Yamaha NS1000M - Tweaks

[drSM]

Slow and steady Ken
Look forward to yr final active set up.
Me, i am gonna try clean up the L pads on my NS - they sound pretty scratchy
Best
S

[Qwin]

Thanks Shahrin - At last, the final batch of discrete opamps are on route from Burson (SS Audio) in Australia.
This will allow me to populate all 10 opamp sockets with discrete modules on this latest balanced input build.
I have acquired a Pre amp with balanced outputs and have made up some leads, I also have the XLR sockets ready to fit into the back of the case.
Things are starting to come together.

My first test is to fit the existing (mkII) board with a full set of Burson modules, this is just to confirm that this is the best way forward. I have experienced with ordinary opamps, a situation where one or two of the same type sounded nice, but fit 3 or more and it didn't sound as good. I had to mix and match using various types and make the most of their individual talents, some are better at bass, or very transparent for mids etc. I found this to work better than fitting one type throughout, no matter what the spec or price of the opamp. Every filter section and the buffers improved when they had a discrete module fitted, but this was in isolation. Things might be different when fitted throughout, if I have to mix some opamps in their, then that's what I will do.

I've done as much prep. as I can, its back to the waiting game now and listening out for the Postman.

[Qwin]

Parts arrived from Burson, so no op amps at all on the boards now, all 10 are discrete modules. Based on the previous sets, they will take 50 hrs to run in, but even after 5 hours they are sounding much better than the op amps.

I will definitely be using this configuration on the balanced input build.

[drSM]

Thats a cool Yamaha box
Whats it sound like?

[Qwin]

Not sure what you mean Shahrin?

The case for the crossover is one I made/adapted, I put the Yamaha Logo on it if that's what you mean.

I've been doing extensive listening tests and have my final views on which op amp combination works best (for me) in this Yamaha application.
I will post my findings soon.

[337alant]

Looking good Ken
I don't see any voltage regulation though supplying the board's just a rectified and filtered supply, do they have onboard regs


Alan

[Qwin]

Hi Alan
No, no regulator, the supply was made and recommended by the maker of the x-over boards (KMTech) and I have also seen it written elsewhere that unregulated works fine with this circuit, which is basically the same, electrically, as Rod Elliott's (ESP) boards. The supply is off a pre amp design of KMTech's and is way over specified for the x-overs, as the pair of boards only draws < 150mA. It seems to work fine, but I have thought about building an alternative.

I'm keeping busy and currently making very early concept designs for an active "FAST" speaker, using a wide band 5" and a 12" sub/Woofer, in a sealed cabinet. I will be using the same crossover circuit in 2way form and using a regulated supply on that one. I've got one of the 5" drivers mounted in the cardboard box they were shipped in and it sounds pretty good, even in this crude set up. I'm well enough convinced to knock up some rough 7L sealed cabinets to give them a proper evaluation. I will start a thread for this if it becomes a viable project.

Bye the way, I caught a couple of your YouTube clips on the R2R's, very informative and well made

Cheers

[337alant]

Hi Ken,
Ah I see strange cant see why it wouldn't benefit from even a 317 / 337 reg supplying each board but I haven't worked with active Xovers before so maybe there is a good reason for it, or the op amps have enough PSRR ?.

Sounds like a great way to experiment with speakers though, Might have a go with them myself when I get though all the other things on the bench

Thanks re the Videos think I do some more when I get time

Alan

[Qwin]

Re; PSRR, the op amps seem very tolerant of voltage variations so regulation is not specified for this application, for the very small additional cost I will be using it in future though. I have a few of these lying around, £5.64 including postage, I change the Chinese caps for some basic Panasonic FC's.



Yeh, active gives you a lot of scope for experimenting.
Because you use separate amp channels for each driver, mixing 4ohm and 8ohm drivers is not a problem, as each amp just sees a single load. If the drivers have different sensitivities, just turn the amp up driving the inefficient one to match. You can also use a muscle amp for the woofers and a lower powered high quality amp for the mids and tweeters. These are the things that sucked me into going active. With passive circuits you quite often have a situation where you address one problem and create one elsewhere due to it all interacting, so you really have to know what your doing. I think active is much more DIY tweak-able, as you can tackle a problem on one individual driver without effecting anything else. Slight over simplification there, as you still have to watch out for phasing issues etc but there are far fewer variables to deal with as a whole.

For complete flexibility DSP is a great tool, and allows easy insertion of filters to flatten the response, or for room correction, but I still shy away from putting my analogue sources through an ADC then back through a DAC in a DSP. I would probably develop using DSP then transfer the knowledge to an analogue circuit. So much easier that way, you can move the x-over point live and listen for the changes using DSP, for my analogue boards that would involve changing 80% of the components every time I changed the frequency.

If you get the time Alan have a go, I started by getting some ready made boards from KMTech, I specified the stock x-over frequencies for the Yamahas and straight out of the box, regardless of their fairly cheap components, they outperformed the stock passive circuit for clarity, detail and dynamics. The bass really improves having a dedicated amp channel per driver. I don't think I'd ever go back to passive on a speaker project.

[Qwin]

Well I've lived with the active crossover for many months now and tried all kinds of variations to the components. Preferences are very much a case of individual taste so YMMV but here are my findings, which only apply to this application.

Capacitor Choice.
With this KMTech circuit, I tried the stock supplied Polyester caps which are 5% tolerance.
LCR Polystyrene caps rated at 1% tolerance.
Vishay MKP 1837 (PP) rated at 1%.

The Polyester aren't bad at all, reasonably transparent, a bit edgy with the treble, still a big improvement over the passive circuit.

The Polystyrene are slightly more transparent, have a smoother top end and a much better defined bass, both in richness and depth, dynamics are also improved.

The PP are the most transparent of the three, detail is also a step up from the others. Bass has a level of detail and texture the others can't match, overall a richer mix tonally and lovely handling of vocals, easily my favourite and half the price of the Polystyrenes.

Resistors
I tried the stock items, some PRP 9372 and Takman, all were 1% metal Film.
If there was a difference it was very very subtle. They are all good quality parts of a similar type so differences would be small anyway, too small for me to pick up on.

Op Amps
I tried a full complement of the Burson discrete units, this initially impressed with the transparency, but gradually I grew less enamoured by it. It was all a bit too HiFi and lost some of the dirt, grime and rough edge character that brings things to life. I found better results by mixing and matching, this applied to other op amps as well, a full compliment of five, of any one type, never sounded quite right. The area where the Burson shone best was in the buffer stage, the neutrality and transparency having a knock on effect to all the downstream filter stages, LM4562 ran a close second. For the low pass Bass, AD825 was by far the best of the bunch I tried, great detail and slam in the upper bass and goes deep, Burson units were my second choice here being a touch polite by comparison. AD8066 works very well for the high pass on the tweeter, great tone and clarity which carries over into the upper mids. For the mid range band pass, it really does come down to personal preference, for me LM4562 worked well in both locations (Highpass/Lowpass) and sits so well dovetailed to the AD825 for added slam which can literally make you jump. The Burson worked in the lowpass part of the bandpass marrying well to the treble. The LM49720 (metal can) also worked well in this location and I still have it in there.
To sum up, use no more than three of the Burson units in the five locations, but make sure one of those is the buffer. It's all good after that but starts to get subtle in the changes and depends very much on your voicing preferences. I won't be moving the AD825 from its bass duties for instance, but that's just me.

I probably have the Yamaha's as good as they can be sonically, from my point of view, with my preferences.

I've had great fun experimenting with this circuit and learned a lot in the process, that will carry over to other projects. I can really recommend it, for anyone wanting to try a simple analogue active solution.

I just adapted a pair of my old boards to 2-way, crossing at 310Hz and have a pair of two way bookshelf speakers acting for mid/tweeter with their passive circuit still in use and the Yamaha 12" bass drivers connected for bottom end duties below the 310Hz. I've had this lash up running for almost a week and have had no desire to change it. It sounds so right that it has me thinking of a new project combining active/passive and reducing the number of amplifiers required.