Whats better 15ohms or 4 ohms for V4 ?

[boxbrownie]

OK....bit of a dilema, I have ordered a Biffo V4 for my Cl55 and have put the larger bass reflex in the tank but wa also wondering about using a small sugar cube speaker under the fans in the body also, hoping for some treble up and bass down. Not sure if it'll work perfectly without a crossover but I figure the speakers are so different maybe it will?

Problem I have is parallel or series?  15 ohms one way or 4ohms the other, I am inclined to wire for 15 ohms (measured not 16ohms).

 

But I really want to keep the magic smoke in the chips.....so?

[boxbrownie]

Answering my own question now......4ohms it appears is the recommended impedance so I am in luck.

 

I usually use Zimo and they recommend 8 ohm......I really should read the instructions more often

[pauliebanger]

Answering my own question now......4ohms it appears is the recommended impedance so I am in luck.

 

I usually use Zimo and they recommend 8 ohm......I really should read the instructions more often

 

Probably should. Most Zimo decoders are happy on 4 Ohms too. (Not the miniature MX646 or 648 which prefer 8 Ohms).

 

My own experience says that a sugar cube will begin to distort long before the bass reflex, so you will not get the required mix of high and low frequencies you are seeking. A 10uF bipolar capacitor in the wiring to the sugar cube will 'favour' the higher frequencies, like a crude crossover, but you will need to experiment.

 

Good luck,

 

Paul

[boxbrownie]

Hi Paul,

 

Weirdly I connected both speakers to give 4ohms and the MX644D cut out the audio after a few seconds (four at most), upon connected each speaker individually all was fine so I connected them up to give 15/16ohms (as it says in the book that this decoder is happy with higher impedance but will give lower volume) and they are running fine, and almost impercivable volume change.

 

This was all to test out the speaker choice before the actual decoder arrives, which will be a V4 and as that is specced at 4-8ohms only I should be able to go back to the parallel wiring to give me 4ohms, interesting about the bipolar cap, I may well try that as there is plenty of room in the body and as it will be parallel wired much easier to change and fiddle with.

 

Thanks for the headsup Paul. 

[pauliebanger]

Hi Paul,

 

Weirdly I connected both speakers to give 4ohms and the MX644D cut out the audio after a few seconds (four at most), upon connected each speaker individually all was fine so I connected them up to give 15/16ohms (as it says in the book that this decoder is happy with higher impedance but will give lower volume) and they are running fine, and almost impercivable volume change.

 

This was all to test out the speaker choice before the actual decoder arrives, which will be a V4 and as that is specced at 4-8ohms only I should be able to go back to the parallel wiring to give me 4ohms, interesting about the bipolar cap, I may well try that as there is plenty of room in the body and as it will be parallel wired much easier to change and fiddle with.

 

Thanks for the headsup Paul. 

 

David,

 

Are you sure the bass reflex is an 8 ohms? Your measurements would suggest it is but your experience with the MX644D is a little surprising. If the bass reflex is 4 Ohms paralleled with an 8 Ohms, the resulting load will be about 2.7 Ohms which would cause problems for the decoder. I know you will be using a Loksound, but the same will apply to Lok V4.0 too, so just check. A 4 and 8 in series will give 12 ohms, which I am sure you already know, and will be equally good with a Lok V4.

 

Paul

[boxbrownie]

Hi Paul,

 

Yes most definately a 8ohm speaker, in fact this particualr speaker measures virtually spot on 8ohms (ok.....7.8 to be precise), I was surprised when it cut out as well, at first I thought I had done something dumb so I rechecked all the measurements and wiring but it all checked out as OK, the load in parallel with the two speakers was 4ohms.