Amplifiers and Speaker Impedance – Rules to Live By

About the Author: Ryan Rockwood is an Electrical Engineer who works in the design lab at Yorkville Sound (parent company of Traynor and VTC). He has been playing guitar for most of his life and has been tinkering with the electronics associated with guitars since he was a teenager. You can submit suggestions or requests for blog articles to guitar.amp.ryan at gmail dot com.

Amplifiers and Speaker Impedance

Ok, so you’re a guitar (or bass) player, and you’re thinking about getting an amplifier head. Or you already have one, but you’re thinking about getting a second speaker cab to hook up to it. That’s awesome, but you should know a little bit about impedance first.

What is Impedance?

Impedance is a measurement of how hard an amplifier has to work to drive a particular load (load is a tech term that refers to your speakers in this case). The lower the impedance, the harder your amp has to work.

You may have noticed on your speaker cabs that they say something like 4Ω or 8Ω (that symbol means Ohms). That’s the impedance of your cab. Some cabs even have selectable impedances via a switch or based on which jack you hook up to.

You may also have noticed that your amp’s speaker jacks have an impedance rating. That’s because your amp has a limit on the range of impedances it can drive without blowing up.

How to Not Blow Up Your Speaker Cabinet

First, there’s a rule that I’m going to ask you to follow: If you’re going to use more than one speaker cabinet, use cabinets with the same rated impedance.

This ‘rule’ can be broken safely, but it’s much easier to follow it than it is to do all the math you need to do to break it. Trust me.

So, if you follow my rule, here’s the punch line: divide the impedance of your cabs by the number of cabs you’re connecting to your amp, and that’s the total impedance your amp will see.

So, two 8Ω cabs means a 4Ω (8÷2) load to your amp, four 16Ω cabs means a 4Ω (16÷4) load, and so on and so forth. This can be extended to any number of cabinets at any impedance as long as they’re all the same impedance as each other.

Also, keep in mind that if your amp is a combo, the internal speakers should be counted as a speaker cabinet when you’re working out your total impedance. Unless, that is, you plan on disconnecting them…

Great! I’m Ready to Rock!

Not so fast. What about the power ratings of your cabs? If you’ve followed the rule about matched impedance cabs, then each cabinet gets an equal amount of power from your amp.

So all you’ve got to do is divide the power rating of your amp by the number of cabs you’re running. For example, with a 100W amp and two cabs, each cab gets 50W. If each cab is rated for 50W or more, you’re good to go. If either of them is rated for less than 50W, then it’s bye-bye speakers!

The Outputs on Your Amp

If the back of your amp looks something like the above picture, and you have two 8Ω cabs, how would you hook it up?

You would have a total impedance of 4Ω (8÷2), so you should hook up to the jacks in the 4Ω group. If you connected two 4Ω cabs to the 4Ω jacks, you would have a total load of 2Ω, and you could damage your amp, your speakers, or worst of all, both.

You should also know that you should NEVER connect to multiple groups of output jacks on a tube amp. Use ONLY one set at a time, or even more bad stuff could happen.

Tubes vs. Solid State

If you have a tube amp, you should ONLY connect the rated load to the amplifier. With some amps, it may be safe to connect a higher impedance to a lower impedance output, but I can’t guarantee this. If you want to do this for, you should consult with the manufacturer of your amp.

On the other hand, if you’ve got a solid state amp, you can hook up a higher impedance cab to a lower impedance output, (i.e. 8Ω cab hooked up to a 4Ω output). Solid state amps should be perfectly OK with this. The catch when you do this is that your amp won’t put out as much power as it would into the rated impedance. You’ll get the best performance from your amp if you use a matched impedance.

One Last Thing

I think I’ve covered everything a beginner needs to know, but I’m not perfect and I may have left something out. If you still have any questions, please post them in the comments below. I’ll try to check back frequently and answer any questions that come up. If you decide you’d like to learn more, or if you feel that you need to break one of the “rules” I’ve outlined above, I would suggest that you start by learning a bit about Ohm’s Law and a few other basic electronics principles. A great place to get started with all that is here.

RJD2 is Commissioner Crotchbuttons

RJD2 has been spicing up his stage show with his controller wielding alter ego Commissioner Crotchbuttons. He found a make shift way to turn a Korg padKONTROL into a wireless midi controller using an M-Audio MIDAIR Wireless Midi Transmitter and a 9 volt battery pack. Check out his breakdown below on how he put it all together. Seems like a fun way to engage the crowd and the spin feature also gets a good reaction:

M-Audio Speaker Review

ProAudioStar blogger Sam checked in again with his take on M-Audio’s entry level speaker. We don’t stock the AV-40 right now but those interested in what M-Audio has to offer should check out the BX5a and BX8a deluxe editions. Here’s what sam had to say about the AV’s, given his take on this entry level edition the upgrade to the BX series is sure to blow you away.

I had a chance to try out the M Audio Studiophile AV 40 Speakers a couple days ago. All I have to say is that I am blown away (pun totally intended). They are incredible monitors. I paid around $150 for the monitors and they were worth every penny. I have been using Ableton to produce music and I needed great monitors to give me an accurate read of my music. I live in an area where it is easy for my neighbors to hear music if I play it too loudly, so I needed speakers that had great sound quality but would not disturb the neighbors. The M Audio Studiophile AV 40 provide exactly what I need.

The speaker setup was quite easy to set up. Speaker wires were already included with the box including an 1/8″ to RCA cable. The 1/8″ cable is very sensitive, so it is important to be sure that you have it plugged in securely and not move your laptop around or else the sound will become distorted. Also included in the box was a manual on how to properly set up the monitors. Instead of including a boring manual, a more of a comic style manual was included. It was easy to read and understand.

The speakers are also lightweight and easy to carry to different locations. This is very convenient for me as I tend to use my computer both in my bedroom and living room. I can now easily transition between both locations without worrying about lugging a large setup with me.

Overall, the M Audio Studiophile AV 40 Speakers are phenomenal speakers. I would recommend them to anyone who needs a small monitor setup to give them accurate sound for producing. If you own an actual music studio, these speakers may not be powerful enough for you. You should look into the M Audio BX5A Deluxe or M Audio BX8A Deluxe if you are looking for a more powerful monitor speakers. I hope you have enjoyed this review, now it is time for me to get back to producing. Happy mixing!

Hitting the street with the Korg Monotron

Korg’s Monotron pocket synth has been getting a lot of buzz among hand held music fans, circuit benders, and analog synth enthusiasts.  This updated take on the stylophone from days of old features a velocity controlled oscillator, a velocity controlled filter, and a low frequency oscillator that can mod either the pitch of the oscillator or the cutoff of the filter. If that sounds like a foreign language to you never fear, the Monotron is an easy and fun way to get familiar with what these basic circuits do. The “keyboard” is a ribbon controller that’s very responsive to touch with either your finger or a pointed object like the tip of a pen cap. The on board speaker and battery power make this unit a fun take anywhere noise maker.  What excites synth fanatics most about this unit though is the eighth inch input that lets you pass any audio source through the Monotron’s filter. According to Korg they use the same filter in this unit that’s in their classic MS-20 synthesizer meaning you can add that classic filter to any sound.

Check out our video above to see the Monotron and it’s oscillators and filter in action in the street and in our warehouse. Many people have taken to moding and circuit bending their Monotrons. Check out the clip below to see Korg’s showcase of some Japanese benders fun with the Monotron:

Grandfather: How to Record and Release an Album in 7 Days (with Steve Albini)

We are really proud to bring you an update on a band really close to our hearts – Grandfather. Mike Kirsch, the band’s guitarist, used to work in here for us at ProAudioStar and is now hitting the road touring behind Grandfather’s debut album – recorded with Steve Albini (Pixies, Nirvana).

You may have also read his classic, still-relevant early 90’s article The Problem with Music an extra popular piece about the state of the music industry, it’s a read if you haven’t checked it out.)

Grandfather has been getting a lot of buzz lately. Both for their their amazing music (download their album at the Grandfather Website) and for the innovative way they are going about releasing their album. Steve Albini just mentioned them in his recent interview with GQ magazine when they asked him “Is there a young artist with integrity who inspires you today?”

I have an unusual perspective in that I make records every day for a living. I see a lot of bands on a weekly basis. I see little
bits and pieces of behavior that are encouraging. There was a band that came into the studio a while back called Grandfather. They were an art rock band that organized the funding of their record through Kickstarter. They were really well rehearsed and came into the studio and knocked the record out in a couple of days. Because they didn’t have a record label or any promotion schedule to adhere to, they were able to get their record manufactured and distributed within a couple of months. That’s the kind of nimble, efficient behavior that was previously impossible when there was a corporate structure involved. It gives me confidence other bands will figure it out. The last time Shellac put out a record, we finished it in June 2006. It wasn’t actually in the stores until June of the following year. It took an entire calendar year for that record to inch its way through the production, manufacturing and distribution steps and get into the store. I’m impressed when I see bands taking advantage of these efficiencies that we’re allowed now. That’s something that gives me great confidence about the way bands are going to function in the future.

Read More

Their album “Why I’d Try” is currently available in high quality audio formats for free online downloads. They are also selling a limited edition run of 12″ vinyl of Why I’d Try with awesome artwork from Brooklyn artist Kendra Elliot.

A while back we post about their Kickstarter page which they used to raise the funds to press their vinyl. This was a great way to have their fans pre-order the album so the costs of the pressing didn’t come out of their own pockets. We definitely recommend checking out if you haven’t yet – it’s an exceptionally simple yet far reaching platform.

To promote their album Mike took to popular gear forums to document and outline their entire recording process with Steve Albini. Their forum thread has become one of the most popular of the year on the popular site

Gearslutz. (Check out the Grandfather thread on Gearslutz here.). The band goes into details of mic placement, and how they approached the recording. This type of documentation is extremely fascinating for all the gear heads out there. It’s amazing to get a peek on such a micro level of Steve Albini’s recording process. To top it off Albini himself even left some posts in their thread. This helped them to find a bunch of fans who were excited to buy their vinyl to hear it for themselves.

Additionally, the back story behind their decision to record with a professional engineer also adds intrigue to their album. For about a year they were attempting to record and mix their album on their own. However, because Grandfather’s sound is so stripped down – guitar, bass, drums, and vocals and with minmal electronic effects – getting a great raw recording was paramount. They played around in Logic for a while, never quite being satisfied with the results. They even tried outsourcing the mix to some freelancers, but again the results were not what their music needed.

The members of Grandfather decided to basically sell all their worldly possessions and go for broke by dropping every last nickel they had on the chance to record with Albini in his studio in Chicago. Once they got the funds together Mike gave us his two weeks notice, and we said goodbye to him as he set off to finally get his band’s debut record completed.

I must say we were all impressed with the balls it took to do this. If the album didn’t come out well it would be like throwing everything away. But, I think they made the right choice because their record really does sound great.

With only 3 days to record with Albini Grandfather opted to record each track ‘live’, meaning one take to get it right. Also, because they were recording to tape there wasn’t room to do tons of takes. The pressure was on. Luckily they devoted months to intense rehearsal and their preparation paid off. Five of the nine tracks on the album were recording in just one take – amazing, really.

If you interested in learning more about their recording process, Mike has a featured 4 part blog series over at Sonic Scoop:
Part I
Part II

Part III and IV are coming soon. This series is a seriously great read.

Needless to say we are super proud of a ProAudioStar alumni doing great things in the music world. We really like Grandfather’s methodology and approach to releasing music as a new band. It is an inspiring and great model for other bands to follow. Be sure to check out their music. You should like Grandfather’s Facebook Page. Whether you like their music or not following their progress as a band will certainly be very educational.

Some Grandfather treats below….

Grandfather – AWOL (Live in Williamsburg) from Big Ass Lens on Vimeo.

Loop Station World Championships

The Boss RC-50 Loop Station may be the most capable loop pedal on the market. It’s no wonder it’s developed it’s own cult following of users that go way beyond it’s roots as guitar player. I posted a video of Cut Chemist using one of these a few weeks go but have since stumbled on an entire slew of videos entered in Boss’s Loop Station Championship. Entries in this year’s contest were submitted via YouTube and the finalists will be performing October 23, 2010, at 6:00 PM at Musicians Institute (MI Concert Hall) in Hollywood, CA. Not sure what the judging criteria will be like but will the multiple formats of talent shows on primetime TV now one can only imagine. Seems like a pretty open format though and cool idea for a contest.  You can see the 6 finalist from the US at the Boss US contest page and above are some of last year’s finalists from the UK (couldn’t find any from last year in the US). Not surprised to see Dub FX in there his street busking video on YouTube is classic at this point. Wonder if he won:

Dicer Giveway Week 2 Roundup

Only 2 weeks left in our Dicer giveaway and some more great photos on our wall this week. Here are thre e that caught my eye. Winner will be drawn on Nov. 3rd but check out these setups in the meantime!

This setup from Matt Longoria also known as DJ Scramble.  Nice use of compact space with a Project Mix I/O rig and lots of controller options at your fingertips.  Launchpad, Maschine, X1, nanoKontrol, LPD8, Oxygen and Axiom so much stuff!

DJ Wildchild Jimmy Mathews has a nice little DJ commune for him and his roommates with Techs, PDX’s, Ecler mixers and NS7 all at the ready.  Nice mood lighting as well.

This setup looks pretty fun.  I imagine most of this stuff gets broken down and brought to the gig but what better way to store it then as a mini arena rock setup for your laptop! Carry on Kyle Cochran.

Two more weeks to hit us up on Facebook.  Upload your photos!!!

Mono Bags In Stock!

A lot of new stuff came in this week so space is at a premium in the warehouse.  We wanted to showcase the Mono bags we got so we packed up some controllers and camera gear and headed up to the roof.  Couldn’t have been easier to tote everything up there in the Mono bags themselves.  These bags have plenty of space for gear, but are still comfortable to wear and not too big or sloppy looking.

We paired up some of our popular controllers with each shoulder bag and backpack in the Mono line. These bags will also swallow your laptop, interface, headphones, and vinyl as each bag has pockets with those accessories in mind. Check out the video above for the full scoop. To get really in depth we’ve also got a flickr set with some nice detailed photos below. These are in stock now and moving fast so give us a ring if you’ve been thinking about getting your hands on one.  For the full line up and colors we have check our Mono product page.

UPDATE:  Mono has a breakdown of all the EFX series bags with dimensions and what they will and will not fit at this link!

VoiceLive Touch video with Shane Grace Allen and Chango

We linked up with Shane Allen to demo the VoiceLive Touch after seeing her perform in Brooklyn and catching her solo performances on the LES. We asked if she’d give the Voicelive Touch a try.  She’d been working on some new tracks with her Turkuaz bandmate Mike Haziza and as soon as they got their hands on the VoiceLive Touch it inspired them to write an entirely new track under the project name “Chango.”

It was really impressive to watch Mike lay down a beatbox and backing vocals for Shane to sing and perform over. Watching Shane sing the verses and change her effects on the fly while playing piano really proved this pedal is effortless to use. This one small unit definitely does a lot and the touch screen makes the effects of the VoiceLive Touch all the more accessible and responsive.

It was great to get an in depth preview of this pedal before it’s release and thanks again to Shane and Mike for showing us what they’ve been up to with the VoiceLive Touch. We’ll have the VoiceLive touch for sale on our website as soon as it’s available so be sure to check back often for purchase and ship dates. If you really can’t wait to get your hands on this unit call us for a deal on a pre-order.

VCI-300 MKII In Depth Review

Welcome ProAudioStar customer Sam to the blog.  He’s been blogging his thoughts on the getting started in the DJ game at Dazemusic but I asked if we could syndicate some of his content here and he was happy to contribute!  Sam is a turntable/serato guy but was looking for a more portable solution for some of his mobile gigs.  He picked up a VCI-300 MKII from us a few weeks ago and I was curious about his thoughts.  Here’s his in depth review reblogged from his wordpress:

So, I have finally taken the plunge. After nearly a year of research and overanalyzing Youtube videos and DJ forums, I have finally purchased the VCI 300 MKII. I have been using two Vestax PDX-2000 Turntables along with a TTM56 mixer and Shure M44-7 cartridges, but I wanted a smaller setup to take to venues without having to take a while to set up. I also live in a city where it is hard to park close to the venue where I am DJ’ing.

Before purchasing the VCI 300 MKII, my biggest issue was deciding between the MKII and the NS7 performance controller. The NS7 is an amazing piece of DJ equipment. The problem with the NS7 for me, however, was the size of the controller. The NS7 is a large, hard to carry performance controller. It however felt better in my hands overall when I compared it to the VCI 300 controller, when I tested the two controllers back in January.

When I heard about the release of the VCI 300 MKII a couple months ago, I knew Vestax would make changes that would improve the controller. I am not going to talk about all of the features and changes between the MKI and the MKII as they are listed all over the Internet. I am just going to speak about the main differences I noticed as a DJ.

One of the things that bothered me about the original VCI 300 MKI controller was that the overall feel of the controller did not feel very good when I was using it to scratch. Something seemed a little off when I tried scratching with it. I always felt a delay or lag when I used it. I realized my DJ skills may not have been up to par and there could be other DJ’s online who had no problem with scratching on the controller. It was because of this that I searched the Internet for every VCI 300 scratch video I could find. It seemed other DJ’s had the same issue. I even found a forum that went through a long methodology about how to eliminate the lag that involved opening the VCI 300 and inserting a couple screws into the mixer board.

I was hoping this issue would be fixed in the VCI 300 MKII, and from all of my testing thus far, it works great. It has a much better feel than the original VCI 300. The mixer seems much improved to me, as are the control platters. I had to take a bit of time to calibrate the settings to find the right feel for my style of DJ’ing. On the previous version of the VCI 300, a screwdriver had to be used to calibrate the settings. I never tried doing this, and I do acknowledge that I may have had the same feel for the previous model had I altered the settings. However, there are  implications of using the previous model if I am spinning with another DJ. If that DJ has a different feel of the control platters and needs to alter the settings, I’d have to take a screwdriver with me everywhere I go. Now, it is much simpler as this can be controlled with knobs.

The mixer itself is also something incredible. All of my mixes flow together well. The options for Auto-Gain, the adjustable settings for the crossfader and upfader really do make my mixes come together very well. As for the software itself, it is amazing. I love being able to pick songs straight from the controller without having to touch my computer. The ease of creating cue points straight from the controller is also great.

Overall, I am extremely happy with my purchase of the VCI 300 MKII. Vestax made adjustments that are important to my style of DJ’ing. I play mainly hip hop music, and scratching is important. Having the ability to scratch while carrying around a portable item is important. From my testing of both the VCI 300 MKI and the VCI 300 MKII I honestly do feel a bit of a difference between the two controllers. Last Thursday I received my VCI 300 MKII in the mail, and I DJ’ed an event with it the next day. Everything worked perfectly fine, as I was  able to do what I would normally be able to do on my normal setup with the VCI 300 MKII.

I will still practice on my turntables and mixer and translate those skills to the VCI 300 MKII when I use it for gigs. I will not be taking my VCI 300 MKII to a DJ Battle and attempt to win with it, however, it is a great controller for me to take to events and still have most of the abilities I would have with my usual DJ setup. If you are a DJ looking for a great controller that is portable, look no further, the VCI 300 MKII is the way to go.

Thanks again Sam for this insight.  We’ll be hearing more from him on gear and general DJ techniques here on our blog but to follow him on the daily be sure to check out Dazemusic.  If you’ve got any interest in contributing these kinds of reviews or other articles to our blog be sure to give me a shout I’m always looking for good writers!