ruffrecords

Re: Vintage Windings EQ-1A inductor in EQP-1A builds - the ring is gone!
« Reply #20 on: September 23, 2018, 06:34:32 PM »
Question is not for me, but I can answer from my experience (knowledge). Soft Magnetic materials are not linear by frequency by many aspects, so in this case by permeability. So, Al value is different for different frequencies. Especially with molypermalloy cores. People who produce this "innacurate" inductors probably measured their values on 1khz what's not enaugh for this kind of filter.  Producing accurate multitap inductor for Pultec's has to be calculated and measured carefully.

OK, I get that but molypermalloy is little more than regular 80%nickel used in transformers and has a very large frequency dependency. On the other hand the Carnhill type of inductors most often used in EQ designs are made of ferrite which  does not.

Cheers

ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'


Moby

Re: Vintage Windings EQ-1A inductor in EQP-1A builds - the ring is gone!
« Reply #21 on: September 23, 2018, 06:38:51 PM »
OK, I get that but molypermalloy is little more than regular 80%nickel used in transformers and has a very large frequency dependency. On the other hand the Carnhill type of inductors most often used in EQ designs are made of ferrite which  does not.

Cheers

ian
They use Moly-Permalloy toroids for their EQP inductors. Also, not all MP cores are "right one" for this design.
For microphone transformers,  BV.8,  Bv.11,  Bv.12, etc.. contact me at mobyelectronics at gmail dot com

ruffrecords

Re: Vintage Windings EQ-1A inductor in EQP-1A builds - the ring is gone!
« Reply #22 on: September 24, 2018, 04:07:55 AM »
They use Moly-Permalloy toroids for their EQP inductors.
Sorry, you lost me. Who does?

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

Moby

Re: Vintage Windings EQ-1A inductor in EQP-1A builds - the ring is gone!
« Reply #23 on: September 24, 2018, 04:09:08 AM »
Sorry, you lost me. Who does?

Cheers

Ian
Carnhill  :)
For microphone transformers,  BV.8,  Bv.11,  Bv.12, etc.. contact me at mobyelectronics at gmail dot com

ruffrecords

Re: Vintage Windings EQ-1A inductor in EQP-1A builds - the ring is gone!
« Reply #24 on: September 24, 2018, 05:28:04 PM »
Carnhill  :)

Which inductor part numbers would those be?

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

Moby

For microphone transformers,  BV.8,  Bv.11,  Bv.12, etc.. contact me at mobyelectronics at gmail dot com

ruffrecords

Re: Vintage Windings EQ-1A inductor in EQP-1A builds - the ring is gone!
« Reply #26 on: September 25, 2018, 02:59:12 AM »
http://www.audiomaintenance.com/acatalog/CA-18-VTA1444_extended_info.html

Ah, now I understand. I was thinking of the VRB9042 through to VTB9055 series of ferrite EQ inductors. The permalloy ones are a fairly recent introduction to the audiomaintenance catalogue. Presumably these are used in the search for some kind of authenticity in clones.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

Moby

Re: Vintage Windings EQ-1A inductor in EQP-1A builds - the ring is gone!
« Reply #27 on: September 25, 2018, 03:33:49 AM »
Ah, now I understand. I was thinking of the VRB9042 through to VTB9055 series of ferrite EQ inductors. The permalloy ones are a fairly recent introduction to the audiomaintenance catalogue. Presumably these are used in the search for some kind of authenticity in clones.

Cheers

Ian
MP sounds quite diferent but
AL is more frequency dependant.
For microphone transformers,  BV.8,  Bv.11,  Bv.12, etc.. contact me at mobyelectronics at gmail dot com

ruffrecords

Re: Vintage Windings EQ-1A inductor in EQP-1A builds - the ring is gone!
« Reply #28 on: September 25, 2018, 05:51:52 PM »
MP sounds quite diferent but
AL is more frequency dependant.

Ferrites did not become commercially available until about 1945. The EQP1A was designed in the early 1950s so ferrites were certainly available to them. However, the EQP1A design was based on a 1930s Western Electric EQ design intended for telephone circuits where distortion was not a primary issue. Clearly the Western Electric design did not use ferrites. Perhaps the simply copied it, telephone distortion and all.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

Moby

Re: Vintage Windings EQ-1A inductor in EQP-1A builds - the ring is gone!
« Reply #29 on: September 25, 2018, 06:02:20 PM »
Ferrites did not become commercially available until about 1945. The EQP1A was designed in the early 1950s so ferrites were certainly available to them. However, the EQP1A design was based on a 1930s Western Electric EQ design intended for telephone circuits where distortion was not a primary issue. Clearly the Western Electric design did not use ferrites. Perhaps the simply copied it, telephone distortion and all.

Cheers

Ian
A standard MPP core saturates at around 7500 Gauss. A ferrite core saturates at around 4500 Gauss.
For microphone transformers,  BV.8,  Bv.11,  Bv.12, etc.. contact me at mobyelectronics at gmail dot com


ruffrecords

Re: Vintage Windings EQ-1A inductor in EQP-1A builds - the ring is gone!
« Reply #30 on: September 26, 2018, 03:18:49 AM »
A standard MPP core saturates at around 7500 Gauss. A ferrite core saturates at around 4500 Gauss.
But I doubt if either of them ever saturates in an EQ. I think it is the shape of the BH curve that is more important plus the point you made about parameter variation with frequency. I cannot think why anyone would choose to use a permalloy core in an EQ design today.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

vari-mu

Re: Vintage Windings EQ-1A inductor in EQP-1A builds - the ring is gone!
« Reply #31 on: October 08, 2018, 04:51:43 AM »
    Hi !



  I have a certain amount of Russian moliphermalloy from semirings MP-140 (Al=140) and MP-250 (AL=250)
  and I made inductors for my EQ Pultecs (7 pieces) 5 years ago.
  Recently I got one inductor, wound on two half-rings MP-250 (AL = 250x2 = 500) for measurement. My LC meter allows me to measure L on two frequencies:  UP (hi freq.) and DOWN (low freq.), which he assigns independently.
The results can be seen in the picture:

 L = 39.268 mH at 15440 Hz and 41.39 at 2460 Hz, Al= increases by 5.4%



        next tap of inductor
 L = 80.54 mH at 10 790 Hz and 91.21 mH at 1670 Hz, Al= increases by 13.2%
 
   Depending on the number of turns Al= "walks" between 350-250 at high frequencies and between 450-320 at low frequencies.
 
 I can not say anything, just information for thought.
Maybe my device does not work correctly.
 Vladimir P.

Moby

Re: Vintage Windings EQ-1A inductor in EQP-1A builds - the ring is gone!
« Reply #32 on: October 08, 2018, 05:02:44 AM »
    Hi !



  I have a certain amount of Russian moliphermalloy from semirings MP-140 (Al=140) and MP-250 (AL=250)
  and I made inductors for my EQ Pultecs (7 pieces) 5 years ago.
  Recently I got one inductor, wound on two half-rings MP-250 (AL = 250x2 = 500) for measurement. My LC meter allows me to measure L on two frequencies:  UP (hi freq.) and DOWN (low freq.), which he assigns independently.
The results can be seen in the picture:

 L = 39.268 mH at 15440 Hz and 41.39 at 2460 Hz, Al= increases by 5.4%



        next tap of inductor
 L = 80.54 mH at 10 790 Hz and 91.21 mH at 1670 Hz, Al= increases by 13.2%
 
   Depending on the number of turns Al= "walks" between 350-250 at high frequencies and between 450-320 at low frequencies.
 
 I can not say anything, just information for thought.
Maybe my device does not work correctly.
 Vladimir P.
Hey Vladimir. "Hi and low" doesn't tell much, but nonlinearity of the core depends from model to model, batch to batch. To trim Pultec inductor correctly variable frequency L meter is must. It has to measured at working frequency, for example 16k. I use HP meter with sweepable singnal generator with accuracy of 0.5% at corner frequencies  ;) and again, it has to be double checked in LC circuit.
For microphone transformers,  BV.8,  Bv.11,  Bv.12, etc.. contact me at mobyelectronics at gmail dot com


 

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