be sure that one (xformer) is of exquisite quality, and connect it as autoformer , to have it at best
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.
Cinemags. Gives 6 or 12 dB, and I think it sounds best at 6.
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?
Would there be a need to change supporting resistors?
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?
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
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
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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?
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.
I have, however, done the same thing with the attached circuit (Juma's current mirror LSK preamp variation). Definitely had an effect.
Attachments
There’s also a “JFET buffer board” on eBay. JFETs cascaded with bipolars. You can tear out the bipolars and possibly exchange the JFETs with the 2SK170/2SJ74 combo.
Post #146 of this thread to catch on. I proudly invented that with spiritual guidance from Zen mod. It works, its a nice compact and simple pcb but no voltage supply compoments on it
of course , one can look at Iron Pumpkin schematics and , with some precise soldering can make pretty good buffer with easily accessible parts
entire thing , including reg (Good Gemini
) can be made on veroboard without too much trouble , especially if using SOT-23 pcb adaptors , cheap on fleabay and around
and yes , for tougher loads , see Borbely WCF option
entire thing , including reg (Good Gemini
) can be made on veroboard without too much trouble , especially if using SOT-23 pcb adaptors , cheap on fleabay and aroundand yes , for tougher loads , see Borbely WCF option
B1 Korg Nutube
Hello Guys!
I bought a Firstwatt SIT 3 and I’m pairing it with a Pass labs HPA-1 and Harbeth P3ESR. The amp has 8db gain and the P3’s sensitivy is 83 db I know I could/should look at high sensitivity speakers probably but I like the sound as is even if I would need more power sometimes...
Anyway, I am interested in the B1 buffer the version with autoformer if I can have some good gain (ideally 12-15db) or the B1 Korg nutube.
I understand the Korg nutube can support well a gain of 15db. Do you. Have any confirmation/suggestions? And how can I get this gain?
Thankssss
Hello Guys!
I bought a Firstwatt SIT 3 and I’m pairing it with a Pass labs HPA-1 and Harbeth P3ESR. The amp has 8db gain and the P3’s sensitivy is 83 db I know I could/should look at high sensitivity speakers probably but I like the sound as is even if I would need more power sometimes...
Anyway, I am interested in the B1 buffer the version with autoformer if I can have some good gain (ideally 12-15db) or the B1 Korg nutube.
I understand the Korg nutube can support well a gain of 15db. Do you. Have any confirmation/suggestions? And how can I get this gain?
Thankssss
From p5 of the B1 Korg project document
http://www.firstwatt.com/pdf/art_diy_nutube_preamp.pdf
"Also note that the circuit as presented has a little over 16 dB of gain, and happily functions as a preamp with a logarithmic input potentiometer"
http://www.firstwatt.com/pdf/art_diy_nutube_preamp.pdf
"Also note that the circuit as presented has a little over 16 dB of gain, and happily functions as a preamp with a logarithmic input potentiometer"
Thank you Dennis! Sorry but I am not diy expert... Ok so if I understand correctly if I build the B1 Korg Nutube buying the pcb from the diy audio store and following the instructions I will get around 16 db of gain whch is exactly what I am looking for to pair it with. The sit 3
That is correct.
You can find much more info at the B1 Korg thread:
B1 with Korg Triode
Cheers,
Dennis
You can find much more info at the B1 Korg thread:
B1 with Korg Triode
Cheers,
Dennis