Building an Amp Cabinet

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dxp
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Re: Building an Amp Cabinet 2013/06/28 17:54:43 (permalink)
Guitarhacker
the main thing is to use good quality wood/plywood, and brace it and glue it so it can survive the bumps and drops and won't start rattling and buzzing over time.Nothing sux like a buzzing cab on those resonate low notes.  



I have never been accused of under building anything. Normally people point and laugh because you can park a truck on my tables...
I suspect this build would fall into the category of 'sturdy'.

(I'm not carrying that damn thing....you carry it...)
#31
dxp
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Re: Building an Amp Cabinet 2013/06/28 17:57:20 (permalink)
spacealf

http://lenardaudio.com/education/05_speakers.html

Musical Education 101 I guess!  


Thx for the link
#32
spacealf
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Re: Building an Amp Cabinet 2013/06/28 18:42:13 (permalink)
I added another link to my last post (which I guess I was slow in adding with Editing the Post).
 
Here it is again:
http://www.duncanamps.com/technical/speaker_cab.html
 
I thought low frequency of the low E string on guitar was 160Hz not 80Hz which I thought was Bass Guitar. I guess I will have to look that up as usually to me Bass Drums were around 60Hz. If that is the case then there is a misprint in that link.
 
Well, other links can be searched for I suppose.
 

 
 
#33
drewfx1
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Re: Building an Amp Cabinet 2013/06/28 19:53:45 (permalink)
The fundamental of a bass guitar's low E = 41.2 Hz.

 In order, then, to discover the limit of deepest tones, it is necessary not only to produce very violent agitations in the air but to give these the form of simple pendular vibrations. - Hermann von Helmholtz, predicting the role of the electric bassist in 1877.
#34
spacealf
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Re: Building an Amp Cabinet 2013/06/29 00:18:33 (permalink)
 My old Electrical Handbook as 88 note piano showing as low frequency in the chart at 30Hz. The graphic shows different instruments and frequency range of such instruments - no guitar though, just Tubas, and Wind Instruments and such.
 
Might be a different way with speaker leads though. One day someone goes in and marks all the negative terminal as the positive one and then when try and hook up the speaker, the leads are reversed. Thus the battery check to ensure that the speaker cone is moving out and not in with that battery test.

 
 Well, good luck. Tweak those frequencies.
 
post edited by spacealf - 2013/06/29 00:42:59

 
 
#35
ampfixer
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Re: Building an Amp Cabinet 2013/06/29 00:41:47 (permalink)
Speaker phasing is only an issue with multiple drivers. Most Fender reverb amps have an output that's opposite to the input. When you hit a note the cone actually goes backwards. The non reverb channel pushes outward on the attack. WHy? Because the reverb channel has one extra gain stage. Every time the signal goes through a gain stage it gets inverted.
 
If you want to see for yourself, slave the normal and reverb inputs together with a patch cord. Very bad tone. Most people can't hear a single driver that's out of phase. Vintage Jensen's often have the terminals incorrectly identified and you have to check them if using multiple drivers. The battery test is great for that, but I use a 1.5 volt, not a 9 volt. Speaker voice coils are designed for ac voltage and putting dc on the voice coil can burn them out or warp them causing a rub. You want to just give them a very short pulse of dc.

Regards, John 
 I want to make it clear that I am an Eedjit. I have no direct, or indirect, knowledge of business, the music industry, forum threads or the meaning of life. I know about amps.
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#36
ampfixer
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Re: Building an Amp Cabinet 2013/06/29 00:41:51 (permalink)
DOH!!!
post edited by ampfixer - 2013/06/29 00:44:04

Regards, John 
 I want to make it clear that I am an Eedjit. I have no direct, or indirect, knowledge of business, the music industry, forum threads or the meaning of life. I know about amps.
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#37
ampfixer
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Re: Building an Amp Cabinet 2013/06/29 00:42:03 (permalink)
OOPS

Regards, John 
 I want to make it clear that I am an Eedjit. I have no direct, or indirect, knowledge of business, the music industry, forum threads or the meaning of life. I know about amps.
WIN 10 Pro X64, I7-3770k 16 gigs, ASUS Z77 pro, AMD 7950 3 gig,  Steinberg UR44, A-Pro 500, Sonar Platinum, KRK Rokit 6 
#38
spacealf
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Re: Building an Amp Cabinet 2013/06/29 00:59:19 (permalink)
Only want to click the speaker with the D cell battery (1.5v) or perhaps C cell and not hold it on the speaker terminal.
I would op for the speaker cone to move out first, and not have the sound of the cabinet be the first thing coming out as the sound though, the speaker sound directly first of all.
 
 
 

 
 
#39
The Maillard Reaction
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Re: Building an Amp Cabinet 2013/06/29 08:16:25 (permalink)
ampfixer
Speaker phasing is only an issue with multiple drivers. Most Fender reverb amps have an output that's opposite to the input. When you hit a note the cone actually goes backwards. The non reverb channel pushes outward on the attack. WHy? Because the reverb channel has one extra gain stage. Every time the signal goes through a gain stage it gets inverted.

 
 
http://www.jblpro.com/BackOffice/ProductAttachments/JBL_TechNoteN1V12C_v5.pdf
 
 
 
 


#40
maximumpower
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Re: Building an Amp Cabinet 2013/06/29 08:41:55 (permalink)
Guitarhacker
You know.... While it's easier to buy something off the floor of a store, it's also a ton of fun to build something.
 
In the day, I have built or been involved in more than one speaker cab build. The interesting thing is store bought speakers come in all sizes and dimensions, so I'm thinking it's pretty hard to go wrong on a guitar cab design/build. Build it to the size you want for the number and size of the speakers you plan to load it with.
 
the main thing is to use good quality wood/plywood, and brace it and glue it so it can survive the bumps and drops and won't start rattling and buzzing over time.Nothing sux like a buzzing cab on those resonate low notes.
 
I was partial to EV 12" speakers. They are highly efficient.... giving a nice SPL for a given wattage input, and crisp and clean sounding with a nice bright sound to them. Power handling is not as critical with a good speaker like the EV, but getting a clean bright efficient sound is. I had EV's in a number of my rigs and in the PA too.


From time to time I have wanted to build a guitar cab. If/when I do, I will build the EV ported cab (plans can be found with a search) designed for the EVM 12L" speaker.
 
My first cab (I had been using the cab/speaker from my old Yamaha combo amp with a JBL in it) was a 4x12 used Carvin. They are easy to find used, built well and very inexpensive. I found one with 4 working 12" speakers for $200. It was inexpesnive enough that I could not make one for less (with speakers).

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#41
Guitarhacker
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Re: Building an Amp Cabinet 2013/06/29 08:45:13 (permalink)
Whether a speaker or speakers move in or out on the first pulse is irrelevant once you are past that first move of the cone.... it then simply becomes a note of music or a sound.   Once that cone is in motion, it doesn't make a hill of beans what direction it moved first.
 
Phase is critical with multiple speakers since you do want them all working together as a team. Swapping the polarity on the leads does nothing that is audibly different since the sound you are hearing is AC.
 
If there is a difference, I believe it would be psychological to the ear of the person who knows the polarity is different.... kind of like how your car seems to run better after it's been washed and waxed.

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#42
dxp
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Re: Building an Amp Cabinet 2013/06/29 11:46:46 (permalink)
Well I am glad I started his thread because now after all the input I am not sure I want to take this on.
Especially if I were to do two speakers in a cab.
Phase etc.
hmmm
#43
The Maillard Reaction
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Re: Building an Amp Cabinet 2013/06/29 12:29:49 (permalink)
Anytime you use more than one speaker you should check phase.
 
Anytime you use more than one amp you should do the same.
 
It's kid stuff... don't let that persuade you to not have some fun.


#44
spacealf
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Re: Building an Amp Cabinet 2013/06/29 14:10:41 (permalink)
Yes, my JBL speakers are so old they are a negative system. But anyone who tells me that you can not hear the difference whether the speaker is moving out or in with the system to me is well - just plain wrong. I think it does make a difference but each to their own. (at least it does to me whether the speaker moves out with first punch or not.)
 
Two speakers are not a worry at all, hook them up for 4 ohms and in parallel. It's the 4 speaker cabinets in series and parallel (to get 8 ohms instead of 4 depending on the ohms of the speaker in the first place) that end up having 2 speakers move out and 2 speakers moving in with first punch (at least to me wired that way like well about all of them are wired that way. (because series means positive to negative lead of a speaker and parallel means positive to positive of the speaker to the input jack). But then there are 16ohm speakers and all of that so perhaps all the speakers in a 4 speaker cabinet are moving all out at first punch also.)
 
 

 
But think of all the fun building cabinets designed by yourself. (and perhaps headaches)
 
And I did not know that about the convention back when of the industry doing the connections on the speakers that way. I thought someone was having a really bad day making speakers or something like that. Well, still learning something even now.
What kind of idea was that in the industry??? Goofy to me.
 
And in this context, I am not talking about very loud re-production, just the normal loudness in a small or medium venue of re-production. In any case the music shall be probably played on.
 
 
 
post edited by spacealf - 2013/06/29 14:51:06

 
 
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