DIY studio monitor

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I visited a friend who studies sound engineering (going into live sound) and met a friend of his who's starting out a recording studio. When he heard that I build speakers as a hobby, he asked me whether I'd be able to build him anything for his studio, because of the great cost involved with purchasing Monitors and the fact that the exchange rate (R12 to the US$ and getting worse) would kill him for what he deemed sufficient. I am not familiar with the requirements in a recording environment and don't know what exactly one needs in a monitor, except that they usually have plenty of headroom.

I was thinking of an active system of sorts with quality drivers. Seas and Vifa (Scan-Speak perhaps) drivers can be readily sourced within South Africa, so drivers from those three manufacturers would be preferred.

I am not sure what s/n one needs for such applications and whether or not amplifiers like ESP 3a and ESP or Marchand active x/o kits would be up to the task. Fortunately he's got 1/3rd octave eq at hand (and thank goodness for gated fr measurements) but that doesn't solve everything.

He will be recording mainly jazz and music with a vocal emphasis and I suppose neutrality would be of the absolute essence. Distortion would also have to be minimal and I'm not on sure footing in designing such a system. My current thoughts were a 3-way as per Rod-Elliot (time aligned either physically or electronically a la Linkwitz Phoenix) with the drivers in separate boxes or an infinite baffle (M-H units' baffle extended by the padded wall)for the M-H and the bass unit in a seperate box all together.

Any thoughts on the matter would be really appreciated.

Martin Goedeke
Dear Martin Goedeke,

I work a lot with "pro" systems in different studios. Compared to "Hifi" it is a kind of different issue: Studio monitors, albeit constructed in the same way than all good loudspeakers, are more a working tool than a matter of "mere" pleasure. Here one will need a maximum linearity, detail and neutrality, more than livelyness and ease for example.

In a "real world" sound studio, which is frequented by different people, DIY monitors are a complete no-no, because here you need known reference loudspeaker system(Genelec or even Yamaha speakers, Bryston and Quad amps, etc.), if you like them or not.

In a special mastering studio or a private spot, where more personal preferences are important, you have a broader choice.
Your suggested path seems then very resonable to me. Three way systems are a difficult task to set up, but when the work is done, they can reveal you with a very open and listenable (also loud) sound. It must sound good for itself, even without a room equalizer.

But it won't come cheap anyway. I would agree on that:
Big woofer in a sealed cabinet, cone midrange in a seperate sealed cabinet, tweeter the same, all speakers from ScanSpeak if possible. All three (plywood) boxes are mounted in a very rigid open steel frame, where you can arrange them manually. All speakers are individually powered - Rod Elliot's amps and xover seem quite reasonable, you can later change the mid and high amps for smaller class A amps if you like them better. Use a simple wiring scheme for the whole studio, all lines balanced, seperate mains etc.
And use a very good mixing desk and the best microphones you can get, but that is evident anyway.

Good luck

ps: Here in my smaller studio I use four Soundcraft Spirit Absolute Zero with DIY AB-amps at the moment. They have been so cheap, that I could not build them myself for that amount. But they are very directional, which is good for work but not always for me...

To design and develop a studio monitor quality speaker is not a trivial task. Audiophile speakers can get away with all sorts of colourations if they happen to be ones the listener likes and finds pleasing. However the purpose of a monitor is to be a tool, and to expressly minimise colouration and distortion, so it can be used as a magnifying glass, to highlight faults in the recording process. However, how loud do you want it to go, what size control room, acoustics/treatment, near/far field listening position, bass cutoff, stand/soffit mounting etc are all answers that would be needed to help in more detail.

I have 3 1/2 suggestions.
1- look at all the recording, studio and proaudio sites and look at what people are using, especially GOOD engineers (Steve Albini for eg). See if you can find something second hand cheap, as studios go out of business all the time.

2- Find some Tannoy Red/Gold Alnicos in 10/12/15" (bigger=better) and build correctly sized and aligned cabinets and with tweaked crossovers they can sound awesome. More details available if you choose this route. Tannoys were the monitors of choice in studios foe about 25 years and their controlled dispersion pattern can help with placement and minimising room acoustics problems. Can often be found for reasonable $$$ second hand.

3- Ariel or ME2 speakers by Lynn Olsen at as the drivers are Scan and Vifa, reasonably priced and of known high performance, especially with classical, jazz, acoustic etc. The design is free, and they are complex in construction, but not that difficult. Depending on the control room layou, they might not be practical.

3 1/2- whatever monitors you get, also find some high quality headphone and a GOOD driver for them. STAX electros would be best, with various Sennheisers, AKGs, Beyers and Grados next. Many good DIY driver designs can be found at in the library/projects area. I like Kevin Gilmore's designs especially.
Good cans will allow you to hear the inner detail that budget speakers cannot reproduce (also removes room effects), and listening in combination with the speakers may produce the best hybrid monitoring system possible.

Amps can be worried about later, as the speaker will have a much larger impact on performance. Once you get the monitors in, tweak them for max performance, and then get the engineer to just listen to them, especially with known high quality recordings. Once the systems limitations are known, it's possible to listen 'around' them to some extent. Many veteran engineers will take their own nearfield monitors with them to an unfamiliar studio so they have something of known performance/faults to work with.

This is a huge subject, and my post only a tiny start. Ask more specific questions and I will try to answer further. I'm sure there are some other knowledgable people here too who will also help. I wish I could give you some simple/easy answers.
Thank your for all the input. I have always liked the idea of a system time-aligned physically, because one could adjust for listening position by adjusting the different units. I thought about using the ME2 or Ariel, but I quite like the idea of active systems. As far as drivers are concerned, I will try and see whether I can get hold of SC tweeters locally. I thought about putting the midrange driver in an over damped terminated transmission like (labyrinth) to even out the phase response around the crossover frequency to the woofer. The control room will probably be rather big (a good guess would be at least 40 square m), but I won’t have exact details until I see this guy again next weekend.

Seeing that absolute neutrality and linearity are of the essence, I have looked around and found that the European DIY press (esp. Klang & Ton) publish distortion measurements along with the FR of drivers . I have still to look at the SC range, but the 13cm Vifa mid in the Ariel looks promising. Interestingly enough, Monacor makes a 10cm mid (SPH-115 methinks) with very promising numbers and extreme bandwidth (something like <200 Hz to 12 kHz +- 2dB) and astoundingly < 40 Euro. K&T gave them very good reviews as well. Other candidates include Seas 4” Magnesium unit (I don’t like impact of the needed resonance suppression filters on the phase response, perhaps with a Marchand 48dB/oct LR)

I am not sure what to use for the woofer. You seem to be fond of sealed enclosures, but at elevated levels, the distortion of ported enclosures is less (but group delay, impulse response, etc…). I even thought about a bass horn (ala LAB Horn), now THAT would rock… (but in a studio?)

I read up on the Headphones, and I finally found some more good information on electrostatic headphones (my next DIY project if time allows). It seems like this might be a good way of getting accurate sound cheaply, but I don’t quite know whether this guy will take to the idea. I think sofit mounting will be the most suitable, an eliminate baffle edge diffraction which isn’t that easy to compensate for correctly in a DIY effort.

Looking forward to any feedback

I actually joined this forum 'cause I was working on this exact problem. I myself am an audio engineer, and have a modest home setup, but crap monitors (edirols), and only slightly better 'phones (AKG 220m). I haven't really found anything good yet, but I can give you some basic specs that I'm looking for in a jack of all trades nearfield.

Freq. Response 40Hz-30+ kHz. Lower would be welcome and if it gets up closer to 50 kHz that'd be great, but this is a good baseline. The reason the response range is so great, is that that is what the mics record, and when you're mixing, anything you don't here can be a problem.

maximum SPL of 110-120dB.

As well as these comments the following are some basic features of the Alesis M1 active monitors that are incredibly common as a basic entry priced speaker, at about $500 u.s.

Low Frequency Driver: 6.5" non-woven carbon fiber with Santoprene surround and dual magnet shielded configuration

High Frequency Driver: 1" silk dome with medium viscosity ferrofluid coolant and dual magnet shielded configuration

Crossover: 1500Hz, 8th-order, 48dB/octave filters

Input Impedance: 20k_ balanced, 10k_ unbalanced

Frequency Range: 38 Hz - 23.5 kHz (-10dB point)

Connectors: Combination XLR-1/4" jack with input level control

I hope this is of some help, and I'd really like to hear how things work out for you.

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