Author Topic: Well, I have a new project  (Read 1186 times)

Offline mspart

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Well, I have a new project
« on: April 08, 2020, 06:26:28 PM »
Well, I have a new project.  I bought a Marshall Code50 amp last year and it is  pretty good, but I like the sound of a cabinet better and have been trying to figure out how to do that.  Today I purchased a cabinet that will hold two speakers so the cabinet is empty.  But cheaper than I could build one.  Next, I need to select the speakers I want for it and then install and wire the cabinet up so that it has the right impedance for my amp.  And then I have to rewire my amp to be able to send the speaker signal out to the cabinet.  That will also be a bit of a hassle.  But not too bad.  I could even add a switch so that I could just play the speaker in my amp or switch it and the sound signal goes out to the cabinet.  I think that would fill the bill for me pretty well. 

I played a guitar through a cabinet a long time ago and now recently, and I really like the sound of a multi speaker cab over a amp/speaker combo.  Here's a pic of the cab:



I am looking for affordable Celestion Greenback (G12M-25) 25 watt 8 ohm speakers.  My amp is 4 ohm and I can wire two 8 ohm speakers in parallel to get a 4 ohm load.  Most cabinets with speakers are either 8 or 16 ohm jobs.  Not quite what I wanted.  So I'll keep y'all informed on my progress.

mspart

Offline Bob H.

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Re: Well, I have a new project
« Reply #1 on: April 08, 2020, 08:04:00 PM »
Good luck.  The only musical instrument I can play is my stereo (I have no rhythym and very little manual dexterity), so I'm glad for those who have the ability to play (or the stereo would do me no good).

Offline RYou

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Re: Well, I have a new project
« Reply #2 on: April 08, 2020, 08:14:12 PM »
Too bad N isn't around.  I'm sure he could offer some insight.  Maybe this will wake him up.

Offline mspart

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Re: Well, I have a new project
« Reply #3 on: April 10, 2020, 10:42:05 AM »
He'd probably have me add an atomic clock sequencer to it, and then a way to hook up one speaker in parallel and the other one in series.  So two 8 ohm speakers would end up having a combined 5.4 ohm impedance. 

I'd love N's input.  I am really looking forward to this. 

mspart

Offline mspart

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Re: Well, I have a new project
« Reply #4 on: April 21, 2020, 01:16:24 PM »
Well, I bought a cabinet with two 12 inch speakers already installed.  For $80!!   The speakers are Celestion G12M-70.  If you look on the internet, you will see that they are not held in the highest regard.  But I'm excited to hear what they sound like anyway.  If it sounds cruddy, I'll get the other speakers I mentioned before.



This  item is an interesting mechanical device.  You plug your guitar into the amp with a 1/4 inch plug.  You connect amplifier to speaker cabinet the same way.  I have a few choices,

1.  I can just cut power to the speaker in my combo amp/speaker and port the power to an external cabinet.
2.  I can add a switch so that I can run the speaker in my combo amp/speaker or send the signal to an external cabinet
3.  I can just add a switching 1/4 jack receiver that automatically ports the signal to the external cabinet with the plug in, or ports it to the combo speaker with no plug in.  No need to add a separate switch.  Cool switch eh?  That is the picture above and that is what I've ordered. 

So as soon as that comes, I'll get moving on it. 

mspart

Offline n9531l

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Re: Well, I have a new project
« Reply #5 on: April 21, 2020, 02:13:44 PM »
If you connect the speakers in parallel, be sure to get the correct phasing. If it's reversed, you won't like what you hear.
Orthography is next to cleanliness, which is next to godliness. - n9531l

Offline mspart

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Re: Well, I have a new project
« Reply #6 on: April 21, 2020, 02:30:35 PM »
Hi N,

Glad you joined the fun.  The speakers are already wired, the cabinet is 8 ohm.  I assume they are wired in phase but will find out for sure.  There is not back opening to the cab, so the speakers are front loaded so that will make inspecting them fun if there is a problem. 

If I get my own speakers to install, then yes, your advice is well founded.  Because it is an 8 ohm, the speakers are 16 ohm and wired in parallel.  I will check the ohms before I get too much further with it just to make sure.  My amp is expecting a 4 ohm output so from that standpoint, I am ok.  I don't need it to be super loud so I don't think that will matter a whole bunch. 

What do you think of that switching connector?  I think it is pretty slick.  I bought two in case one fails.  If both fail, I'll just buy a switch and be done with that experiment. 

mspart

Offline n9531l

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Re: Well, I have a new project
« Reply #7 on: April 21, 2020, 04:51:06 PM »
Connecting an 8-ohm load won't cause any problem unless you want to drive it at the full power of the amp. The switching jack should be fine if its power rating is sufficient.
Orthography is next to cleanliness, which is next to godliness. - n9531l

Offline mspart

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Re: Well, I have a new project
« Reply #8 on: April 21, 2020, 05:54:29 PM »
Yeah, I'm hoping so.  It says each contact is rated at 3 amps.  The amp is 50 watts so I'm hoping it works.  Let me do the math:

50 watts, 8 ohm resistance, that gives 20 volts. 

20 volts and 8 ohms gives me 2.5 amps.  So it should be good.  The math is on a piece of paper. 

Watts = VA,    Amps=V/R     Watts = V^2/R

Hopefully i did the math right. 

mspart

Offline n9531l

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Re: Well, I have a new project
« Reply #9 on: April 22, 2020, 12:22:25 AM »
Or you could figure amps=sqrt(watts/ohms)=sqrt(6.25)=2.5 amps for 50 watts into an 8 ohm load. But the current will be less than that since your amp probably won't put more than about 25 watts into an 8 ohm load. That should be plenty of power, unless you're hoping to wake up your neighbors down the block.
Orthography is next to cleanliness, which is next to godliness. - n9531l

Offline mspart

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Re: Well, I have a new project
« Reply #10 on: April 22, 2020, 11:13:14 AM »
They need some excitement!!  Right, with the extra load, the current will be less.  True.  But I think this little auto switching  jack will work.  I think it is a great idea, who thought it up I'd like to know.  Probably someone messing around like me that didn't want to put in a switch.

I was going to put in a three way DPDT switch and that would have worked.  I had one picked out, a rocker switch.  But that is just extra wiring and drilling and stuff and I saw this item by chance and went that direction.  I guess we'll see if it was a good decision or not. 

mspart

Offline mspart

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Re: Well, I have a new project
« Reply #11 on: April 23, 2020, 01:00:29 PM »
I just bought an amp to speaker cable.  I figured I could use my instrument cable but found out that they are not the same as a higher powered  capable speaker cable.  So I just purchased one.  12 footer, too long for normal use, but might be fun to have the sound coming from further away.  I should be up and running within 2 weeks if the parts all get sent to me within that time. 

I'm just sure this will make me play like Jimi and sound at least as good.  Ha Ha   ;D

mspart

Offline Bob H.

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Re: Well, I have a new project
« Reply #12 on: April 23, 2020, 03:23:36 PM »
I'm sure you can play better than Jimi can today. :D

Offline mspart

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Re: Well, I have a new project
« Reply #13 on: April 23, 2020, 04:47:27 PM »
Jimi's grave is just down the road from me, about 3-5 miles away.  There is a memorial to him that takes a good bit of space there.  But I think you are right, I can play better than Jimi can now, but only because he is dead.  I can't play better than most people, yet I still have fun with it.  Hopefully this will give me some more fun. 

His grave is in Renton, WA   https://www.roadsideamerica.com/story/17559






mspart

Offline mspart

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Re: Well, I have a new project
« Reply #14 on: April 27, 2020, 04:51:59 PM »
Well, my speaker cable arrived.  Thick cable, 12AWG wire, some heavy duty stuff.  I'm expecting the hardware here in the next day or two.  I'm really looking forward to this.

mspart