Studio Monitors technical discussion, impedience matching, biwiring, etc.

[phangeaux]

I am very fortunate to have acquired a used "Rolls Royce quality" set of studio monitors from a pawn shop. They are KEF Reference Series Model 101/3 (the '/3' refers to 3rd generation) manufactured in the 1990s with patented Uni-Q technology and are still 'state of the art' in studio monitors. I tested them and the transparency and clarity is unbelievable. I could post a whole page or two about these but I am not posting this to discuss details of these monitors.

However:

I am being extremely careful with regard to selecting a perfect amplifier, proper impedence matching, wiring, etc., because obviously I don't want to make any mistakes that could damage these monitors. The same care should apply to any set of good audiophile speakers or studio monitors.

What I have been learning thus far should be helpful to beginners and professionals. I am basically going to address three things in this topic by posting urls to relevent information on the following:

1) Matching power ratings and impedence of amplifiers to speakers:
Mistakes here can result in damage to amplifiers and speakers. This might be one of the reasons why there are so many damaged/blown speakers and damaged amplifiers lying about in thrift stores or in dumpsters. People probably didn't consider proper matching of power ratings and impedence ratings.

2) Biwiring: If your studio monitors have 4 terminals on the back of each monitor, then they are 'biwireable'. When biwired the high frequency and low frequency signals from the amplifier are separated and sent separately (through different wires) one to each monitor's high frequency driver connection and one to each monitor's low frequency driver connection which provides more clarity. Otherwise, when single wired, the high frequency and low frequency terminals on the speaker have a jumper across them and both high and low frequencies travel through one wire and are divided by circuitry in the speaker, which is suboptimal. This will be explained along with 'how to' biwire them. (in following posts)

3) Biamping:
This is carrying the purposes/advantages of biwiring a step further by using two amplifiers. That will also be explained with a 'how to' (in following posts)

I will be looking for even better articles with clearer instructions when I have the time. If you happen to find good info on these topics, put it on.

[phangeaux]

Speaker Impedance Matching

http://wolfstone.halloweenhost.com/T...eakerImpedance

http://hyperphysics.phy-astr.gsu.edu...dio/imped.html

I found quite a few highly technical webpages discussing this topic but if someone has the technical education to understand that stuff they can go and find those pages themselves. I am trying to keep it practical and simple. Personally, I am not pursuing a career as an electronics engineer, I just want to make some good basic decisions about setting up my home studio and then make some good music.

Although these topics might seem complicated at first, I think that all in all, it's simpler than it looks.

[phangeaux]

This is one of several articles sent to me by a KEF rep. In my next post I will post a couple of good URLs with wiring diagrams:

Source:
http://www.whathifi.com/newsMainTemp...ewssectionID=3


Biwiring and biamping your speakers

Judging from our postbag, readers seem to be in a right old tangle about the pros and cons of biwiring, not to mention how it's actually done. And when it comes to biamping, the confusion just gets worse.

For example, reader Ming Chong Yap wants 'a step by step way of biwiring and biamping - despite the definition at the back of What Hi-Fi? I don't seem to understand them'. And Stuart Manners has a question about his Aiwa NSX-A90 system: it has three way speakers, and he wants to know if it's worth opening up the speakers to triwire them. Here come all the answers...

The simplest hook-up between an amplifier and a pair of speakers uses a two-core cable per speaker - one conductor is designated positive, and marked with a '+' symbol and/or red plugs and terminals. The signal goes into a crossover in the speaker: an electrical circuit that splits it between the drive units.

So in a two-way speaker, the bass and midrange signals go to the woofer, while signals above a certain frequency (often around 3kHz) go to the smaller tweeter. In a three-way speaker, the signal is split into bass, midband and treble. Bear in mind, however that a speaker with three drivers may not be a three-way speaker - the term purely refers to the way the signal's split. Mission's 753 Freedoms, for example, use five drivers, but are in fact only two-way speakers.

But we digress - back to the crossover. One of the problems with a standard crossover is that since one pair of cables carries the signal to and from the amp, bass signals can tend to swamp the more delicate treble stuff, especially in the return (or negative) connection back to the amp.

By separating the signal all the way back to amplifier's output stage, using two runs of cable or a purpose-made four conductor biwire cable, these effects can be greatly reduced. To do this, you need speakers designed for biwiring. That means the crossover needs to be completely split, without the common negative found in standard design.

To all intents, a biwirable crossover is two separate circuits - one to filter the treble out of the signal for the bass driver, the other to prevent the bass from reaching the treble driver. The dead giveaway is four terminals - two positive, two negative - on the back of a biwirable speaker. No multiple terminals, no biwiring - sorry, Stuart, that means it's not worth ripping your Aiwa speakers open!

To allow them to be used with a single two-core cable, the terminals on biwirable speakers are usually connected by some kind of jumper bar or link - the speaker instructions will tell you how to remove these to prepare the speaker for biwiring. That done, you need two positive and two negative connections between the speaker and the amp.

Whether you use two separate two-core cables or a four-core biwire run is a matter of taste, but most users will find the latter tidier. At the speaker end, the four conductors - two positive, two negative - are connected to the terminals, but what happens at the other end depends on the outlets the amplifier provides.

With the possible exception of amps with springclip terminals, which have trouble accommodating even single cables, any amp can be used for biwiring. Some provide twin sets of speaker terminals specifically designed for biwiring, while others have A and B speaker outlets you can use to the same effect. If the latter's the case, you need both sets of terminals turned on all the time.

An amp with a single set of terminals (ie just left +/- and right +/-) can also be used: the two positive conductors from the left speaker are connected into the left '+/red' terminal, and the two negatives into the '-/black'. Repeat this for the right speaker, and that's it. If you have an amp with 4mm banana socket terminals, most cable manufacturers and dealers will supply biwire cables 'commoned' into a single set of plugs to make this even easier.

If, however, you have to use bare wire connections or are soldering up your own cables, check and double check the polarity of each amp-to-speaker connection - it's all to easy to get, say, the left tweeter out of phase with both the left bass and the right speaker. You won't do any damage to either amp or speakers, but it'll sound pretty odd. Get it all right, and what you should hear is better focus and clarity in the treble and (particularly), plus better soundstaging. But you can go further...

If a speaker can be biwired, it can also be biamped, which involves using one amplifier channel for each drive unit to give further improvements. A stereo pair of two-way speakers will thus need four channels of amplification, and there's a variety of ways of doing this. The currently fashionable way is the use of an integrated amplifier along with a power amp.

There are two provisos, and the first is that the integrated in question must be fitted with a pair of preout sockets for this purpose. Some models are designed in this way, having preouts that work in tandem with their own power sections. Amps such as some NAD models, in which the pre and power sections are linked with jumper bars, are generally not suitable for biamping. If in doubt, check with your amp's manufacturer.

The other point is that the power amp you use should have the same gain (though not necessarily the same power output) as the integrated amp you have. That means that for a given input voltage, both the integrated's onboard power section and the external power amp you use will give the same output. If they didn't, you'd have a sound with much louder bass than treble, or vice versa. In general terms, the requirement for this gain-matching means using combinations from the same manufacturer, designed to be used together.

To biamp, your four-conductor runs to the speaker will need four connectors at the amp end, be these plugs or bare wires. The integrated amp and the power amp are connected together with a stereo pair of interconnect cables, pre-out on the integrated to pre-in on the power amp. You then use one amplifier to drive the left and right treble (or high frequencies), and the other to power the left and right bass. In general terms, the integrated drives the treble, and the power amp the bass, but it's worth experimenting to get the sound you want.

Let's recap: the four conductors from your left speaker will split between the two amplifiers, the two conductors hooked to the speaker's 'high frequency +/-' terminals going to the integrated amp's 'left +/-' outputs, and those from the 'low frequency +/-' to the power amp's 'left +/-'. Repeat for the right channel. Make all these connections with both amps turned off, and double-check all connections before switching on.

Then, as your finger hovers over the power buttons, go back and check it again - it's all too easy to get your wires crossed, and the result could be that you trip one or both amps' protection circuits, blow an internal fuse requiring service attention to fix, or even wreck the amp's output device. No, you can't fry yourself, but mistakes could prove costly.

Finally, it's also possible to biamp using a preamplifier and two stereo power amps or, as in our Audiolab reference system, a pre and four monoblocs. The hookup is the same as the integrated/power amp configuration, and the best thing is that each of these steps up is worth every penny!

WhatHiFiSound+Vision

[phangeaux]

And... here are some simple to understand HOW TO'S on Biwiring and Biamping:

http://www.davidmannaudio.com/faq/faq3.html

The next URL explains both Biwring and Biamping with diagrams. Quoted from that page:

"Taking the next step, or biamplifying, affords you even more advantages while admittedly greatly increasing the overall cost. In the standard configuration, you use one amp to reproduce the high frequencies and one to reproduce the low frequencies."

http://www.soundstage.com/synergize/synergize031998.htm

[brandondrury]

1) Matching power ratings and impedence of amplifiers to speakers:
Mistakes here can result in damage to amplifiers and speakers.

I just wanted to add that I've seen way more speakers blow from not having enough power that I have with too much power.

I'll write an article on this one fairly soon.

Brandon

[phangeaux]

Brandon,
Take your time to research the subject well before writing your article. There is alot of 'opinion' out there and alot of people who act like they have adequate knowlegeble and write seemingly convincing answers to questions on forums, etc., but who really don't know the correct answers. In the absence of true engineering knowlege and expertise they just don't know that they don't know, and assume that their interpretations are adequate.

I completed electrician's school, with some basic electronics in 1982 with straight A grades. I focused on the very technical stuff, I didn't care much about learning how to pull wires in a house or rewind a pump motor or generator on a bench, I was more into the technical science and engineering stuff, like what exactly are electrons, what do they do etc. I should have stayed in that field.

Unfortunately, that education has lead me to do alot of reading on these recording studio equipment subjects and as I have pointed out many times I would rather just be playing music. I was afraid I would get too much into tech stuff. I din't want to be "a recording studio geek" remember? I just wanna play the blues. However I am finding this all too interesting and challenging to my intellect and I have spent all of my time reading up on this stuff.

ANYHOW, I am completely convinced that in a recording studio environment everything should be as perfectly matched as possible with the best equipment one can afford. One can do well on a low budget, I am proving that. There are REASONS for all of those detailed specifications, a speaker is not just a speaker and an amplifier is not just an amplifier. There is also a reason why one 100W amplifier costs $149. and a different 100W amplifier costs $849. There are reasons why some speakers are designed at 4-Ohms and others at 8-Ohms, and of course why some cost $149. and others cost $1,490.00- yet ointerestingly enoughn they can use similar sales propaganda. Learning to integrate all of these specs in the most efficient way into a recording studio is going to yield a top notch recording studio, even on a budget. DANG, I might become a recording studio geek after all, when all I really wanted to do was play and write some blues and trippy music.

As I mentioned, I am now seeking the best amplifier to power my studio monitors which are rated at 4 Ohms with amplifiers up to 110W. I am certainly not going to hook up an amp rated at 450W through 4 ohms! That would be stupid.

I have looked at probably 2,000 amps on EBAY (seriously I have looked at that many and probably twice as many) under $200, sometimes up to $300 which is within my budget estimate and I have read specs on numerous amps and am learning quite a bit. The Alesis RA100 for example will put out 100W through 4 Ohms which is pretty much right on target and only costs around $100 used ($199. new), The RA150 is more desireable for input connections as I recall, rated for 75W at 4 ohms. However I looked at a couple of Crown amps, like one that pushes 35W and another 75W through 4 Ohms and it costs like 3 times as much as the Alesis RA100, BUT when I look at all of the detailed specs, like distortion etc., I understand why that particular Crown amp is a 'better' amp and therefore why it costs so much more.

I have seen quite a few other amps that will fit into the design criteria and pretty reasonably priced.

I am still researching this and will probably make a choice and have a hnice amp in a few weeks.

OK, so HERE are a couple of quotes from a webpage that give a little bit of an inside view of what is going on inside speakers with regard to their power/amplification ratings.

UNDERSTANDING LOUDSPEAKER DATA
http://editweb.iglou.com/eminence/em...s02/params.htm

A couple of paragra[hs quoted from that page:

>Xmax/Xmech: Short for Maximum Linear Excursion. Speaker output becomes non-linear when the voice coil begins to leave the magnetic gap. Although suspensions can create non-linearity in output, the point at which the number of turns in the gap (see BL) begins to decrease is when distortion starts to increase. Eminence has historically been very conservative with this measurement and indicated only the voice coil overhang (Xmax: Voice coil height minus top plate thickness, divided by 2). Xmech is expressed by Eminence as the lowest of four potential failure condition measurements times 2: Spider crashing on top plate; Voice coil bottoming on back plate; Voice coil coming out of gap above core; Physical limitation of cone. Take the lowest of these measurements then multiply it by two. This gives a distance that describes the maximum mechanical movement of the cone.<

>Power handling: This specification is very important to transducer selection. Obviously, you need to choose a loudspeaker that is capable of handling the input power you are going to provide. By the same token, you can destroy a loudspeaker by using too little power. The ideal situation is to choose a loudspeaker that has the capability of handling more power than you can provide lending some headroom and insurance against thermal failure. To use an automobile as an analogy; you would not buy a car that could only go 55mph if that were the speed you always intended to drive. Generally speaking, the number one contributor to a transducer?s power rating is its ability to release thermal energy. This is affected by several design choices, but most notably voice coil size, magnet size, venting, and the adhesives used in voice coil construction. Larger coil and magnet sizes provide more area for heat to dissipate, while venting allows thermal energy to escape and cooler air to enter the motor structure. Equally important is the ability of the voice coil to handle thermal energy. Eminence is renowned for its use of proprietary adhesives and components that maximize the voice coil?s ability to handle extreme temperatures. Mechanical factors must also be considered when determining power handling. A transducer might be able to handle 1,000W from a thermal perspective, but would fail long before that level was reached from a mechanical issue such as the coil hitting the back plate, the coil coming out of the gap, the cone buckling from too much outward movement, or the spider bottoming on the top plate. The most common cause of such a failure would be asking the speaker to produce more low frequencies than it could mechanically produce at the rated power. Be sure to consider the suggested usable frequency range and the Xmech parameter in conjunction with the power rating to avoid such failures. The Eminence power rating is derived using an EIA 426A noise source and test standard. All tests are conducted for eight hours in a free-air, non-temperature controlled environment. Eminence tests samples from each of three different production runs and each sample must pass a test exceeding the rated power by 50 to 100W. The Eminence peak power rating is double that of our standard RMS rating.<

[phangeaux]

Here is something a little more fun:


From 2003 consumer electronics show in Las Vegas:

This year the outstanding leader in the conventional box speaker category was the $40,000 TAD Model-1. A superbly executed design under the leadership of Andrew Jones (KEF, Infinity, Pioneer), it exemplifies what can be achieved within the box paradigm
(See them here):
http://tadhomeaudio.com/specs.html

Now, regarding that show, I read an article from a reporter at a similar recent show in the UK.? There were audio cables on display that cost something like $6,000 for 3m length,? (about 10 ft.) I could be mistaken on those figures but it was something like that.? This reporter then was looking at a very expensive speaker system being demonstrated at another location. He noticed the bright orange speaker cables and asked the presenters if they were using some kind of high tech expensive audio cables.? The reply was something like, "No, we liked the bright orange color and decided to use them.? They are in fact weed eater extension cords from Home Depot.

LOL, this was on one of the websites that attempts to dispell the myths used as marketing propaganda to sell very expensive audio components that questionably do not add anything to improve the system other than a placebo effect.? If the customer THINKS or is led to BELIEVE that the system? will sound better by buying, for example, very expensive solid gold connectors for $800 then that customer is? going to believe that it sounds better simply by the POWER OF SUGGESTION.

I should also note that advertizing and marketing research delves heavily into this effect and is exploited in advertizing. Even top notch alternative medicine practitioners/experts admit that the 'placebo effect' is a huge part of the success of their treatments.? It's psychology.? One of the most misleading is the 'Testimonial' like "yeah I tried this stuff and it is totally awesome!"? People are so easily mislead.? If you can be lead to believe that something is 'better' then to you it seems 'better' even when it isn't.

I'll put up some links to those sorts of sites later.

Meanwhile here is some interesting stuff:
This is the links page.? See the lefthand column on this guy's page as well:
? ? http://www.linkwitzlab.com/links.htm

Here is something on:

'Understanding Speaker Frequency Response'
'The Secret Behind The Industry's Most-Cited Spec.'

http://forum.ecoustics.com/bbs/messa...79/131062.html

[phangeaux]

It's hard to figure out where some of this stuff should be posted (which forums and topics) but I mentioned sites like this earlier so:

Five (5) Audio Myths Dispelled (several pages)
http://www.audioholics.com/news/edit...AudioMyths.php

More Audioholics Editorials
http://www.audioholics.com/news/index_editorials.php

[phangeaux]

This looks like a really good information resource to help figure out and understand alot of this stuff. I haven't had a chance to go over it yet but have bookmarked the site as a 'favorite'. Check it out:

Speakers page:

http://www.epanorama.net/links/audiospeakers.html

[phangeaux]

Here is ALOT of stuff that looks very interesting, just take your pick of articles.

http://sound.westhost.com/articles.htm



Here is a good page on impedence:

Understanding Impedence:

>>No home studio is immune from issues of impedance, yet the subject can seem very confusing. In this workshop we explain what the recording musician needs to know about impedance, and show you how to avoid lifeless guitar sounds, digital glitches, and fried amps!<<

http://www.soundonsound.com/sos/Jan0...ceworkshop.asp


Now for the rest of the night I am going to wire up my 4 ohm studio monitors in SERIES to get an 8 ohm load and then I am going to connect them to my home stereo receiver CD/DVD player so I can listen to some good sounding music for a change...
AND I will do some reading from these websites I have posted.

If you run out of stuff to read, let me know, LOL.

Just kidding, I'm sure you can find some.