Those who are following my post might be aware that I had a pair of Sachenwerk field coil drives from 1934 era and was using them since 2019. It lasted for 5 years and post that due to environmental dust and age the paper cone started to disintegrate slowly. This caused SQ issues and I had to dismantle them and install my Russian FR since past 2 years. I had last year attempted a recone with locally available materials off the shelf but they did not work well with the field coil and had to abandon the project.
Two weeks ago, I started to rethink about the recone and used AI for designing the driver material. I primarily used chatGPT and Grok to design and fed them my requirement. I also considered the ML-TQWT box where these field coil will go and also my living room dimension so that it will give a perfect recipe for the paper cone, surround, spider, whizzer cone, phase plugs, glue etc so that i can try to procure these materials as per my other design goals. It came out with a ribbed paper cone with foam surround with a mass of 8 to 10gms, a small 2.5" whizzer cone and 1.5" depth with an opening for phase plug, a medium-soft spider. This will allow a resonant frequency of around 45hz to 50Hz. The Qts of the driver will be tunable between 0.3 to 0.7 by varying the field coil motor strength. For my TQWT i will require a Qts of around 0.4 to 0.5. The total MMS should not exceed 12 gms which is a challenge. Below are the weight of my materials,
Paper cone - 10gms
whizzer cone - 1gm
Spider - 2 gm
Voice coil - 2 gm
This itself total to around 15gm. Add one gram of glue and the total MMS will be around 16gms minimum. There is an advantage of a slightly higher MMS as it help to reduce the resonating frequency. But this will also reduce the HF response of the driver and it will start to roll-off earlier. The whizzer cone will need to be carefully mounted on the voice coil edge to get maximum HF coupling and the phase plug wiil help in reducing phase cancellations. I ordered all the material from Bhopal and its scheduled to arrive this weekend. I have been reasonably successful in reconing large 12" woofer drivers which is more easy. Recone of the small field coil is a bit of a challenge as its a short gap and long length type. To prevent the voice coil grating require enormous skills as even a micrometer error will cause the grating of the VC against the pole piece causing enormous distortion. I am excited to start this project and keeping my fingers crossed about the outcome.
I had earlier this month thought of buying the SB Acoustics 8" FR driver as it was available at a reasonable cost, but both chatGPT and Gork suggested me to go with the field coil re-cone over the SB purchase for more organic, dynamic presentation of music from the field coil.
Thanks for looking.
Two weeks ago, I started to rethink about the recone and used AI for designing the driver material. I primarily used chatGPT and Grok to design and fed them my requirement. I also considered the ML-TQWT box where these field coil will go and also my living room dimension so that it will give a perfect recipe for the paper cone, surround, spider, whizzer cone, phase plugs, glue etc so that i can try to procure these materials as per my other design goals. It came out with a ribbed paper cone with foam surround with a mass of 8 to 10gms, a small 2.5" whizzer cone and 1.5" depth with an opening for phase plug, a medium-soft spider. This will allow a resonant frequency of around 45hz to 50Hz. The Qts of the driver will be tunable between 0.3 to 0.7 by varying the field coil motor strength. For my TQWT i will require a Qts of around 0.4 to 0.5. The total MMS should not exceed 12 gms which is a challenge. Below are the weight of my materials,
Paper cone - 10gms
whizzer cone - 1gm
Spider - 2 gm
Voice coil - 2 gm
This itself total to around 15gm. Add one gram of glue and the total MMS will be around 16gms minimum. There is an advantage of a slightly higher MMS as it help to reduce the resonating frequency. But this will also reduce the HF response of the driver and it will start to roll-off earlier. The whizzer cone will need to be carefully mounted on the voice coil edge to get maximum HF coupling and the phase plug wiil help in reducing phase cancellations. I ordered all the material from Bhopal and its scheduled to arrive this weekend. I have been reasonably successful in reconing large 12" woofer drivers which is more easy. Recone of the small field coil is a bit of a challenge as its a short gap and long length type. To prevent the voice coil grating require enormous skills as even a micrometer error will cause the grating of the VC against the pole piece causing enormous distortion. I am excited to start this project and keeping my fingers crossed about the outcome.
I had earlier this month thought of buying the SB Acoustics 8" FR driver as it was available at a reasonable cost, but both chatGPT and Gork suggested me to go with the field coil re-cone over the SB purchase for more organic, dynamic presentation of music from the field coil.
Thanks for looking.
