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B1 Rev. 2
B1 Rev. 2
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Old 26th January 2019, 08:18 PM   #181
Zen Mod is offline Zen Mod  Serbia
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B1 Rev. 2
be sure that one (xformer) is of exquisite quality, and connect it as autoformer , to have it at best
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Old 27th January 2019, 04:56 PM   #182
Nelson Pass is offline Nelson Pass  United States
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B1 Rev. 2
I have one here selectable between 1:2 and 1:4 using the Jensen or
Cinemags. Gives 6 or 12 dB, and I think it sounds best at 6.

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Old 27th January 2019, 07:48 PM   #183
Zen Mod is offline Zen Mod  Serbia
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B1 Rev. 2
mine is having better name

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Old 28th January 2019, 02:02 PM   #184
BigE is offline BigE  Canada
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If the main reason for a sonic improvement is drive capability, can we not do the same by paralleling the 2sk170's in the base B1 or DCB1?

Would there be a need to change supporting resistors?
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Old 6th February 2019, 09:16 AM   #185
ludkokanta is offline ludkokanta  Croatia
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If I set it to negative dc offset of a couple of mV and use it with a capacitor do I get some of that negative phase second?
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Old 6th February 2019, 11:10 AM   #186
6L6 is offline 6L6  United States
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B1 Rev. 2
No.

DC operating point and harmonic spectra are not linked line that, and as the B1 is such low distortion anyway, it will make no difference.


EDIT - See post #190

Last edited by 6L6; 6th February 2019 at 06:14 PM.
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Old 6th February 2019, 02:20 PM   #187
Hikari1 is offline Hikari1  United States
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Quote:
Originally Posted by ludkokanta View Post
If I set it to negative dc offset of a couple of mV and use it with a capacitor do I get some of that negative phase second?
I would argue yes you can. Dc offset in the b1 rev 2 is nulled by adjusting the jfet source resistor values, same as the p3 trick in the f5. You can adjust the pot in b1 rev2 to achieve increased 2nd harmonic and then null the dc with cap on output.
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Old 6th February 2019, 05:36 PM   #188
Berny is offline Berny  Belgium
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Originally Posted by Hikari1 View Post
I would argue yes you can. Dc offset in the b1 rev 2 is nulled by adjusting the jfet source resistor values, same as the p3 trick in the f5. You can adjust the pot in b1 rev2 to achieve increased 2nd harmonic and then null the dc with cap on output.
Well, I tried this... without measurable H2. Even using parts with an offset up to almost 4mA Idds (k170 at 8mA and J74 at almost 11mA). Don't know if I did something wrong... my source resistors were each adjustable from 0 to 10Ohm. Did you try in real?
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Old 6th February 2019, 06:12 PM   #189
Hikari1 is offline Hikari1  United States
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I have not tried this. I do feel that my B1 rev2 sounds 3rd harmonic dominant although I haven't measured it or attempted to adjust it. It does sound "too clean" to me. Perhaps B1 rev2 does not have enough distortion to make a difference.

I have, however, done the same thing with the attached circuit (Juma's current mirror LSK preamp variation). Definitely had an effect.
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Old 6th February 2019, 06:14 PM   #190
6L6 is offline 6L6  United States
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B1 Rev. 2
OH! Rev.2, the N-P pair!! Sorry, I had standard B1 in my head.

Yes, I think you could. Sorry for the previous reply.




Quote:
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No.

DC operating point and harmonic spectra are not linked line that, and as the B1 is such low distortion anyway, it will make no difference.
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