This is another build for desktop speakers, but I’m limited to 7” wide, 8” deep, and 12” tall (SWIMBO requirements). I’ve chosen the Fostex FE103E as my driver (already ordered them).
The speakers are to be desktop speakers for SWIMBOs computer, and will be driven by a Single Ended Pentode amp with about 4W output. (6P1P-EV).
I'll probably build a second pair to go in the garage for my system out there, and to use with tube amps I build/work on.
I’ve read up to page 50 of the Full Range Reference Project, but that is going a bit big, and as I said I already have the drivers ordered.
I like the Fonken, but again it is a bit too large and I would like to stick with a simple tuned port if possible.
The mFonken (FE127E) looks like it is very close to what I had in mind. How adaptable is it to the FE103E?
It appears to me that the vent in the bottom has a 19/32” X 15/32” port that widens to 15/32” x 5 5/8” in the front. Is this correct.
I would expect the port in the back vent to change dimensions for the difference in resonant frequency of the two speakers (79.5 for the FE103E and 70.4 for the FE127E). How do I calculate the new dimension?
Thanks
Steven
The speakers are to be desktop speakers for SWIMBOs computer, and will be driven by a Single Ended Pentode amp with about 4W output. (6P1P-EV).
I'll probably build a second pair to go in the garage for my system out there, and to use with tube amps I build/work on.
I’ve read up to page 50 of the Full Range Reference Project, but that is going a bit big, and as I said I already have the drivers ordered.
I like the Fonken, but again it is a bit too large and I would like to stick with a simple tuned port if possible.
The mFonken (FE127E) looks like it is very close to what I had in mind. How adaptable is it to the FE103E?
It appears to me that the vent in the bottom has a 19/32” X 15/32” port that widens to 15/32” x 5 5/8” in the front. Is this correct.
I would expect the port in the back vent to change dimensions for the difference in resonant frequency of the two speakers (79.5 for the FE103E and 70.4 for the FE127E). How do I calculate the new dimension?
Thanks
Steven
There is an mFonken103. We built a pair so that we'd have something to compare head-to-head with the mMar-Kel70 (CSS EL70).
Looks like i never did any drawings, the email to Chris says an mFonken with ports shortened to 103mm (i didn't see the syncronicity of that till just now, honest)
dave
Is that the 152mm dimension that would be shortened to 103mm, and keep the vent opening 19/32” X 15/32”?
I found this site that using the FE103E parameters looks like the volume would be 5.5L compared to the 4.5L of the mFonken.
http://www.ronshaw.citymax.com/f/Designing_Bass_Reflex_Loudspeaker_Enclosures.pdf
How well do these formula follow for design? I put both the FE103E and FE127E in a spreadsheet and got 5.5L and 13.17L respectively, which is way off from the design.
I found this site that using the FE103E parameters looks like the volume would be 5.5L compared to the 4.5L of the mFonken.
http://www.ronshaw.citymax.com/f/Designing_Bass_Reflex_Loudspeaker_Enclosures.pdf
How well do these formula follow for design? I put both the FE103E and FE127E in a spreadsheet and got 5.5L and 13.17L respectively, which is way off from the design.
it looks like a simple, slightly resisitive damped, slot vented BR, as made prolifically in the 70's......
....albeit a nice one, theres nothing new in that. Id totally agree with the NOT using a 127 and swapping in a 103. I have no heard the latter but the peak in the former driver is a little unmanagable for me-i would notch it, but that defeats the object really doesnt it?The Fonkens(generally speaking) do open up possibilities for self experimentation though, rather than mathematical modelling, which is always appealing...that surprises me Dave, I thought you were a modelling type of guy?
Last edited:
All the miniOnkens i design are modeled, then built, After having to redo the 1st few i got the mental handle on the translation between the standard vent (which the modelers deal with) and the high aspect ratio vent i've been pretty much spot on 1st time out.
When i'm done with the FE127 (ie it is an FE127eN) it has no measurable peak, althou you can still hear a hint of it. FE127eN goes lower, higher and is more dynamic than a similarily treated FE103eN.
dave
When i'm done with the FE127 (ie it is an FE127eN) it has no measurable peak, althou you can still hear a hint of it. FE127eN goes lower, higher and is more dynamic than a similarily treated FE103eN.
dave
Personally i quite like the fonkens. It seems to almost fulfull the OLD philosophy of a port near equal or equal in area to the cone SA, except with a smaller Vb and longer port, which is slightly damped. this i would beleive gives rise to the lower amplitude of the lower BR impedance peak. this in the old port area=cone area tunings would give 2 near equal impedance peaks, if i remember right. with all other things being equal(Fs,T/S etc) id expect an audible difference in bass response from the larger SA of the 127, though ive no idea of the HF response in comparison. personally in a FR design, i would always go for a FAST approach, with as small as possible and as low Mms as possible driver. i would assume, without knowing the Mms of both drivers, that the 103 was lower in Mms and be better transiently. that being said i dont know and could possibly be wrong. after all VC has quite an impact too. to this end i wouldnt opt for a driver of more than 4" for the wideband driver, and an Mms of less than 5g(and as far under 5 g as possible), to preserve HF transient response and reduce the possibility of HF distortion which i feel the 127 has in copious highly audible amounts.but thats my view.
Last edited:
I can see that it makes sense that the FE127 will have a broader frequency response and more dynamic range than the FE103.
I'm trying to find a moderatly uncomplicated enclosure design that can be tweeked to suit the FE103. The FE127 is close, and if all that is needed is to change the port length by shortening the bottom shelf, then hopefylly it will do.
Another possibility is the SOLO-103, but it is slightly more complicated with top and bottom tuned ports.
I'm trying to find a moderatly uncomplicated enclosure design that can be tweeked to suit the FE103. The FE127 is close, and if all that is needed is to change the port length by shortening the bottom shelf, then hopefylly it will do.
Another possibility is the SOLO-103, but it is slightly more complicated with top and bottom tuned ports.
The Mms of a fully done up FE127eN is <3g.
If i was doing a FAST (which i have), my 1st choice is the FF85KeN. Monster nagnet, Mms of 2g. It is a better tweeter than some costing twice as much.
Next up (ignoring the MJK/Shearer OB) is a miniBlade with 2 Silver Flute 14 cm woofers.
dave
In my most humble opinion ( I have only built ~ 2 dozen enclosures for the FE103) it would be very hard to beat the Bee Ess-10 as seen here for a simple box, or perhaps most other reflex boxes.
N.B. the Bee Ess are the initials for Bull Excrement (shite) but the forum does not allow those initials.
Redirect Notice
BTW I think those above are overdamped but thats just me.
For a little more effort the BK-10, a small horn.
The plans for both are on the net, Google is your friend.
N.B. the Bee Ess are the initials for Bull Excrement (shite) but the forum does not allow those initials.
Redirect Notice
BTW I think those above are overdamped but thats just me.
For a little more effort the BK-10, a small horn.
The plans for both are on the net, Google is your friend.
Last edited:
Dave, I read you are quite busy
The BK-10 is a newer version of the 101, mostly a shorter horn (you already know that I'm sure), mine I made some subtle modifications to, but yes, a lot more similar than different. I suppose your Alinco drivers don't hurt either.
The **-10 really suprised me though, I did not add them to the green skip behind my office at work which means a lot.
The prototypes sounded great on my desktop. It wasn't easy returning them to Dave.
Jeff
thats very light indeed! i wonder...do you know what the HF THD figures look like for the 127 versus the 103 versus the 85 ? obviously im talking 'standard-non-eN' drivers for now. Or perhaps figures for the alpair 5 and 6. a comparison between these 5 drivers, un eNabLed, would provide the clearest insight into the THD and behavoir at HF of these drivers and would be incredibly useful for the OP and myself(in the persuit of a future FAST system). IT terminology 'garbage in garbage out' would apply, and if i could start with an FR driver with very low THD at HF aswell and also a light membrane for good transients, enabling them would only improve things. if the reverse were done, all i would be doing is to better a poor driver. EG visaton b200. nice in theory, very nasty HF with oodles of THD abound.
ok. im not sure how extra harmonic content added as a distortion to the original signal can be insignificant, and inaudible.......triangle waveforms are certainly very easily distinguishable from a sine, even the 'stepping' of a sinewave produced by a misaligned push pull amp is clearly audible, even at 10kHz.
As with everything, there IS a threshold where THD becomes unimportant. a THD level of 0.001% versus a level of 0.01%, is unlikely to be distinguished. However, a level of 0.1% to 1% certainly WILL, from my experience with amplification at least. If the level of ANY driver falls in this range it is certainly very significant indeed, although perhaps not noticable to the users of SETs at near max power...
In any case, I was only asking about the levels of THD measured in these particular drivers, and i certainly was not expecting a defensive rebuke. im sorry if i had an opinion that offended you.
As always, the threshold of THD which is acceptable for realistic reproduction not production is ultimately up to the end user, as well as researchers to decide. I dont beleive Toole would be so foolish or blinkered as to make such a blanket statement.
If there are such THD measurements out there concerning a range of popular FR drivers to be read and examined I, for one would enjoy reading them, whether they turn out to be insignificant or not.
A suggestion from left field ...
If you'd like the way-cool retro look, you could consider cloning the classic Akai Jetstreams:
AKAI A&D SW-30
cheers
Doug
If you'd like the way-cool retro look, you could consider cloning the classic Akai Jetstreams:
AKAI A&D SW-30
cheers
Doug
Geddes' research shows a threshold of something like 25%. ie it has to be pretty bad to concern yourself about when attention could be be elsewhere more important.
In his book he has a chapter on distortion. Now after his research he says not to bother reading it...
dave
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.