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News from Feastrex Japan

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#42
fulken said:
Amplifiers in Progress, with all finemet irons

Maekawa-san (Amplifier builder @ Feastrex Japan) is working hard on my amps. CV4055 push-pull and TA300B SET. These will be my demo amplifier for Audio Feast.

If you are a Feastrex owner in USA, please contact Audio Feast for special pricing!😀

Both amplifiers use finemet transformers and finemet chokes. Yes, power transformers are also finemet, and rectifier cuircuits are choke input.

CV4055 push-pull
8w/ch
This amp is just assembled and finalizing the detail. Conceptual design for CV4055pp was done by Teramoto-san at Feastrex. Detail design and building were done by Maekawa-san.
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Takatsuki 300B SET
9w/ch,
Urushi wood work is done by Tanaka-san.
We are waiting for some parts for finishing capacitor wiring on the top of the amp. I am expecting to have this amp in early May in Nashville, TN.
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Vintage Maxonic drivers are very popular in Japan. Some of their drivers are field coil drivers. Their price on auction market is much heigher than original retail price. We had demonstration with all finemet TA-300B SET, with all finemet field coil power supplies (6 channel). Speaker crossover inductors and level attenuators are also finemet inductors. CD player in the picture is also heavily modified with finemet DAC transformers and other special devices. 😉
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Click to expand...
Hi Kenji,

Really lovely idea to have all finest transformers/chokes in the amp!

Can I ask, what kind of sound changes/differences would a finemet choke do? (compared to say a Lundahl choke)? I am thinking of using a finemet output transformer for my DHT preamp.

Thanks!

Regards
 
#43
Ben,

WOW, this is about a decade old thread!

I no longer distribute Feastrex, but I can supply FINEMET transformers and chokes!

When you replace GOSS (grain oriented silicone steel) to Finemet in the same spec choke. Sounds change night and day. Finemet output transformer is transparent, and we can hear the quality of the power supply. Changing the power supply choke is same or larger difference than changing the output transformers! Once you change to Finemet chokes, GOSS is muddy less information and slower transition.

If you are investing for Finemet output transformers, you must have the Finemet chokes. By the way Finemet power transformer will top it off the sound!

Cheers,
Kenji
 
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#44
fulken said:
Ben,

WOW, this is about a decade old thread!

I no longer distribute Feastrex, but I can supply FINEMET transformers and chokes!

When you replace GOSS (grain oriented silicone steel) to Finemet in the same spec choke. Sounds change night and day. Finemet output transformer is transparent, and we can hear the quality of the power supply. Changing the power supply choke is same or larger difference than changing the output transformers! Once you change to Finemet chokes, GOSS is muddy less information and slower transition.

If you are investing for Finemet output transformers, you must have the Finemet chokes. By the way Finemet power transformer will top it off the sound!

Cheers,
Kenji
Click to expand...
Dear Kenji

Thank you so much for the reply!
Just to check, will too much finemet make it too bright/loss of musicality?

Thanks so much!

Regards
 
#45
Ben,


Finemet transformers are transparent, but KISS is important. Keep It Simple Stupid.😉

Finemet transformers have lower core loss and bigger is always better. I use 50W SET output transformer size core for DAC output line stage. (Yes it is a custom transformer for TDA1545A)

Mixing Finemet with GOSS core transformer and choke are mixed results. Less GOSS is always better.

Cheers,
Kenji
 
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#46
fulken said:
Ben,


Finemet transformers are transparent, but KISS is important. Keep It Simple Stupid.😉

Finemet transformers have lower core loss and bigger is always better. I use 50W SET output transformer size core for DAC output line stage. (Yes it is a custom transformer for TDA1545A)

Mixing Finemet with GOSS core transformer and choke are mixed results. Less GOSS is always better.

Cheers,
Kenji
Click to expand...
Hi Kenji, wow cool! SET amplifier output transformers for DACs! Must be massively oversized! Does the soundstage beecome a lot bigger or its more musical or more transparent?

Thanks for sharing your advice! 🙂)

Regards
 
#50
Dear community members! Please, if any of you have T/S parameters for Feastrex D5e Type II, or at least other 5 inch Feastrex, could you share them please? Either factory-made, or if you check them yourself (without installing them in the cabs, free-air specs). I would be extremely grateful for your help! I can't find it anywhere, I need this information to choose the type and design an enclosure for a pair purchased by my friend, unfortunately I have no way to measure them myself, we are in different countries at the moment. Thank you in advance!
 
#51
I do not have what you need. D5e Type II is a field coil driver, and the parameter varies based on the supply DC voltage. NF5 and D5e had the same diaphragm and damper. I will list information for NF5ex below. (this is all I have).

If you raise the supply DC voltage, the permeability of the magnetic circuit gets lower from some point, which means the field coil driver starts sounding like an Alnico driver. When permendur is used for field coil driver, maximum DC voltage without losing permeability is higher. This is why permendur is used for D5e Type II.

Field coil optimum Vdc
NF5ex 4.5V
NF5ex PIP 5V
D5e 6.5V
D9e 8.5V
NF9ex 6.3V
NF9ex PIP 6.7V

NF5ex:
14 Days. 61 Hours used.
Date: Oct 31 2008
22:02 PM
Temperature 21.9 degrees C
Humidity 38%

Fieldcoil voltage V,C 12V 0.91A
Revc= 15.4497 ohms
Fs= 85.3554 Hz
Zmax= 214.3177 ohms
Qes= 0.5549
Qms= 7.1430
Qts= 0.5149
Le= 0.3759 mH (at 1 kHz)
Diam= 105.0000 mm ( 4.1339 in )
ConeArea = 8659.0145 mm^2( 13.4215 in^2)
Vas= 3.5561 L ( 0.1256 ft^3)
BL= 12.3988 N/A
Mms= 10.2959 g
Cms= 337.6864 uM/N
Kms= 2961.3276 N/M
Rms= 0.7730 R mechanical

Fieldcoil voltage V,C 15V 1.13A
Revc= 15.4691 ohms
Fs= 84.9798 Hz
Zmax= 239.2929 ohms
Qes= 0.5163
Qms= 7.4706
Qts= 0.4829
Le= 0.3483 mH (at 1 kHz)
Diam= 105.0000 mm ( 4.1339 in )
ConeArea = 8659.0145 mm^2( 13.4215 in^2)
Vas= 3.8215 L ( 0.1350 ft^3)
BL= 12.4348 N/A
Mms= 9.6657 g
Cms= 362.8888 uM/N
Kms= 2755.6650 N/M
Rms= 0.6908 R mechanical

Fieldcoil voltage V,C 17V 1.23A
Revc= 15.5141 ohms
Fs= 84.7074 Hz
Zmax= 245.7816 ohms
Qes= 0.5032
Qms= 7.4680
Qts= 0.4714
Le= 0.3373 mH (at 1 kHz)
Diam= 105.0000 mm ( 4.1339 in )
ConeArea = 8659.0145 mm^2( 13.4215 in^2)
Vas= 3.9916 L ( 0.1410 ft^3)
BL= 12.3628 N/A
Mms= 9.3134 g
Cms= 379.0446 uM/N
Kms= 2638.2122 N/M
Rms= 0.6637 R mechanical

Best,
Kenji
TheAudioFeast.com
 
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#52
Looking for info on the d5nf and having noticed that the Feastrex website has disappeared, I came here and then saw the notice that Akiyama-san had sadly passed away. Condolences to his friends and family.

My question is regarding xmax or perhaps better the air gap and voice coil height to calculate it for the d5nf model. Does anyone know this; I am trying to ascertain the max SPL at low frequencies.
 
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