JieTu HMI

Earlier several posters mentioned the coollights CDM (like HMI fesnel).
I know Richard sells the 70 and 150 watt versions and I've been really tempted to buy these but have hesitated because I'm worried about audio and buzz coming from the coollights ballast. Would appreciate any responses about this kit in real life applications like drama narrative or interviews.
edit: sorry if I'm off topic but it seemed like a good thread to ask this question
 
Well, there's a screw missing on the igniter cover. I don't know what else might be substandard in construction?

As for the CDM150 -- it does buzz. It buzzes less when it's warmed up, but it buzzes at the start (well, to be fair, mine does, but mine is one of the first ones he sold, so I don't know if later models are any different). It's not terribly loud, but you definitely wouldn't want the mic near the light. Get it ten feet away and it'll probably be silent.
 
Hmmm ... thanks for the info Barry.
Does anyone know if the Richards 70 w CDM is quieter than the 150?
also Richard if you are on this thread can you comment whether your newer CDM's are quieter than the first ones you sold?

edit: I'm looking to buy a hard light daylight where the unit can operate inside a 12' x 15' room where audio is being recorded (or I keep renting arri hmi's)
 
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A sound blanket on the ballast would take care of any noise from it. But there's a little buzz from the head. It's really pretty minor though.
 
You know how the buzz you get from a fridge in an adjoining room really shows on an audio track.
Would you describe it as similar or way less?
 
I haven't noticed any sound from my recently purchased 150 W CDM fresnel, but so far, I've only used it from a fair distance in a very large room. I'll have a chance to turn it on in my office tomorrow and will listen more carefully.

- Greg
 
J Davis said:
You know how the buzz you get from a fridge in an adjoining room really shows on an audio track.
Would you describe it as similar or way less?
Click to expand...

It makes no difference whatsoever. I've done shots where the 150 was about four or five feet away from the mic and it didn't pick anything up.
 
Why would you buy one of these things when you can find good used Arri's, LTM's or Sunrays for the same price. They are silent and built like tanks?
 
phudsontx said:
Why would you buy one of these things when you can find good used Arri's, LTM's or Sunrays for the same price. They are silent and built like tanks?
Click to expand...

"Built like a tank" can be a disadvantage when you're literally a one man operation and must move all your own equipment from office, to car, to location and back again for every shoot.

- Greg
 
All metal halide under electronic ballasts will make some noise. Some head noise and some ballast noise. Head noise comes from the bulbs which were perhaps never made to be driven under the higher frequencies of electronic ballasts so there is a bit of resonance. Some bulbs of same type but different brands may be noisier than others.

The ballast may make noise in terms of the transformers inside and that will be sometimes like a very small low frequency buzz. Some ballasts have fans that are loud, we have avoided fans as much as possible and certainly loud ones. The higher the wattage the more the noise. So the 70w will be one small noise level, the 150w a bit more. A 400w CDM I have been working on for ages is still another noise level, etc.

I think people do the trick of covering the ballast if its a problem but the later models have had less noise than the earlier ones and I have also noticed that they make less noise at 220v than at 110v. If the cord is long enough you can put it in the other room, etc. No shortage of ways to fix the issues if you really want to. Not much can be done about it at the electronics and bulb level though.

In pro environments, people have realized that when sound is a potential problem they may use a magnetic ballast or one that's capable of lowering the frequency like our 575/1200 because its all based around frequency and wattage. Lower to 50 or 60 hz and the noise goes down dramatically, but you have to pay more attention to potential flicker at that point. Dim the light using the integral dimmer and the noise goes down even more.

When flicker prevention is of utmost importance you definitely go to an electronic ballast and you find ways around the sound issues so you can drive at the higher frequencies.
 
The responses in this thread have me reassured. Will order 2x 70CDM soon from you Richard.
edit:
just ordered!
 
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I will say Richard does make fine products unlike many of his Chinese counterparts. Additionally Richard is ALWAYS available to help with any questions or concerns. Truly one of the rare manufactures you can talk to one on one.
 
Richard,
Do you have any plans to sell your ballasts separately? I have a great 575 deSisti head and cable, but the ballast is dead. I know of another nice 1200 head I can pick up from a buddy but I don't want the monster mag ballast. I am sure I am not alone in this need.
 
We've never figured out all the warranty and support issues for selling the ballasts separately. For example, not every head will work with our ballast and require a new ignitor to be compatible. Who would change that out and how would we be sure they are qualified. And what happens if the ballast has an issue while using with another head/ignitor that seems to be compatible. For now, given that we have to provide warranty and service its been simpler to just sell them in sets as the behavior is predictable and more easy to guarantee.
 
Richard,
Good to know. Thanks for the fast reply. I was in touch with Galaxy and they have some that are compatble,but with HMIs it is always a matter of $. Cheers.
 
Hi everyone,

I know this topic is old, but I found it when I was searching for informations about thoses chinese arri looking like HMI.
Feedback from Barry Green convinced me to go and try this 1200w unit.
Until know, it works perfectly fine. I was so afraid about build quality because I do own a lot of equipment from north american manufacturers, japanese manufacturers, european manufacturers, and chinese manufacturers and all the problems I have were from chinese no name products.
This 1200w will never last long if you rent it. But if you take care of it and use it for personal use, It should be just fine.
I haven't tested the unit for long operating hours, but only for few short shoots.
Bulb provided is just unusable indoor because it produces too much high frequency noise.
Just by a Phillips MSR or Osram HMI and noise wiil be gone.
Ballast makes fan noise. If you want to use it indoor while working with boom operator, which is 90% of my work, the only way is to get a longer cable to head.
There's no other way. Put it in a different room and it's ok !
Overall I'm really happy with it. For this price, it is a must buy.
Hope this help.
 
boyadjy, how much did you end up buying it for?

Richard (if you find your way back in here) - i too would be interested in your ballasts (with my LTMs).
 
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