Swapping 10" drivers... another impedance question

[John Bigboote]

I'm sorry... I know this is probably covered in 115 other threads, but if so, I'm not finding them.

I just picked up a G-K 700RB kickback combo with two 10" drivers. Weighs a ton. I have two DeltaLite 2510s from another cabinet that I would like to swap into the combo to get the weight down.

The G-K's drivers are clearly marked as 16 ohm. They're wired in series; the wires come from the amp's crossover to one speaker, then from that one to the other.

The 2510s are *not* marked--no sticker or stamp indicated the impedance. But it seems to me that cab is clearly wired in parallel; two wire pairs come from the crossover, one pair to each speaker. The crossover and speakers came from Avatar together to make an 8-ohm cab.

So I would have assumed the DeltaLite cab would have two 4-ohm speakers. But the raw DeltaLites read between 11 ohm and 12 ohm on my RadioShack multitester, and the heavy drivers from the G-K read in the high 10-ohm range. So it seems to me they're in the same ballpark.

I'd love to swap them, but am afraid that if the Deltas are really 4 ohm, I now have a 2-ohm combo, and the RB700 isn't rated for that (and I def want it to be 8 ohms anyway). But would I be getting such similar ohmmeter readings if the heavies are 16 ohm and the Deltas are 4 ohm?

Any guidance from the hive? Thanks!

-jb

 

[agedhorse]

Aside from the issue of cabinet tuning (the DeltaLites could end up being a downgrade), it looks like you have 16 ohm driver that should have been wired in parallel for 8 ohms.

What are the numbers on the gray tag on the new drivers? We may be able to help you out. The gray tag may be on the underside of one of the basket spokes depending on the era.

 

[Redbrangus]

They're wired in series; the wires come from the amp's crossover to one speaker, then from that one to the other.

Do both wires go first to one speaker and then both wires go over to the other? If so, it's likely those two drivers are wired in parallel.

Also, if the "2510" drivers aren't marked, how do you know they're 2510's?

 

[agedhorse]

Do both wires go first to one speaker and then both wires go over to the other? If so, it's likely those two drivers are wired in parallel.

Also, if the "2510" drivers aren't marked, how do you know they're 2510's?

Exactly what I am wondering too.

 

[Redbrangus]

So I would have assumed the DeltaLite cab would have two 4-ohm speakers. But the raw DeltaLites read between 11 ohm and 12 ohm on my RadioShack multitester ...

Your DC resistance measurements are consistent with the 'Deltalites' also being 16-ohms, so two wired in parallel would yield an 8-ohm cab, just as indicated by the manufacturer. So the impedance part of the situation isn't a problem -- the potential mismatch between the replacement drivers and the tuning of the cab you're putting them in could very well be, though.

 

[Dino Boreanaz]

As suggested above, please check the tag on the drivers to confirm what they actually are. A year or so ago I bought two used DeltaLite 2510s, except one wasn't. One of them was a speaker made for Avatar that uses some of the 2510's hard parts. The parameters for this driver are considerably different than the 2510 and modelling shows that it would perform quite differently in a cab.

I've since sold the driver, but you can see the T/S parameters and a photo of the tag in my old classified post here.

 

[agedhorse]

As suggested above, please check the tag on the drivers to confirm what they actually are. A year or so ago I bought two used DeltaLite 2510s, except one wasn't. One of them was a speaker made for Avatar that uses some of the 2510's hard parts. The parameters for this driver are considerably different than the 2510 and modelling shows that it would perform quite differently in a cab.

I've since sold the driver, but you can see the T/S parameters and a photo of the tag in my old classified post here.

This is my suspicion as well, it’s come up several times before.

 

[Old Garage-Bander]

Resistance, which you measure with your multi-meter is not the same as Impedance. But as mentioned, you can usually derive impedance of a speaker by measuring the resistance.

When measuring a voice coil with a multi-meter, you are only measuring the DC (Direct Current) resistance of the wire in the coil. Impedance measurements involve Alternating Current (AC). Audio signals are all AC in nature. Impedance measurements take into account additional electrical properties like the inductance and capacitance inherent in a coil of wire, the frequency of the signal is also a factor. And yes the wire resistance is involved as well. This results in numbers that can be quite complex.

That impedance number assigned to a speaker is not exact. Rather it is nominal, a kind of "ballpark" figure, if you will, for lack of a better term. The nominal impedances that we usually encounter are 4, 8, and 16 Ohms. You only need to concern yourself with knowing, or determining (with an interpretation by multimeter) the nominal figure.

There are ways to measure actual impedance, but it involves more sophisticated test equipment and knowledge that many people do not ever acquire. For your purposes, it is safe to say that the resistance measurement will be slightly lower than the nominal impedance but not so low as the nominal impedance of the next lower rating that we normally encounter. For instance 16 Ohms, nominal will read less than 16 on a multi-meter, but it will read more than 8.

Impedance and resistance use the same unit of measure, the Ohm. For those who aren't aware of this, it can often lead to confusion. I hope this helps clear it up a bit.

 

[John Bigboote]

As suggested above, please check the tag on the drivers to confirm what they actually are. A year or so ago I bought two used DeltaLite 2510s, except one wasn't. One of them was a speaker made for Avatar that uses some of the 2510's hard parts. The parameters for this driver are considerably different than the 2510 and modelling shows that it would perform quite differently in a cab.

I've since sold the driver, but you can see the T/S parameters and a photo of the tag in my old classified post here.

That's a bingo! The speakers came from Avatar; I assumed they were just OEM'd 2510s, so lacked any of the usual Eminence identifiers (sticker on the magnet, etc.). The sticker showing the impedance is devilishly hidden under the spider per your listing--I never would have seen it if I hadn't seen your post, so thanks for that!

The sticker confirms that they're 16 ohm, so straight swap. Yay.

The combo is going to be used exclusively for rehearsals and on-stage monitoring, so unless the cab's tuning does something truly awful, I imagine they'll work fine. It would be worth it to me to shave the considerable weight from the schlep.

All the other info has been incredibly useful. Thanks to everyone!

-jb

 

[Old Garage-Bander]

The combo is going to be used exclusively for rehearsals and on-stage monitoring, so unless the drivers' tuning does something truly awful, I imagine they'll work fine.
-jb

That assumes you don't damage the speakers. Or have to play them at a low enough level as to be useless for rehearsal.

You should consider this as being experimental. In which case you should be aware of the risks, which I think have been adequately spelled out. Likewise you should be willing to take responsibility for those risks if something bad happens. If you are OK with all that and wish to proceed, then I wish you all the luck.

 

[Thumpin6string]

I agree with most of what has been said, except IMHO the Deltalites would be an upgrade. They are rated at 250 watts each, so the pair would handle 500 watts at 8 ohms. The 700rb only puts out 380 watts at 4 ohms and near half that at 8 ohms. The factor GK speakers are probably 150-200 watts each. I say try it. If it doesn't work out, put the original drivers back in.

 

[cheechi]

Iin 115 other threads

but not the 210 or 410 other threads.

 

[mmbongo]

but not the 210 or 410 other threads.

I see I'm not the only one that was wondering how a 115 was involved here

 

[agedhorse]

I agree with most of what has been said, except IMHO the Deltalites would be an upgrade. They are rated at 250 watts each, so the pair would handle 500 watts at 8 ohms. The 700rb only puts out 380 watts at 4 ohms and near half that at 8 ohms. The factor GK speakers are probably 150-200 watts each. I say try it. If it doesn't work out, put the original drivers back in.

Except this assumes very good tuning and a HPF around 40Hz. The mechanical power handling at 50Hz could be as low as 1/2 of the published thermal power handling. Without the above, sweating the power handling would be wise.

 

[agedhorse]

That's a bingo! The speakers came from Avatar; I assumed they were just OEM'd 2510s, so lacked any of the usual Eminence identifiers (sticker on the magnet, etc.). The sticker showing the impedance is devilishly hidden under the spider per your listing--I never would have seen it if I hadn't seen your post, so thanks for that!

The sticker confirms that they're 16 ohm, so straight swap. Yay.

The combo is going to be used exclusively for rehearsals and on-stage monitoring, so unless the cab's tuning does something truly awful, I imagine they'll work fine. It would be worth it to me to shave the considerable weight from the schlep.

All the other info has been incredibly useful. Thanks to everyone!

-jb

What are the numbers on the sticker under the basket spoke. Avitar has used many different drivers that were referred to as the same part. There are significant differences.

 

[John Bigboote]

What are the numbers on the sticker under the basket spoke. Avitar has used many different drivers that were referred to as the same part. There are significant differences.

The sticker (damn, it was hard to get this) says:
AVDLITE21016 [I'm taking this to mean 16-ohm DeltaLite for Avatar 210... or 16-ohm 10" DeltaLite II for Avatar?]
101377 16OHM
67-0 929A 0451 L2

Comically, with the neo drivers installed, this "tilt-back" cab now flops over onto its back like a poorly balanced tortoise. I'm going to need to install a kickstand!

-jb

 

[agedhorse]

That’s one of their own versions of the DeltaLite 2. The parameters are different and you need to get them from Avitar.