FAQs
Room and furnishing
What can I do with acoustic modules by HOFA?
HOFA acoustic modules are suited for improving the acoustics of any room. Whether in professional recording studios or ambitious project studios, rehearsal rooms, home cinemas or HiFi rooms – the fexible concept of using frames in conjunction with perfectly aligned modules makes it easy to optimize the sound in all rooms.
Are the modules suited for any room, notwithstanding its size and geometry?
Yes. Due to the pricinple of modules in frames our modules can be used in every room. Quantity and type are determined by the room and its usage. For example, well-directed selection and positioning can compensate for acoustic asymmetries and so make for the best possible “listening situation”.
I rent and am not allowed to make modifications in the rooms. Is it possible to use HOFA acoustic modules anyway?
Yes. The basstraps can be placed on the floor without further fastening.
The HOFA Mobile Wall presents an alternative and flexible solution for the installation of our diffusors and absorbers without any alterations of the room’s walls.
I want to use my room both as a recording room (guitar, vocals, drums …) and as control room for mixing and mastering. What can I do?
Recording and control rooms differ considerably regarding their reverberation time and the placement of acoustic modules. Using your space as an outstanding recording room but also as a dry control room is only possible with interchangeable elements. This concept is the main idea behind our system of frames with demountable modules.
How many modules do I need for my room in order to achieve an improvement?
The quantity of modules is determined by the room’s size and shape, the materials of walls, ceiling and floor, the furniture and the usage of the room and also your individual preferences.
For instance, a room with 5 m x 4 m x 2,5 m, concrete walls and ceiling and a laminate floor can be fitted with the following modules:
Control room with a reverberation time of 0.3 sec: 12 basstraps + 22 absorbers + 22 diffusors
HiFi room / home cinema with a reverberation time of 0.5 sec: 6 basstraps + 10 absorbers + 16 diffusors
Rehearsal room / recording room with a reverberation time of 0.7 sec: 4 basstraps + 8 absorbers + 12 diffusors
As a guideline you can assume 1 module per m³ for control rooms and 0.5 modules per m³ for rehearsal rooms.
In which way should my room be furnished to get the most pleasant sound?
It’s our experience that organic materials make for the warmest and most pleasant sound. Parquet and cork floor as well as wooden ceilings and walls are suited best for good acoustics. Plain concrete walls and glass surfaces on the other hand reflect sound and are therefore not advisable.
The furnishing affects the dispersion of soundwaves in the room and consequently the quality of the sound. Bookshelves for instance make for a diffusion of sound, a sofa is absorbing sound energy. A systematic improvement of acoustics though can only be achieved with combined specific acoustic modules.
Acoustic Curtains
What is the difference between the HOFA Acoustic Curtains “STUDIO” and “ISO” and which is the right one for me?
We decided to design two kinds of curtains, so we can treat every acoustic problem more precisely.
The HOFA Acoustic Curtain “STUDIO” is designed to reach maximum absorption. Manufactured of extra heavy fabric, the absorption – unlike regular curtains – works very effectively far into the low mid-range frequencies. It is used in cases where a maximum possible linear absorption is required, for example in recording studios, control rooms, recording rooms or home theaters. Also for living rooms where it is very reverberant, it can provide a calming of the room’s acoustics.
The HOFA Acoustic Curtain “ISO” combines sound absorption and sound insulation. Two layers of heavy acoustic material enable efficient absorption of high and mid frequencies. In addition, an acoustic impermeable foil is incorporated in order to enhance the sound insulation. Due to its internal structure, the curtain can be used as acoustic isolation for front doors, doorways, stairways or windows.
Which curtain variant is right for me?
The STUDIO and ISO product ranges are available in different variants to meet different requirements.
The absorption of STUDIO acoustic curtains is related to the number of layers of fabric used. The STUDIO 2 acoustic curtain is an inexpensive yet effective alternative to conventional curtains, which usually have little acoustic effect.
In the case of ISO acoustic curtains, the sound insulation achieved also depends on the number of layers used – however, here an alternating combination of fabric and sound insulation foil is used. The ISO 7 acoustic curtain provides the peace and quiet required for particularly loud ambient noise. However, the ISO 3 acoustic curtain should be used on ceiling constructions with a low load capacity or wherever space is at a premium. The ISO 5 acoustic curtain offers an attractive intermediate solution.
Our ISO sound insulation curtains are a sensible and inexpensive alternative to structural measures.
Which maximum absorption coefficient can the HOFA Acoustic Curtain reach?
HOFA Acoustic Curtains are made of multiple layers and extra heavy quality. Sound absorption therefore already start at about 150 Hz. At 500 Hz, a STUDIO curtain with a gathering of 1,5 (orange line) already absorbs more than 80 % of the sound energy.
What are the delivery times and production times?
The production time is usually 7-8 working days after the order is placed. The delivery time is approximately 1-2 working days within Germany. Don’t hesitate to contact us concerning worldwide delivery times.
Is a mounting system included?
A mounting system is not included in delivery. The choice of a suitable mounting system is often dependent on many factors, so we’d rather give you personal advice. You are most welcome to contact us:
akustik@hofa.de or by phone: +49 7251 3472-400
Can the HOFA Acoustic Curtain be helpful to isolate noise from outside, for example street noise?
Yes it can be helpful, but: street noise is usually a very wideband noise mixture. It includes high, mid-range and sometimes very low frequencies, for example buses or trucks passing by. In the mid and high frequency range, the HOFA Acoustic Curtain works very effectively. For physical reasons it is not possible to achieve an effective insulation in the low end. So it depends on the exact nature of the (street) noise, whether the HOFA Acoustic Curtain is the right approach to improve the acoustics in this case. We would like to talk to you personally on your individual acoustic problem. Feel free to contact us:
akustik@hofa.de or by phone: +49 7251 3472-400
Is it possibile to mount the curtain on “normal” curtain tracks/rods?
Basically this is possible, but you should consider the following:
- Is the installation system of sufficient strength for a curtain of about 5 kg (for custom sizes even more)?
- Do the eyelets fit with the existing hooks?
How can the HOFA Acoustic Curtain be attached to a wall or a ceiling?
The HOFA Acoustic Curtain can be attached by using the eyelets (diameter 40 mm, every 20 cm, color: silver) on any sufficiently stable curtain rod. The curtain weight in the standard sizes is approximately 5 kg. We can provide eligible mounting systems in individual lengths.
It is also possible to mount the acoustic curtains to a curtain track at the ceiling. In this case, suitable hooks should be used. We can also offer you compatible curtain tracks – feel free to contact us:
akustik@hofa.de or by phone: +49 7251 3472-400
Can I purchase curtains in individual customized sizes?
Yes, custom sizes are possible. We can manufacture precisely for your individual needs in any dimension in height or width. You can create your own curtain easily with the HOFA Acoustic Curtain Configurator.
What is the distance from an eyelet to the upper curtain edge?
The distance between the middle of the eyelet to the upper curtain edge is approximately 5 cm. See the detailed drawing with all relevant dimensions of the curtains in standard size attached:
What is the gathering?
The effect of a curtain can be significantly increased if it is gathered. We recommend a factor of at least 1.5 to 2 for optimal reuslts. To calculate the right size of the acoustic curtain, for example at a window or door, the following equation can be applied:
B (width of the curtain) = b (width of the window or door) x r (gathering = 1.5 to 2)
Are the HOFA Acoustic Curtains washable?
Due to fire protection the curtain is not washable. After cleaning, we can’t guarantee the low flammability according to DIN 4102 B 1, so we do not recommend washing the curtains.
Is it also possible to manufacture the HOFA Acoustic Curtains with a curtain tape?
Yes, there are black and white curtain tapes, which you can order in the Acoustic Curtain Configurator.
Is it possible to obtain fabric samples or color sample cards of the curtains?
Sure, we are glad to send you fabric samples or color patterns. All we need is your postal adress. Feel free to contact us:
akustik@hofa.de or by phone: +49 7251 3472-400
Basstraps
The low end in my room is boomy. What can I do against that?
Rumbling low frequencies often indicate modes: resonances in the room. Remedy can be found in HOFA Basstraps which absorb especially low frequencies and thus stop the booming.
Why should I place basstraps mainly in corners?
Sound is reflected by hard surfaces like ceilings, walls and floors. At an edge between wall and ceiling (or floor), it is reflected twice, in a corner it is reflected even three times. This leads to an increase of sound pressure which is absorbed by the basstraps.
With this fact in mind it is evident that for all resonances in the room – so-called modes – an increased sound pressure level (SPL) can be found in the corners. Thus, placing the basstraps in the corners absorbs energy of all room modes.
Absorbers
I’m currently using pyramid foam in my room. In what way does that make sense?
Pyramid foam and also other thin acoustic foams and carpets are mainly absorbing sound energy in the high frequencies, mid and low frequencies stay unaffected. This leads to a dull and muffled sound of instruments or voices. In addition, the absorption of high frequencies is not balanced what may provoke comb filter effects. In a room with good acoustics all frequencies should be equally present. That’s why our absorbers work in a frequency range from 250 Hz up to the high end. In combination with the absorption of low frequencies by our basstraps you can design your acoustics accurately.
What’s the difference between the HOFA Absorber and the HOFA Absorber ECO?
Concerning the acoustic quality, there is no difference between the both of them. With its extra frame, the Absorber has a more elegant look and fits exactly into the HOFA Frame. Because of its tighter fit we recommend this type if you have to place modules at the ceiling.
Diffusors
Is it advisable to place diffusors behind the speakers?
In most cases it is not recommended to put diffusors behind speakers. It’s common practice to absorb low and mid frequencies behind the speaker in order to avoid annoying direct reflections.
What are the reasons for the design of the HOFA Diffusor?
The division into small squares with different depths makes for a balanced dispersion of soundwaves over a wide frequency range in all directions. For reasons of a better sound, HOFA Diffusors are made of untreated birchwood. This results in a warm and lively sound. For our coloured Diffusors we use wood stain, in order to retain these material characteristics.
Acoustic effect
What are the effects of acoustic modules in my room?
Basstraps and absorbers uniformly reduce the reverberation time in the entire frequency range by linear absorption. This results in a dry and clear ambient sound.
Room modes with a booming low end can be absorbed with HOFA Basstraps. Diffusors disperse direct reflections and create a softer, larger, more lively and homogenous ambience.
What do I have to consider when putting acoustic modules in place?
In general, the positioning of acoustic modules on walls and ceiling can be determined by utilizing a mirror. The mirror should be moved along the walls or ceiling until the speakers can be seen in it from the listening position. This is the ideal position for the most important acoustic modules.
Because of the acoustic reflections on walls, ceilings and floors, basstraps work best when placed in the corners of the room.
The positioning of diffusors and absorbers on ceiling and walls depends on the room’s use. In a recording or rehearsal room a balanced allocation of absorbers and diffusors is likely to come up with the best results.
In control rooms you normally use the “Live End – Dead End (LEDE)” principle. This means: a large amount of absorption behind, above and at the side of the speakers and the listening position in combination with diffusors at the back of the room.
I can hear flutter echoes in my room. How can I get rid of them?
Flutter echoes result from high frequency reflections on plain surfaces. Placing diffusors and/or absorbers on walls and at the ceiling eleminates these flutter echoes.
In which frequency range do HOFA acoustic modules work?
Our basstraps mainly take effect in the range between 60 and 1000 Hz. An increased absorption of frequencies below 60 Hz can be achieved by using several basstraps.
The absorbers take effect between 250 Hz and 20 kHz, the curtains up from 500 Hz. HOFA Diffusors work in the mid range between 700 Hz and 2.2 kHz.
Delivery
How do you send the modules and how fast do you deliver?
In Germany our acoustic modules are delivered with no additional charges via DHL or truckage company.
Costs and delivery times abroad depend on the place and the volume of delivery.
You will see the production and delivery time when you place the selected acoustic modules in the shopping basket.
Do I have the right to return the modules if I’m not content?
We offer a 14-day right of return after receipt of the goods. Customisations, e.g. special curtains, are exempted from this arrangement and can not be returned. The return shipment is at your own expense. Please enclose a copy of the delivery note or invoice for this. As soon as we receive the product, it will be checked for damages. If everything is ok, the purchase price will be refunded.
The modules were damaged in shipment. What should I do?
Please check the modules immediately upon receipt. Even with the best possible packing, shipping damage can not be prevented completely. If you receive obviously damaged goods, you should accept only under reserve or refuse the delivery.
If you spot the damage after unpacking, please take photos and send these with a description by email to: akustik@hofa.de
You will receive free compensation.
