Need advices, First DIY Project, Back Loaded Horn

[#60619]

Curious, what will be the main differences between the Dallas, Jericho, and this one:

Fostex - Page Not Found

I noticed that this is the only design that Fostex recommend for the F208EZ.

Curious also to know how low the bass can go with this design too..

 

[#60619]

https://www.fostexinternational.com/docs/speaker_components/pdf/recom_enclose/208ez_enclrev.pdf

 

[Scottmoose]

Curious, what will be the main differences between the Dallas, Jericho, and this one:

Fostex - Page Not Found

I noticed that this is the only design that Fostex recommend for the F208EZ.

That's because they only recommend their own designs.

Curious also to know how low the bass can go with this design too..

Fp = 42Hz, flat tending to high gain.

 

[#60619]

Please, let me know what do you mean with "flat tending high gain?

Thanks.

 

[ColinA123]

Well just my 2 penny worth.
I have Jericho horns with Fe206 E sigma. (With phase plugs fitted)

large, high room.
Fitted with BSC filter as per the article.
To my 66yr old ears they sound great.
I do use a small REL sub woofer to just boost the bottom end a little.
Listening is mostly acoustic and folk type music so bass is not heavy to start off with.

 

[ColinA123]

One addition, in my experience Fe206 need a lot of running in before they sound their best.
Absolute minimum 100 hrs, more like 200.

 

[mp9]

FWIW, I originally was going to do the Fostex special ed FE166EsR Fostex design BLH. IIRC, the Fostex BLH plan was considered to be one of their ok designs, the general consensus being some are good, more of them are not. Having followed the related post here, I ended up going with Scott L's Woden design Victor 2x mouth BLH, and although I'm listening room space challenged, I don't regret the decision.
IIRC P10 Chris and or Dave heard the FE166EsR drivers in both the Fostex BLH and the Woden Victor 2X BHL and preferred the Woden Victor.

 

[chrisb]

Yup, as large as they might seem compared to more compromised BLHs, the V series family from Scott (Valiant, Victor, Vulcan) would definitely be my choice for the Fostex FE series drivers (other than the late "XX7" models).

Being manifold/ labyrinth designs, those three are not the simplest of the hundreds of builds I completed over the years, and I think the carefully calculated tall bifurcated path common to all is the key to their performance, but in terms of actual floor space, there are lots of BLH designs with greater footprints and internal complexity. Of course there are probably few members here who've heard every possible combination, so any "opinions" not based on personal experience need be seasoned with your favorite flavour of salt - pink Himalayan for me, thanks.

Full disclosure - while I've built and lived with a fair number of Fostex/BLH/SET amp systems in the past, I've long since stopped using any model of Fostex -except in my computer desk top system- in favour of Mark Audio drivers, and currently all SS amp types.

 

[Mancave62]

Yes, I think i will give up of this dealer.. many thanks for all the advices, there's a lot of great info that I'm still digesting, because some are very technical for me, and I'm not much versed on some technical concepts, I will dedicate some time to read everything again...

Have you considered Elekit, they are Japanese and have a reputation for high quality, reasonably priced kits (I have built several and they are great for my budget and ear). I'm pretty sure you can get them fully assembled from Victor, if you're not into kits. Great informative thread, thanks

 

[planet10]

Have you considered Elekit, they are Japanese and have a reputation for high quality, reasonably priced kit

In an earlier post i pointed ou tthe 3 that ar eon the diyAudio Store.

dave

 

[GM]

by the way, I see that on the pictures of the amp, it have 4ohms / 8ohms / and 0 ohms??? speakers terminals..

0 ohms connection is speaker [-]/common/gnd.

GM

 

[#60619]

Have you considered Elekit, they are Japanese and have a reputation for high quality, reasonably priced kits (I have built several and they are great for my budget and ear). I'm pretty sure you can get them fully assembled from Victor, if you're not into kits. Great informative thread, thanks

Thanks will take a look closely, but for now I'm in contact with other handmade independent japanese tube amps manufacturers, I think a kit is not a good solution for me... but thanks again for the advice!

 

[#60619]

0 ohms connection is speaker [-]/common/gnd.

GM

thanks for clarify this, best regards.

 

[jazbo8]

Threads merged, please do not start multiple threads for the same project.

 

[#60619]

Hello guys,

I found an amp manufacturer that provide very complete specs, including damping factor.

Please, take a look at this one:

Application Notes : SV811-3 SE Power Amplifier

Appreciate very much the explanations why this can be a good or bad choice for my loudspeakers.

Will just put the specs of the speakers here again, just for be in hand for you guys check it out

Enclosure:
https://www.fostexinternational.com/docs/speaker_components/pdf/recom_enclose/208ez_enclrev.pdf

Full Range Driver:
https://www.fostexinternational.com/docs/speaker_components/pdf/fe208ez.pdf

Super Horn Tweeter:
https://www.fostexinternational.com/docs/speaker_components/pdf/t900a.pdf

Many thanks everybody for all the help, it has been a nice learning process.

 

[GM]

Greets!

You're welcome!

Technically, damping factor [DF] is the specified load impedance (speaker system) divided by the amplifier's output impedance, so dividing 8 ohms [speaker tap]/3.8 [DF] = 2.1 ohms output impedance [Rs].

Qts' = Qts + any added series resistance [Rs]: HiFi Loudspeaker Design

Hornresp automatically does this, so using a classic reflex alignment for comparison; inputting 0.5 ohms for wiring and 2.1 ohms amp [Rs] = 2.6 ohms in the [Rg] field and with a so called matching impedance 8 + 0.5 = 8.5 ohms.

Big difference and will be more extreme loaded in a BLH, so figure you'll need a relatively large series resistor, which won't sound the same as a matching impedance amp, i.e. DF = 1.

GM

 

[#60619]

Greets!

You're welcome!

Technically, damping factor [DF] is the specified load impedance (speaker system) divided by the amplifier's output impedance, so dividing 8 ohms [speaker tap]/3.8 [DF] = 2.1 ohms output impedance [Rs].

Qts' = Qts + any added series resistance [Rs]: HiFi Loudspeaker Design

Hornresp automatically does this, so using a classic reflex alignment for comparison; inputting 0.5 ohms for wiring and 2.1 ohms amp [Rs] = 2.6 ohms in the [Rg] field and with a so called matching impedance 8 + 0.5 = 8.5 ohms.

Big difference and will be more extreme loaded in a BLH, so figure you'll need a relatively large series resistor, which won't sound the same as a matching impedance amp, i.e. DF = 1.

GM

I must say that is very difficult for me to understand, when involves do this kind of calculations, but I understand that you are trying to explain me via the most technical and scientific way possible...

When the explanation is via the theory turning into the practical situation, with a more simplistic way for me to understand the concept, helps me very much, but I promise that I will try to study this with more profundity...

Meanwhile, it's possible for your to look at the amp specs and speaker specs, and tell me what do you think about the synergy of that matching amp and speaker, considering the damping factor specs of the speaker?

Many thanks sir!

 

[GM]

The whole point of my post was to explain as simply as I know how, complete with examples to show you its a poor choice overall for the Fostex 208EZ in its BLH.

GM

 

[#60619]

I do not understood why, so if this is the most simple way to understand the why, I really need to understand more the calculations of this technical values, I need to work on that.. I thank you very much for your efforts explain this to me anyway...

Let's see if someone appears with a more simples way that I can understand at least a little better hehehe

 

[#60619]

And here's another possibility, via an tube amplifier builder, that I'm discussing the possibilities of build the amp with appropriated output impedance for my loudspeakers.

I explained to him that is important the amp to have a high output impedance, showed to him the driver's specs and etc...

Here's one option the he provided me:

OTOMON Laboratory　(音門ラボ) / Special order made 2A3PP amplifier with all HIrata TANGO transformer * Excellent !!!

His my question to him and his reply:

Me:
Let me ask you about an important spec for me, it's possible for you to provide the output impedance (damping factor) about the amps?

Amp Builder:
It is not fixed number but it is about 6-8 due to tube and schematic you use. Generally, damping factor should be higher than 5 with SE amplifier.

What you guys think about this values for my speakers?

Many thanks!