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Help! How do I turn up bass on Naxo 3-6?

PeteM

PeteM

Supreme being
The title says it all.

I have a Naxo 3-6 which produces less bass than our TV soundbar!

I realise I can adjust LF, MF and HF output separately by turning the preset pots on the PC board (photos below). Thoughtfully Naim have labelled them LF1, LF2 etc so I know which ones to tweak. Presumably they are in pairs for a six-pack setup (mine's tri-amp), so I just turn both LF pots equally? Which directions give more/less output? I might be answering my own questions here, but I'd like to be sure before I fiddle. The outputs have been altered by Witch Hat to give a vertical amp arrangement, presumably this makes no difference to the task in hand. It'll all be done with the Naxo un-powered out of the system of course.

Any advice gratefully received!

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The LFs are the ones you want, indeed. Mark the directions of the pots with a pencil before you tweak - I can't remember if they're clockwise or anti-clockwise, sorry. But at least the pencil marks will get you back to where you started. Do them both equally.
 
I thought they were 'tap-like'...turning them clockwise shuts the 'tap' off and reduces the output.
But seriously...if your speakers are producing less bass than a soundbar then there is something seriously amiss. For instance if you are using SBL/DBL then the sealing gasket may be blown, or the interface between speaker and floor is sub-optimal. Only resort to the SNAXO trimpots when every thing else is just right. Trying to correct for a huge bass suckout (like I once had) due to an air gap in the suspended flooring by cranking up the bass gain will only make things worse. The first thing I would try would be seating your speaker (and I am not sure what they are) spike on cross headed machine bolts, Naim Chips, granite slabs, Mana or Sonority bases. And then and only then think about changing system gain.
 
No chance the bass units are out of phase is there? I've been impressed how well LF drivers can cancel each other out when one has its wires crossed.
 
Hi, there is no need to disconnect the naxo while adjusting the levels, I see from you pic that there is alot of difference between the positions for the hf and the mid /bass . I would turn up the mid/bass sections (usually anti clockwise) so that they are about 5degrees less than the hf section(hf at the rear ,mid in the centre,bass at the front of the case) and have a listen for a while.
 
There are some good points here.

The speakers are a newly built pair of Pro-9 TL's (Chris Rogers, Practical HiFi & Audio, circa 1976!). Only one is finished, so it can't be the out-of-phase suggestion, and I also ran the speaker passively with its (external) crossover connected and it's fine, so the speaker itself is OK. So it has to be down to the Naxo settings. I'll have a go as suggested, it isn't as daunting as I had expected.

Thank you all!
 
Well, the SNAXOs are NOT universal active cross overs and it may well be that the x/o point for your TL speakers (as well as the order/phase) is very different from the Linn/Naim speakers that the Snaxo were designed to mate with. If this is the case, then no amount of trim-pot tweaking will ever result in a satisfactory sound. You probably would be better off with an active x/o that allows customization of band-pass points.

For instance...http://www.bryston.com/products/other/10B-STD.html
 
My suggested approach:
(1) eliminate any possible power amp issues with the setup by switching two of them around (e.g. bass and mid swap). If the bass problem persists, then it's very likely the NAXO.

(2) To adjust the NAXO, you must have the whole system powered up with the top off the NAXO. Your objective is to have at least one pair of the adjustment pots to be at maximum rotation. This will effectively take that pot out of the circuit and give you the best sound quality.
(3) Mark the original pot positions if it makes you more comfortable, but it's really not necessary.
(4) Turn both woofer pots all the way up (not sure which direction but you'll know immediately as you start to turn) and the other 4 pots all the way down (after marking the original positions). Make sure the signal is coming through on both woofers OK. Try using a monophonic signal if you can.
(4) Turn up the mids slowly until the sound is balanced. Remember, there is no test instrument as sensitive as your own ears. If you can't get the mids loud enough even at max, then leave them on max and turn down the woofers a bit to get the balance. This can be caused by either driver efficiency differences or power amp gain differences. Nothing to be concerned about.
(5) Now turn up the tweeters until the sound is balanced. In the highly unlikely event that you can't get enough tweeter sound, then put those on maximum and turn down the mids and woofers to match. From the looks of the original settings, the tweeters were probably turned down from max a bit. This is typical since most tweeters are more efficient than most woofers.
(6) listen to a few favorite cuts to make sure the adjustment is good, then close up the NAXO cover.

One last thought is that Linn used to recommend that the midrange speakers on their Isobariks (which I have) should be wired OUT-OF-PHASE with the woofers and tweeters. I ran my Iso's that way for years until my friend suggest I put them back to IN-PHASE. Guess what, we both like the IN-PHASE presentation much better - better central image. No bass issues either way, though.

There is no magic here so don't be afraid to do the adjustment yourself. You can't break anything. Remember what Duke Ellington said: "if it sounds good, it IS good".
 
My Naxo is set up for Linn Isobariks, so the crossover points will be set at 375 Hz and 3 kHz with a slope of 18 dB/octave. The Pro-9 TL's require 460 Hz, 3.4 kHz and 18 dB/octave. That's close but not identical, but reading Chris Rogers' reasoning for choosing these freqs suggests they are by no means cast in stone. For instance, the mid driver (Peerless Ko4o) is curtailed at 3.4 kHz because "its polar distribution starts to fall off at 4 kHz". Hence curtailing it a bit earlier shouldn't be too much of a problem, I guess. Anyway, we'll see!

The saving grace in all of this is that, around 15 years, ago I converted my first and very elderly pair of PRO-9 TL's to active operation, with an Olive Snaxo, and it produced the best-sounding system I've ever owned. Those speakers were later binned (house move, less space!) but that's why I've built another pair. So I've every confidence it's just a matter of tweaking those Naxo pots. Wet-wipe ready for removing egg from face!

And thank you RyanSoundLab, that's a brilliant guide to setting up the Naxo, which I shall follow carefully.
 
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