| OzMikeH |
I have built a pair of Singular cabinets with 18mm MDF, I heard a friend's singulars with AER Mk1 drivers and was instantly hooked.
I just HAD to have some but could not afford the superb (and incredibly efficient) AER drivers.
I wish to tinker and tweak to see how good I can get these relatively cheap drivers to perform.
I still haven't painted/finished the cabinets yet.
The back chambers are stuffed with a shredded polyester pillow from our guest room (the shops were closed, ok?)
Layers from the other guest room pillow were carefully peeled off and trimmed to make a 3cm thick layer to fit in the bottom of the U bend.
So here is a thread to share my experiences and for people to contribute ideas. Hopefully people can learn from my experiences.
So far I have added some blu-tac secured with wool to try to damp the frame/magnet connection. (see picture)
There are various comments here and there I've made on related strings, I'll attempt to distill them here.
So far I installed the drivers to the cabinets about 4 days ago and gave them an 8 hour run at "watching TV" volume, a couple of CDs at "I'm listening to music" volume and a fair thrashing for half a Metallica CD at "let's see what they can take" volume this afternoon, (until my better half had a headache from it).
They are certainly sounding a lot better than when I first listened to them. (or I'm getting used to them) I have dropped the applied signal volume by about 12-14 dB since I started to maintain a normal listneing volume. my old Speakers are Tannoy M15 at 85 dB/w/m. These are a 2 way 8 inch bass reflex speaker. The worst sounding of the new and old speakers will be used for the rear surround channels.
Pit Hinder had some comments I cut and paste here and add my comments in <like this>:
Tweaking the drivers...YES! But taking a knife to them to add a phase plug amounts to open heart surgery. Try reversible measures first, you'll be astonished by what affordable drivers can do. <OzMikeH: if it helps a little bit I am not afraid to do it>
#1 The .98c trick. (Thanks GM for reminding us). Wrap a thread of wool around the whizzer, down where it meets the main cone. <I will try this, what size? thick and fluffy? what about a pipecleaner or too heavy?>
#2 Felt, or as innerconflict, the Nonphony from Caliphony, has proven to be good, simple household sponge. Use double sided adhesive tape to fix it to the inside of the basket legs. <I do not trust the double sided adhesive, I will try this tied on with string with some silicone sealant underneath>
#3 Caulking on the outside of the basket legs and (very effective) on the front of the magnet and in the gap between magnet and basket. <I have applied blu-tac so far, I was nervous about irreversible changes at first and blu tac can be removed, then I disassemble to finish/paint I will use caulk> |
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| OzMikeH |
I've given them a good listen and decided I need a super tweeter. The high end isnt there in the flesh and not on the datasheet for the driver either.
I'm thinking of a shaped high pass filter on the tweeter starting at about 12-13kHz where the Fe207E starts rolling off.
I want fair off axis (30 degrees) response and nice flat freq response from 10k right through to 20k.
I've only looked at fostex driver so far.
They need to be same or beter efficiency than the main speakers, (95dB/w/m) which rules out the fostex ribbon tweeter, this also has a weird looking off axis performance.
It's come down to the T90A (a little cylinder thing) or a FT96H (panel mount) spec sheets here:
http://www.fostexinternational.com/...-Tweeters.shtml
The cheaper FT96H actually looks better performance-wise other than the slightly lumpy response.
Has anyone used either of these?
Doesn anyone have any other recommendations? |
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| ttan98 |
I have a FE167E and thinking of adding a tweeter to it, the dispersion or off axis performance is not very good above 6-8khz, by adding a good tweeter would improve situation greatly. the same with FE207E.
go and do a serach on this forum on "adding a tweeter to full range" you will find an extensive discussion". |
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| OzMikeH |
thanks Ttan98.
Having read the thread..
1: wide dispersion on a helper tweeter for a fullrange is not necessarily a good thing. I should look for similar dispersion of the FR driver and tweeter within the crossover freq. range. Since I am fitting phase plugs to widen the HF on my FE207E the factory information is useless to me. I'll just have to estimate what will match and see how it sounds.
2: Ribbon tweeters can be integrated but only with great care. It is easy to get it wrong.
3: I might not want a tweeter after I fit the phase plugs.
4: Filtering the extreme highs and lows off the fullrange driver can help it's mid-range performance.
5: Time coherence is critical for good imaging. I need to figure out what phase offset the high pass capacitor for the tweeter will cause and whether it will be audible. Physical position of the tweeter is minor compared to the effect of the filter components. I need to do some more reading on the phase effect of crossover parts.
I may need to consider some fudge on the Fullrange driver to give it the same phase offset as the tweeter.
My main aims are good imaging and extended response.
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| ttan98 |
get Sound easy s/w an australian product which will help you calculate the time delay hence offset....
s/w not cheap but fair price, it has so many features, I acquire this s/w and learning heaps....highly techincal if you are into it....an excellent s/w. |
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| G |
| quote: | Originally posted by OzMikeH
I've given them a good listen and decided I need a super tweeter. The high end isnt there in the flesh and not on the datasheet for the driver either.
I'm thinking of a shaped high pass filter on the tweeter starting at about 12-13kHz where the Fe207E starts rolling off.
I want fair off axis (30 degrees) response and nice flat freq response from 10k right through to 20k.
I've only looked at fostex driver so far.
They need to be same or beter efficiency than the main speakers, (95dB/w/m) which rules out the fostex ribbon tweeter, this also has a weird looking off axis performance.
It's come down to the T90A (a little cylinder thing) or a FT96H (panel mount) spec sheets here:
http://www.fostexinternational.com/...-Tweeters.shtml
The cheaper FT96H actually looks better performance-wise other than the slightly lumpy response.
Has anyone used either of these?
Doesn anyone have any other recommendations? |
Take the plunge and put in the phase plugs. You will not regret it. It is easy to do with a steady hand and a sharp exacto knife. After you cut it close with the exacto grab some 180 grit sand paper and smooth it down to a finished edge. Also, make sure you have one of those battery operated keyboard vacuums handy to suck out any debris. It's not that hard. |
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| OzMikeH |
Phase plugs are in the mail...
Thanks for the tip with the sandpaper.
I'll also put a brick under the back of the cabinet while I am doing it, then run them for a while that way to shake any bits out.
Planet10 has suggested the much cheaper Fostex FT17. this is a third and a quarter of the price of the other two tweeters I was considering.
thomaseliot is using this combination, Last I heard with a single 1uF capacitor.
http://www.diyaudio.com/forums/show...970#post1056970
The power handling of the FT17 is only "30W music power" so I might end up blowing it up anyway. Especially with a simple crossover, the LF will be too much for it.
Planet10 said:
"I actually have FT17s i'm planning on using with with my 207s --- i'm going to start out at 7-8k 1st order series XO -- maybe 2nd order on the tweeter. Experiments i did awhile back with tweeters XOed quite high is that you can get away with a lot." |
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| G |
| quote: | Originally posted by OzMikeH
Phase plugs are in the mail...
Thanks for the tip with the sandpaper.
I'll also put a brick under the back of the cabinet while I am doing it, then run them for a while that way to shake any bits out.
Planet10 has suggested the much cheaper Fostex FT17. this is a third and a quarter of the price of the other two tweeters I was considering.
thomaseliot is using this combination, Last I heard with a single 1uF capacitor.
http://www.diyaudio.com/forums/show...970#post1056970
The power handling of the FT17 is only "30W music power" so I might end up blowing it up anyway. Especially with a simple crossover, the LF will be too much for it.
Planet10 said:
"I actually have FT17s i'm planning on using with with my 207s --- i'm going to start out at 7-8k 1st order series XO -- maybe 2nd order on the tweeter. Experiments i did awhile back with tweeters XOed quite high is that you can get away with a lot." |
I'm using FE206Es and their top end might be a little hotter. I would hold off on the tweeters until I give the phase plugs a good listen. I also toe in my speakers slightly and that may make a difference. There is a suggested setup on the FE207E datasheet for running the 207 with the FT17H utilizing a cap anf a t-pad. Just be aware that it will reduce your impedance to 4 ohms if you use the tweeter. |
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| OzMikeH |
I think I'll need the tweeter anyway.
the FE207E runs out of puff at about 12kHz, from what i understand phase plugs will help disperse what's already there better, they will not extend frequency response by 8kHz.
I need that top end filled up, otherwise I may as well be listening to cassettes. :)
So I will be installing a tweeter, the only questions are where, what type and at what crossover frequency.
The frequency can only be determined after I install the phase plugs.
I want to put it underneath the main driver, it is closer to ear height for my seating and has a much higher WAF than something sticking out the top.
Please let me know if this is a horribly wrong thing to do.
I Am skinning over the MDF with some thin plywood, I can then run a quarter round router bit along all edges to take it down to leave a thin line of MDF then stain it all a dark cherry. I was trying to figure out how to hide the edges then I thought I should just make them a feature. |
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| G |
| quote: | Originally posted by OzMikeH
I think I'll need the tweeter anyway.
the FE207E runs out of puff at about 12kHz, from what i understand phase plugs will help disperse what's already there better, they will not extend frequency response by 8kHz.
I need that top end filled up, otherwise I may as well be listening to cassettes. :)
So I will be installing a tweeter, the only questions are where, what type and at what crossover frequency.
The frequency can only be determined after I install the phase plugs.
I want to put it underneath the main driver, it is closer to ear height for my seating and has a much higher WAF than something sticking out the top.
Please let me know if this is a horribly wrong thing to do.
I Am skinning over the MDF with some thin plywood, I can then run a quarter round router bit along all edges to take it down to leave a thin line of MDF then stain it all a dark cherry. I was trying to figure out how to hide the edges then I thought I should just make them a feature. |
You obviously are free to do what you choose but the FE207E does not "run out of puff" at 12K. Check the spec sheet and ask some people who own them. They are essentially a shielded version of the FE206E with a little higher QTS. I have not found my FE206Es to fall off in the highs at 12KHz and I seriously doubt that Fostex would be selling many of them if they did since they state that the frequency response is "Fo to 20KHz". Just an opinion but you may want to listen to them by themselves in a suitable enclosure before you start diddling with crossover points and tweeters. Just a suggestion. |
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| OzMikeH |
I know datasheets aren't everything. but what I see here is a 10dB drop between 11k and 13k
My ears tell me something similar.
At these frequencies it's mainly the whizzer, so the enclosure probably wont have a huge effect. I should have got the 206 I think. |
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| G |
| quote: | Originally posted by OzMikeH
I know datasheets aren't everything. but what I see here is a 10dB drop between 11k and 13k
My ears tell me something similar.
At these frequencies it's mainly the whizzer, so the enclosure probably wont have a huge effect. I should have got the 206 I think. |
Maybe there is more difference between the 206 and the 207 than I thought. The only one that has to like your speakers is you. I was only hoping to save you some time and money. I would still do the phase plugs. Let us know how it turns out. BTW are you using a SS or tube amp to drive them? |
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| OzMikeH |
I was hoping to save me some money too. :)
I am away from home at the moment and my Phase plugs are there waiting for me.
I am using a SS amp. A Harman Kardon AV receiver,
50W when used in 2 channel mode.
Allegedly good to 100kHz, with high current capability, not that it matters with such a benign load as a single driver. The speakers are always the worst part of any reasonable system so I started with them.
On a listening test on my friend's singulars with AER drivers I was very surprised I could still hear right up to 20kHz, I am a radio communications technician, so I often tune radio receiver front ends by ear. I have listened to a very nice tube amp that could be run in triode and pentode mode with variable negative feedback. I liked it better with lots of negative feedback in pentode mode. So If I build an Amp it will probably be a low noise SS one. My sensitivity to high frequencies has me wary of T amps, I turn the television off once I have started the PSX cd player because the 16kHz noise is distracting.
I must say that I am peased with the bass and midrange, it's just the high end that needs something. AER Mk1 drivers would be the technically better fix but they will cost 10 time the price of the Fostex ones. They are very nearly worth the price to me.
My current thinking is to build a 12dB/octave Linkwitz riley style crossover at 10kHz using metallized polypropylene capacitors. I have just ordered some Fostex FT17H. I wanted the steeper crossover to attempt to reduce nulls from both drivers producing the same frequency, I'll tame the 98.5dB /w tweeter down by 3dB with a resistor network arranged to maintain the 8 ohm impedance. I haven't ordered the crossover components yet, I will see what changes with the phase plugs. I can play with this easily, the crossovers will be extrnal, Fortunately I used 4 core cable and neutrik connectors.
I was going to put inside the basket with some 1/4 inch thick foam triangles near the centre, something as wide as the basket "spoke" tapering to a point about 2/3 of the way out from the centre. Will this help or will it increase the effective mass of the cone? (I am sticking it to the basket, not the cone) With an Xmax of 1.5mm i should be safe.
I want to glue some wooden wedges on the back of the basket "arms" back to the magnet cover to really stiffen it up and reduce turbulence over the sharp edge. I'll take pictures. |
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| OzMikeH |
A passing comment from someone just made me realsie something,
The impedance of the FE207E at 10kHz is close to 16 ohms.
So should I be using 16 ohms as my driver impedance value for my crossover calculations?
I'm still learning about this speaker business, any advice is appreciatred |
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| OzMikeH |
I have stumbled across some very dense damping material, the only problem is keeping it in place during loud passages.
It moves around so much I am worried about damage to the rear of the driver.
Any suggestions?
But seriously now, I think I need to make something to keep him out, any serious suggestions? |
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| Scottmoose |
A fair question -having a cat enter your speaker cabinet could get expensive, and also damage the cat if it happens to be sleeping in there & you fire up Bruce Dickinson's latest solo album.
I'd try a stiff wire grill across the opening. It shouldn't ring significantly, and a touch of that is a sight better than a pair of ruined drivers or a deafened cat. |
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| OzMikeH |
How would I go about estimating the acoustic centre of the FE207E at 10kHz?
I'm guessing it might be something to do with a plane through the whizzer where it's diameter is a certain portion of a wavelength of 10k?
While I'm at it I need to do the same for the FT17H.
My test equipment consists of a PC for test tones and easily fooled ears. I can borrow a sound level meter (with A or C weighting scales) but it is a real hassle to get it.
The cabinets will be clad with ply, so I can chose the ply thickness to match my required offset between the two drivers.
Is it a horrible thing to mount the tweeters under the fullrangers? It's closest to ear height on these cabinets. I am also considering mounting them slightly off centre toward the outside - this appears to reduce the edge diffraction effects because the edges are now different distances. This leads me to believe there is an optimum offset distance so the edges null each other too.
I've bitten the bullet and ordered the crossover components and an inductance meter. I'll unwind some pre-made inductors until I get the right value. I may as well soak them afterward in some cheap varnish too.
For the 10k frequency the capacitances work out at 1uF and 0.5uF so I have ordered eight 1uf metallised polypropylene caps. I can match a pair and a double pair and use the last two for the playstation DAC output.
Oh yeah, Planet10's phase plugs helped a lot, My wife thinks "they look much better than the beady little eyes did" too. the speakers are a lot more listenable and seen more "even" in the high end. I have no idea why Fostex doesn't do this in the first place, it wouldn't cost much more for a plastic bullet instead of that little mesh stuck in the dust cap.
A tip when cutting the dust caps out on the Fostex 206 and 207. cut around the little mesh in a circle, approx 9/16 of an inch diameter. Cutting through the mesh results in lots of little bits of the mesh going everywhere.
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| Scottmoose |
| Good tip. BTW -FWIW, I'd mount the tweeter firing upward on the top panel. But I'm strange. |
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| OzMikeH |
Time alignment idea went out the window after reading the "Time alignement fundamentals" thread. (search for that exact spelling if anyone wants to read it.) I like the idea in that thread of notching out the edge of the tweeter mounting flange to get it closer to the centre of the woofer. That thread was very interesting reading until the little tiff broke out.
The whole time alignment tangent came about because of the potential "suckout" issues from getting the phase out of whack due to the high pass filter for the tweeter. I'm learning new things all of the time with this project, it's great.
Tweeter position is the current thing rolling around in my head, I only get one chance to get this right, I can play all I like with the external crossovers later on.
Upward firing tweeter sounds interesting, probably sounds good all around the room but with vague imaging?
there is a relatively cheap fostex ring radiator tweeter with a remarkably broad radiation pattern which I may try in future. The Ft17 ones are dirt cheap so I don't mind demoting them to filling-the-hole-in-the-cabinet status later on.
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| OzMikeH |
Ok Guys, be Honest, Would I be better off with a Bruce?
I have been skimming through the Frugal horn offspring thread and saw this passing comment from Dave (Planet10) in response to offsetting the driver.
"I don't think enuff to worry about... that's what we plan for our 207/FT17 Bruce...."
It just happens that I have a 207 and FT17.
These boxes only owe me about 2 cartons of beer worth of materials anyway. Still useful as cat house. What are your thoughts Scottmoose? Reading your comments elsewhere you seem to be one of the boffins on these drivers. I know it'll be harder for the damn cat to get inside the Bruce anyway. |
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| OzMikeH |
FT17H have gone in the cabinet, In the interests of laziness the 1uF capacitors are stuck on the back of the tweeters.
I've used neutrik 4 pole connectors and 4 core wiring, I can drag the amp out later and experiment with crossovers by splitting the wiring at the amplifier end. I'll relocate the capacitors then.
Summary of FE 207 E mods:
More blu-tac wrapped around the magnet, shaped for better airflow.
Bitumen and foil deadener applied to outside of basket legs.
4mm self adhesive felt stuck inside basket legs. smaller than the basket leg to ensure clearance for the rubber surround.
bits of felt stuck over the back of the magnet.
I've fiddled the photo to try to show the felt better.
Next: crossover and cone treatments, not sure what to go with, Mamboni/Enabl or the Planet 10 stepped thirds dammar pattern. Neither is reversible. should the dammar pattern be applied to the whizzer too?
I'm really interested in the Curvy Bruce cabinets too. |
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| OzMikeH |
| Here is the orientation in the cabinet. Note the felt wedge, an attempt at reducing reflections. |
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| planet10 |
| quote: | Originally posted by OzMikeH
the Planet 10 stepped thirds dammar pattern. Neither is reversible. should the dammar pattern be applied to the whizzer too? |
That pattern is specifically for resonances in the FE126/127 cone, how it would work on a 207 would take a flyer...
dave |
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| juanito |
hi,
well I'm quite interested on what you are doing with FE207 speakers as ntusI did my 207's on bass reflex cabinet with Aurum Cantus super tweeters G2i.
I play them with DIY amp solid state from pcpaudio.com
They sound nice and smoothe, but somehow I miss the beat in some rock pop music, not to mention electronic music. But It sometimes depends on the recording. I can listen to very bad jazz recordings, and I can listen to very good Depeche Mode classics. I don't know much, because I'm quite newbie with DIY world, and I get advice here and there, but it's very strange alltoghether: One year back I wouldn't bother at all about speakers, I would go for the od comercial speakers and that's it. Now I listen... but I enjoy it!!
It has been lately that may be I should change them to a "4 Wheel drive", as we say here in Spain. Something that you can drive elsewhere... that you can play with any music sounding great.
I was planning to add a subwoofer with active amp, but then I thoght that it would be a good idea to give a try to phase plugs and dammar varnishing. What do you think about the phase plugs changes? are they really worth them?
Have you tryed the Dammar allready? :confused:
At a point I was thinking to change completely my DIY speaker system into a 2 way kit. Still, I like my speakers and I'm shore that they can improve.
thanks
;) |
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| OzMikeH |
Phase plugs work miracles. do it! do it! do it!
No cone treatments yet. I'm looking closely at the Mamboni/EnaBL thread in Loudspeakers.
I tried out an EL34 push-pull tube amp. WOW. Bottom end much better now. Try adding a couple of ohms in series with your speaker cable.
I'm building new cabinets soon. "Curvy Chang" thread. The way my room is arranged I can't corner load both of the singulars, the image is skewed to the right in the low end.
Crossover is simply a high pass for the tweeter, I tried a 12dB/octave LR type. Both with and without attenuation for the tweeter it was terrible.
I now have 4x33ohm wirewound in parallel for a cheap way to make a low inductance 8ohm resistor. This reduces the level of the tweeter by 3dB to match the efficiency of the FE207E.
Then I started with 1uF, then 0.47, 0.68 and I finished up with 0.57uF. |
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| happy.gringo |
| Could you describe what you heard with the 10khz 12db LR crossover? It seemed like it would have been ideal. |
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| planet10 |
| quote: | Originally posted by OzMikeH
#1 The .98c trick. (Thanks GM for reminding us). Wrap a thread of wool around the whizzer, down where it meets the main cone. <I will try this, what size? thick and fluffy? what about a pipecleaner or too heavy?> |
Note that what you describe is not the 98 cent trick, but a variation. The original trick involves cutting a thin strip of low density foam (furnace filter foam in the original) and bracing the outer lip of the whizzer against the main cone.
(i have an illustration & pictures on my other 'puter if you want me to post them)
dave |
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| OzMikeH |
Dave:
please post the pics here. A few people will be using this driver in the Changs soon so here might be a good place to collect such things. I searched for the 98c mod and I couldn't find anything.
Furnace filter will be impossible to get, Air conditioner filter is very common though.
H.G.:
It was ok on my SS amp which has extremely low output impedance. Really not the right amp for these speakers. They sound nicer with extremely thin speaker wire or a tube amp.
When I tried it on a tube amp it distorted badly at high volumes around 10k. I suspect from a low impedance at the crossover range because it was an overdriven tube sounding distortion.
It was a very simple crossover, the FE207E is 16 ohms at 10kHz, so I used parallel 0.5uF capacitance with a series inductor somewhere around 0.5mH (I can't remember the value, I bought a big inductor and removed turns until I had what I needed)
The tweeter was 8 ohms with a series 1uF and a similar (not the same ) inductor in parallel. After that was a couple of resistors to reduce the level 3dB while maintaining the 8 ohms impedance.
The 6dB/octave filter I have now should have a flatter impedance with both drivers, the increasing impedance of the FE207E with frequency and the 8 ohm tweeter with 8 ohms in series (16 ohms again) coming in with frequency should make for a nice impedance for the amplifier.
I need to get my test equipment organised. someone should sell a Wallin Jig kit to save time searching for all of those parts. |
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| planet10 |
| quote: | Originally posted by OzMikeH
Furnace filter will be impossible to get, Air conditioner filter is very common though. |
I hand pick foam that comes in with the parts boxes i get from the computer shop.
Here is a diagrametic illustration -- the blue is the foam.
dave |
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| planet10 |
| And a driver with trick installed |
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| OzMikeH |
oh that stuff, I have heaps. By hand pick do you mean starting with a chunk and plucking bits off until it's the right shape?
Tip: an electric carving knife is perfect for shaping foam. You can quickly cut bits to make anechoic panels that way too.
I never thought I'd say this but: that speaker is way too "loud" for me. |
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| planet10 |
| quote: | Originally posted by OzMikeH
By hand pick do you mean starting with a chunk and plucking bits off until it's the right shape? |
By hand picked i mean i pick the lowest desity foam from my stash of 100s of pieces of foam.(that is also the appropriate thickness -- 5-10mm)
I cut it with scissors.
| quote: | | I never thought I'd say this but: that speaker is way too "loud" for me. [/B] |
:)
Those are the heart of a system i put together for my 20 month old god-son (gotta start em early). A true frugal-phile(tm) speaker... drivers were $18 CAD (and finishing materials doubled that). Built on the carcass of a set of KEF Calindas (the woofers & PRs are now in Oz)
dave |
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| zenesh |
With regards to the crossover, I just wired a 0.33uF to the positive terminal of the FT17H and wire it in parallel to a FE-206.
Might be able to ditch the resistors if you crossover higher, let the natural 6db rollover do the attenuation.
At this point, sounds from the tweeters are just cymbals and triangles.
But i suspect the crossover affects the 206 in a positive way too sounds clearer with the supertweeter attached |
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| OzMikeH |
I tried that, The rising response of the tweeter is too much for me. My hearing is good to 19kHz and is particularly sensitive around 16kHz. As part of my job I was trained to fine tune radio receiver filters by ear. In some ways this is unfortunate, it means I need more effort for a sound I am happy with.
There is a lot of information up there also from the breathing, ffff and ssss in female vocals.
The FE207 is very different to the 206 in the high end. it starts to run out at 12kHz,
The effect on the 206 from the tweeter will vary with amplifier type. lower impedance with rising frequency will pull the voltage down on certain amps. On a SS amp that is happy into very low impedances it won't make noticeable difference.
You can test your theory, put an 8 ohm resistor in place of the FT17H. A/B it with and without the resistor and capacitor. |
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| Lostcause |
Hi guy's, I have the MLTL's with the 207/17H combination and I just dropped the tweeter in with 8 ohms and a 0.57uf cap (approx.)
The thing is that I already had a series resistor on the FE207E to bring the base alive and I just left it there.
I've been playing with this for some time and need some technical input on how to calculate the resistors on this set up....
Or do I even need the series resistor anymore?? Need help!
It just doesn't seem right...... |
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