Grateful Dead Music Forum

can i use a single k120 or a d120 cab with a dual showman reverb? How should it be wired? extremley confused on this subject

Incaroads77 wrote: ↑Sat Mar 10, 2018 9:47 am can i use a single k120 or a d120 cab with a dual showman reverb? How should it be wired? extremley confused on this subject

Yes sir, there is not problem when your amp see's more ohms than it wants to, (just dont want to see less ohms that your amp wants to, so say if your amp wanted to see 8 ohms you would not want it to see 4ohms)

-best
Nathan

It wants to see 4 ohms. Two 8 ohm speakers wired parallel. For using only one speaker, it has to be a 4 ohm speaker or you can pull two inner or outer power tubes and use one 8 ohm speaker.
https://www.thegearpage.net/board/index ... an.277237/

You can use a single 8 ohm JBL with the Dual Showman Reverb 4 Ohm speaker tap. The output transformer is spec'd for a 2:1 mismatch in EITHER direction. The consequences are slight changes in output and headroom. It's negligible.

As Nathan pointed out the problems start with a larger disparity load-wise when the speaker load is too little.

would a single 4 ohm one of these be a better option than an e120?

you would probably blow a d with a dual showman, an e or k would work. and e120 would work great with a dual showman.

lovetoboogie wrote: ↑Sat Mar 10, 2018 11:03 am You can use a single 8 ohm JBL with the Dual Showman Reverb 4 Ohm speaker tap. The output transformer is spec'd for a 2:1 mismatch in EITHER direction. The consequences are slight changes in output and headroom. It's negligible.

As Nathan pointed out the problems start with a larger disparity load-wise when the speaker load is too little.

+1 I plug an 8ohm load into my 4ohm twin all the time, with no issues

Incaroads77 wrote: ↑Sat Mar 10, 2018 9:47 am can i use a single k120 or a d120 cab with a dual showman reverb? How should it be wired? extremley confused on this subject

To reiterate what others have said, yes, you can use one 8-ohm speaker. No problem. No need to pull tubes (pulling tubes may create a unique clipping effect that you may like--pull two inner or two outer). Use a K or E120 speaker. Just wire it normally--one end into one lead, second end into the other lead--tape the open ends of the second cable).

i landed on this today
https://www.ebay.com/itm/Vintage-JBL-E1 ... 2749.l2649

Dented dust cap, so i purchased a replacement aluminum cap just in case i cant pull it out with my vacuum cleaner. 72 bucks aint half bad for an original speaker& cone etc. with virtually nothing wrong with it! I contacted Tim at TRM and he's building me a 1x12 to go along with it. Now to replace my cs69's with super 2's and buffer then off to the races

Incaroads77 wrote: ↑Sun Mar 11, 2018 6:39 pm i landed on this today
https://www.ebay.com/itm/Vintage-JBL-E1 ... 2749.l2649

Dented dust cap, so i purchased a replacement aluminum cap just in case i cant pull it out with my vacuum cleaner. 72 bucks aint half bad for an original speaker& cone etc. with virtually nothing wrong with it! I contacted Tim at TRM and he's building me a 1x12 to go along with it. Now to replace my cs69's with super 2's and buffer then off to the races

Looks good might be cheaper to just have her re-coned I've had a couple done by Alan. He does a very good job, in a timely fashion, and is great with communication. High recommend him!

https://www.facebook.com/spiralrecone/

best,
Nathan

wouldnt replacing the cap be a better idea? i've read alot on here about how the original jbl re-cone kits are scarce, and that re-coning a jbl changes the sound somewhat.

i could be wrong but thats why i landed on that speaker. the dent doesnt change sound, and its original.

I actually prefer to plug my 4ohm Fender amp tap into a single 8 ohm speaker

The amp doesn't really care about number of speakers as much as it's worried about ohms.

It wants to see 4. you're safe with 8 or 2ish (forget the exact).

Incaroads77 wrote: ↑Sun Mar 11, 2018 7:26 pm wouldnt replacing the cap be a better idea? i've read alot on here about how the original jbl re-cone kits are scarce, and that re-coning a jbl changes the sound somewhat.

i could be wrong but thats why i landed on that speaker. the dent doesnt change sound, and its original.

Replacing the dust cap requires you to remove the old dust cap. I have not done one of these, but my understanding is that its fairly easy to damage the cone when you are using your knife to cut away the glue to remove the older dust cap.

Try the duct tape method--put a small section of tape on the crease, slowly pull away. This method has worked for me to smooth out some dents in the aluminum cap. I used Gorilla Glue tape last time I did it, so that's very strong tape that has a good hold. But be careful when you pull on the tape because you can also do more damage than the dent. If your speaker is behind a grill I would just leave it.