As far back as I can remember I was always told to maintain the purest signal path for listening to stereo music, using 'Pure Direct' or bypassing any tone controls so was surprised when looking at the Classé CP-800 digital stereo pre-amp which includes what looks like a fairly comprehensive PEQ setup.

http://www.classeaudio.com/delta/delta-cp800.htm

Does anyone here have experience of using any sort of PEQ with a stereo setup and have a view on:

a) is it necessary?
b) does it make any difference?
c) what is the best way to determine what settings to make?

Phil

EQ is a funny one.

For decades, we've done without it, and everything has sounded great. AV receivers start using it (and not particularly well up until recently) and now some people won't listen to anything without it! I'm in two minds with it. On one hand, it helps reduce room modes where bass is exaggerated and this clouds detail, so reducing those bass peaks helps you hear what they're masking. On the other hand, we want to pass the signal from source to speakers without changing it, but EQ processes the signal, therefore changing it. The last few years has seen this processing move to the digital domain, within which it is theoretically impossible to degrade the signal - there's a can of worms waiting to be opened

It definitely makes a difference, good or bad is subjective (and I suppose to some extent, objective). Personally, for 2-channel audio, I'd rather leave be, but if the room is causing some major issues, I would like to address that. PEQ can help that, but you need some way of knowing what your room is doing to the signal. This isn't an area that I've had much experience in for 2-channel, only home cinema, but I know that with my intended speakers, I may well need some sort of control over the bass to cover any issues I may have. I'll be crossing that road when I come to it.

Ultimately, it really comes down to how much your room is affecting the signal, so getting hold of something to measure the signal is the first step. I'm sure BlueFalcon will be along shortly, as I know he's been looking into room EQ units for a while.

I've recently been looking in to measuring my system, so may be able to help a little, but my aim is to try and get the best out of the Audyssey Pro calibration of XT32 - so quite different. I'm not familiar with Classe or the PEQ in the CP-800. I'm guessing that it just includes an onboard PEQ, but no way of measuring what is going on, right?

The first thing you need to do is measure what you are hearing, so you know what changes to make. You can obviously do it by ear, but anything you do will be to your preference - which is fine if you are only interested in trying to make it sound how you want it to. It's not cheap to measure accurately, so unless you want to spend about £200, you may as well give up now.

If you are still here, then you will need to purchase a Mic and Pre-Amp to be used with a Computer - preferably Windows based as I've seen a lot of people having problems when trying to use a Mac. There are many options, but the most popular choice of Mic is a calibrated 'Behringer ECM8000' or 'Dayton EMM-6'. You then need a box that will power the Mic and convert the signal to a USB output, for use with a Computer. An 'Art USB Dual Pre' is probably the cheapest decent option, but the most popular tends to be a 'Tascam US-122 MkII'. For software it is best to use REW, which is free. It can take some time to get to grips with it, but it is very popular and there are a lot of people out there than will help out if you have problems or questions etc.

Either Mic can be ordered from Cross-Spectrum Labs, choose between the Basic+ and Premium+

http://www.cross-spectrum.com/measureme ... inger.html
http://www.cross-spectrum.com/measureme ... ayton.html

The prices of the Pre-Amps are roughly £80 for the Art and £110 for the Tascam, but prices fluctuate.

Another option is Omni-Mic, which I don't know that much about, but some people have tried it and got good results with it. It's a bit more expensive (about £280 I think) and it comes with everything you need to get started, even software which is apparently fairly easy to use - but not as in-depth as REW. The main problem with this option is that I don't think it is very well supported (from comments I've seen on AVSF) so you may not be able to get the answers you need if you are stuck and need help.

Yup, just PEQ, no measuring.

I guess that if you're using the digital inputs rather than analogue there may be more of an argument for using EQ as you're not dealing with a pure analogue signal and have to process it through through the DAC anyway.

That's more than a little help, thanks very much.

I've got a Behringer ECM800 mic with my Velodyne SMS-1 so that's a bit of cost saved but I am worried about how complicated REW looks in terms of interpretting the output.

The other solution I've been looking at for measurement is the XTZ room analyzer II pro at €260 which is a whole kit in a box. Don't know how this compares?

http://www.xtz.se/uk/products/measurement-system/room-analyzer-ii-pro

I guess all of this is hypothetical if leave the PEQ switched off and that's part of the dilemma in the first place

More new speakers. Tell more

Well, the speakers are already here, it's just where I intend to use them

Do you have a calibration file to use with it though? As it's useless without one.


Yes, I forgot about that one - but again, it's not as commonly used, in depth, or well supported as REW.

no I don't as you don't get a calibration file with the sms-1

If you measure your room you Will find issues, some or possibly all of them you did not know you had, I did this just out of curiosity a few years ago and from that point on the issues in 2 channel music playback bugged me, system and room has significantly changed since but I think knowing spoiled my experience o the music so unless you know you have an issue you think you can fix it may be better not knowing.

Just my thoughts

That is my dilemma right now. I have an idea of what is going on in my room with the equipment I have at the moment, but I don't believe it is accurate enough. So I looked in to what I would need to get a better idea and I've decided what to buy (as discussed above). But I'm wondering if it's best not to know and just enjoy what I'm hearing - as I am pretty happy at the moment.

I'm putting the idea on hold for a while, for a couple of reasons.

That's a bit like saying you'll enjoy eating Iceland burgers because you've never tasted 28 day Aberdeen Angus or Asda chardonnay is acceptable if you've never drunk Montrachet

A little bit yes, but I'm really happy with what Pro XT32 is doing in my room.

But you only know the difference because you have sampled (presumably) those 'extremes'. If the Aberdden Angus never existed, the Iceland burgers would be the best burger you've ever tasted and you'd be quite happy. Well, sort of

I was more getting at the concept that what is mesureable is not necessarily perceivable or even bad for that matter, the mere fact though thet you you know about it is there may spoil your enjoyment.

The real dilemma for anyone who enjoys hifi is knowing when to stop 'upgrading'