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This active crossover will be good for my speakers?

CosmicJazz

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Hello to all music lovers and audio enthusiasts out there, I'm new on the Forum, looking forward to start to contribute to the Forum, share my experiences, and also to learn with more experienced people.

I'm planning put together my first "high end" system, I'm building a 3 way loudspeakers, and thinking about go trough the multi-amp and active crossover solution, appreciate very much enlightening thoughts from more experienced people, if the crossover that I'm considering is a good or bad option for my speakers, and why?

Here's the speakers that I'm planning to build:

Super Horn Tweeter: https://www.fostex.jp/products/t925a/

Compression Horn Driver: https://www.fostex.jp/products/d1405/ with Radial Horn: https://www.fostex.jp/products/h400/

Woofer: https://www.fostex.jp/products/fw305/

Enclosure plan: https://www.fostexinternational.com/docs/speaker_components/pdf/recom_enclose/w300aII_encl.pdf

Will look like this:

Caixa.jpg


I'm considering acquire this vintage Sony amps, preamp, and active analog crossover:

Amp
http://www.thevintageknob.org/sony-TA-N86B.html
Preamp
http://www.thevintageknob.org/sony-TA-E86B.html
Crossover
http://www.thevintageknob.org/sony-TA-D88B.html

Many thanks, best regards to all!
 

Juhazi

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Nice project plan! The problem with that analog xo is that it can't do equalization of each drivers response nor set delay.
Most important is to learn to use a measurement system to analyze the response/distortion curve and directivty profile of each driver. Based on that info you start to test different crossover scenarios (frequency, type). Acoustic responses should match and phase too.

Please study this info (it being open baffle 4-way is irrelevant, same principles apply)
https://www.hifizine.com/2010/12/prototyping-4-way-open-baffle-speaker-with-the-minidsp-2x4/
 

Neddy

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Looks like a neat project!
That Sony sure looks sweet - but probably not as custumizable as needed, as mentioned.
FWIW, since you're evidently looking at rack mount gear, I've been real happy with the dbx Venu360 I use for crossovers (2-way biamped mains, plus subwoofer), and also use to implement room EQ and a touch of (safety) peak limiting....as well as other so far unused modules.
3 in (analog or AES) to 6 outputs.
https://dbxpro.com/en/products/driverack-venu360
I got mine used for quite a bit cheaper....:)
Happy hunting!!
 

sergeauckland

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As someone who's done much the same as you're intending to do, here's my contribution.

Firstly, with the sensitivity of the drivers you're intending to use, noise will be an issue. The amplifiers you're intending to use are pretty quiet, but you may still find there's some audible hiss/buzz when connected to the crossover. The best way of overcoming that is to run the crossover as hard as you can, and attenuate the crossover's output. You can do nothing about the power amp's own noise, but that should be low enough according to the spec.

As others have mentioned, you don't get EQ and delay adjustments on an analogue crossover, and in my own case, I used a DSP based crossover, the Behringer DCX2496. This will also give you a greater slopes, up to 48dB/octave, which will help reduce distortion from the drivers. It also includes limiters to protect precious drivers from over driving.

One further thing, do put a capacitor in series with the mid-range and tweeter to protect then in case the amplifier goes faulty. If an amp fails, it can puts some 50v of DC directly across the drivers, and these will take out tweeters and midrange, although bass units may survive rather better. I suggest you calculate the value of the capacitors to be, say, 5x the minimum impedance needed at each crossover point. It's not critical, just enough to pass the audio, but block the DC.

Finally, invest in a calibrated measuring microphone as you'll need it to set it all up. Doing it by ear on a two-way is just about doable, a three way becomes much more difficult. Software like ARTA and REW are free and work really well.

Good luck with the project, I have no regrets about doing mine, all still in use after more than 5 years.

S.
 
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CosmicJazz

CosmicJazz

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Hello, thanks for the feedbacks guys, really appreciate.

Interesting... I must say that sometimes I think it's too much go through the active crossover route on just my first project hehehe...

The other path that I consider, is multi-amplify, but with passive crossover, will put the passive crossover plan here, appreciate if you guys can take a look, and solve a doubt that I have about it.

Crossover.gif


As you can see, the woofer on the crossover plan is a different model to the one that I will purchase, I'm trying to figure out, if the crossover scheme of components will change, or will remains the same.

I will use:
http://www.loudspeakerdatabase.com/Fostex/FW305

Displayed on crossover scheme:
https://www.fostexinternational.com/docs/speaker_components/pdf/w300a2.pdf

Please, let me know, anything must be changed on the crossover scheme using the FW305 instead of the W300A?

Many thanks guys!
 

sergeauckland

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Don't Do It !!!!!!!

Passive tri-amping will do NOTHING of any use to you. If you read up about the Superposition Principle, you'll understand why passive bi or tri-amping is just a way Dealers can sell more amplifiers.

Either use the 'speakers with a passive crossover and accept the limitations, or go active with an electronic crossover.

Yes, it's a challenge, but the results will be worth it. I've never looked back since I did the same with my B&W 801s.

S.
 

gene_stl

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I remember when the Sony crossovers came out. They were intended to compete with Pioneer D-23 which I have been using since 1976. It was the first product that had a Linkwitz Riley characteristic at 12 db / octave even though it came out several years before Linkwitz published his seminal paper in 1976. (Which I copied out of JAES the day I saw it for .10 per page at the Washington University engineering library). It was the first product to do so even though I am presuming that Pioneer engineers discovered that transfer function on their own and kept it to themselves. I remember being surprised at studying the manual and seeing the -6db crossover points when set to 12db/octave. The Sony products were later.

An interesting thing about the Sony is that in order to have flat response they did not use Butterworth filters. They used something with some slight ringing in the response. I still lusted after them but they were very expensive and I was very happy with the Pioneer.

I agree with Sergeauckland about anything passive. The single most economical and simple way to improve any stereo is to biamp it.

I think you could also consider starting with an analog crossover since there is likely a little learning curve to the miniDSP gear. I am certainly very interested in that but not in a hurry. I have a musician friend who has a dbx DriveRack which he is very happy with. The Behringer is very reasonable in price. Both these allow response tailoring , and a host of corrections and have good S/N

https://www.hifiengine.com/manual_library/pioneer/d-23.shtml

the Pioneer is a bit more convenient to use than the Sony however. It has knobs for crossover frequencies, level(shelving) and slope. One of the most versatile analog components ever built. They have gotten kind of pricey used :
https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=Pioneer+D-23+crossover&_sacat=0

If you aren't ready to go digital with the miniDSP or Drive Rack or Behringer and don't want to spend 1-2000 on a Pioneer or likely more on the Sony
(In spite of what it says in the link you posted, I doubt they sold more of those than Pioneer. I have never seen one in person) you could get any number of professional crossovers that are available almost for free. You will discover that these things "sound" great. Which is to say that you will discover that good electronics don't add much sound when correctly applied.

https://www.ebay.com/sch/i.html?_fr...leDesc=0&_osacat=0&_odkw=electronic+crossover

https://www.ebay.com/itm/EV-Electro...496102?hash=item469a4dbae6:g:w3EAAOSwFGxdO6lL

https://www.ebay.com/itm/Furman-TX-...738078?hash=item4b69cf435e:g:NsUAAOSwAIddZyFl

https://www.ebay.com/itm/MUSYSIC-MU...a=0&pg=2047675&_trksid=p2047675.c100005.m1851

https://www.ebay.com/itm/Peavey-PV3...a=0&pg=2047675&_trksid=p2047675.c100005.m1851

Pro gear will likely have balanced inputs and outputs and either xlr or 1/4" phone plugs so your power amps and cables will need to be selected to match. The pro gear may be 2 3 or 4 way and mono or stereo so care needs to be taken ordering. ANY of these is better than passive and might be simpler than digital but I don't know. If I were starting from scratch I would probably get a Behringer.

Also why are you so interested in Fostex. They have been around forever and have an excellent reputation but they are very high priced.
Perhaps for a starter you should try something easier to buy. Get yourself some JBL or Altec or some of the new and wonderful Italian made drivers. These are all widely available for much less money.

Also how big is your room. Do you really need horns. With amplifier power being free maybe driver efficiency is not that important. Avoid the temptations of tube amps. Maybe use class A instead but even that probably will not be discernable in a four way system with active crossovers.
"Stay out of the way of the long tongued liar" who will try to sell you expensive cables.
 
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CosmicJazz

CosmicJazz

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Edit: Thanks for this great recommendations, about the Fostex, there's no turning back, already purchased the drivers, but thanks...

Anyway.... I must say that I'm surprised to know that passive tri-amp don't provide any benefit

For example: I was thinking about to use 2 3 channel amps, that are affordable, have a good sound signature, and are well engineered.

Denon POA-T3
https://www.hifiengine.com/manual_library/denon/poa-t3.shtml

denon poa T-3.jpg


So with 2 of this, I can amplify each driver separated, and use they with the passive crossover scheme already mentioned, not worth at all?

So considering that I already using this amps in a tri-amp passive situation, the next step would be just start get into active crossovers....

But not worth it this passive tri-amp solution? Nothing? Zero? Nada? hehehe :)

Many thanks guys!
 
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gene_stl

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I don't think you have made clear what you mean , by the passive crossover scheme. Regardless it certainly has no advantage and depending on what you mean, at its best it still would more heavily load your preamp or whatever else you are driving your system with.

Do you mean a passive crossover before the amps and the amps driving the speakers directly. Or some kind of stupid bi wiring situation where each amp does the whole range but feeds a speaker high level crossover. This would utilize all the disadvantages of both methods.

Also +1 on adding capacitors in series with the output on tweeters and even on upper midrange too. I would double them and put one on each side of the voice coil. They are a short to audio and a blocker to the DC put out by an amp which is stroking out. I also have used series fuses. Interestingly on my speakers shown at left I put 250 milliamp fuses in series with the tweeters and upper midranges and they never ever blew.
 
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Ron Texas

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I wonder how that fostex woofer and enclosure would work with a JBL compression driver and wave guide (or whatever) in a two way setup.
 
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CosmicJazz

CosmicJazz

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Hey gene, this lead me to another question that I would like to ask.. for example, for the pictures that I saw of some of this passive crossover scheme, it's made in a box, outside the speakers, more or less like this, with the two attenuators for the horn and tweeter:

PS: I know the picture of this passive crossover is not the exact scheme from the one that I mentioned, that is the recommended by Fostex for my loudspeakers, I'm using just as a similar example, I think it will be more or less like this no?

Crossover.jpg

So this lead me to the questions.

How would be the correct way to connect the preamp out, into the passive crossovers, and the two 3 channel amps that I mentioned? In order to amplify each speaker's driver?

I wondering if the preamp will have the capability to drive two 3 channel power amps... and how all amp's channels will be connected to the preamp... this is one of the reasons why passive tri-amp not worth?

Many thanks.
 
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levimax

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I agree with most of what is posted here especially to use active x-overs and to get a measuring mic / software (REW). The only other perspective I would like to offer is I use "analog active crossovers" with a home made tri-amp speaker system and use "Rephase" to do the final EQ tuning and phase alignment. I only need 2 DAC channels and you can use a two channel pre-amp. The good thing about the design you are looking at is that you can physically time align the drivers easily using REW and a microphone. Having physically time aligned drivers is a better and simpler solution than doing so with DSP.
 

gene_stl

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The picture looks to me like an external high level crossover. Notice that it has speaker banana plugs , not RCA nor XLR connectors. It is designed to go between a single amplifier and the speaker drivers. The only difference(between it and a regular speaker internal crossover) is that it lives in its own box. Notice the heavy and unshielded wiring and the power inductors. This is not a tri amp system. It is a three way passive crossover. Also a tri amp crossover should be in a shielded box or it would hum and pick up emi like crazy. Not necessary with an after the power amp crossover where the low output impedance grounds the hum and RFI.

You can't just take one of these and stick it in between power amps and your preamp. They are designed at much lower impedances (ie speaker at approximately 8 ohms versus amp inputs at 500 to 10,000 ohms. ) Current versus voltage operation.

There ARE designs for passive HIGH level crossovers that go between the power amp and preamp. I have built these for friends who were starting out in bi amping. But they are only easy to do for a two way system and they are not as versatile as an active system and there is really no good reason to used them with all the inexpensive crossover solutions that one can find these days.

You will probably be very happy with the Fostex. Very well respected in Japan where they audiophiles are , well, fanatics.
If you can find two identical three channel amps that would be great. The amps DON'T need to be identical. Lower power on the tweeter. more on the mid range. The most on the Woofus. I use three different types of amps on a four way system.

A clarification in case you are confused. Active crossover means it has transistors or op amps driving the filters and buffering the inputs and outputs.
Passive means only resistors capacitators and inductors and variable versions of same. High level crossover means it goes between the spikkers and the output of the ampleflyer. Low level means it goes between the preamp and several (at least two stereo) power amps and divides the frequencies before power amplification. The amps then drive the speaker driver terminals directly the way God intended.

A low level crossover can be active or passive but active has numerous advantages. Even a passive low level has many advantages over a high level system. (ie a regular system) This why most all active speakers are bi or tri amped. Although they usually also incorporate DSP which is like active on stereoids. Don't let some audiophiles make you fall in love with some nostalagia that was obsolete before you ever got interested in the hobby.

A high level crossover is inherently passive.
 
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CosmicJazz

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I think I not fully understood, let me forget about the multi amplification for a while, and organize this stuff inside my head, if I try to figure out a lot of different solutions at the same time, I will not reach anywhere, appreciate very much the patience, I still learning...

So, first of all, I have to make a decision:

The crossover will be the passive one recommended by Fostex according to the drivers that I bought, DECISION DONE.

The power amp will be a normal stereo amp, DECISION DONE.

Crossover.jpg


Doubts:

1. This crossovers will be assembled in boxes outside the speakers, this design means they have just 2 RCA connections (ground and music), that goes out from the woofer, no more +- connections from each respective drivers on this crossover box.

Correct?

if yes, it's very straight forward to connect to a stereo amp, and I understood the design.

Need to know If my interpretation of this is correct, in order to formulate another doubts that I have, about other types of amplification and crossover variation, sorry for slow down too much with this, still learning, appreciate very much the patience.
 

gene_stl

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If you use a passive high level crossover designed by the folks that built your drivers you won't go far wrong and that is a reasonable starting point.

RCA connectors are designed for line level (ie. preamp, tuner, electronic crossover) low voltage and low current. Although they have occasionally been used for speaker connections they are not optimum.

To connect to speakers you need a speaker connector. This would either be 1) a five way binding post 2) a Speakon connector (newer and kewler)
or 3) bring wires straight from the speaker driver components out and attach them to the box using a 4)barrier terminal strip. Five way binding posts are what you usually find on the back of stereo amps.

I don't see how a crossover can have no + and - connections to the mid range and the tweeter. I don't think that can be correct. It does not correspond to either of the two diagrams you have uploaded. Both diagrams have level controls that are immediately before the mid range and tweeter. a three way has three pairs of wires coming out of the speakers and going into the crossover. Then there is the input pair from the amplifier
 
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CosmicJazz

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Will take a closer look on the type of connectors that you mentioned, for see how they looks like, thanks.

Doubts:

1. so the + - connectors mounted on the crossover box must be the same type of the connectors that the power amp of choice have?

2. I really would like to understand the diagram from Fostex, I will tell for the speaker builder follow strictly the Fostex recommended crossover plan, here are the pictures of the atenuattors that I bought and are the recommended ones.. let me know how to interpret this diagram correctly please, even if you guys think the recommended diagram was not designed properly by Fostex...
So my interpretation is: This digram design unifies the +- wires that come out from horn and tweeter, into the +- that comes out of the woofer? so the crossover box indeed will have just 1 set of +- connectors? or my interpretation about the Fostex diagram is wrong?
Many thanks.
fostex rt100t2 inside.jpg

fostex rt100t2 front.jpg

fostex rt100t2 back.jpg
 
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Juhazi

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CosmicJazz, you do have a lot to learn! You should start from basics, about electrics and reading circuit diagrams
Here is a good resource https://speakermakersjourney.blogspot.com/2016/02/crossover-basics.html

The boxed attenuator you have has wire connectors and it is easy to connect just by the diagram. This is however difficult to explain in written words, you should ask a friend to show it to you hand-to-hand IRL.

The major benefit of using technology of this millenium - digital sound processing - is that you don't have to understand so much of physics. I am too dumb and lazy to learn passive xo design, but I have built some passive speaker designs found in the WWW. After learning to take and comprehend acoustic measurements, I have set up several active 3 or 4-way systems using minidsp and Hypex and they are far superior.

https://www.minidsp.com/applications/digital-crossovers/digital-crossover-basics
 
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CosmicJazz

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Thanks, I just would like to know if I'm interpreting the crossover plan correct, appreciate if you can check the doubt 2. on my last post... my interpretation that the +- from horn and tweeter be unified to the +- from the woofer is wrong?
 

Juhazi

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If I understood your question - yes. I will try to explain...

A crossover (be it in a box or not) for one channel ((left or right of stereo) has one pair of speaker level input connectors, labelled + and - (red/black) and the minus is typically "earth/ground" in diagrams, on the left side of diagram. Inside the xo both wires will be split to three parallel wires (connection points in diagram marked with black big points), in this case the crossover type is called parallel xo. Some of the components are connected serially along the red wire, other parallelly to both red and black wire going to each driver, like the attenuator in this case. Finally both red and black wire of each "way" are connected to the red/black connectors of each driver.

A layout wiring diagram is sometimes published to show how the wires can be routed in real life, taking in to account the physical dimensions of components.
Troels Gravesen shows these of some his designs, like this for example (go to the bottom of page)
http://www.troelsgravesen.dk/SP44.htm
 
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CosmicJazz

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Hello,

Let me see if I understood fully.

The crossover will be assembled in a separated box, for what I saw on the R100T attenuators, they have two sets of +- terminals, one set is input, other is output, so +- wires goes out of the tweeter and horn, and are plugged in the +- input attenuator's terminals, after that, +- wires from tweeter and horns goes out from the +- output attenuator's terminals, after that, tweeter and horn +- wires are unified into the +- woofer wires, so in that way, I'm visualizing the crossover box with just one set of +- -connectors, so this scheme not offer +- connections for each driver on the crossover box.

My interpretation of the crossover scheme is correct?

Many thanks if you can tell me, best regards!
 
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