DIY Simple laptop Karaoke system

Posted by Aleksey on Dec 26, 2013 in Audio

My in-laws asked me to research Karaoke players for them. There were some hidden nuances. The system should be able to work for Russian songs, and should also score the participants. I looked at several multi-format players online including Vocopro, but since I never used any of them, I had no idea if they would work with different Karaoke formats. The disks are so last century anyway. What can I do using software and online sources only? After some research, I came up with a solution that uses pretty much any laptop/desktop, a hardware mixer, and your regular home theater components like a receiver and a TV. Here is what I have done.


The most interesting part of the whole system is a audio mixer. It has to combine the audio from a mic or two, mix it with the Karaoke audio stream coming out of the laptop, feed it to the amplifier (home theater receiver), and also feed the voice only signal back to the laptop for scoring. That last part puzzled me, because I could not find any useful guides online. I came to the conclusion that I would need an audio mixer with 2 buses in order to route the voice signal separately. Here is the mixer I chose, Behringer Xenyx 802. I bought it on Craigslist for $40:



I bought a cheap dynamic microphone at Bestbuy for $15 or so. Keep in mind that this mic would not work as a computer mic well. It would need a pre-amp or something like that. It’s not a problem for this setup, because the mixer has a built-in pre-amp. It comes with 1/4″ (6.35mm) mono connector, which is what’s needed for connecting it to the mixer:



For my testing purpose, I used Creative D200 speaker with 3.5mm audio jack as an input. The home theater receiver will need a different type of connection, such as 2 RCA audio jacks. Here is my speaker for testing:



Any laptop or desktop with a soundcard should work fine, but there is a trick if you use a laptop. Many new laptops have an audio output combined with a microphone input in one socket. This is what’s in my Macbook Pro 13″ laptop. It requires a special adapter to split it into 2 different female sockets. I decided to use an HP laptop with a line out socket and a separate one for microphone only.


Big Screen TV

A large TV is good for parties, but isn’t strictly required, because you can use a laptop screen just fine. However, it’s more fun to have a big screen hooked up. If you know how to connect a TV to your laptop, it’s not any different in this case. I used an RGB video connection to hook up an LCD TV, and configured the laptop to mirror displays. An HDMI or another connection should work fine, as long as it doesn’t disable the audio output. It may happen if you use an HDMI cable.

Cables and Adapters

I used several cables and adapters to wire the mixer to the computer and speakers. Here is a stereo 3.5mm male to a stereo 1/4″ male cable (using adapter):


here is a stereo 3.5mm male on one end and two mono 1/4″ male plugs on the other end (you may notice RCA adapters, because it’s what I had in stock):


Here is effectively the same cable, but without extra RCA adapters:


Wiring steps

1) Connect speakers to the mixer

I used a wire with two 1/4″ mono plugs on one side and 3.5″ stereo plug on the other side. Make sure to set all level knobs to the minimum. At this point, I think it’s okay to power the mixer, because I want to monitor the sound, but some people may say it’s not a good idea yet. I’ve done it anyway. I used the main output to wire the speaker:


2) Connect the mic

I connected the mic to the line 1 like that:


At this point it’s a good idea to get the audio level tested. Add some volume to the main output, and to the mic’s level. Say “check, 1, 2, 3″ until you are happy with what you get from the speakers. Don’t forget about the on/off switch on the mic, it should be on now.

3) Connect an audio output line from the laptop to the mixer

I used a cable with 3.5mm plug on one side and two mono 1/4″ plug on the other side to connect the laptop output to the line 3/4 in the mixer:


Now, you can play any song on the laptop (use any music player, I will tell you about Karaoke software later) and adjust mixer levels to make it sound good using the level knob for the line 3/4 in the mixer. Make sure you can still hear the voice if you say “check” into the mic. You may need to adjust the mic’s gain knob, level 1, level 3/4, and main level knobs to get a decent result.

4) Connect the FX output from the mixer to the microphone input in the laptop

This is the tricky part that I could not find explained online much. In order for Karaoke software to score singers, it needs to get an audio feed from the mic back to the laptop. That’s why I used the mixer with 2 buses. I want to split the voice only audio coming  from the microphone(s), and send it to the computer and to the speakers at the same time. The Xenyx 802 is one of the cheapest mixers that has a simple routing option for this task. I used the FX output to send the voice signal using a cable with a stereo 1/4″ plug to connect to the mixer’s FX out, and 3.5mm plug to connect to the microphone input in the laptop. See that greenish cable below:


5) Test the FX audio feed

Now, you should be able to turn the FX knob on the mic’s line in the mixer to produce audio feed that will go back to the laptop. You may use system setting in the operating system on your laptop to verify that the audio is getting into the laptop. Her is an example of the screen I used on a Windows 7 machine:

Fullscreen capture 12262013 32621 PM


Now the whole system should look like this:



Karaoke Software

I haven’t tried a lot of software Karaoke packages. I looked at a few and selected two of them to test: KaraokeParty.com for my US/English needs, and Karaoke.ru for my Russian friends. I haven’t tested these sites for malware. The Russian one might have tried some suspicious port scans, but I did not have time to deal with that, and just ignored it for now. Use them at your own risk.

Here is a screenshot of a song. The scoring is working, it’s low, because of my vocal skills, but the system should be working fine:

Fullscreen capture 12262013 34057 PM


Keep in mind that if you decide to record your voice and music at the same time, you should mix the FX music or record using the main output.

Next steps:

- You may use the second microphone to sing a duet. I may try a condenser mic to see how much difference it makes. The dynamic one was awesome at a very noisy party, because it picked up the singer’s voice perfectly, and filtered out ambient noises.

- I plan to get an adapter that I can use with my Macbook Pro. I have to buy one online, because I could not find it at any local stores. Here it is:





Colorado GiveCamp – pros and cons of using Orchard CMS

Posted by Aleksey on Apr 28, 2013 in Software Development

We tried to use Orchard CMS in the Colorado GiveCamp Boulder 2013. Here are quick notes of the pros and cons that we identified:

- It’s .NET based that we hoped would be easy to customize with the skills we had
- Easy install on DiscountASP.com
- Easy to configure membership features for users
- Open source license, free

- Difficult to find free responsive modern themes
- Some plugins are only available in one flavor, not many options

- Not as popular as WP, not as much information online


I ditched cable TV

Posted by Aleksey on Oct 2, 2010 in Uncategorized

I tried to ditch cable TV a couple of times, but I kept going back for different reasons. I am trying it again now. This time, I got a few more tools at my disposal:

  • Channel Master DVR and HDTV antenna
  • Netflix on Wii
  • iPad with VLC, and ABC players

I don’t watch a lot of sports, but my wife and I like TV series, and shows such as “all you can dance”, or whatever the right name is. We also want to make it pretty simple to record and watch shows. A home theater PC (or Mac) would probably work, but in order to make it simple, it would either be expensive or require accessories, and it still would not be perfect in my experience. For example, if you watch ABC shows online, you get them 1 day delayed, and if you do it on a Windows based PC, the ads seem to turn off the full-screen mode. That’s why I started looking for HDTV over the air. Here is what I got for that:

Channel Master CM-7000PAL DVR (detailed information)

It’s just like your cable/satellite DVR, but it receives HDTV signal from an antenna. It’s free, and it doesn’t require subscription like TiVo. Why would I pay $12/mo for a TiVo subscription just to get a few air channels? I am a happy camper so far. The CM DVR works as advertised. I got a dozen or so local channels including PBS, ABC, CBS, FOX and etc. You can see what channels you can get on antennaweb.org

CM-2016 digital HDTV antenna (detailed information)

This seems to be a good antenna, I tried a cheaper and simpler one. It worked, but it did not seem to have a super reliable reception.

Netflix streaming on Nintendo Wii

I bought a Wii console when it came out a few years ago. It can now be used to stream Netflix videos, which is working fine. It may not have super HD quality, but it’s enough to watch movies that don’t rely on special effects only. Netflix has a decent collection of movies that can be watched instantly. My daughter loves it, because there are a lot of cartoons. They don’t have annoying ads either. It bothers me when the networks push their commercials even during shows for toddlers.

iPad and etc.

The ABC app is cool! In fact, I think it’s better than what they have online, because it seems to have fewer problems with ads and full-screen mode (at least in my experience). My wife keeps catching up with Grey’s anatomy episodes. There is also VLC player for iPad. It allows you to upload your AVI’s/etc and watch them on iPad – very nice.

That’s all. Nothing super fancy, but very doable on a budget.

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Agilizing my house remodeling

Posted by Aleksey on Sep 30, 2010 in Agile

My wife and I bought a house recently. Considering that it’s almost 2 decades old, it’s not in a bad shape. An inspector found a few problems and recommended that if we remodel anything, we should start and finish one thing completely so we can enjoy it. Isn’t it just like WIP limit to me? Well, should I come up with a backlog then? As a home owner, I can remodel my master bathroom, so I don’t have a problem with tile in the shower, and I can enjoy the new modern design.

We decided to do it, and completed our first remodeling story a couple of weeks ago. We love and enjoy our new simple and stylish bathroom design!

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My iPad Crashlog

Posted by Aleksey on Jul 14, 2010 in Software Development, Web

I’ve had my iPad for a couple of months now. Somehow, before I got it, I had Utopian expectations about the AppStore apps. I thought they would never crash, or leak memory. Wrong, while the iPad platform is impressive, the apps are still written by humans, and they crash! They die silently, not a blue screen of death, not an exception window, nothing. You’d have to dig up the crash log in Xcode to get a report. I counted about 14-15 different apps that crashed on my iPad since I got it:

Air Hockey Gold
B&N eReader
Gaia Lite
Lose It!
LowMemory (not an app)
MobileSafari (oops!)
mediaserverd (is it a built in one)
The most annoying one was Foursquare, it kept crashing and it was hard to figure out how to make it to work at some point. I should have given up on Foursquare altogether.
What is the root cause? I am not talking about the root cause for the specific issues, I am talking about general quality. I think it could be iPhone Gold Rush symptoms. The developers rush to release their apps, they cut the corners, you know, the usual death-march development issue. Apple, despite their very long approval process, simply cannot be the last-resort QA authority.
Hey iPhone and iPad app developers, please test your apps. Run the Memory Leaks detection in your Xcode, use some (or better a ton of)  automated tests, do it now!

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Camping with iPad, Part 3

Posted by Aleksey on Jun 27, 2010 in Uncategorized

According to the spec, iPad has a magnetometer (digital compass) sensor. I did not have much time to calibrate Magnetometer compass app that I had downloaded before the trip. For some reason, it did not seem to work properly, or I was not patient enough to figure it out. Anyway, we did not really need it.

By the way, another interesting app is  uPackingList (free, iPhone version only). It seems to to be either for the total bean-counters or for someone who is going on a long trip and needs to get everything perfectly right. Not me. Hence, I played with it, but did not use it.

Finally, there seems to be a useful app – Gia Gps Lite (free, iPad version). It worked well. I am not an expert user of the topo maps, but this one seems to be pretty intuitive. It allows to take a snapshot of the area in advance so you can use it offline. It show real time GPS coordinates, and provides a reasonably good bearing. I wish it allowed copying or saving the current coordinates. I could not figure out how to do that and had to retype it manually to send them to friends

To summarize my short overview of a few apps, here is the list:

  • Gia Gps Lite (free, iPad version)
  • MagnetMeter (free for now, iPad version)
  • Waze (free, iPad version)
  • built-in maps app
  • uPackingList (free, iPhone version only)

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Camping with iPad, Part 2

Posted by Aleksey on Jun 21, 2010 in Uncategorized

I came back from a really good camping trip. My brain is kind of resetting now, but I want to write about a few navigation tips that I learned. On my way to the camp site, I used the stock Google Maps app that comes pre-installed on iPad, and also used free Waze app. I have been using Waze for a few weeks now, and I like it, but it needs to mature a bit more. It helped me to see ahead a traffic jam near Berthoud on I-25. The information was pretty accurate, and I even reported an accident to the Waze network. I like the Waze’s audio directions and the way they pause music if it’s being played on iPad at the same time.

I also found out that the built-in Google Map does a pretty good job caching map information near your route. It was very handy, because ATT data connection got very spotty after we passed Ft. Collins going North on 287.  One of the problems with the built-in Google Map is that I cannot figure out how to email my route. I wanted to do it the same way as in the regular Web-based Google Maps, but I could not. It sucks, because in my case, I arrived to a point that was not really on the map, so I wanted to use my current location and send the directions to my wife. Not cool.

(to be continued)

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Camping with iPad, Part 1

Posted by Aleksey on Jun 18, 2010 in Uncategorized

Going camping today, yea! It’s been awhile, and I really need to get my tent, and sleeping bags ready. Instead, as a real geek, I am thinking what to upload on my iPad. I got the usual music, videos, podcasts, and a few simple games for my daughter. I hope that covers most of the entertainment. Now, what else do I need to make it useful? I got the stock Maps app, and downloaded Waze awhile ago, but I suspect these apps will be useless offline. A friend of mine is going to setup a radio transmitter with a pretty big antenna (hey, we are not really backpacking, we are car-packing), and he needs a compass to do it properly. I found a free compass app – MagnetMeter. It looks pretty cool, and it seems to work too. Let’s hope it will. Check.

Next, when we find a place to camp, I need to get the GPS coordinates and give them to the rest of the group that is coming later.

(to be continued…)

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The Cleantech Open’s Press Conference in Denver

Posted by Aleksey on Jun 15, 2010 in Green Technology

I attended The Cleantech Open’s Regional Semifinalist Press Conference this morning. It was a pretty official event in an atrium of Wellington Webb municipal building downtown Denver. It’s good to see local companies getting to the semi-finals of the Cleantech Open competition. I was pleased to see a lot of support from the local government too.

Here is a list of the semifinalists from Rocky Mountains region:

DIAL Emissions Monitoring
Go Natural CNG
H.O.T. Water Company
Verdant Earth Technologies

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Security questions

Posted by Aleksey on Jun 7, 2010 in Security, Web

- What was your high school football team’s mascot?

- Hmmm…. first of all, I assume you don’t mean soccer, but let’s ignore that for now. There were no such thing as a football or even any dedicated soccer team in my high school. We did play, and had a lot of teams organized on the fly, but since I was not very athletic kid and sucked at soccer, I did not really participate much. Plus I wore glasses, and it was not a cool thing at that time for sports. Oh, yeah, a mascot…. That would be a super stupid thing to have in my school. We did not even have cheerleaders. How awful? I know, but that just how it was. Can I pick a different security question please?

- What is your sibling’s middle name?

- Great, I do have sibling, but neither of us has a middle name. Wait, we both have a patronymic name that we may use a middle name. Though, I see a couple of problems with that: first, my siblings middle name is the same as mine, and many people can guess it, and second, it’s so hard to spell that even I cannot spell it without making a typo two times in a row. Please please, can I try again?

- What was your first pet’s name?

- Super, I think it’s an easy one. I just need to decide if it was a bird that I barely remember I had when I was 4 years old, or perhaps a semi-domesticated cat my grandma kept at home so it could catch mice. I am not sure I can remember their names though. I can make one up. Yup, that’s a good one. I’ve got an imaginary childhood pet! Done. Sign me up.


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