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Lp values for guitar amp OT
Lp values for guitar amp OT
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Old 3rd May 2005, 06:37 AM   #1
offpeak808 is offline offpeak808  Taiwan
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Default Lp values for guitar amp OT

While geeking around Taipei, I found some mom/pop OEM tranny shops in my neighborhood that will wind for spec with a couple day turnaround. I thought it was worth checking out for an amp project I'm building now.

Problem is, since I don't have an original amp to tear apart and test, I'm having problems "guessing" what the primary inductance was for the old Fender OTs so I can give the shop some quality guidelines. (BTW I'm building a simple 5E3 Deluxe, 2 x 6V6GT for my daughter).

Basic specs:
Watts: 25
Zpr: 6,600 CT
Zs: 8
Turns ratio: sqrt(Zpr/Zs) = 29

8H per kohm of reflected load seems to be a general rule of thumb for audio amps, and working backwards, this would give me 53H of Lp.

I'm wondering if this is way over the old Fender guitar OT measurements?

Any gurus know and willing to share some knowledge?
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Old 3rd May 2005, 10:18 AM   #2
Yvesm is offline Yvesm  France
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Hey,

You colud try that (see attached pix)

By the way, let me know how many $ to have the finished bobin (without iron, too costly to ship ! )

Yves.
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File Type: gif guitar6v6opt.gif (28.1 KB, 115 views)
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Old 4th May 2005, 06:53 AM   #3
offpeak808 is offline offpeak808  Taiwan
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what is that program? sure nice to design tranny specs with!
thanks
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Old 4th May 2005, 07:01 AM   #4
Yvesm is offline Yvesm  France
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Here is:

http://perso.wanadoo.fr/yves.monmagnon/OPT_da-211.zip

Have fun.

Yves.

Ooops !
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Old 4th May 2005, 06:08 PM   #5
offpeak808 is offline offpeak808  Taiwan
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i'll ask the bobbin price, and thanks for the program link!
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Old 10th May 2005, 06:31 AM   #6
offpeak808 is offline offpeak808  Taiwan
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with or without iron, about US$40. They weren't too keen on having me give them H values as a spec for quality.
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Old 11th May 2005, 05:24 AM   #7
Yvesm is offline Yvesm  France
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Quote:
Originally posted by offpeak808
with or without iron, about US$40. They weren't too keen on having me give them H values as a spec for quality.
Tnx, looks a bit expensive.

It's true that the Lp value for a PP OPT is seldomly a problem since it's always large enough when Induction is keep low

Yves
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Old 12th May 2005, 12:02 PM   #8
Trout is offline Trout  United States
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Quote:
Originally posted by offpeak808
with or without iron, about US$40. They weren't too keen on having me give them H values as a spec for quality.

Seems fairly high concidering you could get
This One Most likely shipped to the door for less. I have a 6V6 x 2 guitar amp running this right now, Excellent deal and quality.
Gene
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