AVS Forum banner

41 - 60 of 132 Posts

·
Registered
Joined
·
507 Posts
The "While Supplies Last!" part of the offer leads me to believe this is a clearance sale, and they are hoping to sell out and be done with it. I can't imagine them reordering more of these from their supplier.

.
 

·
Registered
Joined
·
3,655 Posts
Discussion Starter #43 (Edited)
.....What about dynamic range? Many of the Mstar boxes seem to perform poorly when faced with strong signals, even on non-adjacent channels. Does the CM-7004 do any better?
I have two adjacent channel combinations, 45/46 and 16/17.



In order to produce strong signals for testing, I had to connect some preamps in series. I tried this first:
Ant > CM7777HD-30dB > CM7777HD-17dB > Variable Attenuator > CM3410-15dB > 4-way splitter for 7004, Sony TV, and Sadelco Signal Level Meter

This setup didn't behave well when I adjusted the attenuator; the second 7777HD was being overloaded by the first 7777HD. I then reduced the gain of the first 7777HD and increased the gain of the second 7777HD. The CM3410 is the last, because it can tolerate strong signals.

Ant > CM7777HD-17dB > CM7777HD-30dB > Variable Attenuator > CM3410-15dB > 4-way splitter for 7004, Sony TV, and Sadelco SLM

I increased the gain as much as I dared to protect the Sony KDL32R400A tuner:

Channel 46: 40.6 dBmV = -8.2 dBm input to tuner
Channel 45: 23.3 dBmV = -25.5 dBm input to tuner

Reception was good on both channels.

Channel 16: 36.1 dBmV = -12.7 dBm
Channel 17: 15.1 dBmV = -33.7 dBm

This is as high as I could increase the signals and still have good reception; any higher, and the reception was bad. The Sony showed pixelation; the 7004 picture freeze. This point was the same for both tuners; the 7004 did just as well as the Sony with this adjacent pair. This pair probably didn't do as well because of multipath.

My report shows some weaker channels that could be used for dynamic range tests, but they are too weak for my tuner to pick up with my present indoor antenna.



Maybe WSKY 9 and WGBS 11 because a friend asked me if he would be able to receive them, or a weak UHF channel.

 

Attachments

·
Registered
Joined
·
7,446 Posts
That's good info.

I don't have the equipment to do precise measurements, but I do have some tough situations. Check out RF 19 vs. RF 20, RF 34 vs. RF 35, and RF 38 vs. RF 39: http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id=9038d370f389a5

I'll have to give my new $56.50 investment a spin and see how it does on those. FWIW, RF 20 and RF 34 come in well on most of my tuners, but Channel Master's DVR+ has the only tuner I own that can lock RF 38 reliably.

RF 24 vs. RF 25 is also tough, though it doesn't appear so on TVFool because they haven't gotten the memo on KXAS/5's move from RF 41 to RF 24 yet.
 

·
Registered
Joined
·
3,655 Posts
Discussion Starter #45 (Edited)
Those are tough pairs. I think you are doing very well. I don't know what antenna you are using (with or without a preamp), and I'm not sure where you have it mounted, but I do see a gap between the trees at the NW and the trees at the SW for 227 to 232 degrees.





RF 24 vs. RF 25 is also tough, though it doesn't appear so on TVFool because they haven't gotten the memo on KXAS/5's move from RF 41 to RF 24 yet.
TVFool doesn't have enough staff to make corrections; they are running on "autopilot."

According to ATSC, a tuner should be able to decode a channel that is no more than 33 dB weaker than a stronger adjacent channel. Note that the maximum allowed difference is only 20 dB for a stronger pair as I did above at my location.

 

Attachments

·
Registered
Joined
·
1,833 Posts
The tuner sensitivity is surprisingly good. I have an indoor antenna on the ground floor, with trees and buildings in the signal path. I used two of my best signals and attenuated them to dropout. The 7004 was just as good as my Sony KDL32R400A on channel 40 and slightly better than the Sony on 13.

All three outputs of the 7004 work; RF, composite, and HDMI.

Equipment setup:

Ant > RCA TVPRAMP1R Preamp > Power Inserter > Variable Attenuator > 4-Way Splitter for 7004, TV, and Sadelco DisplayMax 800 Signal Level Meter (SLM).

There was a second preamp added between the splitter and the SLM to increase the sensitivity of the SLM, because it doesn't read below -20 dBmV in the single channel scan mode.

Channel 40:
Dropout at -39.2 dBmV = -88.2 dBm, 7004 signal quality < 20 %

Channel 13:
Dropout at -38.4 dBmV = -87.4 dBm for the Sony
Dropout at -39.3 dBmV = -88.3 dBm for the 7004, signal quality < 34%

For both channels, the Sony dropped out below 15 dB SNR, but the 7004 shows different readings for signal quality at dropout. The 7004 SQ doesn't have a good correlation with SNR, but it does give a useful relative reading. My guess is that the Sony SNR is actually MER; it would be difficult to read the noise in a channel being used.

The higher 7004 CH13 SQ at dropout suggests that it has been inflated by multipath reflections, which are common with indoor antennas. I quote Dr. Bendov from his paper DTV Coverage and Service Prediction, Measurement and Performance Indices:



My indoor antenna only has a folded dipole for channel 13. My first location for the antenna was near the dresser, but the antenna needed a VHF reflector added to the dipole to reject multipath reflections for good reception. (It would not decode without a reflector; see my avatar at the left.) The best location for the antenna was, of course, in the middle of the room in a high traffic area. The signal was stronger and a VHF reflector was not needed. The present antenna is in the corner of the bedroom without a VHF reflector. The ability to handle multipath reflections well would seem to be useful in Mexico, where indoor antennas are often used.





There is usually a chair in front of the antenna to hide the 5 gal Home Depot paint bucket which contains old magazines as weights.
@rabbit73 Base on on your testing I ordered a 7004. If the tuner is as good as Sony then I’d be pretty happy with that.
 

·
Registered
Joined
·
3,655 Posts
Discussion Starter #47
@rabbit73 Base on on your testing I ordered a 7004. If the tuner is as good as Sony then I’d be pretty happy with that.
I hope they send you a good one; if not, return it.

After you test it, please tell us how well it works for you and how you are using it.
 

·
Registered
Joined
·
507 Posts
The "While Supplies Last!" part of the offer leads me to believe this is a clearance sale, and they are hoping to sell out and be done with it. I can't imagine them reordering more of these from their supplier.

.





It's past 7/18 and they are still on sale.

.
 

Attachments

·
Registered
Joined
·
7,446 Posts
IDK what happened but USPS refused to deliver mine yesterday. Got this message on their tracking page:
Unable to deliver item, problem with address
GARLAND, TX 75043
USPS was unable to deliver your item as of 4:20 pm on July 18, 2018 in GARLAND, TX 75043. The address may be incorrect, incomplete, or illegible.
I checked the order I placed with CM; the address is correct. I don't have any problems receiving mail or other merchandise at my address.
 

·
Registered
Joined
·
3,655 Posts
Discussion Starter #51 (Edited)
Good one? What should I look for?
Manufacturing quality control isn't perfect; sometimes a lemon slips through. If it doesn't do what it is supposed to do, it isn't a good one. If you bought it from Channel Master, they will accept returns. Generally, companies that have a generous return policy, charge a little more for their products, like Channel Master and Antennas Direct.

Third party sellers on Amazon and Walmart usually don't have return policies as good as the primary seller, if you read the reviews of the third party sellers.

What do you hope the 7004 will do for you?
 
  • Like
Reactions: keeper

·
Registered
Joined
·
3,655 Posts
Discussion Starter #52 (Edited)
IDK what happened but USPS refused to deliver mine yesterday. Got this message on their tracking page:I checked the order I placed with CM; the address is correct. I don't have any problems receiving mail or other merchandise at my address.
That's odd.

Sometimes FedEx will deliver my package to another address. Sometimes USPS will say unable to deliver when it was getting late and the carrier wanted to deliver it the next day.

Some companies that are trying to save on shipping costs, start the shipment with one carrier and then it is transferred to USPS to make the final delivery. What does the tracking history show?
 

·
Registered
Joined
·
1,833 Posts
Manufacturing quality control isn't perfect; sometimes a lemon slips through. If it doesn't do what it is supposed to do, it isn't a good one. If you bought it from Channel Master, they will accept returns. Generally, companies that have a generous return policy, charge a little more for their products, like Channel Master and Antennas Direct.

Third party sellers on Amazon and Walmart usually don't have return policies as good as the primary seller, if you read the reviews of the third party sellers.

What do you hope the 7004 will do for you?
Just looking for a better tuner. Have Dish but they have a software issue with ota channels on their hopper. Been a year and haven’t been fixed. Tried hdhomerun and it appears to be flaky with Vhf channels. Tried another same deal. Signal goes up and down. This doesn’t happen on my other tuners. The best tuner I tried is in my Sony tv. So I am glad to hear that this is similair in performance.
 

·
Registered
Joined
·
7,446 Posts
The gods did NOT want me to get this box

That's odd.

Sometimes USPS will say unable to deliver when it was getting late and the carrier wanted to deliver it the next day.
That may be what happened. USPS delivered it today.

So I went out my front door to pick it up, and while I was looking at the shipping label, trying (and failing) to see if there was any reason they had trouble delivering it, I got stung by a wasp. Twice!

Right next to my right eye, too. Good thing I wear glasses! So naturally, I dropped the box, my glasses, and my glass of Dr. Pepper (soaking my glasses with sugary goo - my wife made a mistake and didn't get my usual diet soda this week).

Luckily I have a pair of prescription sunglasses, and it was still daytime. So it was off to the store to get some Hot Shot, then back to find and spray the nest, pick up my glasses, clean them off, and finally bring the box inside.

Most expensive $56.50 I've ever spent.
 

·
Registered
Joined
·
3,655 Posts
Discussion Starter #55 (Edited)
Just looking for a better tuner. Have Dish but they have a software issue with ota channels on their hopper. Been a year and haven’t been fixed. Tried hdhomerun and it appears to be flaky with Vhf channels. Tried another same deal. Signal goes up and down. This doesn’t happen on my other tuners. The best tuner I tried is in my Sony tv. So I am glad to hear that this is similair in performance.
Chances are good that the 7004 will improve your reception.

OTA signals constantly vary in strength. I have a marginal channel 9. My indoor antenna only has a folded dipole for VHF-High. The strength will vary about 5 dB in a short period of time with the SNR going from 14 to 19 dB; dropout to good reception. This evening I added a temporary reflector behind the dipole giving me a few dB more gain. My VHF-High noise level is quite high from electrical interference, with the signal barely above it, so a little more gain really helps the SNR.
 

·
Registered
Joined
·
3,655 Posts
Discussion Starter #56 (Edited)
So I went out my front door to pick it up, and while I was looking at the shipping label, trying (and failing) to see if there was any reason they had trouble delivering it, I got stung by a wasp. Twice!

Right next to my right eye, too. Good thing I wear glasses! So naturally, I dropped the box, my glasses, and my glass of Dr. Pepper (soaking my glasses with sugary goo - my wife made a mistake and didn't get my usual diet soda this week).

Most expensive $56.50 I've ever spent.
What a disaster.

Thank you for sharing your story with us.

The gods did NOT want me to get this box
That does seem to be the message.

The message they sent to me was that the box went on sale just after I bought mine.
 

·
Registered
Joined
·
453 Posts
That may be what happened. USPS delivered it today.

So I went out my front door to pick it up, and while I was looking at the shipping label, trying (and failing) to see if there was any reason they had trouble delivering it, I got stung by a wasp. Twice!

Right next to my right eye, too. Good thing I wear glasses! So naturally, I dropped the box, my glasses, and my glass of Dr. Pepper (soaking my glasses with sugary goo - my wife made a mistake and didn't get my usual diet soda this week).

Luckily I have a pair of prescription sunglasses, and it was still daytime. So it was off to the store to get some Hot Shot, then back to find and spray the nest, pick up my glasses, clean them off, and finally bring the box inside.

Most expensive $56.50 I've ever spent.
With your luck, the box will wind up being defective.

Nice cherry on top of your sundae to top off your miserable day. :D
 

·
Registered
Joined
·
7,446 Posts
I finally got it hooked up. Several random observations:


  • The remote is the same as the DVR+ "enhanced" remote, but it's programmed to send different codes. My DVR+ didn't respond at all when I tried to use the remote with it. Edit: That turned out to be wrong - the remote does send the same codes as the DVR+ "enhanced" remote and can indeed control a DVR+. Don't know why it didn't seem to work when I first tried it. (However, as noted on the DVR+ thread, the remote can be reprogrammed easily with a PC, a JP1 cable, and some free software.)
  • (Good) The initial channel scan starts at the first setup question (language) and runs in parallel with you answering the setup questions, so by the time you get through the setup, several channels have already been scanned and you don't have to wait quite as long for the scan to finish.
  • (Good) So far, it seems to be compatible with the Stellar Labs ATSC RF modulator (model 33-11980). That's good news because a lot of tuners aren't.
  • (Bad, but like the DVR+) Unlike Mstar boxes, the volume and mute buttons don't do anything unless you set up the remote to control your TV.
  • (Good) As you know, it has a grid-style channel guide. When you pull it up, the box starts scanning the visible channels to fill it out. As you move through the guide with the cursor keys (bad: page up/down doesn't work) it fills out the stations you page to.
  • (Bad, slightly) It doesn't update the guide when in standby and not recording. Thus, after it has been off for a while, you'll need to wait for the guide to fill back in the next time you access it.
  • Interestingly, the RF output has a "loop through" notation that the box doesn't support. This makes me think the case was designed for an Mstar box, although I haven't yet found an Mstar box with the same case. (The HW-180 and Terk are close.) I'll keep looking, though....
  • (Bad) If your USB drive isn't FAT32 format, you have to fix that on a PC. Unlike Mstar, it won't format over another existing format (such as NTFS). That may be intended to protect against accidentally erasing something important, but it isn't very convenient. (BTW, Windows 7 doesn't offer FAT32 as a formatting option for a 128GB partition - only NTFS and exFAT are offered! I had to use MiniTool's Partition Wizard to get FAT32.)
  • (Bad) Once you format the drive as FAT32, it starts "initializing" as soon as you plug it in. Not sure what "initializing" does but with a 128GB drive it takes quite a while. (A progress bar would have been nice, CM!) My guess is that it zeros all data sectors to maximize flash writing speed. Edit: That guess couldn't possibly have been right - I had to zero my data sectors on a PC to get remotely adequate performance from my flash drive. Anyway, you can still watch TV, access the guide, and lock/unlock channels while this is being done, but you can't access the settings menu until it finishes! Edit 2: I don't know why I didn't see a progress bar the first time, but I just tried it again (to see if a different FAT32 formatting program would improve recording performance - it didn't) and I got a progress bar this time. It was strangely uneven, though; especially when it got to 90% and just sat there for several minutes, before finally jumping to 100% and saying it was done.
  • (Good) Unlike Mstar boxes, you can manually set the date & time. It also supports both 12-hour and 24-hour time formats; a feature that has appeared in Mstar boxes only recently.
  • (Good) It seems to display the first I-frame it receives, then "freezes" the picture until it gets a second I-frame and can start playing video. Other tuners usually don't show anything until they get that second I-frame. This makes channel surfing seem more responsive than with other tuners.
  • (Bad, slightly) The channel scan produced a few anomalies. In DFW, KODF is virtual channel 26 on RF channel 27. Channel 26.1 came up correctly, but 26.2 through 26.5 came up as 27.2 through 27.5. Thing is, I also have KDFI, which is virtual channel 27.1 through 27.5! So there are several apparent duplicates in my guide. For example, I have two 27.2's; one from KODF and one from KDFI.
  • (Bad, slightly) Also, for some reason, if a channel label has seven characters, it's followed by an eighth character, which always seems to be the ASCII character equivalent of the virtual channel number! So for example, my 33.n subchannels have an '!' after their names. Obviously no big deal; just kind of weird-looking.
  • (Bad) After doing a channel scan, it's very easy to accidentally start another channel scan if you go back into the Settings menu. And once it starts, it's too late: everything is gone and you just have to let it rescan everything again. Best practice is probably, after doing a channel scan, carefully go back into settings and move the cursor up to a less destructive option.
  • (Bad) There doesn't seem to be a way to delete or hide unwanted channels. Nor does there seem to be any way to add a new channel later (without going through a full scan again), rename channels, or flag "favorites." (Mstar boxes can do all of these.) This was my biggest complaint with CM's original HD tuner, the CM-7001. It was inexcusable then and even more inexcusable now. Modern digital TV offers a plethora of OTA channels, but I don't want to have to muddle through a lot of shopping and foreign-language channels when I surf.

    But at least there's a workaround: the CM-7004 can lock out unwanted channels with parental controls. Channel up/down then skips them. They don't disappear from the guide, but they are replaced with the word "LOCK." Trying to tune a "locked" channel just brings up the message "channel locked." Oddly, it doesn't ask for the pass code; I guess if you did want to watch, you'd have to go to the lock menu and manually unlock the channel first.

    Edit: I just discovered a problem with this workaround. If you rescan, the locked channels remain locked, and channel up/down still skips them, but they no longer appear in the guide with the word "LOCK," and you can tune them from the guide, without even entering the password!
In summary, so far I've found some good things and some bad things, but for the most part, the bad things are pretty typical for an under-$50 box. I got my money's worth (ignoring the delivery issues and wasp stings) but am glad I waited for the price to drop. Here are a few things it doesn't have, and that I wouldn't necessarily expect for $49 but would for $89, given that many Mstar boxes have these features:


  • RF pass-through
  • Component video & coaxial digital audio outputs (would need a bigger case though)
  • Front-panel channel display (to be fair, I've only seen one Mstar box that does this right)
  • Media player function (plug in a USB drive with videos/photos/.MP3s and play them)
 

·
Registered
Joined
·
1,833 Posts
Chances are good that the 7004 will improve your reception.

OTA signals constantly vary in strength. I have a marginal channel 9. My indoor antenna only has a folded dipole for VHF-High. The strength will vary about 5 dB in a short period of time with the SNR going from 14 to 19 dB; dropout to good reception. This evening I added a temporary reflector behind the dipole giving me a few dB more gain. My VHF-High noise level is quite high from electrical interference, with the signal barely above it, so a little more gain really helps the SNR.
Yeah I can watch what is happening through the Sony diagnostic screen. Snr varies like you say but the hdhomerun box flat out drops in the danger zone every few seconds while my other tuners hold steady. This is signal quality I’m referring to. The tech for them couldn’t figure it out and they sent a new box. Same thing. We tried everything from removing the amp to just using vhf. No change at all. In my opinion my network has something to do with it.

The pic I added is an example of about 30 seconds. I have no preamp as I took it off to see if things changed- wjz didn’t. It’s the same pattern for hours and days and never improves even when conditions improve. Again my other tuners hold steady. There does seem to be a pattern to what I’m seeing so I would assume it’s some kind of interference with the networked box. If I switched the cable to my Sony tv or even Dish the signal would be steady pretty much and in the superior range. It’s early morning and these signals are strong. In day to day use even with Dish I do occasionally get breakups with these channels but mostly they are pretty good. I can go hours without seeing an issue.

I get the 7004 tomorrow and will report my findings.
 

Attachments

·
Registered
Joined
·
7,446 Posts
That sort of pattern - signal strength good but quality varying rapidly - is typical of multipath interference. It can be pretty weird, hitting some stations and not others. Tuners also vary greatly in their ability to handle it, which may explain why it's only a problem on that one station and only with the HDHR.

The "ultimate" solution is to replace or at least reorient the antenna, but that's not always practical, especially if different stations are in different directions from your home (say, DC and Baltimore stations). And it can be pretty tedious to move the antenna, scan through all the stations looking for problems, move it a little more, etc.
 
41 - 60 of 132 Posts
Top