Frequency Response: let’ make it clear (part 2)

Frequency Response: let’ make it clear (part 2)

In the previous article we talked about how sound is composed by a superposition of mechanical waves. These waves have different frequencies and « colour » the sound in different ways. Knowing this, the task of a good sound system is to reproduce these frequencies in a balanced way: playing around with them is the job of musicians and composers, and we don’t want to mess around with their work when we play it for an audience.

The first problem to solve for a sound system maker is that different frequencies require different technical choices. Generally speaking low frequencies are best reproduced by « slowly » moving larger membranes, while high frequencies come out better from smaller and stiffer objects moving « fast ».

There are several ways, mechanical and electronic, to ease this task. In many cases the first approach is to use a transducer for the low and mid/low frequencies, often called woofer, and another one specialized in high and mid/high frequencies. You may hear many different names for this one, corresponding to different technologies, but let’s just call it tweeter for now. When this double approach is used we call it a two way speaker. As of 2020, all Partybag products are two way speakers.

A nice example: Partybag!

In a Partybag 7 for example the rectangular opening on top of the « face » is the tweeter, and reproduces high frequencies, while the large round loudspeaker under it and covered by the grid is the woofer. The electronic board inside, that includes a DSP (Digital Signal Processor), between many other jobs distributes the sound between the two allowing each transducer to work with its favourite frequency range. In this way we make sure that the sum of the two contributions is a clean continuum. In order to get more bass frequencies, that between other things are the ones that put more stress on the battery, the woofer works in synergy with the two circular openings you see next to it. These form a sounding board, kind of like the one you see on a classic guitar, and that configuration is called bass reflex. This is another solution very widely adopted on professional and semi-professional sound systems.

So what about this “Frequency Response”?

In an approximated and very down-to-earth way we can describe the Frequency Response as the measure, often shown in a 2D chart, of how loud a sound system reproduce each frequency or frequency range when given a constant-level input. For example, we can feed a Partybag Mini a sound signal including all the frequencies in a way that no one is louder than the others (something quite horrible to listen at), and then measure the level of the output from our beloved speaker at different frequencies. Ideally we would like for them to be all at the same level, that would mean same level in – same level to your ear for each frequency, in which case the chart would appear flat. But reality is never ideal, and looking at the Frequency Response you can see how much your speaker differs from being acoustically « transparent ». The easiest thing is to just show it, here is our Partybag Mini:

A common way to summarize charts like this is, as we do as well, to declare « Frequency Response (-3dB) 100-20000Hz ». Meaning? That between 100 and 20000Hz there will be not a point on the chart lower than 3dB from the maximum. Hey, that’s not bad at all! Another common way is to talk about the frequency response « +/-3dB », more permissive and so more appreciated by marketing departments.

Unfortunately in advertisements you can find the most bizarre things, and it’s not rare to read vague statements such as « Frequency Response 40-20000Hz » without further specifications: could be +/-6dB, +/-10dB, who knows? It depends on how much the producer has been generous with himself. This is just a quick way to showcase the speaker as extra capable, expecially when it comes to low frequencies: since the line unavoidably falls down in the lower part of the spectrum, using a larger tolerance allows a seller to say « we got extra bass! » and play with the unknowing customer. We are more inclined to use the verb « play » in association with « music », that’s why we are writing this.

What Frequency Response doesn’t say

  • It doesn’t say how the situation will change at different volumes. Ideally it remains the same, but in the real world almost nothing does. By the way, some producers use techniques to increase bass frequencies that only work at low volume. This certainly has a nice effect in some situations, but makes the behaviour of the speaker very different at higher levels such as during an event. We at Partybag prefer to avoid this, because for us « normal » means « at high volume »!
  • It doesn’t say how the speaker will sound when you are not « on axis », so not exactly in front of it. To describe this there are directivity measures, but that’s another story and possibly an idea for more articles. In the Partybag products so far we have tried to privilege wide coverage over long throw, because it fits better their most common usage cases. That’s why we don’t provide as accurate directivity data as the ones you can find, for example, on the datasheet of line array systems for large concerts in stadiums.
  • It doesn’t say how the speaker will interact with the surrounding environment depending on the positioning, on the reflecting surface, on atmospheric conditions such as temperature and humidity.

For these reasons, but also because we believe in our products, what we suggest is to try them hands-on in our shops or even directly in our headquarters, where we are always ready to meet you, answer to your questions and offer you a good Italian coffee. In any case a look at the technical specifications can’t hurt, and we hope these articles can be helpful in giving non experts a better understanding of them.


Frequency Response: let’s make it clear (part 1)

Frequency Response: let’s make it clear (part 1)

Following our previous article « Power, Sound Pressure Level, Let’s make it clear », we’ll now discuss a topic that is mainly related to sound quality but also has many more down to Earth implications. As we said before, we would like our Partybag customers to be well aware and to receive correct information about our products, so we’d like to provide some basic explaination. If you are audio professionals you probably know it all already, but for all the others here we’ll try to talk in simple terms about a property of sound systems that is often « abused » for marketing purposes.

(Yes we do marketing as well, but let’s agree that there are many different ways)

It’s a complex topic so we’ll need two chapters, but don’t be scared, here’s the first.

This « Frequency » thing:

Everybody knows about the colors of the rainbow, those ranging from red to violet. What you see with your eyes is a combination of those colors, appearing in different proportions and mixed in many ways every moment in front of you. In a similar way, when you hear a sound, it’s formed by a sum of many components: as it happens with light, the different mix of those components will define what you will actually perceive.

Both for light and sound these components are waves, in the first case electromagnetic and in the latter mechanical. It’s like sea waves, but with air instead of water, and everything is happening in 3D with the air itself compressing and expanding periodically all around us. This can happen more or less quickly, or better said at different frequencies. Just like the sea surface shape is determined by short, fast ripples overlapping longer, slower waves, the sound we are constantly immersed in is formed by many waves at different frequencies. These frequencies the air around us vibrates to are a bit like the « colors of sound », at least approximately.

How do we distinguish these frequencies then?

Unfortunately in popular culture there are no words as commonly established as « yellow », and for sounds we often speak in vague terms about « low », « medium », « mid-high » frequencies and so on. The best way to describe the audible frequency range is to brutally use the standard unit: the Hertz. One Hertz (1Hz) means « once per second ».

The human ear can generally perceive frequencies between 20Hz, so the air compressing and expanding 20 times per seconds, and 20000Hz, or « 20KHz » (from 1 KiloHertz = 1000 Hertz). However if you are exposed to noise during your workday, if you have a solid clubbing reputation as many good Partybag customers do, or simply if you are above 30 years old, it’s very unlikely you can still hear something above 16000Hz. Too bad. Evolution made us humans expecially sensible to our own voice of course, so the frequencies we hear the best are those typical of human voice, ranging about from 300Hz to 3500Hz this side of Barry White and Janis Joplin.

That’s great but… so?

So the problem we face as sound system manufacturers is a bit like we had to build a screen such as the one you are reading from. The screen manufacturer needs to show you all the colours and with some fidelity, so that a good photo on screen will show the colours as similar as possible to the real life subject in it. Well we have to do about the same! To be fair there are two main problems we face:

  • Building a speaker that is able to play all the frequencies a human being can perceive, or as many as possible.
  • Do that in a balanced way so that some frequencies are not too louder than others, just like in a screen you don’t want for example the blue to be much brighter than the red. If we don’t do that, what you record with a microphone will sound different when played.

In doing so we have to take in account two important differences between light and sound:

  • Sound waves are mechanical, so we need to actually move air and there is no way out from this.
  • The frequency range a human being can hear is very, very large compared to what happens for light (where colors correspond to different frequencies as well but in a different world, the one of electromagnetic radiation). From 20Hz to 20000Hz there is an entire universe, and the techniques used to create and handle the different vibration frequencies can change a lot.

After this much needed introduction, in the next chapter we will explain how you can understand the capability of a sound system when it comes to reproducing the various frequencies that form sounds in a complete and balanced way.

Power, Sound Pressure Level, let’s make it clear

Power, Sound Pressure Level, let’s make it clear

Still in 2019 there is quite some confusion around about all that concerns measuring a speaker output in general. Concepts like « power », « sound pressure level » and similar are very often abused for marketing purposes, and we at Partybag don’t want to do that. We would much like our customers to be informed in an honest way about what they are doing.

We know many of our customers are professionals, but not necessarily in the audio field. The most common case is simply someone who needs a speaker to do whatever he/she likes or needs, and has a right to understand what to expect. So let’s try to explain this in simple terms without becoming too technical. All in all, if you are an audio professional you already know this, so move along! 🙂

Now: how loud is a speaker? There are two ways you can figure that out.

  1. Search for the Sound Pressure Level (SPL) in the specifications. That’s the measure, taken with an instrument called a Sound Level Meter, generally at 1m distance straight in front of the speaker, that is most closely related to what your ear perceives as « loud », and that’s what we like to report in our technical specifications. Compare that with other speakers you know, compare that with a table like this one, get your own idea.
  2. Try it. Try. It. Seriously, there is no better way. In the end it’s you who will use it to do your own thing, it’s not a matter of show-off between different datasheets. And while you are at it, you can get also an idea of the sound quality, that is entirely another story, and in the end figure out if it’s ok for you. So go to one of our shops, come visit us in Reggio Emilia, ask a friend who owns it, that will always be the very best way no matter what.

What about power then? Power is that thing power companies charge you for at the end of the month, and that’s not even so true because they actually charge for energy provided (at least that’s how it works in Italy). Power is an electrical measure, not an acoustical one. A speaker does precisely the job of transforming electrical energy into sound pressure, and it can do that in so many different ways that the « power » figure barely tells you anything about what you are expected to hear. It depends on so many constructive details of the speaker that it’s basically pointless to talk about that unless it’s about power consumption, and by the way in a battery powered speaker you don’t want this to be high, right?

Also, people use tricks and in many cases you read about « peak » power, that doesn’t mean « the power I experience when I listen to techno at maximum volume » but a power that can be substained for a very very short time meaning a few seconds or way less, there is not even a standard. Are you listening to music for a few seconds? We really doubt that, that’s why we use good batteries. The power that makes more sense (but still you could just not care about) is RMS Power. Without too many technical details, it’s an average power that can be substained, and the number is normally a half or even a third or a quarter of the « peak power ». Again, there is not a fixed standard definition for peak power. And yes, music can also include short peaks or bursts, and peak power is also needed, but that’s definitely not the reason you read peak power around, or even just « power » unspecified. It’s just a cheap way to say « hey look I have more power! ».

But wait: isn’t, for example, a 200W speaker louder than a 100W speaker?

As we said before: it depends on how the speaker is designed, on the components, on many factors. But suppose you take two otherwise identical speakers and feed one with 100W and the other with 200W, what will the difference be? The answer is: just 3dB of Sound Pressure Level that means: audible, but just a little. Not so impressive, to be fair. In exchange for what? A much higher stress on the batteries, so either a reduced range or the need for larger batteries, more weight, more waste of space and so on.

Power is basically the last and easy resource you can use to gain some extra Sound Pressure when nothing else works. That’s why at Partybag we don’t take part in the pointless race of showing off a higher power figure, but we focus on efficiency and on the best possible tradeoff between sound pressure, battery duration, light weight and comfort.

In the end don’t mind power, mind SPL. Or even better, test our Partybags yourself! We have nothing to hide.

P.S. there are also other important parameters such as frequency response, directivity… but that’s for another day. Let’s start from the basics and enjoy the next weekend, with Partybag hopefully!

Partybag Staff

Did you say free shipping to USA?

Did you say free shipping to USA?

Yes we did. From now on you can order Partybag 6 and Partybag Mini from our online shop, with free shipping to the US. Check it out! 

As some Partybags are already doing their job around the US on the shoulders of private owners, professional musicians such as Lee England Jr., outdoor/sports groups such as Midnight Runners (Boston, Los Angeles, S.Francisco, New York) and the staff of a big sportswear company like Brooks Running, we decided to make things easier for Partybag enthousiasts across the ocean, and by the way other nations will follow soon!

…and yes, of course in the package you will also find a 110V compatible recharger with US plug, don’t worry, but still the same power, battery range and great Italian design!

More news will follow soon, follow our website or Facebook page to stay in touch!

Partybag Staff

Partybag @AltoFest

What do people do with our Partybag? The artists from AltoFest, for example, use it massively on their festivals around the streets of Naples and Malta, mixing theatre, dance, music and performative arts with the local popular culture and bringing the performances directly inside the locals’ homes and meeting points. Doing this, they turn the cities into real open air laboratories and create situations of cultural exchange and positive contamination. All this with our soundsystems of course, as you can see in this beautiful video:

Renting Partybag: an Italian summer favorite

Renting Partybag: an Italian summer favorite

As summer approaches people are more and more willing to go outside and outdoor events are thriving. From larger scale concerts, sport competitions, arts and literature contests, guided tours of monuments and nature landscapes, to more private but still very enjoyable happenings. Who doesn’t like an outdoor barbecue for example, or a surprise birthday party, or the wedding of a good friend? In all these cases a Partybag may come handy indeed… or even more than one!

Since the very beginning of our activity it has been very clear to us that many events, big or small, very serious or just plain fun, can be made more special with our Partybag, and somebody always required us some Partybag for rent. So we began to provide this service, at first directly and then also through our reseller network, and during the years our products proved themselves to be not just colourful speakers for casual music lovers, but also professional solutions with all the features and the reliability required for an ongoing rental activity.

It quickly became routine for us to provide one, two, 4, even tens of Partybags for a special weekend or more. Marathon events organized by Italian Radio Deejay in Milano and Bari featured massive numbers of Partybags scattered along the track, cultural events promoted by Elastica in the streets of Bologna used Partybags on bikes and carts, student parties and travel/events organized by ScuolaZoo were and still often are powered by Partybags (operating in a harsh testing environment as you can imagine), side events at the latest Formula E Grand Prix in Roma also had Partybags on the back of skaters running around the track.

That’s just a few examples, but even more than these large scale happenings we are proud to help making a huge number of small events special in their own kind: marriage ceremonies and parties featuring wireless Partybag systems, outdoor dance and yoga demonstrations, skate/BMX contests, religious processions and happenings, even a simple barbecue in the countryside can become something different. So many stories, so many different people, a solution for each of them! That’s why in Italy renting a Partybag has become popular and other countries are catching up too.

Do you need to rent a Partybag? Check our Contacts page for the nearest available shop!

Do you have a shop or a rental company for events, big or small? Contact us and join our network of fun providers!

In any case, enjoy the incoming summer!

Back from Frankfurt…

Back from Frankfurt…

Back from the Prolight+Sound we can say for sure that, also for this edition, we have been greeted with a sincere smile by all the visitors passing by our booth thanks to our colours and positive attitude. So we thank everybody: long-distance travellers from China, Australia and South-East Asia, fellow Italians who met us for the first time in a foreign land, audio professionals from India and Africa plus their colleagues from every corner of Europe and America, accomplished musicians like N’Faly Kouyate and Caparezza, less famous players who will be the stars of tomorrow or at least they will have fun trying. It was great to share a good vibe with this great variety of people, it was a challenge we happily took to explain them how our products can fit in their very diverse needs.

We hope to have given them some good idea and to work with many of them in the future, and in any case we hope to keep on making friends. On our side we came back with a lot of interesting contacts of course, but also many ideas, feedbacks and stories that will help us shaping the evolution of our future Partybags and enrich our work and our experience. That’s why, while we wait for the next event, we would like to invite everybody to follow us in our website and social network pages, to stay in touch and up to date with all the news.

See you soon and all the best by Partybag staff!

Partybag: not another throwaway

Partybag: not another throwaway

We at Partybag staff would like to tell you a very important thing about our products, and the way we work in general. Partybag is not one of the many products that beg for your attention before sale just to deteriorate once in your hands, until disposal: we want your Partybag to faithfully work for you for years to come, keep its value as much as possible, extend its life even beyond its original purpose. We don’t want to sell you an object ready to become waste in a few years, but something that can keep on working and evolving.

That’s why Partybag models are realized with resistant and easy to repair materials, with as little plastic as possible, and with simply replaceable components. That’s why we are always ready to help you for any technical problem or special request about your Partybag. That’s also why, even after the warranty has expired, we provide check-ups, repairs and upgrade at excellent prices, and we can also give you a fair offer to swap your old Partybag for a newer model.

We know that on the market there are many « disposable » products for very low prices, and we know that money is always a delicate subject, but we also want you to know that your Partybag has a long term value, and that the landfills in our only and beloved planet are just too full to keep on filling them with waste.

Partybag @ Prolight & Sound 2019 – Frankfurt

Partybag @ Prolight & Sound 2019 – Frankfurt

Partybag staff is happy to invite you, as usual this time of the year, at the Prolight & Sound in Frankfurt, the most important European exhibition for professional audio, lighting systems and stage gear.

You can find us from 2nd to 5th of April in Hall 8, Booth C94, to have a chat with us, drink a good Italian coffee, taste some Parmigiano-Reggiano cheese from our home land but most of all try our products and find out what’s new from Partybag!  We’ll be waiting for you.



Partybag 6 Bass Test

In this video, Diego Onorato presents the sound of the portable wearable speaker Partybag 6.
First with an handmade electric bass of Nicola di Leo, then with a contrabass Gewa with Fisherman pickups.

The audio is been recordered with a cardioid microphone (Shure 55SH SII).

Special thanks to Luthier Nicola Di Leo for hosting us in his atelier in Giampaolo Orsini Street, Florence.

Here is the video: