Best Amp & cables for Fostex FE206En BLH

Hey!

On my quest to escape the perils of dead sounding boxes filling the shelves of every hifi store, a long search for affordable efficient speakers ensued. Recently I have stumbled upon a set mentioned above (fostex recommended design) on a Swedish marketplace, which I'm enjoying quite a bit. Being a complete newbie in this company of real? sound, I am trying to learn about how to get the most out of them.

Currently I am driving them with a Vista Audio Spark 2, which is small & simple 20w class AB amp based on a LM3866 from TI's Overture Series. They are connected with 5m (15ft) of 16 AWG Belden 9497 (the twisted orange/black) tinned copper wire. They are playing in a roughly 30 sqm room. Still experimenting with short- and long-wall positions. They sound neater out in the room, but better balanced with boundry reinforcment, so they sit now along the wall (almost in corners). I'm finding dead forward or extreme toe-in work best.

I have not yet looked inside the cabinets to see if any damping has been used, but in short I'm loving the lively, open and pinpoint presentation. What I would like to try and improve:
-more weight in the low bass 50-100hz
-some voices and instruments have a slight "horn" quality (like coming from the top of the throat instead of chest)
-sometimes slightly too forward in the upper mid-range, makes violins and trumpets for instance scream over the rest a bit too strongly

Having done what I can (I think) to optimize placement I'm looking to equipment next. From my homework on this forum and some other places I have learned that they love to see high output resistance from the amp / low damping factor. I have emailed Vista Audio to get more specs, but currently have no idea what this amp is doing to the speakers in absolute terms. Jives well with my Soundartist LS3/5A in the near/midfield. Tonally very pleasant.

So now looking forward to experimenting with amps. Some recommendations I have gathered from internets (again, mostly here):
  • small/affordable SE triode amp (smooth mids and highs, but what about bass weight?)
  • small/affordable class A FET amp, like Pass ACA (like above but stronger bass, true?)
  • Tripath amp, bit of a wild card for me, as I've just learned abut this tech a few weeks ago) TA2024 seems to be the smoothest but also lacking in bass (hearsay)
  • what else? class D?

Obviously looking for reasonable pairing, so no 5k amps at this point, unfortunately. Also, looking only at finished products or kits. I would also like the opinion on the Belden wire. Its skinny and long, not sure if this is a + with this pairing or a -.

Any input on this matter greatly appreciated and I'm looking forward to learning more from you guys and gals!

Aleksander, Stockholm
 
The Fostex really wants a highish Rout amplifier, so only the first 2 listed are really suitable. your Spark is not.

Even an SE EL84 (in triode) amp will likely be sufficient power, a pair of bridged/balanced ACA has a more appropriate output impedance.

And the current needed is small, so a 16g wire looks like welding cable.

I suggest getting some solid core CAT5/6 cable, strip it apart, and use a single pr per side. You will need 10m of cable, with a different twist on each colour, you want the same colour each side. The added resistance will make the Spark look more like a highish Rout amp. There are other assets they bring to the table IMO. Try it an slet us know what you experience.

Long term you want the right amp and as short a cable as possible.

It is also worthnoting that the Fostex recommended horn is middling (and originally designed for the precursor ro the FE206e). There are also some driver mds that you can do that significantly help deal with isues the FE206 has. Is the horn plywood?

dave
 
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tansand

Member
2016-08-03 8:18 am
Open the zobels on your amp outputs, if it has them, by removing the cap or resistor, taking the zobels out of the circuit. It might blow your amp, because they are ostensibly there to prevent oscillation at high frequencies if your load impedance is high at those frequencies, as I understand their purpose. Removing them will help all that you mention as needing help imo. Alternatively find and buy an amp that doesn't have zobels on the outputs. Uncommon.

Again though, removing them could blow your amp. I have no doubt some/most/all think I'm a crank for this pov, but it's worked for me every time anyway.

They'd be Rsn and Csn on the LM3886 datasheet schematic.
 
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AllenB

Moderator
Paid Member
2008-10-18 11:31 am
@tansand , does this have anything to do with the desire to have interaction with the speaker impedance to raise the higher frequencies? I'd point out that an amplifier Zobel is covering a different range and if it is doing its job properly, by removing it you should expect no noticeable change in response.
 

tansand

Member
2016-08-03 8:18 am
It seems to lower the high frequencies, while making the midrange nicer sounding, more cohesive and realistic. I didn't do it the first time because I had a theory to test, just a crappy sounding amp and a curious impulse. It was a surpising improvement alltogether, first tonally and also in instrument placement. So, I keep doing it and it keeps doing that.

I linked a french language site a few months ago that showed phase angle around speaker resonance changing more quickly (not more angle) with frequency with a zobel than without. It took place in a shorter span of frequency. I cant find the link atm, I will look more tomorrow.

That isn't the best or even good evidence that something is happening in the audible range, I know.

edit: oh, here are the graphs I'm thinking of, taken from the link

https://www.diyaudio.com/community/threads/zobel-phase-damping.246525/#post-3717548
 
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The bass has landed!! :eek:

Thank you guys for the insight, especially dave! I had an old solid core 26awg cat5 cable laying around, exactly 10m of it. Stripped it, used a pair (one color with a complimentary ground and cut in half. I must admit it felt rather uncomfortable fiddling with this strand of hair around the binding posts, but eventually secured it.

Immediately, more extension in the lower-bass as well as mid-bass thump. Its not even subtle! The fullrange descriptor now makes sense, presentation is much better balanced - i could not achieve this before even using Chord Mojo2's inbuild dsp. Not in a balanced way at least. Upper-midrange also seems to be slightly subdued (perhaps related to bass increase), that warrants some further testing.

For the downsides, perhaps lost some clarity and smoothness compared to the Belden 16awg 9497. That also might be perceptive, as there is less shout and fizz now, needs a more careful consideration. But using a generic ethernet cable here, do you think I would see improvments in clarity with the neotech wire linked above?

The frequency anomaly in the lower-midrange persists however, making some male vocals sound a bit throathy/thin at times. Also noticeable with lower saxophone notes. That, as far as i've understood could be due to impropper damping of the cabinets? (Yes its 21mm plywood all round).

As for the amp, thanks for the suggestions. I guess the ACA and Triodes are the way to go. But will the bass still be there with a weak SET amp? 2-3w? I rarely play loud as the room acoustics don't allow it, but I would like the amp to keep up with peaks in a classical piece.

So no love for tripaths here? Are they gone and done?

Will be back with more impressions! So fun to learn like this:)
 
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tansand

Member
2016-08-03 8:18 am
No. This is not the same Zobel. The post in the link refers to a speaker Zobel. It is OK to remove the speaker Zobel.

It is not OK to remove the amp Zobel. The thread in the link has some confusion about the difference between an amp Zobel and a speaker Zobel.
Yes, I know. It gets a little iffy distinguishing between the same two components on the amp output or the speaker input, though, don't you think? It's been OK to remove them for me, the amps become actually listenable. Ymmv, and ofc the amp might blow.

OP, as far as I know there aren't any real tripaths made any more, the new chips are regular class D?
 
OP, as far as I know there aren't any real tripaths made any more, the new chips are regular class D?

Well I have found a few:

This one based on TA2024
https://www.audiophonics.fr/en/inte...ath-ta2024-class-d-2-x-15w-4-ohm-p-11845.html

This one one TA2020 for more power:
https://www.amptastic.com/

A battery powered one in a familiar chassis
https://www.soundimports.eu/en/dayt...HOzGygBrMlbh22WNbMnF9H4glBNyndNRoCiFAQAvD_BwE

Audiophonics also carries a few different amp boards based on tripath designs, to be assembled. The implementation on the finished ones really doesnt look all that considered, not in absolute terms at least. So when I cant even find a small manufacturer working with this design, it conclude that nobody wants to bother with it any more. ALTHOUGH, having just successfully upgraded the sound in my system with a thin stand of wire salvaged from an old ethernet cable, I am humbled and reserved to draw quick conclusions :D
 

tansand

Member
2016-08-03 8:18 am
How is it a problem distinguishing them?
What is the difference in a zobel on one side of the speaker wire or the other side, other than semantics? Why would removing one be OK and removing the other not, if there is no more difference than that?

No. This is not the same Zobel. The post in the link refers to a speaker Zobel. It is OK to remove the speaker Zobel.

It is not OK to remove the amp Zobel. The thread in the link has some confusion about the difference between an amp Zobel and a speaker Zobel.
Why would what you think is OK for your amp have any influence on what I think is OK for mine, or the OP's?
 
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AllenB

Moderator
Paid Member
2008-10-18 11:31 am
There are two reasons. Firstly the speaker one is after the filter capacitor which will change the response. The amp one will not change the response since it is in parallel with the Voltage source. Then there's the frequencies at which they are designed to operate. Only the speaker Zobel is in the audible band.
 
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tansand

Member
2016-08-03 8:18 am
For the downsides, perhaps lost some clarity and smoothness compared to the Belden 16awg 9497. That also might be perceptive, as there is less shout and fizz now, needs a more careful consideration. But using a generic ethernet cable here, do you think I would see improvments in clarity with the neotech wire linked above?
I don't know anything about the neotech wire, but what I use is cat 5 with teflon insulation on the individual strands. I forget what the spec is but it's the kind that's rated for permanent installation in buildings that has the teflon, rather than the kind for just making cords. You can figure out the spec/type of cable, and look on ebay or wherever for unterminated lengths of it.
 

tansand

Member
2016-08-03 8:18 am
Absolutely a possibility, I checked the heatsinks for heat and they run cool it seems to me. What it comes down to is that I don't think I can get this much of an improvement in sound quality without an endless triapse amp shopping, building and swapping. It simplifies my life and it sounds good. It's not just the tonality, as I said above. Instrument placement is much better too.