms. TCE does not say that the RH heads supports any three 8 ohm cabinets. Three RS cabs are ~3.5 ohms, and that is known to be safe for the heads that support three 3 RS cabinets. Three cabinets with nominal 8 ohm rating that have measured impedance of ~6.5 ohms would mean less than 2.2 ohms.

You'd need to know what the measured impedance...and that would just be a start. I don't know that the rest of your plan is going to come together so well.

[Daniel Piper]

Yah - TC cabs aren't 8 ohms. They are higher. Tricky, tricky.

Great head - I have been playin mine for over 2 years now. Never skipped a beat.

GK Neo cabs. 4 ohms.

[4-string]

Then again, if I remember correctly you wouldn't destroy anything, the amp will protect itself and simply shut down.

You probably want to get that confirmed from a more reliable source.

[drpepper]

Originally Posted by Daniel Piper

They are higher. Tricky, tricky.

It's not a matter of being "tricky." The established practice for labeling speakers is to use 4, 8, 16 etc. ohm ratings. A given 8 ohm cabinet may be lower or higher (probably in the range from ~6 to ~11) or it might be exactly 8 ohms. I believe a very few makers label with measured impedance.

[drpepper]

Originally Posted by 4-string

...the amp will protect itself and simply shut down.

You probably want to get that confirmed from a more reliable source.

Ha! to

[wayneward]

Might be better up connect them both together in parallel and measure the impedance do you think ? So I'm I right in thinking that one cab won't me louder than the other!?

[Daniel Piper]

Originally Posted by drpepper

It's not a matter of being "tricky." The established practice for labeling speakers is to use 4, 8, 16 etc. ohm ratings. A given 8 ohm cabinet may be lower or higher (probably in the range from ~6 to ~11) or it might be exactly 8 ohms. I believe a very few makers label with measured impedance.

Agreed.

The end result is, that if you want to run three TC cabs with an RH head, the sound will be massive.

If you want to run two similar 8 ohm cabs , from another manufacturer with an RH head, the sound will be massive.

[B-string]

Impedance is not a "Fixed" value. A Handheld meter will not give the nominal impedance unless it can sweep the frequency range. All you can measure with a normal meter is the DCR (Direct Current RESISTANCE) not the impedance to AC.

[wayneward]

So it's tricky then?! Run it and if it cuts out that's it you think? Obviously the modern amp will have protection for this I'm hoping ?.. Any suggestions
Plus both cabs are Eden not TC

[B-string]

JIMO three 8 ohm non TC cabs are not such a good idea. There should be a protect circuit of some kind. No protect circuit should be relied on to be 100% effective. It is there to help in an emergency situation. It is not there to rely on for avoiding purposeful misuse?
BUT, it is yours so roll the dice if you like.

A 4 ohm Eden and 8 ohm Eden IMHO is asking for trouble, don't blame the amp head if you have a failure.

[wayneward]

that's what I'm thinking its a bit let me say iffy
I'm thinking the easiest way is the 4 ohm speaker in the 1x15 cab and then try a series connection lead giving 8 ohms otherwise I'd have convert the 2x10 to a 8ohm cab which I'm not certain if the horn is 8ohms In parallel to the two 10's at 8ohm creating 4ohms so disconnecting the horn might end with a 8 ohm cab! Ill have to attack it with a screw driver and multi meter!!
I have a gig for it next month and I could do with the full rig for a show so just trying all avenues with out blowing my amp up half way through the set and without having a rig that's to small !!
Cheers for feedback so far

Ill use talk bass now I got a iPhone client / android client a lot !! Very handy
Wayne

[B-string]

A 210 4 ohm cab will most likely have two 8 ohm 10" drivers wired in parallel (don't think I have ever seen 2 ohm MI 10"). Rewire the 10" in series will make a 16 ohm cab (don't worry about the horn, the impedance won't be affected due to the crossover it gets treated separately).
You will now have a 8 ohm and 16 ohm cab that will make a 5.33 ohm load.

[wayneward]

Now that sounds more like it
It's been a while since I messed around with this kinda stuff but it's not a massive job - great idea

[MrLenny1]

Let me know how that works out. I have the same cabs but cannot run
both with my Eden 400.
I am very interested in the RH450 but their specs are iffy.
drpepper is right about the ohms rating on a cab. It is nominal.
An ohm meter would be good to check the actual ohms of each cab.

[drpepper]

Originally Posted by MrLenny1

An ohm meter would be good to check the actual ohms of each cab.

I don't think that's the case.

I only have a layman's understanding of this, but as B-string pointed out, grabbing a multi-meter and turning the knob to "ohms" is going to measure resistance (DC), while impedance applies to AC. The number will will not be the one that's being sought. From various posts on the subject where people have tried to use a meter, the number tends to come out lower that what would have come out with a proper measurement. How much lower? I don't think you can really say, because testing to begin with means that the properly measured rating number isn't known.

[B-string]

Originally Posted by drpepper

I don't think that's the case.

I only have a layman's understanding of this, but as B-string pointed out, grabbing a multi-meter and turning the knob to "ohms" is going to measure resistance (DC), while impedance applies to AC. The number will be the one that's being sought. From various posts on the subject where people have tried to use a meter, the number tends to come out lower that what would have come out with a proper measurement. How much lower? I don't think you can really say, because testing to begin with means that the properly measured rating number isn't known.

Exactly. If you grab a "meter" and set it to Ohms you are not measuring the speaker's AC Impedance. There are AC impedance testers out there, they are expensive. One term people don't include most often is "Nominal" when talking about impedance. The impedance at the cab's resonant frequency for example will be MUCH different than at 1KHz.

[wayneward]

Mrlenny1 what happens when you do? I've had mine on low levelish at home and it's fine ? Do you have to drive it first before it stops working ?.. With the 400