Saburo / Fostex FE126En: initial verdict

[CastleJohn]

They took up a whole load of time, space and effort to make them, so what do I think of my Saburos now they're installed in my living room? Well, some and some. I believe the cabinets are doing their intended job very nicely. Only low end sounds emerge from the horn mouths, just as intended. The sensitivity is high, the dynamic range vastly expanded over my Audio Note type Ks, and there is a much deeper and more accurate level of detail coming through. Best though is a lovely low-end response which recreates almost tangibly the ambience of recording venues. Well done Scott, I'm impressed. Now the downside: the top end, coming straight from the Fostex drivers. Frankly, as it stands, the sound is untenable in the long term. There are some very obvious resonances in the treble, as well as a general mid-treble emphasis which leaves my ears feeling stressed after listening. And very occasionally, some notes set off a kind of fly-in-a-bottle sound on heavy bowing of upper cello strings. I don't think there actually is anything loose inside, although they do make good fly traps.

Any comments on the following ideas, or any others, would be most welcome.

1. I did make one error in construction. I forgot to bevel the inside edges of the round driver holes. To alleviate any problems from this, I stuck thin sticky felt all around the hole sides. Do you think there is any value in going back a step and reworking the holes now? Goodness knows how I'd do it, what with everything glued rock solid and sticky felt all over the compression chamber.

2. I mounted the driver using only the foam washer supplied. No putty or anything. Is that OK?

3. Are Planet 10's modified Fostex drivers worth the money?

4. Might some kind of simple cone treatment improve things? I thought paper cones were renowned for sibilance.

5. Are there better drivers I could use?

All said, I'm probably a convert to the clear, larger-than-life sound of these speakers, if only I can get these niggles sorted out. All ideas most welcome. My equipment, for anyone interested, comprises Roksan Kandy K2 CD, Benchmark DAC1, John Linsley Hood 5W Class A transistor amp (with gain reduced to 4), unidentified silver-coated micro-strand.

[tubesurf]

Congradulations on completing the build. How many hours on the drivers?

[talaerts]

I think that for the mid-treble emphasis you should try a filter. I know, full range purists usually hate the idea, but if it delivers more music...

(edit after reading about the system)
I would put the filter between DAC and amp (can I assume that the DAC has an adjustable output volume?), otherwise it will "consume" a non-negligeable part of your 5 Watt power output.

[CastleJohn]

Probably about 30-40 hours on the drivers so far.

I did wonder about this, talaerts, but what sort of filter to use, and how to go about getting it just right? Would I need to do some sort of frequency analysis of the system? Yes, the DAC has an analogue volume control built in, so I could in theory do this. I'd rather it be a last resort though. I had also wondered whether a digital parametric equaliser between the CD and DAC would do the job, but at what cost to sonic purity?

[Scottmoose]

Stuck away from home at present, but briefly

1/ Yes, probably. Just pull the drivers & take a rasp to it, then get the old hoover to extract the dust.

2/ Should be. The Fostex gaskets aren't great, but they're OK.

3/ Given your requirements, IMO yes, because they aim to address the issues you mention in the upper mids / lower HF. Some people who don't mind the breakup / peaking etc. prefer the units raw. Case of name your poison.

4/ It's a matter of design rather than material. You could try doping your existing units, but this is a bit of a sledgehammer approach; you're better off addressing the specific breakups etc.

5/ No. The cabinet was designed for the FE126E. As it happens, I've done a revised version for the new En -it just hasn't been drawn yet. The site needs some fairly major updates, it's a case of finding the time.

[planet10]

Get the driver holes rasped out, early reflections cause some "hollow" resonances and further push forward the tendency of the Fostex to be forward.

Get some hours on them. At least a hundres. 2 or 3 times that before you make final evaluation.

Some pretty major changes can be made with subtle changes in damping (but get some hours on them)

dave

[rjbond3rd]

Absolutely get out your rasp. But while you're at it, a very fine point: don't over-torque the screws. Lightly torque them just so much as to squeeze the foam ring. It's extremely subtle but free so why not?

Of course that doesn't address the treble issue. Break-in will calm them down but the peaks are still there (just maybe not as ear-stabby). So even before break-in:

1. Try increasing the degrees off-axis in increments of 5 degrees. Use masking tape on the floor to mark the 5 degree increments and test a whole bunch of positions.
2. Try a little square of felt to shave off .25db or whatever off the treble.
3. Sit a little further back.
4. Stick a cheap tweaker on the back of the cab to bring back an ambient (non-beaming) sparkle).
5. Use just a tad of a filter with a bypass cap (so you're shelving down the upper mids but not the treble). Trial and error will get it just right for your room, listening position and system (time-consuming but fun and fairly cheap).

And if possible, just measure the response. If you were to use a computer as a source, you'd get "free" EQ. Ultimately, it's an incredible way to wring the maximum performance out of fullrangers (unless you're a vinyl nut, there's really no reason not to do it).

Bob Brines is the king of computer EQ and I've been lucky to hear the stunning results. Night and day. (He also does room EQ and a slight BBC dip -- tasty!). It's just the best a fullranger can do. He doesn't just apply one shelf like a BSC -- he does several things and the mix of everything is fantastic. Even though I have a similar setup, I haven't quite got the results he gets because it takes skill and time but I'm slowly getting there.

Lastly, if that's not to your cup of tea, a friend of mine has accomplished much the same thing by swapping out this or that component / tube / cable (because he -can-) but that's all art (not science), it's -vastly- more expensive and time-consuming than just biting the bullet and using a computer-based source with whatever outboard DAC (or hell, just use the line-outs if you're on a budget).

In the end, you're stuck with the room so don't neglect the idea of a rear-firing tweeter. That way, you can really get the on-axis behavior correct while still having lots of ambient shimmer on the cymbals and the harmonics of percussive attacks. Hang in there, you're about half-way there.

[talaerts]

I had also wondered whether a digital parametric equaliser between the CD and DAC would do the job, but at what cost to sonic purity?

This may well be an interesting option. I once used an older Behringer Digital EQ on my coaxial speakers and yes indeed they did sound a bit more "right". However, I had a slight preference for the un-eq'd sound.
I think it is worth investigating, and such a device can be reused for other speakers. I recommend you to check out this Behringer together with their measurement microphone. The price is ok, and you can slot it in between CD and DAC, purely in the digital domain.

[Bob Brines]

Here's the deal of computer EQ: Blue-Ray has been a godsend to computer audio. Most desktop computers and some laptops have 5.1 output. They are required to handle 24bit 192kHz sound tracks. So, the current generation of computer DAC's are vastly superior to the crappy sound cards of just a few years ago. You will have difficulty telling the difference between these a kilobuck stand alone DAC's.

So. You can do all kinds of magic to an audio file and keep it in the digital domain. This is what I do. All of my CD's have been ripped to a hard drive, along with HD downloads up to 24/96. I have a 31-band equalizer plug-in for my music player. If you choose, you can use a parametric EQ. There are plenty of options in the Windows world and more (better?) options for MAC.

Step 1 is to do an RTA at the listening position. Step 2 is to create an inverse image of the RTA on your equalizer. That gives you a flat in-room response. Step 3 is to tune the EQ for your personal taste. No magic here.

For tube types, feeding the DAC ouput into a tube amp gives you your tube sound with all of its glory. warts, whatever. If you are into vinyl, rip your brand new disks at 24/96 or even 24/192 and proceed as above. You won't here the difference.

Bob

[woodturner-fran]

My 206 drivers in a sachiko certainly tamed down over time but also I made wooden phase plugs which also helps. Also, the 206 has a whizzer cone and I fitted a foam ring behind it. This also helped. There's a few things like that that are worth trying.

Fran