It is currently Mon Mar 16, 2020 8:26 pm

All times are UTC - 7 hours



Post new topic Reply to topic  [ 12 posts ] 
Author Message
Post subject: Fender Bassman parallel outputs, expert help needed.
Posted: Thu Nov 03, 2011 1:55 pm
Offline
Hobbyist
Hobbyist

Joined: Thu Nov 03, 2011 1:45 pm
Posts: 6
Hi,

I have 1969 silverface bassman (4 ohms) and a 16 ohms cabinet. As I read before, not an ideal combination.

But... my cabinet has 2 parallel inputs, meant for an additional cab (stereo 8 ohms).

Wat would happen if I hooked up 2 speakercables from the 2 parallelled outputs on the amp, to the 2 parallel inputs on the cab.

Would this mean my impedance is 8 ohms with just one cabinet?


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: Fender Bassman parallel outputs, expert help needed.
Posted: Thu Nov 03, 2011 2:07 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
1/Rf = 1/R1 + 1/R2, as long as cabs are IN PARALLEL with source.

For your cabs:

= 1/8 + 1/8 = 0.125 + 0.125 This is for two 8-ohm cabs. Are you saying you can break the 4 X 12 cab into two 12-inch 8 ohm outputs... from its oringal 16-ohm quad setup?

= 0.25

1/Rf = 0.25

Rf = 4 ohms


Last edited by BMW2002Ti on Thu Nov 03, 2011 2:13 pm, edited 1 time in total.

Top
Profile
Post subject: Re: Fender Bassman parallel outputs, expert help needed.
Posted: Thu Nov 03, 2011 2:13 pm
Offline
Hobbyist
Hobbyist

Joined: Thu Nov 03, 2011 1:45 pm
Posts: 6
Thanks for the reply, but I guess you misunderstood. I don't own an additional cabinet.

What I want to do is use both of the outputs on 1 amp, and plug the two cables into 1 cabinet with 2 inputs.

What would this do?


Top
Profile
Post subject: Re: Fender Bassman parallel outputs, expert help needed.
Posted: Thu Nov 03, 2011 2:19 pm
Offline
Hobbyist
Hobbyist

Joined: Thu Nov 03, 2011 1:45 pm
Posts: 6
To be more precise, this is my cab.

http://www.musicstore.com/en_EN/EUR/Pea ... 008966-000

Check the specs.


Top
Profile
Post subject: Re: Fender Bassman parallel outputs, expert help needed.
Posted: Thu Nov 03, 2011 2:21 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
OK, got in I think. :?:

Both outlets from the one amp want to "see" 4-ohms" I believe. You cannot change what they want to "see" (not without changing OPT). The load or the speakers can be maniputlated. If you break the 16-ohm quad into separate 2 X 8-ohm inputs. That's what you have. 8 ohm inputs.

Still not too great for the 4-ohm outputs of the amp.


Top
Profile
Post subject: Re: Fender Bassman parallel outputs, expert help needed.
Posted: Thu Nov 03, 2011 2:24 pm
Offline
Hobbyist
Hobbyist

Joined: Thu Nov 03, 2011 1:45 pm
Posts: 6
But better :)


Top
Profile
Post subject: Re: Fender Bassman parallel outputs, expert help needed.
Posted: Thu Nov 03, 2011 3:35 pm
Offline
Hobbyist
Hobbyist

Joined: Thu Nov 03, 2011 1:45 pm
Posts: 6
Correct me if I am wrong, but:

if it's possible to have 2 x 8 ohms inputs on my cab, wouldn't that make 4 ohms when I use both speaker outputs on my bassman?

http://eledar.net/Music/64bassman_resto ... neback.jpg


Top
Profile
Post subject: Re: Fender Bassman parallel outputs, expert help needed.
Posted: Thu Nov 03, 2011 4:12 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
Open the cab and check the impedance of the individual speakers. I'm betting the cab can be reconfigured for the correct four-ohm load using some AWG 18 speaker wire.

HTH

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: Fender Bassman parallel outputs, expert help needed.
Posted: Fri Nov 04, 2011 4:38 am
Offline
Hobbyist
Hobbyist

Joined: Tue Sep 27, 2011 6:21 am
Posts: 71
The specs state there is a stereo/mono switch. Does the label give any indication of impedance if switched to mono?


Top
Profile
Post subject: Re: Fender Bassman parallel outputs, expert help needed.
Posted: Sun Nov 06, 2011 9:37 am
Offline
Professional Musician
Professional Musician

Joined: Wed Aug 26, 2009 4:50 pm
Posts: 1339
Location: Denver, CO, USA
"16 ohms mono, 8 ohms stereo"

Stereo splits the cab into two independent 8 ohm 2x12 cabs (housed in a shared box). If you set the cab to stereo you can run two cables from it to the Bassman's two parallel outputs. Two 8 ohm loads in parallel is a 4 ohm total load, perfect for your Bassman.

As said earlier it would be easy to rewire the cab so it's four ohms mono. (Currently it's wired so it connects the two 8 ohm 2x12 pairs in series for the mono position -- you'd just have to move a couple of wires around so that it connects the two 8ohm 212 pairs in parallel instead for a 4 ohm mono load.)


Top
Profile
Post subject: Re: Fender Bassman parallel outputs, expert help needed.
Posted: Mon Nov 07, 2011 12:31 am
Offline
Hobbyist
Hobbyist

Joined: Thu Nov 03, 2011 1:45 pm
Posts: 6
There is no visible switch. So I am going to rewire it, just to be sure.


Top
Profile
Post subject: Re: Fender Bassman parallel outputs, expert help needed.
Posted: Mon Nov 07, 2011 1:26 am
Offline
Professional Musician
Professional Musician

Joined: Wed Aug 26, 2009 4:50 pm
Posts: 1339
Location: Denver, CO, USA
Ah, well, we were all going by the specs listed on that product description page you linked to. When you said there's no switch I looked at Peavey's product page for the VK 412 Angled cab.

It's a mono-only 16 ohm cab. The dual input jacks are regular parallel jacks.

http://www.peavey.com/products/InstAmplifiers/guitaramps/412//index.cfm/item/116190/ValveKing%26reg%3B412Slant.cfm

They don't specify the individual speaker impedance anywhere that I could find. But no worry -- they have to be either 16 ohms each or 4 ohms each and either way you can wire them for 4 ohms total load.


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 12 posts ] 

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: