Dr Bass 1260 Speaker replacement impedance query fixed thanks for the advice.

[ash]

Dr Bass 1260 cab

I recently bought one of these cabs off eBay as I’d heard great things about the product - although dodgy things about the business practices of the builder. 

The cab arrived but had been badly handled by the courier resulting in the midrange 6.5” speaker coming adrift and being thumped around in transit.

I reseated this and drilled new mounting holes. There appeared to be no obvious damage however the driver is no longer functional. I checked all connections and nothing appears loose or damaged. I have no other measuring equipment than my ears, eyes and putting my fingers on the cone to feel if it is moving, it isn’t and I can only hear a signal through the main 12” driver and tweeter. 

My question is about replacing the mid driver. The main woofer is an Eminence Gamma 12 presumably 8ohms and the mid is a 6.5 Eminence LA6 CBMR. This is labelled 8 ohms. There’s a tweeter and some kind of crossover, with two speakon sockets and an attenuater for the tweeter. 

The speaker cab was sold to me as an 8ohm cab and online info indicates 8ohms  when manufactured. However both speakers appear to be 8ohm drivers so I’d expect the total impedance to be 4ohms? Even with the defunct mid it sounds really punchy so I’d like to replace the mid speaker to bring it up to full spec. So would it be advisable to simply buy a replacement mid speaker of the same specifications as a direct replacement? 

Will the crossover have any effect on the total load? Any suggestions, advice would be most welcome.

 

 

 

Edited July 3, 2019 by ash

[sifi2112]

I asked the same question once as was told by the experts that both 8 Ohms speakers (mid & woofer) will stay 8 Ohms with a crossover. Don’t ask me how it works I’ll let others chime in

[itu]

An accurate replacement is the best option, as the specs will be as planned. Another type of element may affect the sound and tuning a lot.

X-over takes care of the impedance, so do not worry.

[andybassdoyle]

Don't know about the repair but I had one of these many years ago and it was a pretty decent cab. Should be worth the effort!

[Bigwan]

The crossover and driver combination will determine the final impedance of the cab. 2 8 ohm drivers in parallel will give you a nominal 4 ohm cab (technically it's not that simple as impedance is a function of frequency, but it'll do for this example), 2 8 ohm drivers connected to a crossover network could end you up anywhere as the crossover plays as big a part as the drivers do.

[ash]

57 minutes ago, andybassdoyle said:

Don't know about the repair but I had one of these many years ago and it was a pretty decent cab. Should be worth the effort!

Yes it’s a very nice cab small but robust and even missing the mid it sounds good

[BassBunny]

Firstly, do you know it's the speaker or it could be the x-over. To test the speaker a very quick and dirty method is to use a 9v battery across the speaker terminals. don't completely connect it, connect 1 leg of the battery to 1 terminal and quickly touch the other terminal in an On/Off motion. If the speaker moves and a dull thud is heard, the speaker is doing something.

Regarding impedance and crossovers. What the x-over does is channel certain frequencies to the different speakers. So in a hypothetical case, if you had a x-over that was designed to send anything under 1KHz to the bass speaker, 1-2 KHz to the mid and above 2Khz and above to the horn, only 1 of the speakers is in circuit at any time so if they are 8 Ohm drivers, it's an 8 Ohm Cab. It's a very basic explanation.

[ash]

I added a new Eminence 6.5 mid at 8ohms and it sounds great! Thanks for all the advice.