Greenhorn Curvy Chang Build

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Originally posted by Dust

I am trying not to be too critical as they are new, but they are a little dissapointing. Mids are good ,quite detailed. Tinkley things are tinkly. theres definately enough treble, but the bass is just not there.

Hi Dust

I'm using the Curvey Harveys in (what looks like) an equivalently large room, and I'd have to say that the only aspect that concerns me is that the bass is somewhat shy. I think that rooms this size just need some augmentation there.

Personally, I'm reluctant to add a subwoofer to a double-BVR, since there are smaller speakers that will do the job if one is going to augment the bass. But I'm a bit stymied about what to try next, since the Harveys please me a great deal in all other ways. I suppose I might try adding some form of bass augmentation to see how it sounded, and then consider how to proceed.

I'd appreciate hearing how your next steps - whatever they may be - work out for you.

Regards.

Aengus
 
Hi guys... Well I've spread them out as far as I can and moved them closer to the corners. This has helped the bass somewhat ,but still pretty lean. Early days so I won't get too cranky! I'll try getting them up as per dzz's suggestion. I also like the look of the Shadow SD12. I am hesitant to add a sub too as I used to have a Rel which was slow and ponderous,very hard to integrate. In the end I sold it as it drove me mad constantly fiddling with it. So I would need something that would keep up with the 207s. It doesn't have to be John Paul Jones on 11(though I wouldn't say no) but just more oomph. Interestingly, I slapped on some Focus, Moving Waves. Plenty of bass there so they can do it. Marce, your Curvy thread inspired me to build these beasties so thank you for putting that up.

Dust
 
:D
The real thanks goes to Scottmoose and Ronc for designing the beasties and tempting me. It was love at first sight for the looks, and later love at first listen for the sound. My previous speakers have included some KEF 104/2s driven by an Audiolab 8000A, not short of bass, but to be honest I prefer the CCs presentation.
What type of amp are you using. I currently use SE el84 valve monoblocks, and get more bass out of them than I do with the Audiolab witch has 10X the power. The low impedance output with high damping factor dosn't work very well with the drivers, adding series resistance helps damp the damping and improves the bottom end with solid state amps.
A couple of idea's that may be worth looking at are:
Have a look at what damping material has been used in the other builds, I used a relatively light, loose fibre wadding (fastened with double sided tape, easy to change and reline), looking at the photo's yours looks quite a bit denser material. I dont know whether it would help the bass.
The addition of the FT17 or other super tweeter again may be worth investigating, the extra sparkle in the top range may help to improve the perception of bass. The caveat here is I have Planet 10 fully modified, ENabled 207's, which of course is a third avenue to examine.
If you have a more normal sized room (ie sub 20' celings) you could always try them in that, it would be an interesting experiment to see if roof loading does play a part and how much.
Thats the beauty of building your own speakers and this site, there are so many things to experiment with, and some interesting discourse on the results, and I've found that even if an idea seems to defy logic its worth a try, youve nothing to loose.
 
Hi Marce. Funny, I had an 8000A too. Pretty good amp. I wanted to try a tube amp so managed to fine a Cayin 88t. It's about 40 watts I think. Sounds good but I'm not blown away. How do I find out what the amps output impedance is? I'm not very technical. It has 8,4 and 16 ohm taps, but I hear little difference in them.
I was wondering about the wool felt I used for damping...might pull some out later see how they sound. Don't want to get ahead of myself here until I've tried the phase plugs and coating the cones. I've been practicing painting some old drivers with mod podge and cutting out the dustcaps. If that goes well then I will do the full enABL. I have a pair of Impulse taus in my study. they sounded thin until I put lots of old thick cutains up and are much better now so I think Curvys room is playing a large part in their sound. I would need a small crane to swap CC's with the Taus. Mod podge and Phase plugs Saturday. Will keep you posted.
 
HI Dave, I'm very interested in doing that. Can you explain a little more?, or point me in the right direction? I am just about able to set the bias but it makes me very nervous poking around a live amp. Maybe when I know more(lots more!) its a possibility. I changed the KT88s for KT90s. I am reading all I can in the Tubes section here but alot of it is way over my head.
What is triode strapping?

Thanks.
Dust
 
frugal-phile™
Joined 2001
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Dust said:
What is triode strapping?

In its simpliest incarnation you connect the screen grid to the plate thru a resistor. Turns the pentode into a (psuedo) triode. You get half the power, but it is usually sweeter and more linear so you can remove or reduce the amount of feedback. The feedback is often used to reduce hum so to completely remove it you need to have a good quiet PS.

dave
 
http://www.transcendentsound.com/amplifier_output_impedance.htm
A brief intro to amp output impedence. It is not that simple though, the way the driver works in the cabinet has a influence. Scott has explained it for me in the past I will try and find the link.
Valve amps are basicly current drive whereas solid state are mostly voltage drive, thus for maximum power transfer the valve amps output impedance needs to match the average impedance of the drive unit. That is a very very basic description, when you look into it it gets quite fun.
Looking into changing triode mode is worth it, my EL34's are run in that mode and it is nicer sounding.
Have fun.
PS. B & Q do a nice folding trolley, wich I have found to be very benifical to my back in moving the Changs around.
 
Hi All. Its been a almost a couple of months since my last post.
Thought I would let my Curvys settle in for a while and play lots of music. I'm sorry to say that I don't really like them. they are OK sometimes with the right music, mainly acoustic stuff, nothing to complicated. female vocals are pretty good, but there is a very shut-in sound to them. they are clear as a bell but thin and very bright with it. With rock music they stuggle bigtime and it becomes unlistenable. I also did they modpodge thing with them and installed phase plugs. Did not hear a difference. Quite disapointing. Took out one side wall of damping hoping to maybe get some more bass, or a least liven things up. Nope. This could of course just be bad system synergy, but I would have thought driven by a tube amp they should really sing. I got so frustrated I bought a little tube buffer stage to try on my Dac (benchmark 1) which does sound a little cold. Waste of money. So, I don't know. So many variables; room, system, cloth ears. I might try making a sub sometime.

Thanks
Dust
 
Hi Dust,
Sorry to hear your not happy with the CC's, after all the work it must be a disapointment. I would love to hear them just to compare them with mine, as I love their presentation. Though as I've said the rooms I've listened to them in have been much smaller than yours, which is going to help the bass. If the bass is lacking they will sound thin, I tend not to listen to the first CD I put on, as untill my system warms up it sounds thin, but after that initial period they sound great.
I am still toying with the idea of adding a subwoofer, and would sugest, if you want to continue this on this thread, as it would be an interesting expansion of the design, and we may yet address some of your problems. The Shadows are not a viable option for myself anymore due to space constraints. So in my case it would have to be a reasonably compact design, but one that is going to complement the clarity of the Changs, but not overwhelming them. I've been looking, but advice and idea's greatly welcome.
Keep heart, the beauty of this site is that a problem shared is usually a problem solved.
Marc
 
Thanks Marce, I quite like the look of sonotube sub. Pretty cheap and seems easy enough to build. The reckhorn looks interesting too. I don't have pre-out so would require an amp change. been thinking of a Sugden a21a that I heard a long time ago at a hifi show hooked up to totems, arrows I think. You could not pass by the room without the sound sucking you in. At first I thought there must be some hidden speakers somewhere. Very 3d sound and clarity to die for. Absolutely stomped a £30k Naim system down the hall. so I'll take a look at one of those. Be nice if I could find a simply kit with that kind of sound (or Better) as their not exactly cheap. I would love to build a tube amp but wont attempt it at this stage. Next week some buddies and I will bring down my Impulse speakers for comparison with the Curvys. A bit unfair I guess as the Impulse are 3 way, but interesting to hear them in a large room. and by the way if your ever around these parts (East London) you are more than welcome to have a listen. Just pm me.

Dust
 
Hey Dust, I dont think your giving your Changs enough time to run in.I built a pair of chilli Changs last year.They sounded pretty Dire for about 4 months,very forward ,harsh etc.honestly most everyone on here will agree you need to realy run these Drivers in.They have by design a very very stiff short throw cone that needs lots and lots of time on them.Trust me on this once run it they are stunning.Being so bloody open though they take no prisoners with the rest of your gear.Best to get a nice 300B amp
if you can with WE 300b's as these are wonderfull,smooth mids
full bass.These are a real high end desighn so as long as you run them in and use smooth amplification you will love these.
And Yes you realy need a sub ,try to get one that will go up to 80hz so as to integrate well.........James
 
Dust, I just wanted to chime in and tell you that your CC's look great, it appears you did a fine job constructing them. ;)

As far as your disappointment in them goes, is it basically that they are bass shy? Or do you you have other issues with them as well?

Have you considered using a different driver in them? Didn't you go with Fostex 206's?

I know first hand that it can be frustrating to put the work into a build and have all that anticipation pent up only to find your creation lacking. My experiments with Lowther DX-3's eventually ended up with me selling them. Also when I bought the Hawthorn Silver Iris' I found them a little lacking in the bottom end, tho the addition of the augies more than fixed that issue.

Rick
 
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