Wondering if the Decca Tree is over-hyped a bit?

[SoundOutWest]

Hi all, I'm a bit of a beginner to orchestral recording but have worked plenty with soloists, small ensembles and post-production.

I think anybody who steps into this space almost immediately gets sold on the decca tree setup and I know that was certainly the case for me.

The thing is, the more I read, the more I realise that the decca tree is a bit overblown in its utility. "The Microphone Book" by John Eargle for example cites ORTF + Omni as the default for large ensemble and briefly mentions decca trees as a rather unwieldy alternative. I admit I've always been a bit of a Decca fan boy but much of what I've read since has taught me that far less is needed to mic an orchestra. To sum up my findings:

- The idea of using cardioids as the main array is not that crazy. The decca tree itself *is* a directional array as it only really works on mics with HF directionality.

- The benefit of using omni mics for the orchestra's central array are questionable. LF response is usually the main reason but very little LF actually comes from here.

- The "hole in the middle" really only kicks in somewhere above 0.67-0.7m for spaced omni pairs. A spacing narrower than this will still give you plenty of width, provided you have outriggers.

- I can find *very* few live performances where a decca tree is used. Even when slung overhead, ORTF or an "OCCO" array is still more common (and safer). The safety and rigging concerns of mounting a decca cannot be emphasised enough.

Anyway, I submitting this here so you guys can check my homework but also because it seems that I get better info on orchestra techniques when I talk to people as opposed to read the headlines or read textbooks alone. Would you argue there's a case when you *really* would prefer a decca tree?

[Bob Bickerton]

I have mainly used ORTF with omni outriggers plus spot mics as required for orchestras, but like you, I'm curious to hear if there are particular circumstances where a Decca Tree is preferable.

Of course some orchestral recordings are highly complicated, and require a similar degree of complex application (knowledge) to achieve success. I've never felt I had the capability or the need to take that approach.

Bob

[SoundOutWest]

One case where I think ORTF + Outriggers may not be satisfactory is symphonic wind bands. Mainly because - unlike nearly every other ensemble - a large fraction of LF comes from the middle of the ensemble. Even then, I think the overall effect is small. Those LF waves will diffract and reflect around until they reach the outriggers.

[Bob Bickerton]

Whilst I have used wider spaced outriggers, I quite like to use omni mics mounted around 600mm spacing on the same bar as the ORTF pair - perhaps the use of outriggers was inaccurate. This configuration I believe was one of Tony Faulkner's ideas.

Keeping a simple approach, I'm relying on the conductor to balance, but having the omnis available enables me to 'open' the space in post.

Bob

[ajay_m]

When I was a teenager back in the early 70s my father subscribed to the World Record Club. Some of the classical orchestral recordings they produced were outstanding and I imagine there is documentation on how those sessions were mic'd up. Philips also produced some exceptional orchestral recordings around that time with a beautiful string tone. Back then you had to get things right first time with limited dynamic range to tape and further limitations mastering to vinyl so the techniques then ought to be optimal you would think, given that mic technology hasn't really moved forward since then.

[Hugh Robjohns]

The thing is, the more I read, the more I realise that the decca tree is a bit overblown in its utility.

It's just one (commonly misunderstood) technique amongst myriad others, with its own set of advantages and disadvantages.

But it has been used extensively for large orchestral recordings for over 75 years, and was widely adopted by Decca's competitors basically because it works well (in appropriate situations) to deliver a particular quality of stereo which many like.

If you know what you're doing it really can work very well, but it can also be a nightmare in my experience and it's not a technique I'd recommend for the novice.

Plus, the real Decca technique employs a minimum 6-mic spaced array, not just the central 3-mic cluster most people know about!

"The Microphone Book" by John Eargle for example cites ORTF + Omni as the default for large ensemble...

Perhaps he means it's *his* default! Every situation is different... every engineer has their own preferences. And there are different 'regional' norms too.

The idea of using cardioids as the main array is not that crazy. The decca tree itself *is* a directional array as it only really works on mics with HF directionality.

I have used a cardioid tree array, and I've seen it used by others a few times. It can be a useful alternative in some situations... but it sounds very different to an omni tree.

The benefit of using omni mics for the orchestra's central array are questionable. LF response is usually the main reason but very little LF actually comes from here.

It's not the bass extension that matters to me; it's the omni mic's absence of LF phase shifts (compared to cardioids) which is far more important and why they sound much more natural to my ears.

I can find *very* few live performances where a decca tree is used.

It's an unwieldy rig for one-off live gig. However, the BBC Proms season usually has a tree (or two!) in the static rig for the full duration....

The safety and rigging concerns of mounting a decca cannot be emphasised enough.

This is certainly true, and I've seen some really scary amateur attempts ! But the required safety principles apply to all other mic arrays too, and doubly so for large immersive mic rigs!

Anyway, I submitting this here so you guys can check my homework...

It reads more like you're looking for external justification for not using a Decca Tree arrangement.... but no justification is needed.

If you can get the sound your clients like with a simpler mic system, that's a win. End of conversation. If you can't get a sound the client likes you have more learning to do...

Would you argue there's a case when you *really* would prefer a decca tree?

I do know several professional orchestral (classical and soundtrack) engineers who would always rig a tree.... and a lot more besides....

[Wonks]

And there is a practical difference between recording an orchestra alone, where setting up a Decca tree doesn't inconvenience anyone, and recording an orchestra's performance to an audience, where minimal obstruction is the order of the day.

And as the Red Bladder constantly tells us, for big classical orchestral recordings these days you'll be setting up a lot of spot mics as well, for solos as well as filling a any sonic holes from the main mic array(s).

[ghellquist]

In my experience, there are several factors here. Budget is definitely one of them.

For simply documenting a community orchestra: go simple and easy. One suggestion is Schoeps MSTC64 (this is the very definition of ORTF) and a Zoom F3 on lithium batteries (runs about 4 hours). Place in the audience space, remember that leftmost to rightmost player should be within 100 degrees as seen by the microphone. Decently high stand to let the mic see all players. Takes next to no time to setup and always gives a workable result in my experience. Quite influenced by the room acoustics.

For Decca tree you are talking a totally different setup time and a lot more equipment. The Decca tree will give a quite dry sound with the players closest to the tree in focus. You need to add at least two outriggers (perhaps omni) and spot mics. It can end up a 100 channels if you do it the Deutsche Gramophone way. Might as well setup an ORTF while your running it. Be wary that some of the violins might be worth more that your full rig, so do a SAFE RIGGING.

So to answer the question in the head: "is the Decca tree over-hyped?". Yes of course. It is one of several tools, and as any good handyman knows: use the right tool for the right job.

[timcmit]

I like it, and it is capable, even in my very amateurish hands, of producing a unique and wonderful sound (against which other arrays can perhaps sound a little bland).

However, it is a sound that you are unlikely to get as a member of an audience, and in my (admittedly limited) experience it does show up orchestras and bands where there is a range of abilities from front to rear desks. AB or ORTF (or combination) allows all sounds to mix more and front desks tend to prevail. With the Decca tree, I tend to find I’m sitting there appreciating the complexities of the sound, whereas musical groups just want what makes them sound better (can’t really disagree with them).

So with a good orchestra and time to set up, I would always like to try the Decca tree, but in many live situations, with more amateur groups, other pairings or combinations might be a wiser choice.