I have tried both and agree a Toroid looks cool. It may have more amps for a dynamic load like Class AB. But for smooth steady current in SE Class A, you can’t beat a SMPS for low noise. With that said, it’s not that a SMPS can’t have as much current - but a low cost LED or laptop smps is very good for the MoFo. If someone has FFT of a linear supply with a toroid running in Class A at 1.7amps with low mains (and 2nd and 3rd harmonic) peaks I would like to j is how to do that. Still trying after years and can never beat my SMPS and cap Mx with CRC combo.
No, the elephant is OK, big animal with a healthy apetite - needs a lot of grass to run happily around 
It's just unrealistic to expect a single, almost undegenerated JFET preamp with about 1V of useful swing and Zout of about 1k to successfully drive unity gain, single MOSFET power buffer to anything more than quarter of a Watt or so...
It's just unrealistic to expect a single, almost undegenerated JFET preamp with about 1V of useful swing and Zout of about 1k to successfully drive unity gain, single MOSFET power buffer to anything more than quarter of a Watt or so...
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I don't know any of these Pass preamps, but I know I've read the BOSOZ should be a lot better than the BOZ. And this BOSOZ is designed to work with the SOZ. And this is a difficult amp to drive.
I can also make a vote for a tube preamp
My 6N6P SRPP has no difficulties driving it.
And I must admit the Korg B1 has my attention. Should be good enough too.
I can also make a vote for a tube preamp
My 6N6P SRPP has no difficulties driving it.
And I must admit the Korg B1 has my attention. Should be good enough too.
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It's a lovely circuit, but with THD = 1% at Vout = 0.6V it might serve you well only for a low level listening of girl & guitar type of music.
Hmm. You're right. I just scanned the thread.
But it should be possible to increase the supply voltage.
Guide | Nutube – English
Running this tube (in this original design) at 30V, should get a 20dBV (10VRMS) output.
And indeed: I like girl + guitar music. Especially on this kind of equipment. Metal is reserved for my car.
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I get your point. Even running this Korg with high voltages, it will still have a very limited (useful) output. Maybe just skip this one.
Or accept more "tube" sound (2nd harmonic). With 10% THD and 30V, the output should get close to 10VRMS.
10% is a lot, but also not uncommon for a SE tube amp.
You could even replace the load resistor by a CCS.
Speaking of bigger hammers, several members with MoFo’s or planning to build MoFo’s have participated in the Aksa Lender 40vpp Preamp Group Buy (GB) to drive their MoFo. GB#2 (second installment of 30 pre-amp sets) has closed and GB#3 has been initiated to cover the additional demand. It’s really an ideal preamp and the build is very easy with just 5 actives and choice of through hole or SMT construction. Lots of flexibility for different input and output coupling caps too.
Here is the bigger hammer driving MoFo to 26.8vpp with a 19.5v Vcc.
This was the verification build before shipping out preamps PCB sets. Notice the choice of TH or SMT amp core modules. Motherboard is all TH.
Thanks to Aksa for giving this design to DIY community and JPS64 for superb professional layout.
Here is the bigger hammer driving MoFo to 26.8vpp with a 19.5v Vcc.
This was the verification build before shipping out preamps PCB sets. Notice the choice of TH or SMT amp core modules. Motherboard is all TH.
Thanks to Aksa for giving this design to DIY community and JPS64 for superb professional layout.
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If you look at the photo above, both TH and SMT daughterboards are shown operating on the same MB. The nice thing is that it is interchangeable plug-n-play. So you can buy the lower cost daughterboards and roll transistors (2SA1837 for example), have different gain settings (3x, 10x, 12x,...), use one as a headphone amp with higher bias current, etc. There is additionally, a metal core SMT board that will allow much higher power dissipation for the headphone amp. I have not ordered those yet due to lack of demand. Certainly, the TH daughterboard can be fitted with local heasinks on the two output transistors (DN2540 and use 2SA1837 biased at 100mA and lower Vcc to 24v).
The daughter boards distill the essential amp to a handful of components that are low cost and easy to build.
If you have more questions please refer to the Aksa Lender thread.
Here is TH board closeup:
Attachments
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include adequate source resistor for LU , reference cascode voltage to point under that resistor ....... node between that resistor and choke
connected as you drew , LU will go poof very soon , besides sounding like drek
remember that entire shebang - {source resistor + LU + cascode mosfet + voltage referencing string for mosfet } is 3 pin-ned black box - substitution for proper bibada$$ SIT
connected as you drew , LU will go poof very soon , besides sounding like drek
remember that entire shebang - {source resistor + LU + cascode mosfet + voltage referencing string for mosfet } is 3 pin-ned black box - substitution for proper bibada$$ SIT
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