Would this mod work on my 1960A in stereo?

Man-Machine · 10-30-2008, 07:52 AM

I'd like to be able to go back and forth between two types of speakers (the stock G12T-75 and some Vintage 30 speakers) in my 1960A cabinet. I want to just swap the speaker cable in the stereo mode jacks to hear each pair of speakers. Is this possible? If so, this is what I gathered so far. Please, correct me if I'm wrong or missing anything. I'm new to all this and I don't want to blow out my new JCM800!

*For this to work I'll need to arrange the speakers in columns, not in an X pattern.

*I can do a straight speaker swap as long as I match ohms.

*I'll need to change my JCM800 to 8 ohms output for the stereo mode of the cabinet.

*I should be ok pluggin into two 60 Watts V30s with my 100W JCM800

Thanks for any help!

JohnH · 10-30-2008, 03:44 PM

OK, if each vertical pair is wired in parallel, so the two 16Ohm speakers make 8 Ohm.

But, there's risk of it sounding really bad if you are only driving one pair of speakers at a time, since the other ones will be driven passively out of phase, and effectivly wreck the bass response. I tried it.

John

Man-Machine · 10-30-2008, 06:30 PM

Isn't that how the cabinet is wired to begin with? It's all stock right now. I'm thinking that all it would take is to replace the speakers and keep the existing wiring scheme, right?

So are you saying that in stereo mode all four speakers need to be used at the same time in order to sound good? I did a quick test earlier using only one pair in stereo mode and I actually didnt' notice any sound difference. I was playing at bedroom levels with a THD hotplate bass switch on...

JohnH · 10-31-2008, 07:34 AM

If you like the sound, no problem! My cab lost a lot of bass with only two driving.

John

PaoloJM · 10-31-2008, 08:13 AM

At lower volumes the speaker interaction wont be that noticable if at all.
I would note the following though:

If your are not using the Hotplate, and running the amp close to flat out, you will be very close to (or above) the max power levels of the speakers. A valve amp can put out up to 150% of it's rated power output. However at these volumes the interaction of the speakers will have become quite pronounced and you'll want to revert to the standard 16ohm mono setting.
Under no circustances should you swap the cables without at least engaging the stand-by and preferably shutting the amp off completely. I'm sure you already know this but it does no harm to say it again.

The speakers in a 1960A are in stacked pairs, ie. the left top and bottom are one parallel pair and right two are the other. You could swap either side for V30s without major rewiring, just remember to set the impedance of the amp head accordingly (8ohm).

Man-Machine · 10-31-2008, 12:13 PM

Thanks, I think I'm gonna go ahead with this project today.

I've deciding on regular Celestions V30 or broken in Hellatone speakers. Are they much different? Opinions?

HOT TUBES 70 · 11-11-2008, 06:03 PM

Check it out !!!! RADIAL ENGINEERING (CABBONE) its a foot control cab switcher etc

mmorse · 11-12-2008, 07:15 PM

Quote:

Originally Posted by Man-Machine

Thanks, I think I'm gonna go ahead with this project today.

I've deciding on regular Celestions V30 or broken in Hellatone speakers. Are they much different? Opinions?

The Hellatones are V30s. Just pre broken in. I had a stereo 1960 and put a bunch of different speakers in it. I noticed no loss of bass when just using 2. In fact, I would think the other 2 would function a little like passive radiators amd reinforce bass response.

coldsteal2 · 11-12-2008, 07:36 PM

I do it all the time, G12H Heritage on one side,
G12M Heritage greenbacks the other side, or all together
sounds great

10-30-2008, 07:52 AM	#1 (permalink)
Man-Machine Junior Member Join Date: Oct 2008 Posts: 6	Would this mod work on my 1960A in stereo? I'd like to be able to go back and forth between two types of speakers (the stock G12T-75 and some Vintage 30 speakers) in my 1960A cabinet. I want to just swap the speaker cable in the stereo mode jacks to hear each pair of speakers. Is this possible? If so, this is what I gathered so far. Please, correct me if I'm wrong or missing anything. I'm new to all this and I don't want to blow out my new JCM800! For this to work I'll need to arrange the speakers in columns, not in an X pattern. I can do a straight speaker swap as long as I match ohms. I'll need to change my JCM800 to 8 ohms output for the stereo mode of the cabinet. I should be ok pluggin into two 60 Watts V30s with my 100W JCM800 Thanks for any help!

10-30-2008, 03:44 PM	#2 (permalink)
JohnH Senior Member Join Date: May 2008 Location: Wollongong NSW Posts: 640	Re: Would this mod work on my 1960A in stereo? OK, if each vertical pair is wired in parallel, so the two 16Ohm speakers make 8 Ohm. But, there's risk of it sounding really bad if you are only driving one pair of speakers at a time, since the other ones will be driven passively out of phase, and effectivly wreck the bass response. I tried it. John __________________ DSL401 8412 cab Crate Powerblock 1 x 12 Vintage 30 cab '76 Shergold Masquerader '93 Les Paul Studio '83 Roadstar

10-30-2008, 06:30 PM	#3 (permalink)
Man-Machine Junior Member Join Date: Oct 2008 Posts: 6	Re: Would this mod work on my 1960A in stereo? Isn't that how the cabinet is wired to begin with? It's all stock right now. I'm thinking that all it would take is to replace the speakers and keep the existing wiring scheme, right? So are you saying that in stereo mode all four speakers need to be used at the same time in order to sound good? I did a quick test earlier using only one pair in stereo mode and I actually didnt' notice any sound difference. I was playing at bedroom levels with a THD hotplate bass switch on...

10-31-2008, 07:34 AM	#4 (permalink)
JohnH Senior Member Join Date: May 2008 Location: Wollongong NSW Posts: 640	Re: Would this mod work on my 1960A in stereo? If you like the sound, no problem! My cab lost a lot of bass with only two driving. John __________________ DSL401 8412 cab Crate Powerblock 1 x 12 Vintage 30 cab '76 Shergold Masquerader '93 Les Paul Studio '83 Roadstar

10-31-2008, 08:13 AM	#5 (permalink)
PaoloJM Senior Member Join Date: Jun 2008 Location: Cork, Ireland Posts: 534	Re: Would this mod work on my 1960A in stereo? At lower volumes the speaker interaction wont be that noticable if at all. I would note the following though: If your are not using the Hotplate, and running the amp close to flat out, you will be very close to (or above) the max power levels of the speakers. A valve amp can put out up to 150% of it's rated power output. However at these volumes the interaction of the speakers will have become quite pronounced and you'll want to revert to the standard 16ohm mono setting. Under no circustances should you swap the cables without at least engaging the stand-by and preferably shutting the amp off completely. I'm sure you already know this but it does no harm to say it again. The speakers in a 1960A are in stacked pairs, ie. the left top and bottom are one parallel pair and right two are the other. You could swap either side for V30s without major rewiring, just remember to set the impedance of the amp head accordingly (8ohm). __________________ www.youtube.com/paolojm

10-31-2008, 12:13 PM	#6 (permalink)
Man-Machine Junior Member Join Date: Oct 2008 Posts: 6	Re: Would this mod work on my 1960A in stereo? Thanks, I think I'm gonna go ahead with this project today. I've deciding on regular Celestions V30 or broken in Hellatone speakers. Are they much different? Opinions?

11-11-2008, 06:03 PM	#7 (permalink)
HOT TUBES 70 Senior Member Join Date: Oct 2008 Location: SASKATOON Posts: 1,675	Re: Would this mod work on my 1960A in stereo? Check it out !!!! RADIAL ENGINEERING (CABBONE) its a foot control cab switcher etc

11-12-2008, 07:36 PM	#9 (permalink)
coldsteal2 Senior Member Join Date: Sep 2007 Location: Chico, CA Posts: 1,555	Re: Would this mod work on my 1960A in stereo? I do it all the time, G12H Heritage on one side, G12M Heritage greenbacks the other side, or all together sounds great __________________ http://www.youtube.com/user/kroftkarl http://www.soundclick.com/bands/defa...&content=music

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