how do you score the fe207 & chr-70

[qingcai]

please forgive my ignorance, I only build a pair of chr-70 in ported box, and I feel very satisfied with it, and I wondering how do you score it compare to the fe207 ( like 90 for fe207, 70 for chr-70, assuming they are well designed box) .

my wife have asked me, you spend so much time on building this speakers, why don't you build a best one, I don't know which is best, I just know the fe207 is high recommended one. so this is why my question come out.


thanks for you opinion.

[planet10]

They are quite different... which one is actually best will be greatly affected by your room and your amplifier.

As an example, in my main room (big) with my main amps (4W tube amps) the FE207 would be all over the CHR. In mu office (small) with my chip amp the CHR is better.

Note that when i talk about these drivers i'm really talking about CHR70eN & FE207eN (the modded drivers, to my ears anyway) far surpass the stock drivers, as good as they are, for musical enjoyment.

dave

[qingcai]

thanks dave,
my room is 12' x 24', half of my room is dinning area, and this side is open, another side is closed, for my TV.

I don't know if I can call it big or not.

[Ian444]

Qingcai,

The difficult thing is to know which is "best" for you. There are so many directions to go. It's good if you can listen to a pair of what you want to build beforehand, but this is often not possible. The Fonkens, the Moose BVR, various MLTL designs, and BIB, they all seem to be popular. There's more designs than that too. Planet10's homepage is a very good site to look around, showing lots of plans for different boxes with different drivers. Also within this Full Range forum there is much information.

The Moose BVR "Lotus" with CHR70 may do well in that room (IMO) with the limitation being they cannot go super loud. If you can afford the larger Fostex drivers then the choices are many indeed. Are the speakers you just built lacking in any way? What is it that you are looking for that your current speakers do not provide? What sort of amplifier are you using to drive these speakers? The answer to these questions may help others more experienced than me to give you some good suggestions.

Good luck and happy building.

Ian.

[planet10]

You're actually listening are is about the same size as my office, but opens into other rooms which give it ~ triple the volume... you could make either driver work in that room... what amp are you using?

dave

[qingcai]

thank you Ian and Dave,

the planet10 hifi website is definitely daily browsing site. I hope I can build every one in the site, but the garage is too hot in these days, LOL.

because I don't have experience with other hifi speakers, the only one I have is JBL music one, and I did enjoy the jbl a lot on movie wathing. after I done the port version chr-70, it does amaze me, so I just wandering if I done right, and where is this chr-70 position in all these full range drivers. and if there is better plan, or full range speakers in reasonable/affordable price.

I browsed this forum about half year, and know the fe207 is high recommend one, if from your opnions, let me know there is a big improvement exists between chr-70 port box and moose' bvr or dave's microtower, I would eager to try these boxs, and same to the fe207, if there is a big difference, I would like to build a pair too.

actually I don't know if the speakers I build have any short, I'd wait for my wife back at weekend , her ear are better than mine, LOL.

I feel little shy when talk about the amp, my amp is denon 1909, it's a 70w output/channel av receivers. the audio source are from two type:
1, laptop to sound card, which is equiped with pcm2702 usb chip with simple OP output , I build by myself. about 30$ cost. highly recommend from head-fi forum.
2, popcorn hour hd movie --HDMI--> denon decoding.

dave, do you think the amp is the weak point of my setup? or the sound source.

[planet10]

With the Denon, i would suggest that the CHR has an advantage.

I would suggest that the 1st place you look to improvement is to get an EnABL kit from Ed, practise on some cheap speakers and practise and then do the CHR.

The stock CHR is good, EnABL transforms them.

Building one of the boxes with 2 CHR really helps in the dynamics department (and 8 ohms will make your Denon happier).

The microTower is not intended to be the be-all & end-all... it is a high WAF box that doesn't need a stand, is easy to build, yet large enuff to allow porting to extract more bass from the driver.



For small boxes i'm sticking with sealed for the CHR, your use of a high aspect ratio port takes the BR design heavily towards aperiodic (ie between sealed & BR). Nice boxes BTW... what is the material? And how do you make them float in space like that ?

dave

[qingcai]

Let me search the forum to see show is Ed,

I will make good stand for the speakers. sorry to surprise you.

I did not use the round tube as port, just because I am lazy to find out the pvc tube material in home-depot. I notice the the wind flow from the port is less than the round one. maybe this changes the box a lot from the original design

the box material:
1. the face is hard maple embedded with walnut.
2. the side is plywood, and cut into slice, then turn each slice 90 degree, then glue it together. then I can get a much thicker board, and I heard that it's more steady than 3/4 plywood.
3. the top is ash, cheapest wood in shop. and very easy to work with.

I just oiled it last night with lee seed oil, don't have pic yet, it's does look better.

I shoot these photos with my cellphone, lots of noise on the pic

[markaudio]

Hi qingcai and fellow thread readers,
I'm taking a little breathing time before I start building New CHR-70's and Alpair 7's next week.

Re gingcai's Fe207 - CHR70 comparison question. Not wishing to disappoint but comparing these drivers to each other is impractical and potentially misleading. These drivers are very different, both in their design and operational envelopes.

Regarding Dave's comments on Enabled and stock drivers, I've had some time recently to test a pair of Enabled CHR-70 drivers and compare them to stock versions.

Quantitative measurement:
The test was carried in an anechoic chamber using LMS (see chart). There's no significant differences in the frequency tracks between the stock and Enabled drivers. The T/S parameters changed little. The only notable difference was the reduced SPL of the Enabled drivers by 1dB. I should add a note of caution. This test should only be viewed as "marginal indicative". For greater reliability, a larger sample of drivers would need to be tested. All the same, there's nothing that significantly stands out from the standard anechoic sweep tests.

Qualitative
I've managed about 4 hours of listening between the stock and Enabled versions in my Hong Kong studio. An additional 3 hour session was held with my HK audio friends, 2 of which are Japanese and very familiar with Fostex.
My my perspective, I enjoyed listening to both stock and Enabled units in similar measure. I liked the Enabled units for their smoothness while I enjoyed the stock units for their clarity. I haven't had time to check the effect of Enabling process on the cone's resonance pattern at the micro-resonance level. However, it is likely that Enabling is applying a subtle damping factor in the mid-high range.
Now comes the really interesting bit. The listening session that included my 2 Japanese audio mates brought something of a division of opinion. For half the group (4 guys), the Enabled drivers weren't favoured over the stock drivers. The damping factor was felt to be too intrusive upon the CHR-70's "character". In particular, 2 recordings got a debate going. Pie Jesu (Requiem Reference recording - Dallas Women's Chorus), the final vote went to the stock drivers for revealing more of the nuances in the soloist's voice. However, the Enabled drivers got the "thumbs up" on Manuela's (Musiclab) rendition of Stand By Me, by way of a silky delivery.

Conclusion
No doubt the debate will carry on with some heat, not only on the effects of Enabling but for all driver enhancements. My own feeling is Enabling is having an effect that may benefit some tracks and for some listeners, will be an enhancement in their listening pleasure. However, for those who want to see measurable beneficial differences, they may be in for a long wait.

I'd like to congratulate Dave on his efforts to enhance drivers. I've encouraged Dave to set up blind trials to further explore the Enabling experience.

As a driver maker, I'm all for experimentation and believe its important to support the the Custom build community in most of these endeavours. Variety is the spice of life, the greater choice in speaker drivers, the more interesting the hobby becomes. I'm continuing to work on every batch of drivers so there's a few modest "tweaks" in the CHR's coming your way soon.

Cheers - Mark.

[planet10]

Thanx Mark.

When listening to EnABLed vrs stock drivers, the biggest thing i note is that the imaging becomes much more 3-dimensional, and the boxes the drivers are mounted in become harder to localize. Sometimes this is hard to hear, but it seems once it catches you it is hard to live without...

This does require a very low noise box. I would speculate that a typical MDF box might have trouble as they tend to ooze low level grunge that can bury extra micro-detail (ie greater downward dynamic range).

I do find that some of the high frequency edge on drivers is removed, i find this a positive thing most of the time, but indeed some people find this a deficit.

dave