1) The first step is to find out your real your internet download speed. I prefer speedtest.net (speedguide.net and dslreports.com are other places to test). This figure is usually slower than your internet provider says. The result will normally be reported in Mbps (Mega bits per second).
JDownloader and most other programs report in KBps (Killo Bytes per second). To convert the speed test number to KBps, divide by 8 (convert to Bytes) and multiply by 1024 (convert from Mega to Killo). Call this D.
Suppose you have an average DSL connection and your download speed test result ix 1.28 Mbps download speed. This results in D=164 KBps.
2) The second step is to estimate the download speed of your most important sites. Let us suppose that you are a free user on Rapidshare, Hotfile, and MegaUpload. Set JDownloader to Max.Con.=1 and Max.Dls.=1. Download a large file show from each site and divide the size of the file by the number of seconds it took to download the file (exclude the time it says "Connecting" or the time for extracting. A movie is a good test file.
Suppose the files is 700 MB. If it takes approximately 7150 seconds to download, then you take 700*1024 KB and divide it by the number of seconds. This comes to 100.25 KBps. Average this for your most important hosts (assume this is the average). We will call this H. H=KBytes downloaded/seconds to download.
Depending on the host, H for free users could range from 1 KBps to 160 KBps. For a Premium user, H ranges from about 200 to 1000 KBps.
3) Your connection capacity C is your total download speed D divided by your speed from a host H. In this example, we get 164 KBps/100.25 KBps = 1.64
This means that the total number of connections should be limited to 2. If Max.Con. is 1, then Max.Dls can be 2. Max.Con.=2 with Max.Dls.=1 is not recommended.
If you have a top speed DSL connection (4Mbps gross) and your speed test result is 3.723 Mbps (this is close to the maximum). D=476.5 K Bytes per second. If the download speed from the hosts is the same, C = 4.75. Your optimum download speed is Max.Con.=1, Max.Dls.=5. You can reduce your speed per connection to about 1/2 of the maximum without worrying about disconnection and other bad outcomes (but it is not optimal). In this case, you could have Max.Con.=2, Max.Dls=5 or Max.Con=3, Max.Dls=3.
If you are a premium user with a maximum host speed H=400 KBps, then your settings should probably be Max.Con.=1, Max.Dls.=2.
If you have a medium speed cable connection that tests as 9.325 Mbps, Your download speed is D = 1193.6 if the 100.25 Host rate is unchanged, C=11.9. You could use Max.Con.=3 and Max.Dls.=4 or Max.Con.=4 and Max.Dls=3 or Max.Con.=2 and Max.Dls=6.
But if you have a good cable connection, you will probably pay for a premium account. If H=400 KBps then C= 2.984 which we can round to 3. Thus, it is optimal to have Max.Con.=1 and Max.Dls=3. Max.Con=2 and Max.Dls.=2 is not a bad choice.
If you have a "Full Channel Capacity" cable connection, and it tests at 40.0 Mbps, so D=5120 KBps. With a premium host download per connection H=400, then C=12.8. Max.Con.=4 and Max.Dls=3 would work well. Max.Con=2 and Max.Dls=4 could be used. Max.Con.=5 and Max.Dls=3 would also work well. Max.Con.=7 and Max.Dls=2 is reasonable. Max.Con. could be up to 20 with this kind of internet connection. It just slows the speed of each download connection.
In summary:
Code:
C = Speed Test
Host Speed
And generally, keep Max.Con. low unless you have a very fast connection.
Download accelerators such as FlashGet or Down Them All generally use a Max.Con. of 4 and Max.Dls.=2 or 3. This C'=12 is generally safe for download speeds D > 600KBps, but it wastes as much as 10% of your download capacity in overhead.
In general, these are optimal settings:
Code:
Sample Download Speed D
C Max.Con. at H=400KBps
<6 1 <2400 KBps or 18.75 Mbps
<9 1 or 2 <3600 KBps or 28.125 Mbps
<12 1, 2, or 3 <4800 KBps or 37.5 Mbps (max. for Cable)
<16 2, 3, or 4 <6400 KBps or 50 Mbps (Needs Fiber)
<24 3, 4, or 5 <9600 KBps or 75 Mbps
<48 4, 5, 6, or 7 <19200 KBps or 150 Mbps
Max.Dls. is C/Max.Con. rounded up.