SOme wondered how that that BiG 200+200W parallel p-p project is going; pic of the business end. It may look horrendous but it's in order. In all about 9 months work in evenings the 100KHz SMPS taking up alot of development time. Some wiring needs tidying up but in the most part the 750W SMPS (within square can) with dual voltage boost power supply runs as expected as do the supplementary power boards; all with hot logic switching and watchdog detection, with programmable stage USB interface.
This is systems engineering complexity, so this project isn't for first timers nor beginners as considerable RF experience is required. The power amp circuit is remarkably basic; capable of bridge mode operation but it's the safety aspect of the very low impedance power supply draws attention to protection. Many don't like SMPS in power amps supplies; the advantage of excellent regulation is a real plus for dynamics.
Some features:-
AC soft start; duff cable and brownout jerk hiccup; 360V intermediate driver stabilised B+; logic controlled auto switching B- with hi & lo power with programmed B+ droop for MI; auto cathode current monitoring (important in bridgemode); large tolerance AC operation; wideband input transformers; DC front end heater; watchdog bias and overvoltage failure protection. Channel separation guaranteed -70dB at 15KHz; hi power thd 0.1% at 200W & lo power 0.05% at 35W.
This amp represents a considerable investment in old and new concepts.
Next to come; in a few weeks time, the complete power running spec with photo.
richy
This is systems engineering complexity, so this project isn't for first timers nor beginners as considerable RF experience is required. The power amp circuit is remarkably basic; capable of bridge mode operation but it's the safety aspect of the very low impedance power supply draws attention to protection. Many don't like SMPS in power amps supplies; the advantage of excellent regulation is a real plus for dynamics.
Some features:-
AC soft start; duff cable and brownout jerk hiccup; 360V intermediate driver stabilised B+; logic controlled auto switching B- with hi & lo power with programmed B+ droop for MI; auto cathode current monitoring (important in bridgemode); large tolerance AC operation; wideband input transformers; DC front end heater; watchdog bias and overvoltage failure protection. Channel separation guaranteed -70dB at 15KHz; hi power thd 0.1% at 200W & lo power 0.05% at 35W.
This amp represents a considerable investment in old and new concepts.
Next to come; in a few weeks time, the complete power running spec with photo.
richy
Attachments
Those output trannies have arrived for that monster project. One on the bench for a suss out. Of course, a British wound custom Williamson 18 sect design. with a specialised primary...got my work cut out now.
Worth mentioning; time is gradually slipping. Output transformers of this complexity, it's all down to the skill of the person on the coil winding machine; with complex interwinding connections and counter directions, no automation can do this and people with such handed-down-generation skills are now heading for retirement. The question whether a 14 sectioned would be a slight tradeoff than an 18 sect..we'll see.
Total amp weight with reinforced chassis around 55-60 kgs.
richy
Worth mentioning; time is gradually slipping. Output transformers of this complexity, it's all down to the skill of the person on the coil winding machine; with complex interwinding connections and counter directions, no automation can do this and people with such handed-down-generation skills are now heading for retirement. The question whether a 14 sectioned would be a slight tradeoff than an 18 sect..we'll see.
Total amp weight with reinforced chassis around 55-60 kgs.
richy
Attachments
And we can only hope that people like that don't take their skills to the grave. It is hugely important to pass knowledge like this on, especially for the next generation of valve enthusiasts.
When the older generation pass on, we are at risk of not keeping this knowledge alive. This is why this site is so important.
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