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February 2004
Posts: 2487
| Curious, I have a 130 Watt Fender amp head. I am going to build my own cabinets as I can't find a matching pair of 2x12" cabs for sale for under $700. In my speaker search I have found a set of four great Celestions that are rated at 75 watts each for a total of 300 watts. I have also found four 35 watt Jensens that would give me a total wattage of 140 watts. All around the same price of $175....These Jensens are not my first choice but they are closer to what my amp can move.
Am I correct in thinking I will get more out of the 140 watts or am I OK with the 300 watt celestions.?
Thanks | |
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January 2006
Posts: 1118
Location: NW Washington State | You don't need to match the speaker watt rating exactly to the amp. Speakers rated at 300 watts will work fine with a 130 watt amp. You probably wouldn't want to use speakers rated at 80 watts since you might blow them up.
Will you "get more out of" the 140 watt rated speakers? If you want to compare how loud they will be, look at the sensitivity rating. Usually the specs will say something like "95 db". Higher numbers are louder, and it's not a linear scale, so 96 db sensitivity is much louder than 92 db.
This assumes that the manufacturers power handling and sensitivity ratings are accurate. I sometimes wonder if they just make this stuff up, particularly on cheap speakers.
Then there's the question of how the speakers actually sound. The specs don't tell you much about that.
-Steve W. | |
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Posts: 10582
Location: NJ | well
I put a pair of m series JBL 10's in my old fender amp. they were very efficient and sounded great clean. to make them break up you had to turn the amp up very loud and it was mind numbing.
so it depends on what kind of sound you want from the amp. if you want it to break up then you absolutely need the lower wattage speakers if you want clean with lots of head room get the higher wattage but then use a distortion pedal in front of it.
as for cabs why build them yourself? there are a ton of companies making empty cabs these days and way under 700 bucks
in fact you want a 4 x 12 crate cab? loaded $200
or a gray rivera era series fender cab 4 x 12 $250
I have an empty peavey you can have for $50 4 x 12 it need corners and some tlc
you would need to pick these up shipping would be a mint | |
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September 2004
Posts: 777
Location: East Wenatchee, WA | Check out Avatar cabinets. Built in Northern Idaho and both high quality and reasonably priced.
Always have more amp than speakers. The greatest destroyer of speakers is not over-driving them, but amplifier "clipping". Basically the amp can't drive the speakers at the level you are demanding and begins to "clip" the high's and low's and will shred a speaker in very short order.
You also don't mention the impedance (ohms) that you are trying to work with. Depending on the amp 4 to 8 ohms is normal, with some amps reaching down to 2 ohms (lower ohms, higher output). Make sure you properly match the impedance of your speakers to the capabilities of your amp, or you will fry an amp. | |
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Posts: 1118
Location: NW Washington State | Maybe avatar is selling the speakers Northcountry is looking at, e.g, eBay item 350191435144.
A powerful amp with lots of headroom is good for PA or hifi, but it seems to me that most rock guitarists are going to be into a lot of distortion regardless. I'd be concerned that someone might interpret "Always have more amp than speakers" as license to hook their big amp to speakers that just can't handle the power. Al's point about speaker breakup is a good one too- depends on the sound you want.
Northcounty, did you figure out exactly what speaker configuration you need for the amp- still working with the Fender you posted about?
-Steve W. | |
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Posts: 7222
Location: The Great Pacific Northwest | I've always insured that my cabs were rated 1.5 times more than my amp. 100 watt amp = 250 watt cab.
Now this also depends on how your speakers are wired.. Two 50 watt speakers in parallel can handle 100 watts. Two 50 watt speakers in series can only handle 50 watts.
I actually have never heard of wanting "speaker" breakup before. Neat idea, just never thought of it. I've always done distortion at the amp either by driving the final stage of the amp (turn up the input, turn down the master) or with an external distortion device (stomp box, etc..)
I believe it was "Revolution" by the Coleoptera's where they used hat pins in the speakers to get a unique sound. | |
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Location: Utah | The wattage rating simply means how much power you can put through it before running the risk of burning something up. A 50 watt speaker isn't going to burn up at 51 watts, but you are being the test pilot when you hook it up to your 100 watt head.
If you parallel wire two speakers, each rated at 50 watts, you have 100 watts of capacity there. Each one will take half the power.
If you series wire two speakers, you are limited to the lowest rating of either one. If you will have two 2x12 cabinets, series wired for 16 ohms, each cabinet will be limited to the lowest rated speaker in that cabinet. If you used the 35 watt Jensens, you would have a 35 watt cabinet. Two of those cabinets would give you 70 watts of capacity.
If you are using different impedances then the above example is not mathematically correct for your application.
How many watts a speaker will handle before distorting is a whole different question that I can't answer. You can run a speaker over-rated for your amp. It might not get to the point of mechanical distortion or break-up. So if you want the sound of speaker distortion you would not want an over-rated speaker. But if you want the speaker to run cleanly and for the distortion to be generated in your amp or effects pedals, you can run the over-rated Celestion speakers.
Have you considered one 2x12 cabinet of the Celestions? If you buy the 16 ohm version and parallel wire them, it is 8 ohms for the cabinet. Since they are parallel, you add the wattage and get 150 watts capability.
Any way you slice it, that's gonna be a LOUD amp! | |
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Posts: 2487
| Interesting........Well lets see I did buy the celestions rated at 75 watts each. they are rated at 16 ohms each.... so in parallel I will have each cab at 8 ohms. This is the output of each side of my stereo head so this is perfect so far.
My question about the speakers is basically like this...........From what I understand when you run 100 watts into a 100 watt speaker you will max out it's throwing capacity and the speaker will be used to its fullest capacity. Now this is not what I plan to do but with this thinking....; If I have a 200 watt speaker and I run a 100 watt signal to it the best response I will get it half the sound movement this speaker is capable of....if you see my point? I would think that a 100 watt amp and a 120 watt speaker would be the best case scenario. Again just my thinking.At some point a high wattage speaker becomes usless if your only pushing a few watts through it....again if you see my point. Everyone keeps telling me about lower wattges and using to much power.......I am quite aware of this problem. This is not.... and has never been my question.
As for the Cab.........I want to run two cabs at several feet apart to get the stereo signal from my stereo head to sound like it should. I do not understand the use of a stereo cab if you can't seperate the speakers. So I have a cyber Twin Fender Head I want the speakers to look like matching Fender Speakers so I am building my own. I plan to build the cab with one speaker enclosed for the nice bass response and the other in an open half of each cab. I think I will end up with the best of all worlds with a set up like this. Besides.....I am a cabinet maker, model maker and woodcarver for a living and have been for nearly 30 years. Making the cabs is not a lot of work as I have all materials and tools and now the time to do this.
I found the vinal and the fender speaker cloth, the metal Fender speaker Logo's and the corners and the handles, screws indented washers, t bolts and everything I need to do this and have already ordered it. So it's a done deal now.
I just hope when I am done it sounds like I think it should. | |
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Location: The Great Pacific Northwest | Thanks Flysig... I correct my typo, I had series and parallel backwards. | |
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Location: Colorado Rocky Mountains | Originally posted by Mr. Ovation:
I've always insured that my cabs were rated 1.5 times more than my amp. 100 watt amp = 250 watt cab. Say Miles, you and others here know a lot more than I will ever dream to know about electrical currents and speaker/amp configuration/computation equations. However, when it comes strictly to the math, I believe that 1.5 x 100 = 150, not 250.
Flysig, when your rig is finally finished, please take some pics and let us see what you've come up with! | |
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Posts: 2487
| Well this is certainly interesting. I guess it's all part of becoming a better musician. I am learning a lot about a great many things as I get more and more involved with this band and this project. There is so much that we all take for granted when it comes to sound. I don't care what Eric Johnson says........We all know you can play at different levels of DRAMA and achieve different sounds but your only as good as your equipment and visa versa. Once you have the tools then you can talk about how to control your guitar and tweek your sound with playing technique. Cripes, he has more equipment to begin with than most of us put together in this group have.
Anyway when I am done with this cabinet project I will post a few shots. Hope I can get these one stage at some point and try them out. Practice room is one thing........setting them up for a big space is another. Then having them mic'd stereo through a system is yet another.
Randy | |
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Location: San Bernardino, California | I've got a couple of these Carvin G212 speakers, they have worked well for me. | |
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Posts: 288
Location: New Hampshire, USA | Originally posted by ProfessorBB:
Originally posted by Mr. Ovation:
I've always insured that my cabs were rated 1.5 times more than my amp. 100 watt amp = 250 watt cab. Say Miles, you and others here know a lot more than I will ever dream to know about electrical currents and speaker/amp configuration/computation equations. However, when it comes strictly to the math, I believe that 1.5 x 100 = 150, not 250.
1.5 times 100 = 150
1.5 times MORE than 100 = 250
(look at it this way: 1 times more than 100 = 200) :) | |
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August 2005
Posts: 3736
Location: Sunshine State, Australia | Originally posted by Mr. Ovation:
I actually have never heard of wanting "speaker" breakup before. Neat idea, just never thought of it. It's very popular amongst blues harp players, Miles. Harp players seem to prefer tube amps rarely over 10W and they bend over backwards to find vintage 15W speakers for their rigs. They get breakup from the vintage microphone element, breakup in the preamp, then breakup in the power stage and again, breakup with the speaker(s). These guys don't do 'clean'.
My latest toy is only 5 watts and it's LOUD... (and breaks up) | |
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January 2006
Posts: 1118
Location: NW Washington State | Originally posted by Northcountry:
From what I understand when you run 100 watts into a 100 watt speaker you will max out it's throwing capacity and the speaker will be used to its fullest capacity. Now this is not what I plan to do but with this thinking....; If I have a 200 watt speaker and I run a 100 watt signal to it the best response I will get it half the sound movement this speaker is capable of....if you see my point? I would think that a 100 watt amp and a 120 watt speaker would be the best case scenario. Again just my thinking.At some point a high wattage speaker becomes usless if your only pushing a few watts through it...
Nope, not true. An efficient speaker with a high power rating will work just fine with a few watts input. I've hooked up a pair of 150-watt rated EVs to my 5-watt Champ and it's amazingly loud.
But going back to the idea of speaker breakup/distortion, lower rated speakers will probably distort more than higher-power ones. Do you want clean sounds, or all-out distortion/overdrive/crunch/fuzz?
-Steve W. | |
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Posts: 2487
| Interesting about the low wattage moving the much higher wattage speakers. Always thought they needed to be similiar in wattage. Like Miles said 1.5 or so.......this makes sense to me.
Anyway I have no interest in breaking up speakers. Others have posted this information I never cared for or asked how to do this, as facinating as it is it is not what I wanted to discuss. My question was actually the opposite and it has been answered now......Thank
you all....... I will be the second guitar for all kinds of prog rock from Yes, Floyd, Genesis and Rush so I will have to find many different sounds but nothing along the lines of breaking up. I want quality clean and deliberate controlled distortions, like most of us. I have a great sounding head but I can't wait to hear this in true stereo.
I have another question now......I have 4 celestion 75 watt speakers rated at 16 ohms each. I am using 2 pairs each in seperate cabs that I intend to build. If I run two of these speakers "in Parallel" in each cab I will end up with 8 ohms per/cab..........which is what I need.
Question is now......Will I end up with 150 watts per cab or 75 watts running these in parallel.
I see no way to confuse this question.... Please do not post information that just confuses the issue. If you do not have a direct answer to this question or for some reason do not understand it please leave it alone. You guy's are all a wealth of information but you often have to much and your posts confuse this simple issue.....You know more than my simple question asks but if you see my point this is a simple enough question and I'd really like to know the answer.
Thanks Randy | |
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February 2004
Posts: 2487
| Never mind..I found a decent web site that explains things very simply, which is perfect for me. Perhaps some of you other guy's might need this so I will post it.
http://www.usspeaker.com/speaker%20wiring-1.htm
Thanks for all the info, please feel free to continue on to the important threads like the Insomniac Quiz. I think I am the only guy who has never posted on that one. Not quite sure why. Guess I like being different. or perhaps I am just ODD. | |
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Location: NW Washington State | If you want a simple, direct, on-topic answer, you should avoid the OFC!
Two 75 watt speakers in parallel will handle 150 watts.
Miles and FlySig covered this in all the extra info we provided above. :)
Here's a page I found with wiring instructions for a 2X12 cab.
-Steve W. | |
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February 2004
Posts: 2487
| Perhaps your right....... but I belong to no other groups. Now I did just get a very good very simple answer from you though. Much appreciated. ! Perfectly done...so I know it is possible.
And Miles's answer was picked apart so much he had to admit corrections were needed. So I was not sure of any of the accuracy of this information as the confusion was being multiplied from poster to poster. Flysig nailed it though and I forgot this info was already posted.
I understand how to run the wires inside a cab, and I understand the difference between series and parallel circuts and have some knowledge. What I did not know was what happened to the Ohms and the Wattage either way and how much power is needed from an Amp to run good speakers in general.
The web site I found explains the basics fairly well and has lots of examples of wiring options.
So once again.......Thanks for all the info, meant no offense about the off subject answers. Was just looking for a simple answer.
You guy's have got to understand; some of the stuff you guy's know and can convey is over the top for some of us who only have a limited knowledge in these areas. Or limited knowledge in general.
Randy :cool: | |
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April 2006
Posts: 2491
Location: Copenhagen Denmark | Simple answer :
Celestion is a brand with conservative ratings, using those will give good results powerwise ...i.e they will not break easy .
However...which ones ?
Do ya play leadguitar exclusively..?
V | |
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February 2004
Posts: 2487
| G12T-75's All New. And like so many things they are made in China now.
I plan to mount them in enclosed Cabs for more low end response but I think I will need to port these as they are not typically used for enclosed cabs. I am working on find the formula for porting for the space I have and the speaker size but it looks like a couple of 3" ports will do fine.
"It is interesting you know; all the shit ya learn in a lifetime" | |
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Posts: 2491
Location: Copenhagen Denmark | NORTH :
That G12T-75 is a typical " Electric guitar-speaker " , with that characteristic peak at around 2.5 KHz. at 8 db ( about 5 times louder than any where else at its freq. response ) ...Exellent for Lead , and with the equalizer ( mid or presence ) turned down , usable for blues / jazz.
Since it is rapidly falling off at 4 KHz , an acoustic thru it ( Treble-range up to 7 KHz. overtones and all ) , will suffer of loss of definition in the treble , ( lacking in overtones ) , and , to compensate for that , a ( switchable ) tweeter can be employed.
Achieving " bottom-end " , by employing the principle of bass-reflex is not necessary , and might cause muddiness.
If I understand ye correctly , then the idea is to build 2 cabinets , each containing 2 x G12T-75 speakers , may I suggest internal cabinet-dimensions of , say :
H 30"....W 16"...D 14"..
I usually give 2" space around the speaker-rim for improved rigidity , 1" space can be used , but when it gets hauled around , 2" space would be advisable.
This will give about - 567 - Liter , which in this case is a substantial Volume !!
Build as an enclosed cabinet , it WILL give lots of bottom-end ... even though , those babies were not really designed with that purpose in mind.
May I suggest that ye mount the speakers from the outside , i.e , with the back-rim to the baffle , using 4 spacers mounted in-between Speaker-rim / Baffle for EACH Speaker , Spacer Dimensions :
( H 1/4" - L 1" - W 1" )
spaced evenly ,
( mounted at mounting bolts ) in-between the speaker-rims and baffle
( speaker " resting " on spacers ) , this will add :
" Clarity " and " Punch " to yer sound.
Will ya build the Cab.s of :
Heavy , high-resonant MDF .( shudder )
Multi-Ply , ( costly )..both are hard to work with.
May I suggest that the Baffles ( and the Backs ) are made out of Multi-Ply..for improved sturdiness.
When Cabinet-Panels are made out of WOOD , they will be :
Light , and with , Pleasing , Musical characteristics , yet , sturdy enough to withstand the rigours of road-use.
May I also suggest that ya line those Cab`s from the inside ( All sides ) with Rock-Wool , about 2" thick ( use gloves ) and ,
a strip of Rock-Wool 2" thick in the Center , spanning the Entire Cab from :
Top to Bottom / Magnet to Back-plate
, this will give a Warm sound with good Clarity.
Mounting the Panels where they join with Braces of 1.5" thick would be a good idea ( 2" would be even better ) , and a BIG brace across the Back-plate would be advisable.
To carry them babies I would get Recessed-Handles , each mounted high-up into Left/Right panels .
Wiring those speakers in parallel per Cab.
( make sure they`re in phase .. Plus on Plus / Min. on Min. ) will cause yer Amp. to deliver more power.
See if ya can mount the speaker-jack high-up on the back-plate , instead of close to the ground , so as to avoid crawling on the floor.
And the FINISH :
Sanded and Applying outdoor Wood-Treatment ( mixed with a little red color ) , metal on the corners , with metal grilles mounted on each speaker , will make them look like exellent pieces of furniture , people will look green with envy when admiring them.
I can n`t think of anything else....
Drop me a line , whenever ya`....
Vic
...that`s the finish of the P.A speakers that I am building... | |
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Posts: 4042
Location: Utah | Vic, what kind of tweeters do you suggest? I'm working on a tube acoustic amp and am seriously considering using a piezo tweeter.
It's a small wattage amp, probably about 5W RMS.
The cabinet will be rear ported. Somewhere I have the equations for figuring the dimensions.
Would a passive crossover work or will it conflict with the output transformer, with all that RLC stuff going on? Or is there a smarter way to use a piezo in a tube amp?
(Sorry for the thread hijack) | |
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February 2004
Posts: 2487
| Very Good, and not at all Flysig, this guy knows his stuff! I am interested in speaking with you about your idea of raising the speaker from the surface of the cab for a baffle? If I read that right?? That is brilliant if it works.
Dimesions are almost what you have, All I know when I do the math I end up with a little less than 3.5 cubic feet per cab and this is supposed to be a good volume for these size speakers before loading and foam. I had actually considered building one side open and one side enclosed so I can the different sounds from these speakers but I like the low end response as I will be playing a lot of Rhythm so I will enclose the whole thing but make the backs in two pieces so I can experiment later with this further.
I have some dense foam that is not so nasty to handle for the inside. And I found out today these Celestions were purchased a few years ago and never used so they are actually British Made! I am happy about this. I also have a lot of 3/4 Birch Plywood and some MDO this should work quite well. MDF is so, so heavy and I am a woodworker I hate pressed sawdust products. I do plan to put a divider inside as well about 3/4 of the depth of the cab to seperate the speakers from each other somewhat also. Again things I have been learning from web sites.
I do intend to make these look like matching Fender cabs, So I have the correct black vinal coming and corners and washers and feet and handles and black face style, silver speaker cloth with the Fender Logo for each. Should be close when I am done. I have to cut those corners nice though...
Going to be fun to see how this works out in the end. Thanks to everyone for bearing with my lenghty post about this.
I have learned a lot actually. In the end it was well worth the effort you freekin people seem to like to put me through!
:cool: :cool: :cool: :cool: :cool: | |
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Posts: 1118
Location: NW Washington State | I'd be interested in Vic's tweeter suggestions too. I'd like to add one to a Yamaha guitar amp that has a single 15". I've been wondering if a sealed-back cone midrange might work to add just a bit of mid-highs for guitar. A piezo might be brighter than I want.
One advantage of a piezo is that it doesn't require a crossover- it effectively has a built-in capacitor. You might want to put a resistor in series so that your amp doesn't see the capacitive load of the piezo. A front-panel switch for the tweeter would be nice.
Northcountry, have we caused enough distraction and confusion yet? :)
-Steve W. | |
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Posts: 2491
Location: Copenhagen Denmark | NORTH :
I hope that ye do n`t mind for me to answer FLY and NUMBY first , as it DOES pertain to yer queree of raising the speaker from it`s Baffle.
FLY and NUMBY :
Let `s start from the beginning , a Piezo-Tweeter is Capacitive , so what is happening , when a Sinosoidal-Wave ( Sine-Wave ) passes thru it.
Imagine how that Sine-Wave looks like , at the positive half-period...it Rises in a slight arch , rolls-over forming a smooth round top , and slopes down in an arch , at the negative half-period it does the same , just in opposite way.
However , when that Sine-W. passes thru a capacitor , it will ...rise in an arch , forms the FIRST Half of it`s Top , then FALLS Down Abruptly !!...causing a " Spike " ,..it will do so at both half periods, it is exactly that ( Spike ), what human hearing perceives as Very Annoying , certainly Not musical.
That is How a Capacitor works.
We can n`t " fill-up " the missing part of the Sine-W. , BUT....we can SHAVE some of that spike off , by coupling a small RESISTOR placed in PARALLEL , by ...connecting one end of Resistor to one end of Capacitor , other end of Resistor to other end of Capacitor.
This is called a " Bleeder-Resistor " , actually ,it causes a small " leak " at the Capacitor , preventing the Cap. to be filled to the max .
Imagine :
A water tank connected to a powerful pump , that fills it with the speed of lightning , when full , a valve opens , and that water gushes out with lightning-speed ,
when ,
a hole gets applied close to the top of the tank , and gets filled-up , when water reaches the hole , it will seep-out thru that hole , while that tank gets filled up further , albeit at a SLOWER Rate !!...and some water has allready passed thru` that hole.
And that is what happens when placing that small resistor in Parallel ( across ) with that Cap.
PARALLEL on Piezo-Tweeter , would be connecting one end of Resistor to PLUS on Piezo ... other end of Resistor to MINUS on Piezo.
Since very little power passes thru resistor ( most power passes thru Cap. ) a quart watt Resistor will be suitable for most applications .
When in doubt , drop me a line.
A Resistor placed in SERIE ( in front ) with a Cap. , will not influence a Cap. ( Piezo-Tweeter ) to behave differently , However , that would change the Impedance of a Circuit , in this case , it would change the Impedance of that Piezo-Tw.
As a " Rule-of-Thumb " , I usually base the Value of said Resistor at ....
100 x ( onehundred times ) nominal Impedance...
when Piezo-Tw. Imp. = 8 Ohms , x 100 = Resistor at 800 ( EightHundred ) Ohms.
Closest standard value would be 1 Meg.Ohm ( OneThousand Ohms )
Shaved-off top is sharper when INCREASING resistor Impedance ...
2 Meg.Ohm ( TwoThousand Ohms ) will give a
" sharper " peak. ,
and
DECREASING Imp. ,for ex. ...
500 Ohms ( fivehundred ) will give a " Flatter " top.
Feel free to X-periment , decide for yerself.
FLY :
Electronic components allways consist-of ...
Voltage
Ampere
Resistance
Capacitance
Induction
The circuit of a given loudspeaker ( drawn as a schematic , there are Caps. , Inductors , Resistors ) is rather complex , especially so , since they are Frequecy-dependant , all those components change their value according to different frequencies , but that`s okay , just use a Stable Amp.
However , to use a capacitor in serie with a Piezo is not advisable , why would ya , I mean , 2 Caps. in serie = 2 spikes in succession !!
A Resistor in serie with a Piezo would only change the cross-over roll-off.
That NORTH was informed of the possibility to use a Tweeter with his Speaker-Cab.s , is due to his Celestion`s rapid roll-off at 4 KHz. ,since most Piezo`s roll-off at about there , his speakers could benefit using a Piezo , in conjunction with the afore mentioned measures.
But...mostly ,usually only when an Acoustic is being employed !!
Since most Piezo`s are horn drivers , reaching a sensitivity of around 105 db , they will need to be matched according to the big speaker`s sensitivity.
Using a Mid-range in conjunction with a bass-driver , the same care needs to be taken , I.E..
1 ) Matching sensitivity ( speakers in between )
2) bleeder resistor on Cap. ( in Cross-Over Circuit )
Yes , bleeder resistors on Serially placed Caps. ( those in signal-path ) in Cross-Overs are recommended .
NORTH:
An Enclosed Cab. will act as a Pnuematic-spring , causing strong damping , ...Raising the speaker from its Baffle will cause a small leak , allowing the speaker-membrane to move freely , hence , more Clarity , yet , the Cab. itself , will add Warmth .
What foam is that ye have ?
foam like in hospital mattress ?
like that used in furniture ?
Lead-foam ? ( very dense..very costly )
Can n`t think of anything else...
( maybe some ramblings about comparing a speaker-cab. to a Capacitor , and the small leak comparing to a bleeder-resistor... naah , ..only when interest is expressed )
Vic | |
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February 2004
Posts: 2487
| I do love this site. There seems to be a wide variety of people who are experts in their fields. And then there are some who are just "outstanding in them" :cool:
Anyway yes I understand the resoning behind raising the speakers I suppose it is the same sort of principle as using a tuned port. It lets the speaker cone move slightly easier and keeps it from getting bogged down in it's own positive and negative pressure within the cab.
Question..........I will assume raising these speakers 1/4" will replace using ports? If so this might help me trim the cab size slightly.
I will not be using these cabs for acoustic at all, I have another acoustic amp for that so I am trying to leave the tweeters out of this, I have had lots of top end but never the low driving punch from my electrics that I like.
The foam is from those memory foam matress top pads. Very spongey, very dense and should do well to run around the corners and sides. I plan to leave the back plywood of these cabs bare. I think that this will help with sending the sound forward alomst like an echo and the speakers will play off that surface nicely.
Thanks for these posts Vic. Your a very knowledgable man when it comes to this stuff. I hope the rest of these guy's all picked up something they can use as well. | |
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Location: Utah | Vic, thanks for the info on bleeder resistors. It will be a big help. | |
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January 2006
Posts: 1118
Location: NW Washington State | Vic, do you have any favorite model/brand of tweeter, and do you like any that are not piezos? My impression is that the CTS (ex Motorola) piezos are worth the extra money. CTS tweeters.
A small parallel bleeder resistor to tune the piezo is an interesting idea, I'll have to try it.
A series resistor (say 20 ohms @ 10 watts) is sometimes added for a different reason. It will keep the amplifier from seeing a purely capacitive load and breaking into oscillation at ultrasonic frequencies. Maybe this is more important with a solid-state amp with extended frequency response.
-Steve W. | |
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December 2006
Posts: 6268
Location: Florida Central Gulf Coast | Originally posted by FlicKreno aka Solid Top:
Closest standard value would be 1 Meg.Ohm ( OneThousand Ohms ) Vic, excellent analogy! Water is a great 'substitute' for electronic theory. I used that analogy quite a bit when I was an instructor (way back when!).
Just to clarify your value above... Shouldn't that be 1 K ohm, 800 ohms ~ 1000 ohms? One meg would be 1,000,000...
Great topic and info! | |
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Joined:
April 2006
Posts: 2491
Location: Copenhagen Denmark | Thank ya all for the roses , and ofcourse Iffy had to keep the thorns on the stem..
Vic
..ouch.. | |
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Joined:
April 2006
Posts: 2491
Location: Copenhagen Denmark | Iffy...Iffy...Iffy..
INDEED !!
Onethousand Ohms = 1 KOhm
OneMillion Ohms = 1 MegOhm
I bow my head in shame , and humbly hope to come out of the corner soon and take the donkey hat off..
Vic
..be nice to the guy who has just received a pair of OLD monitors , loaded with FANE`s .. ( yummy ) | |
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Joined:
December 2006
Posts: 6268
Location: Florida Central Gulf Coast | Vic,
You had written "(One Thousand Ohms)", so I knew the "Meg' was a brain fart. ;)
The last part of my post way for those that didn't know.
Besides, you're WAY beyond me in 'tronics!  | |
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Joined:
February 2004
Posts: 2487
| Funny, have not heard the name Fane in many years. We had 18" Fane's in a pair of Down Firing Sub Cabs we built back in 79. Those monster speakers actually took most of the bottles off the top shelf one crazy night at the bar. I think where ever they are they still work. You couldn't kill them no matter how many crown's you had behind them. | |
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Joined:
April 2006
Posts: 2491
Location: Copenhagen Denmark | NORTH :
Raising the speaker from its baffle will NOT have the same effect as a bass-duct , its a different principle , and yet...
There are many formula`s calculating bass-ducts..
..none of them is " ultimately " correct , wittness that they all end their rethory with :
" Tuning the ducts ( vents ) for optimum results by experimentation "..
Let us examine yer speaker-cabinet:
The CELESTION G12T-75 has a main-resonance at app. 85 Hz. , tuning ( enhancing ) to that freq. will cause " boominess " , drowning yer Sound considerabely , Yes , that`s right , that particular freq. WILL be Louder than the rest of yer sound .
Furthermore , when ye want to keep the back-plate " naked " , do realise that it will reflect sound right thru that Very thin speaker-membrane , a resonance that ye migt be comfortable with..or..?..
We can bicker back and forth , and I`d like nothing better , but , lemme ask ya..
Are ye familiar with ; ( I can n`t remember title nor performer )
.." I can feel , the earth , move under my feet " ...
If that`s what yer after , than perhaps ye could do the following :
Build the Cab. that YOU like to make ,
and then stuff sound-damping material at will , try out Spacers of different Thicknesses ,
and mount the Lowest speaker flush to the Baffle , and ,
the top-speaker resting on spacers , this will :
1 ) Cause a phase-shift. ( phase-shift WILL cause a " Thin , Detailed sound " ).
2 ) Flush-mounted speaker induces Cab. to come into "play " ( cabinet-rumble ) .
3 ) Top-speaker ( freely-moving ) takes care of Clarity.
The Foam that ya describe I`m not familiar with , is it like ;
Furniture foam , used for sofa`s and chairs ?..or...?
At any rate , try lining the walls ( panels , back-plate ) ye may want avoid lining the baffle at the inside.
The above will , at one point induce :
Bass injection
Fleeting Highs
Much like the Ovation model 1617
which has also warm articulate Lows.
Tilted back mid-range.
Fleeting Clear Highs.
That way , Rumble is the name of the game ( Bass-Injection ) ,
Calm Intent Voicing ( Mellow-Mids ) ,
HERE it COMES !! , overwhelming Highs.
( I do realise , that this IS a Guitar-Site , and the Topic being part of an Instrument )
No tweeters , No Bass-reflex..
That`s about it , if there`s anything , drop me a line..
Vic
FLY is building a Valve-amp. at 5 watts rms ,...?..is he building a Valve-driven HeadPhone amp. at 50 MilliWatts...?..with bass-ducts situated at the back of those head-phone shells..?
COOL !! | |
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Joined:
April 2006
Posts: 2491
Location: Copenhagen Denmark | NUMBY :
I am not in favor of Piezo tweeters , however , overhere them MOTOROLA Piezo`s carry a good reputation , the KSN 1005 is widely used in f.ex. guitar amps. ( I have a handful in my parts-bin ) , and even in low-cost P.A systems .
My Fav. Tweeter... choosing between ALTEC , JBL , FANE , B&C , I guess that would be the JBL 2404 Bi-Radial UHF transducer , my All Time Fav. would be off course the ALTEC 511 and 811 SECTORAL Horns driven by the 802-8G Driver ( equipped with TANGERINE Phase-plug ), unfortunately ALTEC is now defunct ( scour 2hnd market ) .
I am a PROUD Owner of a pair of SECTORAL 811A `s , albeit with non-ALTEC drivers , even so , dispersion is PHENOMENAL , I hear `em on a daily basis ( coupled to 2 x ALTEC 416-B Bass-drivers ).
I am in the process of rebuilding , but can n`t make up my mind , main idea is to build a look-a-like of ALTEC`s model 19 , but with GOODMANS 18HP ( 18" Bass-Drivers ) , on the other hand , in a corner , a pair of ALTEC 421-8LF are beckoning , and next to those , a pair of 421-8H II , what to do ..?..
The Piezo marks an Imp. of 8 Ohms , so the amp. would see a load , I`ve not tried the 20 Ohm R in serie , never deemed it necessary , allways had stable amp.s at my disposal , but , next time I use an amp. with a skimpy transformer I`ll give it a try .
Vic
Thanks. | |
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Joined:
October 2005
Posts: 4042
Location: Utah | Originally posted by FlicKreno aka Solid Top:
FLY is building a Valve-amp. at 5 watts rms ,...?..is he building a Valve-driven HeadPhone amp. at 50 MilliWatts...?..with bass-ducts situated at the back of those head-phone shells..?
COOL !! With any luck (regulations, taxes, and ordinances permitting) it will be a line of thoroughly modern tube amps for the modern guitarist. Low wattage for sane sound levels, portable for us old guys with bad backs, simple operation for the technically challenged, a few features for modern performing venues, and GREAT looks. At an affordable price, and built in the USA.
The 50 mW headphone amp? Yeah, it's in there too! But you'll have to provide your own bass-ducted headphones. | |
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