Setup Calibration Kit for Revox A77
Nagravox Calibration kits are different to what you might expect. A lot more than just a calibration tape!
Developed over the last 3 years specifically for discerning audio enthusiasts and professionals, the rationale is to provide an appropriate set of tools, instructions and media to test, calibrate and setup a specific model Revox or Studer machine properly. Three resources based on the three fundamental chains of signal processing.
* INPUT OUTPUT CHAIN * PLAYBACK CHAIN *RECORD CHAIN
A cheap short generic reel of tape recorded by an enthusiast to try and make some money from his tape machine on eBay is not realistically going to help you setup and calibrate your machine properly. Calibration is the final step and is not just a process of throwing on a playback tape, tweaking some trimmers and hoping it will all come together. All 3 chains must be considered singly and then together. You also need to understand what gear and instruments are needed and how to use them. Awareness of modern tape formulations, relevant steps, differences, peculiarity's and nuances of a particular model, later factory updates not in factory manuals and hints and tips based on experience make calibration and setup a science and not a hit or miss affair.
The Nagravox calibration kit is designed to setup and calibrate your machine fully and properly. Each kit is tailored for a specific machine and your tape type preferences. Feel confident that your machine is setup and performs the way it was designed and manufactured.
PLEASE NOTE: This kit is for the Revox machines that require 1 playback chain calibration tape. A77 B77 A700 A-G36 PR99mk1. Generally the playback chain on these machines are calibrated at the higher speed only. The other speeds are hard wired and are not adjustable for playback level. There is also no high frequency calibration in playback, which is also hard wired preset. The record chain is similarly calibrated for level at one speed only BUT the bias and high frequency equalisation are individually calibrated for all speeds.
The NS A77 can only be NAB equalisation whilst the HS can be NAB or CCIR/IEC. On HS you cannot calibrate for both equalisations.
Nagravox Setup and Calibration kits include:
• Playback calibration tape or tapes - most Revox are 1 except the PR99 mk2/3 and C270 which are two. Studer machines variably require 2 or more depending on speeds and equalisation.
• New fresh record setup tape for calibrating the record chain
• A set of detailed instructions, explanations, required equipment (which are not too onerous nor expensive), diagrams and check sheets SPECIFIC to your particular model machine. These are based on Revox Studer manuals, Factory Tech Bulletins, industry best practice and Nagravox’s own experience repairing, updating and restoring tape machine’s.
You need to decide:
• Machine model and whether you may want the kit to cater for multiple models.
• Speeds and equalisation
• The tape type and formulation you will be using to set the machine up for. We recommend SM900 or LPR90 but can accommodate SM911, LPR35, ATR Master and ATR MDS36. (All currently manufactured new tape). SM468 is unfortunately discontinued in 2023 by the manufacturer
The playback calibration tape/s are long length on a 7" special somewhat 'ugly' blue reel (so it can’t be mixed up or easily recorded over in error) and includes a plethora of appropriate length tones (the important ones are in minutes not seconds!) at calibrated levels with full commentary and explanation. Everything on the tape relates back to the calibration manual notes and explanation.
The Record chain tape is a brand new full length 7" tape of the type you will set your machine up on.
Instruction Manuals are requested and sent to you via a download service as a pdf
Do you want add a second machine model or equalisation speed or want to set up on multiple tape types? We offer extra add-on kits for purchasers of this full kit which provides additional options and usability to this base kit in an economical bundle.
SOME GUIDELINES ON TAPE TYPE
- SM900 and ATR Master are durable studio grade mastering tapes able to handle up to +6 to +9 Db saturation with minimal increase in distortion.
- SM911 is a max +3 Db tape. This 'over drive' is not the only difference but I am hesitant to pass comment on nebulous terms such as 'warmth'. You just need to try and decide for yourself. Certainly be circumspect in being guided by www forum hot air and nonsense.
- LPR90, LPR35 and MDS 36 are thinner commercial grade tape with similar (but not exactly the same) magnetic characteristics as their standard play cousins. Their main advantage is economy in that you get 44% more tape and time on a reel. However you dont get something for nothing and lifespan is reduced.
- SM900 (std play) and LPR90 (long play) have similar but not exactly the same magnetic properties despite what the manufacturer implies. Similarly for SM911 / LPR35 and ATR Master / MDS 36 . So setting up on one and using the other could mean a variation of 0.75 - 1.5 Db difference in level between std and long play and the optimum bias will also not be the same.
- How critical is it that I use the exact tape formulation all the time? You can use any tape formulation on any machine no matter what it has been set up on and it will work OK but not optimally. You wont break anything! The key here is 'optimal'.
- How many times can I re record over and play tape. I suggest the following rough use guidelines.
- Re-recording over SM900 / SM911 - 15x LPR35/LPR90/SM468 8x
- Playing pre-recorded. This is dependent on machine but generally I would apply the following based on tape tension and spooling speed / handling:
- Revox 36 series & machines with basic tension control 300 - 400x
- Revox A77, B77, PR99 400 - 500x,
- Revox C270 & A700 and all Studer machines 200 - 300x
Test Instrumentation and leads / adapters required for calibration
Our service manuals detail the typical instrumentation you need for calibration. Here is a summary.
- Millivolt meter - analogue not digital ( definately NOT your digital multimeter!)
- Signal Generator - required for inputting record chain pure sine waves at various frequencies and amplitudes. Digital or analogue OK.
- Adapters and cables - quite a few including dummy loads
- Oscilloscope - although not absolutely essential, an oscilloscope is really fabulous to visualise and understand what's happening. Modern ones are mostly really good, not very expensive and boast a range of useful functions such as auto setup and measurements of frequency and amplitude.
Have a look at what we have listed here:
These are nice to have but not really necessary as you can accomplish much with what's already listed.
- Frequency meter
- Wow and flutter meter