RS 4.5 Info Advice Needed

[goat67]

Hi All
Need some info and advice on the pair of RS 4.5s I can purchase

1.) For the owners of these do you have the electronic crossover unit ECU mentioned on the classic site

2.) If not how are you running them I understand there is alot of options

3.) I was going to Bi Amp with a pair of Soundcraftsmen amps RA7502 and RA7501 horz or vert?

These do not have the ECU so how will they sound without it can or should I use another active crossover unit? If so what one

So let me hear all about your set ups and advice on how to make these sing

 

[phaedrus]

I use the Infinity crossover, and run a pair of SAE X-25 (250 watts/8 Ohms) amps. If you want to vertically biamp, you'll need identical amps for the left and right. I'm not familiar with the Soundcraftsmen, but, assuming those are two different amps, I would expect you would need to run them horizontally biamped. You can do so either with or without a crossover; the Infinity manual has diagrams of all the various options for setting them up.

Just my $0.02 worth; I am sure Vito will be along shortly and can give you the authoritative answer.

David

 

[goat67]

Did the RS 4.5 allways come with a ECU or was it optional
The amps are the same wattage only diff one does not have LEDs for output

 

[Vitopanch]

Hail goat and David,

Goat, as David has explained, you have many options. Yes, I have the active croosover box with my RS 4.5's. As far as I know, it was not an option, it was part of the package. Back then, it was a critical part of the package, but, not so now because you can obtain an after market one that does the same job. When I say critical part of the package I mean that if you want to "properly" bi-amp the RS 4.5's, which is highly recommended to "get the most" out of them, you need a FIRST ORDER active crossover box. Or you can buy a crossover box which is "dialable" as to the order. Behringer for example sells one.

So, you do not have to bi-amp the RS 4.5's, however if you do, the results will be spectacular.

As far as bi-amping without an active crossover box, you certainly can. What the active crossover box brings to the table is that it will only send the selected frequency range to the power amplifier that you select for that range. This lessens the load on the power amplifier BIG TIME, which is really what bi-amping is all about. With an active crossover box, you have the ability to send the mid/high frequencies to different amplifiers than the low frequencies. This reduces the work on the stereo amplifier and leaves more available current to handle the dynamic range of music. This is also why I am a big proponent of vertical bi-amping as opposed to horizontal bi-amping. If you are unfamiliar with the terms, veritical bi-amping means using two amplifiers(one stereo amplifier) for one loudspeaker and two amplifiers(one stereo amplifier) for the other.

Identical power amplifiers are not mandatory, and many folks have different opinions about the best setup and that is probably because there might not be the best setup. I personally, after experimentation with many loudspeakers, think that the best results are with, if not identical power amplifiers, ones with similar available current and wattage, preferably the same make. This is probably because as I stated earlier, I find that vertical bi-amping is the way to go. Power amplifiers with the same or similar capabilities will help create a coherant soundstage. The reason for this is that the "big" vintage Infinities claim to fame, justifiably so, is a huge, coherant soundstage. Surely the EMIT's, EMIM's and Watkin's woofers contribute to that, however, it is more than that. The passive crossovers are key here in that each driver has disimilar demands for current. Ensuring that ample current is always available for the drivers within an RS 4.5 loudspeaker can best be acheived through vertical bi-amping with high current power amplifiers because that way, the enormous responsibility of driving four Watkins woofers is not settled on one power amplifier, but two. Additionally, at high volume the EMIM's and EMIT's want a decent share as well.

So, if you can not afford or want to pick up a FIRST ORDER capable active crossover box, you can bi-amp them with good, not the best, but good results and pick up a box later on. Try out vertical and horizontal for your self and see what you like.

My RS 4.5's are vertically bi-amped by two Phase Linear 700 using the active crossover box. My RSIIA's are also vertically bi-amped by two Bell Labs Phase Linear 700's.

I hope that this helps.

Vito

 

[phaedrus]

Identical power amplifiers are not mandatory, and many folks have different opinions about the best setup and that is probably because there might not be the best setup. I personally, after experimentation with many loudspeakers, think that the best results are with, if not identical power amplifiers, ones with similar available current and wattage, preferably the same make.

Vito,

Great post, but it leaves me confused. Based on my understanding of vertical biamping, the left and right amps need to be identical. I'm not sure how left/right balancing would work if you were using dissimilar amps. On horizontal biamping, you can use different amps for the highs and the lows. What am I missing here?

David

 

[Vitopanch]

David,
You are correct. What I am allowing for however, is that there may be some amplifiers out there that have identical specs but are different makes or models. I am not knowledgable enough to make the statement that two 350 watts per channel into 8 ohms high current power amplifiers from different companies are going to be sonically different or incapable of a balanced load between them to use the word MUST, is all. People may be out there with two rare power amplifiers from different companies, but they are very similiar power amplifiers in the critical areas, for example and want to use them in a vertical bi-amp setup. I do not want to dissuade them from trying it out, because they may be similiar enough in the critical aeas to make whatever difference is realized negliable. I am also from the school of thought, I may be one of the few pupils, that there are a basic set of specs for power amplifiers and that if the power amplifiers fall within the basic spec parameters that they are going to sound pretty much the same. I feel that most differences, positive and negative fall with the pre-amplifiers. However, unless someone is positive about that fact, it is very important sonically for them to be the same.
Vito

 

[EchoWars]

Why must they be vertically bi-amped? You don't need massive power for the mids and highs...only for the woofers. Get a big-dog amp for the bottom end, and a good 100WPC (or so) amp for the mids and highs.

First-order (6db/octave) isn't a requirement for a nice 4.5 sounding speaker either. Army can attest to that, and having heard them for extended periods, I can too. Plus, a higher-order filter does a better job of protecting the now near-unobtanium drivers. It may not be what Infinity intended, but it works well.

 

[Vitopanch]

Why must they be vertically bi-amped? You don't need massive power for the mids and highs...only for the woofers. Get a big-dog amp for the bottom end, and a good 100WPC (or so) amp for the mids and highs.

First-order (6db/octave) isn't a requirement for a nice 4.5 sounding speaker either. Army can attest to that, and having heard them for extended periods, I can too. Plus, a higher-order filter does a better job of protecting the now near-unobtanium drivers. It may not be what Infinity intended, but it works well.

I never said that they MUST be vertically bi-amped. He asked for opinions, suggestions and what we had for setups and I gave him MY opnions based upon MY experiences.

If Army has a different setup and he likes it I am happy for him. We all will pick what setups that we like and when someone asks we will them render our opinions based upon our experiences.

As concerning the First Order, I offer what I was told on numerous occasions from folks at Infinity. Your knowledge far outstrips mine in the area of electronics, so I aquiesce the point.

Vito

 

[EchoWars]

Whoa dude...not so touchy. I didn't contradict a thing you said.

I scanned the posts rather quickly, and it seemed to me at the time that the vertical bi-amp was presented as having some serious advantage. Since goat has two different amps, vertical really isn't an option (and I didn't catch the mention of two different amps the first time).

As far as the crossover, re-read my post. Regardless of what Infinity says and what negative effects it may (or may not) have on final sound quality, a higher-order crossover offers advantages regarding driver protection for those rare EMIT and EMIM's. I just wanted him to know that there's more than one way to get it done with an active setup and you aren't chained to the way Infinity says it ought to be done.

Relax bud...we're on the same team.

 

[totem]

goat67 I say if the 4.5,s are in good shape, and the price is OK, grab them.
The eq. can dealt with later in various ways. Running 2 of your Soundcraftsmen
amps in a vertical bi-amp should make you pretty happy right away.

 

[Kencat]

This is as much a question as well as a cautionary note. Without looking at the schematic for the 4.5, if it is designed with a 1st order crossover network, then putting a higher order active setup in upstream could create some phasing issues could it not? Also, the mid and tweeters would still be connected to each other by the original 1st order passive anyways, so the higher order active split between woofers and mid/highs wouldn't have any impact on the tweeters anyway as the recommended crossover range is at 110 to 440 Hz.

Just looked at the schematics - yikes. Looks like 1st order stuff but there are other weird connections in there so not sure. The outer and center tweets are already wired out of phase though, relative to everything else, so phasing could get interesting.

Very good reading here - manual for the Infinity crossover box - http://www.infinity-classics.de/infinity/technik/manuals/RS 2.5 - 4.5 Crossover Manual.pdf

Seems to me the purpose of the 1st order network of the Infinity box was to ALLOW the listener the ability to fine tune the "peak" and "dip" in the crossover region, and to not mess up the passive networks left intact to do their job properly. Nice touch.

Experimentation beyond this, as always, is in the ears of the beholder.

 

[EchoWars]

Rgr that...a higher order active on a 4.5 protects the EMIM, not the EMIT. I misspoke, but the overall point is unchanged (and I think ya'all grasped it anyway).

The advantage of the 1st order is that, unless the drivers are seriously misbehaved in the crossover region, there's not a lot of funny-business with peaks and dips. The disadvantage is, of course, a lot of energy going to regions outside the ideal.

I'd love to see impedance graphs of the EMIM and EMIT, and for the Watkins too, for that matter. Would make decisions about straying from Infinity's 'ideal' setup a lot easier.

 

[goat67]

Thanks for all the input

All Right clarifications

The two amps I am using are identical in output one has LEDS for output indication the other does not.
Rated at
250 Watts 8 Ohms
375 Watts 4 Ohms

I understand Bi Amping
So I can do either Vert or Horz.
In regards to this the concept of vert bi amping has some merit as it is true that you are spreading the high current demand for the wolfers between two amps.

But in the end a person must try out both ways and see what sounds the best.

I am horz Bi Amping the RSIIbs right now this is because one of the amps has shown its tendency to go into protect when drivin my Q5s when reproducing sound with demanding bass. The Watkins woofers and its crossover circuitry I believe are dropping down to 2 ohms or lower impedance and this amps protection circuitry is borderline and shuts down. I know this is the case because the other amp has no problems driving the Q5s.

ANYWAY
My main question is what should I do with the RS 4.5s if it does not have the active crossover unit.

From the Infinity Classic site RS 2.5 and RS4.5 Crossover Manual
-----------------------------------------------------------------
The Electronic Crossover/Equalizer Unit
The active Crossover/Equalizer control unit,which is part of the Reference Standard 4.5 system and optional with the RS 2.5, makes it possible for the user to compensate for room acoustics and speaker placement.

The unit is connected into the signal path between the preamplifier(s) and power amplifier(s). In the case of a receiver without an externally accessible link between its pre-amp output and its power amp input, the connections are made through the tape monitor circuit for equalizer use only.

When active bi-amplification of an RS 4.5 or RS 2.5 speaker system is desired, the Crossover/Equalizer must be used.
-------------------------------------------------------------

Does anybody have a RS 4.5 speaker instruction manual ? This might help me figure this out.

So what options do I have if I get the speakers without the active crossover box what could I get to acheive this.

Thanks Jerry

 

[Vitopanch]

Hail goat and David,


So, if you can not afford or want to pick up a capable active crossover box, you can bi-amp them with good, not the best, but good results and pick up a box later on. Try out vertical and horizontal for your self and see what you like.

I hope that this helps.

Vito

I can mail you a copy of the RS 4.5 manual and the active crossover box manual if you PM your mailing address. My scanner is down ATM so it will have to be snail mail.

Vito

 

[totem]

Jerry since the eq. was an option on the RS-2.5,s I don,t have it,and the same unit is used on both models, I don,t see a big down side. Yes there are additional drivers in the 4.5,s big deal. that site does have the eq.s on once and awhile. I guess if there where someone who has driven the 4.5,s with no eq we could get another real world opinion.

 

[goat67]

Why must they be vertically bi-amped? You don't need massive power for the mids and highs...only for the woofers. Get a big-dog amp for the bottom end, and a good 100WPC (or so) amp for the mids and highs.

First-order (6db/octave) isn't a requirement for a nice 4.5 sounding speaker either. Army can attest to that, and having heard them for extended periods, I can too. Plus, a higher-order filter does a better job of protecting the now near-unobtanium drivers. It may not be what Infinity intended, but it works well.

EchoWars what is Army using for the Active Crossover? Is it the Infinity model or is it something else if something else WHAT as I want to get an Active crossover unit so I can BI amp these.

 

[EchoWars]

As Vito pointed out, they can be bi-amped (in an odd sort of way) without even the active crossover, but in order to benefit from all the advantages bi-amping has to offer, you need an active crossover.

Army (Scott) has your basic Behringer CX2310 stereo two-way crossover. These are designed for professional sound reinforcement applications, and as such have XLR balanced inputs and outputs. Conversion adapters are necessary to change over to unbalanced RCA-type connectors (Scott found some rather nice cables and adapters somewhere).

Something like this CAN be tricky to set up, and it's not a bad idea to ask someone for a bit of assistance since it is quite possible to smoke your EMIM's if you do something wrong. I'm resonably certain that Scott would be glad to help steer you in the right direction.

http://www.parts-express.com/pe/pshowdetl.cfm?Partnumber=248-664

I don't have a lot of doubt that the stock Infinity crossover is more flexible, and may even have sonic advantages over the inexpensive Behringer, but the Behringer is a good introduction to how it gets done, and does have the advantage of offering more protection for the EMIM drivers with its 24db/octave filters.

Vito also alluded to the fact that you can spring for the Behringer DCX2496 digital unit, which would let you choose the filter slope so you can mimic Infinity's 1st order crossover if you like. Cost of admission is a tad higher though, and the complexity might not be to your tastes.

http://www.parts-express.com/pe/pshowdetl.cfm?Partnumber=248-669

 

[Vitopanch]

Something like this CAN be tricky to set up, and it's not a bad idea to ask someone for a bit of assistance since it is quite possible to smoke your EMIM's if you do something wrong. I'm resonably certain that Scott would be glad to help steer you in the right direction.

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Very good advice Jerry. Also too, if you run into a balancing act with your Soundcraftsman between the RSIIB's and RS 4.5, you can horizontal bi-amp them with less powerful and therefore probably less expense power amplifiers handling the highs and mids, as Echowars pointed out. That approach may save you some coin for an active crossover box.

You have many options at your disposal.

Vito

 

[goat67]

Army (Scott) has your basic Behringer CX2310 stereo two-way crossover. These are designed for professional sound reinforcement applications, and as such have XLR balanced inputs and outputs. Conversion adapters are necessary to change over to unbalanced RCA-type connectors (Scott found some rather nice cables and adapters somewhere).

No prob with handling the balanced cables the Soundcraftsmen supports both balanced and unbalanced inputs

I would need to get the XLR adapter from the preamp out which is RCA

Thanks for the info on the Behringer Xovers this is what I wanted to know.

 

[Army]

No prob with handling the balanced cables the Soundcraftsmen supports both balanced and unbalanced inputs

I would need to get the XLR adapter from the preamp out which is RCA

Hi Jerry
That is a nice feature on the Soundcraftsmen amps and saves you quite a bit of coin. Yes you will need one pair of cables or an adapter for the preamp. I used the adapters and they worked fine. Later I purchased these after I had gone with ZU speaker cables and I like them a lot. :thmbsp:

As for active crossovers there has been some debate as to what sounds better. Some think the behringer CX3400 sounds better than the CX2310 I use. I may at some point spring for the 3400, but the 2310 does a fine job IMHO.

When you go to pick up the 4.5's have someone with a strong back, those things take two men and boy to move
Best of luck as always!
Scott