Question about adding a tweeter-HELP PLEASE!!!!

I may have asked this question before, so forgive me if I am repeating myself. In fact, I found a link back here to BTF about a similar article posted back in 2009 while doing a web search.

In my simple-minded world, I figure this ought to be a simple question to answer. I’m not asking how to split the atom. Or how to get to Mars. Or even how to properly fold laundry. No, those burning questions most certainly require minds much greater than mine will ever be. All I really want to know, in simple English, yet spelled out in easy-to-understand steps is this:

How best to add a tweeter to my bass cabinet?

Let me explain. I am really digging my new Carvin BR210 (even with the country vinyl covering), and the tweeter adds a lot of life to the sound.

So I want to add a tweeter to my 2x15 cabinet. This would be my Seismic Audio 2x15 loaded with two Carvin 15’s that are each 400 watts, and 8 ohms impedance. They are wired in parallel for a total of 4 ohms impedance.

I still use my trusty Crown XLS1000 Drivecore power amp, which puts out 350 watts into 4 ohms.

Now, I have only just begun to learn about standard tweeters vs piezos. How you need to use a crossover or a high-pass filter with a standard tweeter, and how a piezo does not need a crossover. How you can still send full-range to the bass speakers, while high-passing to the tweeter. How you need to add a resistor to a piezo to prevent the power amp from going into thermal shutdown due to a dislike of capacitance loads. How the different frequencies going into the speaker coming through the crossover affect the overall impedance depending on the ratio of power in watts vs the voltage with regards to the curve of roll-off when applied to the L-pad circuit rated at 100 ohms, but only really needing to handle 75 watts due to the lower power requirement of higher frequencies….blah, blah, blah, blah….my head hurts from reading so much crap!

Simple, easy, effective. That’s what I am asking. How to add a tweeter to an existing 4 ohm 2x15 cabinet that takes on 350 watts, without changing the impedance. A list of recommended parts and a wiring diagram will win you my un-wavering gratitude.

Anyone?

i know how this works only because ive ripped it apart. what your describing is a two way speaker system. the best way that i can imagine to do this is with crossover.

.....aaaaaaaaaand finding the right components is needle in haystack. i feel like eric has given me a homework assignment. your looking to do it with carvin speakers ... ill probably start there and not wander too far to eminence. all the crossover on my old carvin rig was eminence. i dont remember why i did that.

ill report back tomorrow.

Excellent! Thank you, MadMike!

I posted my questions on a speaker tech forum, and I am still getting piecemeal answers without any clear procedures as to how to do this. But one guy did say that tweeters were a bad idea, and suggested using 6" midrange drivers instead while employing a high-pass filter.

I then asked the following for further clarification:

1. Can I simply parallel off my existing 2x15's with two high-pass circuits going into the two drivers?

2. If I did this with my existing 8 ohm drivers already wired in parallel to give me a 4 ohm load, what impedance should the new midrange drivers be in order to keep the cabinet at 4 ohms?

3. If my amp is putting out a total of 350 watts into 4 ohms, should the power rating of the high-pass filters be 350 watts apiece?

4. My existing 15's are rated at 400 watts each. What should the power handling rating be for the new midrange drivers?

OK, I am going to take this in baby steps. Here is what my current 2x15 configuration is:



My next post will be what I THINK is the correct way of adding a pair of midrange drivers, and if anyone can please confirm or deny this will work, please let me know.

And here is what I THINK will work:

even w/out doing research i can answer some of those questions.

#1 yes ... if you can find the correct filter. go to carvin. there is an easier way to do this.

#2 depends on the filter used, what its rated and how its wired. if its all speakers wired 8ohms in a 4ohm filter, the load is still 4ohms. different filters are rated for different frequency ranges and wattatge tweeters and drivers too.

#3we'll start by finding the right filter for your 15's.

#4 we'll see what filter we find as to what drivers we can use. what were you looking at? 6"-8"? horns?

since this is what you got ... lets start here ......

http://www.carvinguitars.com/products/PS15-8

with the wattage and load rating you gave and the process of elimination im guessing you have these. the "TS" and "NE" models are rated at 600w, your PS15-8 are rated at 400w. correct?

and im assuming that you want to add something like this?

http://www.carvinguitars.com/products/NE6-8

(and yes, there are better HF drivers.)

the debate of HF or no HF rages on. two things to consider. those 15's you have are frequency range 38 - 3.5k. thats pretty high. last carvin 2 cab rig i had with no HF drivers or smaller drivers just (2) NE10's anda NE15. my current rig is back to the 150w 215 peavey rig with black widows. i get plenty of highs and nice mids with no horn or smaller drivers. i got tired of burning the drivers out and replacing them. recordings dont pick it up. most bassists agree the only time you can really hear / use the drivers is on stage. i mean ... i understand. i wanna sound good at practice too. i have used them and i have not. i have no opinion either way and im sure everything has its proper place for a reason ... but who sez?

and i also wonder if your on to something using a lower frequency rated paper cone small driver. speaker technology has come a long way. my living room amp has a 3" driver and its got decent bass tone. cab design goes a long way too. again, everything in its place, if there is a certain effect your going for .... more mids.

the reading that ive done ive also noticed some iffey vocabulary. inconsistencies in what they say and ill own some of my own lack of knowledge. just wanted that out there before you go buy something that doesnt work thinking i told you to buy it. im just tryna help.

this is certain. if you put 4ohm load on a 8ohm crossover its 8ohms. if you put 16ohms of speakers on a 8ohm crossover its 8ohms. and researching this multiple times ive gotten this logic from multiple sources. no no, no regard for ohms law. we'll just throw that out the window when it comes to crossovers. fun - right?

i went and looked at the carvin first and remembered why i didnt buy it before. the way we are using their drivers is not the way they designed their equipment. the crossovers fs to me, are more for PA and reinforcement backline type equipment. i couldnt easily match up numbers; this crossover can handle these drivers this way, that way, blah, blah. i remember talking to customer service on the phone and i remember they made a recomendation for my application but couldnt explain why and didnt sound too confident in their reasoning. perhaps you could get someone different on the phone. oddity, because i usually get stellar service from carvin.

and why i ended up buying an eminence unit.

hey ... chek this out ......

http://www.eminence.com/pro-audio/hf-products-components/crossovers/

aaaaaaaaaaaaah! but those numbers make more sense.

im wondering if way to acheive the right wattage rating is to parallel two crossovers in one cabinet to get your 4ohm load. most of the crossovers i see are 8 ohms. i think my design was rewired to be paralleled out to another 8 ohm cab for a 4 ohm load.

allright. im gonna take a break and try designing this later today. my brain is starting to sizzle.

Again, thank you Mr. Sheehan....and my apologies....for dragging you into this, since I can easily tell that your head is spinning like mine is right now.

In fact, as I read through your post, and opened all of the links, it is clear that you have traversed the exact same territory as I have in during this process.

You are correct, my 15's are the Carvin PS15-8's.

As far as the additional driver goes, I was starting to lean towards using a piezo tweeter since it seemed the easiest and cheapest way to go, but the aforementioned tech dude on the other forum said that a piezo/horn tweeter is not the way to go due to the roll-off of high frequencies coming from a bass, and that a mid-sized driver, such as the Carvin 6" you mentioned, would be the optimal choice in terms of sound quality. He also said that most companies use bullet/piezos because they're cheap. This actually made sense to me. He also suggested some model of Eminence 6" driver.

I guess I am on this little path mainly because of what my drummer Doug said about the difference in sound my old 8x10 cabinet had whenever I switched on the tweeter. He said it was like night and day. I say this because I also hear what you are saying about the frequency response of the Carvin's on the high-side, but I can't help but wonder what the difference would be in adding some sort of higher-frequency speaker.

So....lemme get this straight....even if I were to put a 4 ohm load into a crossover that is rated 8 ohms....the output impedance is going to be....8 ohms? Huh????

And yes, I, too, found that same Eminence crossover, and said the same thing as you.

I am tempted to rip open my new Carvin BR210 to see how they did it, since it is a 2x10 4-ohm cabinet with a tweeter.

It boggles my mind that, whenever I go to the "experts", they somehow can't just say "this is want you need, and this is how you hook it up".  

just remember because you bust open the carvin and they do it that way doesnt mean thats the way to go. ive seen propritory wiring for specific components.

its like ..........

a peavey 300W head and an ampeg 300W head arent the same 300W.

yes, you caught my drift with the ohm loads. seems strange if i had 4 200w speakers in series for a load of 16 ohms on a 4ohm, 300W crossover. its 4 ohms and 300w on the amp.

and are the crossovers' wattage ratings exclusively for the amp? so lets say we have this 4 ohm, 300W crossover. experience tells me to put 150 - 200w at 4ohms into it from the amp. does this mean i can drive any wattage of speakers or configuration at any load rating and the amp still sees it as 300w @ 4 ohms?

i think i need to be a bit more practical than that.

EricHaven wrote:

And here is what I THINK will work:

thats 1200W of speakers into a 250W crossover. thats 800W available to the 15's  and 400W needed to push the mid drivers. i dont think iddid be very efficient the way you propose eric. and when i look at a crossover i wanna know what kind of speakers its rated for ... and they dont tell you that part. why not? i want a crossover rated for these speakers i got. nope. just its wattage, load and where ittl crossover.

i'm looking at your diagram and wondering if you even know what terminals are available (what makes it a 2 way or 3 way) and how to hook them up. most boards are printed. a two way will have 6 terminals; positive and negative from amp, to woofer(s) and to tweeter(s). its easy once you look at it.

i'm looking at this crossover ... now hear me out .....

http://www.eminence.com/speakers/crossover-detail/?model=PXB23k5

this is rated 400W @ 8ohms. its not a rear mount so you just have a regular back plate with 1/4 or speakon connector and TWO of these eminence PXB2:3k5's wired in parallel to the back plate and mounted inside the cabinet wrapped in insu. i havent seen crossovers rated at 4 ohms more than 200W and i wouldnt feel allright about that. none of the eminence crossovers are less than 8 ohms. if you want a 4 ohm load with enuff circuitry power to handle your wattage ... ide do it like this .........



so lets run thru this in theory. the crossover sees the speakers as 8 ohms. thinking along these lines, the crossover allows wattage to pass to the small drivers on a curve around 3.5kHz ... as it allows the wattage to bleed thru does it have the impedance fluctuate too??? IDK. anyhow ... it doesnt matter because the amp just sees the crossovers. that looks to the amp like two 400W 8ohm speakers wired in parallel or 800W @ 4 ohms ... same as it sees now. the crossover isnt capable of putting out more than is going in and your speakers handle the crown's wattage efficiently now. perhaps the impedance fluctuation is why crossovers are designed to be a standard load regardless of its speaker load. kinda how it works maybe?

the only changes i would make is if the parameters of the small speakers or horns you choose are a drastic change and or you wanted them to start crossing over at a lower frequency like 8" or 10" speakers.

but this just kinda makes sense that way right? everyone is getting the power they need or not getting overloaded right? is it efficient? is there a better way to go? or am i just crazy?

its like two 15" PA cab speakers with drivers wired in parallel ... they are just in the same cabinet.

  

Ha!

http://www.eminence.com/speakers/speaker-detail/?model=LA6_CBMR

neato!

madmike wrote:

i'm looking at your diagram and wondering if you even know what terminals are available (what makes it a 2 way or 3 way) and how to hook them up. most boards are printed. a two way will have 6 terminals; positive and negative from amp, to woofer(s) and to tweeter(s). its easy once you look at it.

Ah! I see what you are asking, MadMike. This diagram was for a high pass filter, not a full-blown crossover per se, so it's not even a 2-way system. Just a small circuit to send full-range to the woofers, but only a high-frequency signal to the tweets. But I think you're right in noting the in-efficiency of my idea.

Hmmm....I am intrigued by your design. It makes a lot of sense. Two different speaker systems using two crossovers, with the circuits in parallel. So....let me understand this....the circuit will for certain provide a four-ohm load to the amp?

verbage.

crossover / high pass filter. i think what its called depends on how the circuitry handles the frequencies and where it sends them. high pass filter is a crossover ... a crossover isnt necessicarily a high pass filter.

basicly you start with your speakers' ideal frequency range. in this instance, and im just guessing, you dont want anything lower than 100Hz going to the 8"s or they'll be inefficient, possibly cook and make that farting sound like playing a bass thru a guitar rig.

you want the 15's to get full range.

the crossover pcb boards are printed and terminaled for pos and neg in (from the amp), pos and neg HF (8") and pos and neg LF (15").

so if you have (1)15 and (1)8 hooked to a crossover, there is no parallel or series wiring in the crossover unless you hardwire it that way into the board. 15 +- to the LF+- on the board and 8 +- to the HF+- on the board. direct this way or trying to parallel with another speaker to get your proper ohm load is pointless because the crossover is still 8ohms.

if you have HF and LF speakers properly filtered in 2 identical cabinets at 8 ohms each and your amp runs on 4 ohms, you would hook up those two cabinets in parallel to get your 4 ohms. basicly your just building these two cabinets inside one cabinet paralleled to one +- terminal on the back of the cabinet.

not only is it more efficient with the ohm load (4 ohms) but the wattage splits between the two ... the crossovers will be able to handle way more wattage. you know the 15's can handle your amp. proper crossover frequency to the 8's will protect them from lower frequencies but i would make sure they can handle the wattage. the only thing thats left is the circuitry in the crossivers. the good ones have fuses. either way ... ive cooked em. these are gonna be inside the cab and you dont want to mess with that. paralleling two of them gives you way more power handling.

ok, i got it.

filter - pos/neg in - pos/neg out. will only let frequency pass to speaker in the frequency range. generally used to protect horns and high freq drivers.

crossover - pos/neg in - pos/neg HF out - pos/neg LF out.

ive used the crossovers but the filters? i dont know how that works wired inline as far as the load goes. the diagram i did is crossovers.

I find myself nodding a lot going "oooh....OK....I think I'm getting it now", which is a good thing, I suppose.

Looks like it would be about $190 to add the 2x8's and the crossovers. Not bad! Now, I just need to see if I can physically fit the 8's into the 2x15 cabinet. Might have to run with 6's for this application.

Oh, and yes, you are correct in my original scheme of wanting to run the 15's at full-range, whilst crossing over the mid drivers to receive nothing lower than 100 hz.

I won't get a chance to gander at my cabinet again until Wednesday, at which point, I'll see what I can fit into the spaces.

And I gotta tells ya. My new Carvin 210 sounds KILLER! Last night during our jam, everyone was really noticing the clarity of the cabinet. I am completely sold on the high-frequency driver concept!

i loved it when i dropped those carvin neo 10's into that stupid hartke vx cab. 3, 15" , 2 10" anda horn ... plenty of mids.

And lemme see if I understand things correctly here.

In my tiny-brained world, I simply reckoned that it was a matter of adding a crossover and a higher-frequency speaker to an existing cabinet. But what I am now surmising is that the parameters of the crossover are dictated by the frequency response of the speakers, as well as the response of the cabinet.

Make sense?

So I suppose that I need to get the exact frequency curve of the Carvin PS15 speakers as they react within my Seismic Audio cabinet in order to figure out the proper specs of the crossover needed.

Or....I could simply buy another cabinet that already has a tweeter in it.

OR! I could enlist you Sir MadMike to design me a lightweight, compact, yet killer 2x15 cabinet that also has a tweeter in it!

Now, I don't mean BUILD me a cabinet, since shipping would be astronomical from your local to mine....BUT....I seem to recall you designing such a thing sometime in the past. Ya?

ha!



its against the wall behind the green and burst les pauls.

ill walk you thru how i look at it.

always, always start with speakers. they will have a resonant frequency value and a frequency range. when designing a cabinet you want the cabinet to have the same resonant frequency. this is achieved by dimensions and porting. if the cabinet has the same resonant frequency it will operate more efficiently not forcing the cones back and forth against air pressure and when you hit that frequency and other modal frequencies (? music theory stuff ?) the cabinet will ring ... you can tell the difference.

you can plug in numbers and get l x w x h dimensions as well as port dimensions for mach values (keep it below mach .1 if i remember) with the winISD shareware.

http://www.linearteam.dk/default.aspx?download=winisd

this is shareware and has limitations as far as types of speakers in one enclosure design, but you can tweak the numbers to include your mids by extending the frequency range to the mids high end. with 15's there will be some tweaking as well with the port(s).

next is the circuit design. the more i look at it the more i like my design. each crossover drives one 15" and one 8" at 8ohms. if you parallel those two crossovers, thattl make a 4 ohm load.

i dont know if you looked at the extensive collection of crossovers available. its all about the slope. its basicly a frequency dividing line. i figured out how that Db / butterworth thing works but i forget.

lets take this sweet, sweet eminence 8" high powered midrange woofer.

http://www.usspeaker.com/delta%20pro-8-1.htm

i know ... right? its frequency range is 100Hz - 3.0kHz. you only want frequencies above, lets play it safe, 500Hz going to those drivers. this crossover will do that ..... eminence pxb2-500

greater than 500Hz goes to the 8", less than 500Hz goes to your woofers.

in all honesty, if your cabinet has that tuned "ring" to it, ide use that cab. (2)8" mid drivers crossed over correctly are not gonna throw the cabinet's and speakers' resonant frequency out of tune. now if your adding some LF 10's ... thatsa different story.

I'm not too sure if my Seismic Audio cabinet has "that ring" to it, and more specifically, I imagine that I just got lucky when I threw the Carvin's into it. Work it does, but I am sure it can be better.

I am still intrigued with the idea of having a 2x15 + 2x8 crossed-over cabinet designed.

i have some time today and havent designed anything in an age. i have or can get or can guess (for the 8's) the data that ide need and come up with a plan for you.

maybe "ring" isnt the best way to describe resonant frequencies. i also think theres alot of it going on that we dont hear ... not like a dog whistle thing but because other tones are louder or more dominant. a good example is when your warming up and waiting for your drummer to get there (again ... drummists ). there are certian notes that youll hit thattl make certian parts of the drumkit rattle and vibrate, usually most obviously an untrapped snare. its really audible because drums are acousticly projective by design. windows in a practice space that rattle on certian notes while trying to record is a resonant frequency that has always made me go crazy!

but the idea is to get the cabinet to resonate to notes within your frequency range. because the soundwaves are further apart, the bass makes things vibrate more noticeably than a guitar so guitarist will usually tell a bassist "hogwash!" but if you can get a cabinet tuned to resonate in the frequencies of the keys you play in, its awesome. really difficult to get it exact as its shareware calculations and too much +- tolerances when building the actual structure and other things. the 15's in my cab are black widows ... they changed the magnet size and frame on these and that changes the internal volume space so ... its a little off from my original calculations. the cabinet still resonates in D, A and E (and a few more i dont regularly "use") so close enuff. i think you want yours to resonate down to B if possible since you play a 5er.

there is no way to calculate for the notes so unfortunately, its just trial and error (for me anyway. im not an engineer, physisist or mouth breather).

if the resonant is tuned correctly at really low frequencies, youll vibrate peoples skulls and give em vertigo on those notes ... teehee!

the other thing i did was force the data to exisist in an already exisisting design. if that cab looks like a markbass 215 (discontinued ... booo) thats because that design is where i started. i liked that cab but it just didnt have enough power handling to justify hunting it down and buying it so i built mine with the black widows for 600W @ 8 ohms.

ill take a look at what you got and look for what options you have with the path of least resistance (easiest). building this cab was a pain. i still really think your cab now might work well if there is room to put the 8's in.

Hmmm....lots to think about....now I'm thinking I need to add tweets to my 2x12 as well.

Or I just need to win the lottery, and buy a wall of ready-made speaks.

http://www.mesaboogie.com/Product_Info/Bass_Cabs/PowerhouseCABS/PHbass2x15-LG.htm

http://www.mesaboogie.com/Product_Info/Bass_Cabs/PowerhouseCABS/PHbass1000-LG.htm

and 2 of these ....

http://www.mesaboogie.com/Product_Info/Bass_Amps/strategy/bassStrategy.html