frequently asked questions

Q: how long will it take for my order to be dispatched ?

A: I try to dispatch orders as soon as possible and try to keep standard length cabled units made up and ready to send. However, at times of high demand or when ordering custom length cabled units, or indeed when I'm mid-way through making a fresh batch of units, do please understand there might be some time between ordering and dispatch. I'm an artist, lecturer, workshop leader and most importantly a father, so there are time when busy elsewhere, I'm away or creating work. Please read the 'important' section on the main page for updates on dispatch schedules.

Q: what methods of payment do you accept ?

A: There are more and more payment platforms now but my advice is that offers the best option in terms of fees and currency conversion rates if you are outside the UK, and indeed also works within the UK. I also accept payment by bank transfer (UK), cheque (UK), paypal etc.  For bank transfers from outside of the UK the costs are often much higher than using a platform like but still possible, remembering that payment must be in UK sterling and any transfer and currency conversion fees must be factored in.

Q: do you use your microphones yourself ?

A: yes. I’ve been involved in the creative exploration of sound for over 30 years and I use contact microphones and hydrophones extensively in my work, some of which you can listen to here and here.  When I began making these units I supplied them only to artists / recordists I knew personally, however a few years ago I started a blog on various aspects of field recording and tested lots of other contact microphones and hydrophones. I was surprised at the disappointing results of lower priced units and knew that the ones I was building would offer better results, and indeed how well they compared to the more expensive models. As more and more people became interested in field recording I heard lots of stories of people not bothering with contact microphones and hydrophones after having trouble with other models on the market, so, I decided to begin selling mine to the public. They are now used by artists, field recordists, musicians, sound designers, aquariums, universities, schools, wetland trusts, film and tv crews, swimming pool technicians all over the world.

you can check out some of my work using my JrF microphones by clicking here

Q: whats the difference between the ‘standard’ and the ‘c-series’ contact microphones ?

A: the main differences are:
. the hand produced element on the c-series is larger, giving a wider frequency response and better definition to the middle and bottom end sounds captured.
. the cable on the c-series is higher spec, with lower handling noise and a more efficient signal transfer to the jack.
. in addition, the c-series are constructed to offer increased durability and sturdiness. . extra coatings of the unique ‘acoustic transfer’ coating have been applied, which further improve the performance of the microphone. (extra cable is available on request at a charge of £3.50 per metre for c-series units and £2.50 for standard units)

Q: whats the difference between the ‘standard‘ and the ‘d-series‘ hydrophones ?

A: the main differences are:
. the hand produced element on the d-series is different and has been specially designed to give a wider frequency response and better definition to the middle and bottom end of sounds captured.
.the cable on the d-series is pro-quality, with lower handling noise and a more efficient signal transfer to the jack.
. the injection-moulded capsule design has been chosen to provide an additional character to the audible range and to assist in the weighting of the unit, which has been designed to suspend itself below the surface in reasonable currents (additional weight can be added by attaching fishing line weights to the cable for example).       
. extra coatings of the unique ‘acoustic transfer’ coating have been applied, increasing the performance of the microphone. (extra cable is available on request at a charge of £3.50 per metre for c & d-series units and £2.50 for standard units)

Q: what is the foam / soft circular dot for on the c-series contact microphones ?

A: this is simply to provide some additional protection to the element when pressing the microphone onto the surface to be recorded. Don't remove it ! NB: the main surface of the contact mic element is on the other side to the dot - it's the 'non-dot' side that should be on the surface to be recorded.

Q: what’s the best way to attach the contact microphones ?

A: I myself use electrical tape. Blu-tak applied directly to the microphone is not ideal as it will leave a residue on the outer coating of the microphone & this could eat into the coatings & affect performance. If you do intend to use it (or other similar putty-style products) wrap some electrical tape around the microphone first.

Q: my recorder has XLR inputs. Why don’t you supply your products with XLR jacks ?

A: as someone who has used and developed this technology over many years I have tried all possible methods to mount this technology directly to XLR jacks without compromising the sound quality or signal stability. In designing reasonably priced units that offer very high quality results the technology used in the elements cannot be mounted to XLR without one of the pins on the jack being hot-wired for example and to do this often leads to background noise and signal instability. It is also important to match the impedance with the recorder and this improves the frequency response (giving much better mid and low frequencies) Therefore, the best results are to use standard 3.5mm or 1/4 inch jacks + an impedance matching adaptor if going to XLR inputs. I myself use a Sound Devices recorder with XLR inputs and use an adaptor to convert the 1/4inch jack units to XLR. The difference in sound quality by using this method is that the mid & low range frequency response has a bit more warmth and definition. I now stock a range of pro-built impedance transforming adaptors and other adaptor cables. Click on the accessories tab on the home page for more info.

Q: are you products compatible with the recorder I use ? and will I need a separate pre-amp ?

A: I've yet to find a recorder they aren't compatible with and for example lots of folks use my products with recorders such as: Sound Devices 702, 722, 744, 788, 442, 633, 644, MixPre, Olympus LS100, LS10, LS11, LS12 etc Fostex FR2le Zoom H2, H4, H4D, H2N, H4N, H5N, H6N Tascam DR100 (mkI - III), DR40, DR680, DR40-wl, 22wl, 44wl, DR60mkII, DR70mkII Sony PCM-D50 Marantz PMD661 Edirol R-44 Korg MR2 Nagra recorders and lots more inc. minidisc recorders You don't need an additional pre-amp in order to get good results and in fact all of the samples on the my soundcloud page were recorded directly into the recorders used without any additional mixers, pre-amps or post production.

Q: what sounds will I hear with a coil pick up ?

A: with these simply devices it’s possible to hear the internal electromagnetic signals of all kinds of everyday items such as radios, tv’s, light switches, computers, mobile phones etc.

Q: it says that you have adapted the coil pick ups - what does this mean ?

A: basically, this technology often has limiters applied in order to prevent them being used for certain surveillance practices. I buy them from the factory and remove the limiters that inhibit certain signals. This means that they are able to capture a wider and more fascinating range of signals.

Q: what is the special ‘acoustic transfer coating’ that you use ?

A: this unique coating basically helps spread any sound captured across the entire surface of the unit, therefore enhancing the performance of the microphones. It's basically a coating similar to one used in sonar technology to assist in the spread of sound impulses. In addition to the other methods I use, this is one of the reasons my microphones offer such amazing results.

Q: why are your contact microphones and hydrophones cheaper than others on the market ?

A: my microphones can compete, in terms of results, with units costing £100’s of pounds but are priced reasonably because, as a passionate listener and field recordist, I believe people should have access to reasonably priced equipment which will also give them results that encourage them to explore further.

Q: are the elements you use made specially ?

A: yes, they are made to certain specifications that offer better results than ‘off the shelf’ elements.

Q: if there’s a problem with any unit I buy from you what can I do ?

A: I always do my best to sort out any issue, no matter how long you’ve owned the item. If the problem is down to damage to the unit I will do my best to repair it for you at cost. If its because of a fault that is obvious on arrival, or shortly after, then it will be repaired or replaced free of charge of course.

Q: what about ethical sourcing of parts ?

A: I spend quite a bit of time researching where the various components I use come from and its fair to say that this is often difficult. I use hand built elements not produced in China and all elements of them are sourced from Europe from manufacturers with high reputations for their standards of production and work conditions etc. The cable I use is produced to a specific design in Europe by a cable manufacturer that usually only supplies audio cable to the installation industry. In short, when buying JrF mics you can be sure that the parts have been sourced in Europe and are not the same as cheaper low quality products.

delivery information;


Please insure you select the correct postage option depending on your location and whether you would like regular postage or the upgraded delivery. 

If for example your address does not have individual letter boxes then please do consider paying for the postage upgrade, as this well assist in minimising the chances of parcel being incorrectly delivered. I cannot be held responsible for parcels sent that do not arrive when incomplete addresses are given or where untracked postage has been used and there is therefore no way to confirm what happened to the parcel. I will of course assist customers in any claim for loss of such a parcel, providing the proof of postage, but any compensation offered by postal companies for regular, untracked parcels is limited to a small amount (£20 here in the UK for example)

If paying by paypal or another platform please monitor the email address associated with it in case there is a need to contact you about your order.

When ordering standard series units please remember to let us know which type of jack (3.5mm or 1/4 inch) you would like on them.

Please understand that we can't be held responsible for delays in sending orders where the incorrect payment has been made or emails about any unclear aspects of the order have not been replied to.

Please supply the correct postal address when placing orders! Every now and then we get an order where a customers old address is linked to the payment account. Please understand that we cannot be held responsible if an order is shipped to a provided address that you no longer have access to.


tips & guidance notes

folks sometimes ask for tips or basic instructions for using contact mics, hydrophones, coils etc. so, here's a page that will be updated from time to time with bits of get in touch if you have specific questions.

hydrophones and contact microphones - a basic guide

input route: with most hand held / entry level audio recorders you have a series of input options:

. mini jack (3.5mm) microphone socket - the recorder supplies plug-in-power to this input. Connecting a single or pair of contact mics or hydrophones to this input with 3.5mm jacks fitted or via a proper adaptor allows for microphones to work as they should via such an input route. An important point here is that if you are using an adaptor make sure it’s not a signal splitting adaptor such as those used to allow 2 headphones to be connected to one output. You need a proper cabled stereo breakout adaptor (see the accessories page).

. 1/4 inch / XLR combination socket - the 1/4 inch input is mostly intended for ‘line level‘ inputs, such as those coming from a microphone with its own power supply, a mixer or a separate pre-amp. Connecting 1/4 inch jack fitted contact mics or hydrophones to this will only give you around 80% of the possible signal. To get the optimum results use a 1/4 inch to XLR impedance transforming adaptor (see the accessories page) - this gives the best results: a higher signal level and warmer mid / low range frequency response.

(NB. hand held recorders can be a useful introduction to field recording - if you haven’t bought your recorder yet and would like some advice, do get in touch. I keep an eye on new models and test units for performance with all kinds of equipment - however, they have thier limitations. You will probably find that with hydrophones for example, you’ll need to raise the gain and do some subtle eq-ing in post production to compensate for the higher level of noise that the recorders pre-amps add to the recordings. For those new to field recording, pre-amps are one of the main reasons some recorders are cheaper than others. Getting super quiet pre-amps that don’t add additional hiss to your recordings means looking at professional recording equipment. If you haven’t done any post production before or are looking for a high quality editing suite then Reaper is one of the best there is and is very low cost. Audacity is a free editing suite but it has some limitations).

. Professional recording equipment will be XLR jack enabled and therefore the use of the impedance transforming adaptors is essential.

placement: there are no ‘rules’ when it comes to placement. With both contact mics and hydrophones it’s a case of experimenting, chance & eventually a level of intuitive skill.

. hydrophones - there are many factors that will affect the results one can get. Sometimes the same location will produce vastly different results on different days, at different times of the year for example. One thing that is important is that once you’ve placed your hydrophones into the water you have to wait for a while for the environment to settle. You have, after all, just disturbed it. Where possible try to get away from the banks of rivers, streams, ponds & canals - look for places where you can deploy your hydrophones so they don’t wash back against the banks / shore (jetties, fishing spots, bridges etc are all good locations).

. contact microphones - attaching the contact mics is the first step. I use electrical tape where needed as it doesn’t leave any residue on the coatings of the mics, unlike gaffer tape or blu-tak style products (which can leave residue that not only affects the look of the mic but can be damage the coatings) If possible  The truth is that every situation you use contact mics in is different and it might take you some time to find the ‘sweet spot’ on the object or surface you want to hear. This is part of the fun and the creative process - take your time and enjoy !

care: as with any audio equipment do take care of your hydrophones and contact mics. There is no reason your mics can’t last years - I still have pairs of the original test units I constructed over 6 years ago for example - but you must handle them carefully. The cost might be reasonable but handle them as if they cost 10 times + more ! Avoid bending the elements (contact mics) or the section of the cable that is coated. If your contact mics get wet in the rain, pat them dry carefully. Also, when you’ve taken your hydrophones out of the water, pat them dry and make sure no water runs back along the cable to the jack.

If using hydrophones in ice, allow them to return to room temperature before coiling the cable. Likewise, if used in high temperature liquids allow them to cool down fully before coiling.

contact mics: 

. the c-series contact microphones feature a larger special element than the standard design, using the ceramic welding technique, and are coated with the unique acoustic transfer material (+ outer coatings).

. the flat surface of the microphone should be placed on the surface of the object being recorded. It can be held in place using a small clamp or electrical tape if needed. Blu- tac should be avoided as it will leave a residue on the surface of the microphone. The white foam dot is there to help protect the microphone when pressing into place - its the other side of the element that is the main surface.

. the choice of pro-cable has been determined by the need to reduce handling noise as much as possible whilst allowing for the unique AT coating to improve signal strength.

. If you have used the contact microphones in extreme low or high temperatures do allow them to return to room temperature before coiling the cable.

. remember, there are several coating employed in the design of these units so even if the edge of the outer coating begins to peel from the cable slightly it will not effect the performance of the element. You can however repair such a peel by using epoxy resin, electrical tape or heat-shrink.


. the d-series hydrophones feature a special element in each capsule, using the ceramic welding technique, and are coated with the unique acoustic transfer material (+ marine adhesives and outer coatings). Unlike some more expensive hydrophones that use one element but employ various baffles between the capsule and the cable, d-series units allow for the full high and mid frequency range of aquatic life to be captured.

. the choice of pro-cable has been determined by the need to reduce handling noise as much as possible whilst allowing for the unique AT coating to improve signal strength. Anyone who has used hydrophones before will know that the key to getting great recordings is to have the hydrophones as stable as possible in the water / liquid. Whilst all JrF hydrophones come pre-weighted, if you are using them in situations where they will be subjected to strong currents it is advisable to apply additional weights in order to keep them as stable as possible (fishing weights that grip the cable are one solution). This will further reduce the possibility of handling noise.

. Always carefully dry your hydrophones after each use to prevent build up of water born pollutants.

. If you have used the hydrophones in extreme low or high temperatures do allow them to return to room temperature before coiling the cable.

. remember, there are several coating employed in the design of the capsules so even if the edge of the outer coating begins to peel from the cable slightly it should not effect the waterproof sealing of the capsule, however do repair such a peel by using epoxy resin or various waterproof sealants.

copyright of all material on this website and in the design aspects of JrF products is in place, as is design registration. Any infringement will be acted up and is simply not cricket !

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