Frequently Asked Questions

What are the payment terms?

For mixing and for mastering service, full amount must be paid upfront, before I start any work. You will receive the invoice once I examine if your files are ready for mixing or mastering, depending on which service you will hire me for. Payment is accepted only via Direct Bank Transfer.

Should you need more than 3 revisions included within the price, I am happy to continue working on your project for additional £20/h (minimum 1h of work).

For studio engineering you will receive an invoice after each session and you will receive your recorded files after I receive the payment. Should my studio engineering role extend to producing, programming or performing on your track (any kind of instrument, virtual instrument or backing vocal), I shall retain all the standard PPL and performance royalty agreements where applicable.

For music production, first half of the fee must be paid upfront. Second half must be paid after the production is finished and accepted as final multitrack. You will receive all applicable files after both payments (including any potential revisions) have been made.

Returns and refunds are not applicable.

How should I prepare my files?

The multitrack that you provide must be ready for mixing (or editing if you choose additional post production service). If your DAW has a   NORMALISE option for bouncing, please make sure to turn if  OFF. Also, please make sure that your tracks are not  clipping before you bounce them out.

 All tracks must be clearly labelled and numbered in the following scheme:

1. Kick in
2. Kick out
3. Snare top
4. Snare bottom
5. OH
6. Room
7. Bass DI
8. Bass AMP
9. Guitar (mic model 1)
10. Guitar (mic model 2)
11. Piano
12. Synth 1
13. Synth 2
14. Lead Vocal
15. Double Vocal
16. Backing vocal

Please note that this is just an example. You can name your tracks the way you like, but please be consistent, make it look clean and label the tracks with numbers as presented above.

Tracks can be mono or stereo.

You must consolidate your session into individual files from the start point of your song, including at least 1 bar of silence before the actual beginning of the song. Ideally the multitrack should not contain effects such as reverb or delay, unless these effects are integral part of the sound (example: guitar pedal fx, creative use of distortion on a synth, etc).

Please make sure that all of your files are correct before uploading. If you have midi instruments please bounce them as audio – I do not accept midi files.

Feel free to include any mix requests that you have and include a rough mix (if you have one) as a reference (Rough mix does not effect your track count).

1. For mixing – I will ask you to send me a folder with the multitracks – I accept the multitrack as  .WAV or .AIFF  files at either 44.1 KHz 48 KHz or 96 KHz  (24bit or  32bit). You must ensure that all of your tracks are of the same file type, bit rate and sample rate and that they are included in the folder, which name consist your artist name, song title, song tempo (BPM) and the date of the upload.

2. For mastering – I will ask you to send me either stereo mix  or mixed stems. I accept the mix or stems as  .WAV or .AIFF  files at either 44.1 KHz 48 KHz or 96 KHz  (24bit or  32bit).  You must ensure that all of your tracks are of the same file type, bit rate and sample rate, and that they are included in the folder, which name consist your artist name, song title, song tempo (BPM), and the date of the upload.

Your multitrack should be uploaded via  WeTransfer. I do not accept Google Drive or Dropbox links.

Should you have further questions, feel free to  contact me.

What is the review process and what files will I receive?

For mixing and mastering services – you will be able to hear the final mix / master & all revisions on a private link with an audio player accessing the lossless, full resolution WAV File. You will receive all applicable files (details below) after the final mix and / or master is accepted.

If you only apply for mixing service, you will receive .WAV files (24bit – 44.1KHz or native sample rate that the multitrack was delivered at) of:
Full mix
Instrumental mix
Backing track mix

If you apply for mixing and mastering, or just mastering service, you will receive the final masters for:
Streaming (.WAV 24bit  – 44.1 KHz or the  native sample rate that the mix was delivered at)
CD (.WAV  16bit – 44.1 KHz)
Video Distribution ( 24bit – 48 KHz)
Instrumental and Backing Track (If provided with this type of mix file) – both  .WAV 24bit  – 44.1 KHz or at  native sample rate that the mix was delivered at.
– DDPi format  (if requested)

Any additional costs (where applicable), such as studio hire, transport or travel costs, must be covered by the artist.

Do you deliver mixed stems?

I do not give mixed stems (mixed group of instruments) to assemble the mix from, because of multiple shared effects, parallel compression and complex mix bus processing.

If you would like to receive a custom set of stems for LIVE performances or custom backing track, apart from the one that I will provide you with, please let me know and I’ll make these for you. Should you need a specific version of a mix for TV, etc (example: full mix without backing vocals, full mix with the lead vocal and drums louder) on top of the ones that I initially provide you with, please let me know and I will be happy to make them for you at no extra cost*

*I will have to charge you an extra hourly fee (£20/h) if I would have to spend some time on potential editing to make a shorter version of a mix for radio or TV. That would require a little bit of post-production work in order to make smooth transitions between different sections of the songs.

What happens if I loose my mixes / masters?

I do my best to keep mix and mastering sessions and all associated files on external hard drives after the final files have been delivered, however, sessions might get deleted (if the computer or external drives require a format without the possibility to recover any files) or the session files might get corrupted, therefore,  it is your responsibility to back up your mixes / master files. Once these files have been delivered and paid for, I do not take any responsibility: if you loose them; if the hard drive with backup sessions breaks; if the session file gets corrupted and won’t be openable anymore.

I will not share any of your sessions, audio files, mixes or masters with anyone except you (or any associated person that has been approved by you to receive those files)

In the future, if I would like to use a production / mix / mastering session of your song for educational purposes, I will contact you to ask for your permission (this would only mean showing the content of the session to the potential audience. I am not going to physically share any of your files unless you specifically ask me to do so).

How do I credit your contribution?

You are obligated to include the appropriate credit in relation to any CD or other record that I have engineered, edited, produced, mixed, or mastered, using the following scheme:

Engineering / Editing / Production / Mixing / Mastering (choose the applicable)
Krzysztof Kessler

Such credit shall be included in a suitable place in the inner sleeve liner notes of the CD or record and shall be in the same size, typeface and font as any other similar information included in such liner notes.

Also, you agree to include the same credit (as displayed above) in the description of any YouTube video, Soundcloud player, Bandcamp track (and any other place where applicable) with the song that I have either mixed / mastered / engineered or produced.

By applying for my services, you give me the right to use your song which I engineered / produced / mixed / mastered as an example of my work to other clients. This includes uploading it to my website (once the song / EP / Album is released) under the “Featured Artists” panel into my own built-in audio player. This audio player will not include a download option. A post with your song on my website will include all appropriate credits, as well as links to your social media.

Where can I listen to your work?

I have a few Spotify playlists which include all tracks that I have been working on:

Mixing portfolio
Mastering portfolio
Production portfolio

If you would like to check exacty what my role was, please visit

Should you need more, I am also authorised by some artists whom I have worked with as producer / mixing and/or mastering engineer, to showcase their yet unreleased music on a private link as my portfolio.

Why should I work with you?

That is a good question!

First of all, every mix / mastering engineer has a different style. However, regardless of my sound and my vision, my priority is to make sure that YOU are happy with the final product! I am always happy to give my feedback on your music prior to any work, so that you can make sure that I understand your vision. I also highly recommend that you listen to my portfolio and check if you simply like what you’re hearing. I always give my best and listen to the client’s feedback in order to deliver a final mix and / or master that you can be proud of.

I do my absolute best to deliver mixes and masters as quickly as possible, so that you don’t have to be worried even if you’re coming to me with a tight deadline. I am also always happy to deliver different versions of the master so that you don’t have to worry about not having a specific file for video distribution, CD distribution, streaming services, TV, etc.

In addition, I have spent thousands of hours on programming, editing, vocal tuning, quantisation and phase alignment, as well as mixing and mastering, so if nescesary, I can do more than what’s included in my initial services, which can be helpful if you don’t have the budget or time to go back to the producer to tune that one last vocal line, or to quantise the drums a little bit more. 

The quality of my work is also validated by the fact, that the mixes that I have done have been featured on Spotify Release Radar & On Repeat playlists , used on viral TikTok videos with millions of views to date and have received airplays from BBC Introducing in London & Midlands, BBC Radio 2 & other national radio stations across Europe. I have also been fortunate enough to work with artists signed to Universal Music Poland, Warner Music UK label East West Records & Sony Music Entertainment Poland  and have co-produced a remix that was featured on Kerrang!

To sum it all up… I will do my absolute best to make sure that your music stands along other professional and commercial releases and stands up to the industry standards!

Should you have any more questions, do not hesitate to contact me either through my contact form or direct message on instagram or facebook.