Hi vzaichenko,
I saw your vSingle front-end (post #409 of this thread) and liked the idea so I experimented with it, changed it somewhat and built a nicely working prototype of 8/16 W (at 8/4 R) amplifier.
The amp is very tame and stable (capacitive load test - 3R3 || 1uF). R6/R5 sets the gain (~20dB) and D7 biases the OPs (Lateral MOSFETs) at about 200mA. TL071 holds the the output DC offset at 2mV. PSRR is not bad either - ear to the speaker detects no noise so I guess output noise is about 100uV or less.
PSU has 4 x 12Vac/200VA toroid, schottky rectifier and two 22,000 uF caps.
As for the sound, I built just one channel so I listened mono only. Nevertheless, the presentation is surprisingly pleasant, tonally coherent and clean - very enjoyable (even large orchestra) and that's why I'm reporting the build.
I won't develop it further or build the stereo version (many projects are waiting) but it's nice to know that this topology performs well.
Best regards
Hi Juma,
Very good job indeed - pretty high ratio of performance/simplicity 😛
Cheers,
Valery
Hi guys,
As a legacy to the great Maestro Valery, I also drafted my own variant of VHex. I just wanted your opinion about the current source resistors in the VAS because I made them in split (double) R24 R10 (18k) in order to speed up heat dissipation.. In the original VHex circuit this was a single 33k resistor and it was getting a little hot (maybe tolerable) but I'm thinking of duty cycle (for instance prolonged use).
Will the split option of the resistor mentioned will work fine as well?
Thanks!
Albert
As a legacy to the great Maestro Valery, I also drafted my own variant of VHex. I just wanted your opinion about the current source resistors in the VAS because I made them in split (double) R24 R10 (18k) in order to speed up heat dissipation.. In the original VHex circuit this was a single 33k resistor and it was getting a little hot (maybe tolerable) but I'm thinking of duty cycle (for instance prolonged use).
Will the split option of the resistor mentioned will work fine as well?
Thanks!
Albert
Attachments
Thanks jwilhelm, yes that was my intent by splitting the dropping resistors because I omitted the zener regulators from the original VHex. I am trying to simplify my version by omitting a few components from the original and I guess without compromising performance quality. LTSpice say's the downscaled version still works pretty good.
Cheers!
Albert
Attachments
Any chance to get the LTSpice file for this project? If possible including some specific parts files. Thanks
Hi,
My work in zip with spice models included. I also attached the original VHex Loop&Gain spice files but this is not my work, it was also a shared file but without the spice models.
Albert
Have you done any real world testing on the input stage without the regulators? These amplifiers are wonderful at rejecting supply noise and interference from external sources. It would be a shame to upset that!
The VHex-CP-EC needs full rail voltage to run. All the others should be fine at lower rail voltage. There might be some minor fine tuning required.