I have two sets of slewmasters in my system:
For main speakers (Klipsch RP280F 8 ohms): dual mono 2x625va with 80v rails and 5p NJW0302/0281
For subwoofers (6 ohms Lab12): Mono blocks with 800va transformers but only 70v rails using 5p Sanken 2sa1295/2sc3264.
Since the speakers has much higher sensitivity then the subwoofers, the subwoofer amps start clipping when playing loud. I can probably run the 70V mono blocks on the main speakers with plenty of headroom.
The question is: Will 625VA 80V be sufficient when driving subwoofers (with music, not full load test over extended periods)? Can the njw0302/0281 transistors take the beating with heavier load or should I replace them with MT200 devices to be on the safe side?
For main speakers (Klipsch RP280F 8 ohms): dual mono 2x625va with 80v rails and 5p NJW0302/0281
For subwoofers (6 ohms Lab12): Mono blocks with 800va transformers but only 70v rails using 5p Sanken 2sa1295/2sc3264.
Since the speakers has much higher sensitivity then the subwoofers, the subwoofer amps start clipping when playing loud. I can probably run the 70V mono blocks on the main speakers with plenty of headroom.
The question is: Will 625VA 80V be sufficient when driving subwoofers (with music, not full load test over extended periods)? Can the njw0302/0281 transistors take the beating with heavier load or should I replace them with MT200 devices to be on the safe side?
Hi Yngvejos, at the moment - a quick calculation - your subwoofer amplifiers allow delivering roughly 65Vp = 46V RMS swing before clipping, resulting at around 350W at 6 ohm speakers. If this is not enough 🙂eek🙂, I would just switch to +/-80V rails for them as well - then the swing will increase to, say, 75Vp = 53V RMS, resulting in up to 500W RMS at 6 ohm, providing plenty of headroom before Lab12 is coming to its edge 😉
MT-200 devices provide higher current delivery and heat dissipation capabilities, serving better at high output power levels.
Cheers,
Valery
5pr of 180W devices have a total Pmax of 1800W
The maximum reliable power into a severe reactance speaker is approximately one fifth of that i.e. 360W
360W into 8ohms needs ~66Vpk
Since you have +-80Vdc you can't get much above 360W of max output.
Your devices will be reliable if properly cooled.
But a bass only speaker directly driven by it's own dedicated amplifier is not a severe reactance speaker, at worst it is medium reactance and maybe only mild/moderate.
Your 5pair of devices are safe.
The maximum reliable power into a severe reactance speaker is approximately one fifth of that i.e. 360W
360W into 8ohms needs ~66Vpk
Since you have +-80Vdc you can't get much above 360W of max output.
Your devices will be reliable if properly cooled.
But a bass only speaker directly driven by it's own dedicated amplifier is not a severe reactance speaker, at worst it is medium reactance and maybe only mild/moderate.
Your 5pair of devices are safe.
Thanks for the replies. Val: Increasing to 80v rails would be the best, but 800va transformers isn't cheap, and those I have has an epoxy core so it's not easy to add windings. :/
I'll test the amp with 80v rails on my subs next time I'm home from work. Maybe I'll order some mt200s for it just to feel better. 😉
I'll test the amp with 80v rails on my subs next time I'm home from work. Maybe I'll order some mt200s for it just to feel better. 😉
I will have around 78-80Vdc for these project 800VA transformer for each channel. Will be good to see how all work out for you.🙂
I have used my amp with two 625VA and 80v rails for more then 1 year without hickups, so there's nothing to worry about. I cheaped out and bought njw0302/0281 transistors for that amp since I have been running it with 8r load on 98db speakers. I probably went overkill with 80v rails for that purpose, but it's nice to know that you have headroom even in drunk mode. 🙂
I am very happy with the final outcome. The amp sounds very good. Very revealing and definitely no shortage of bass, It betters my lateral mosfet which is a very good amp. Thanks everybody for the help and advice . KND frontend is superbbb!
Cheers
Great design - looks like a real thing
I am very happy with the final outcome. The amp sounds very good. Very revealing and definitely no shortage of bass, It betters my lateral mosfet which is a very good amp. Thanks everybody for the help and advice . KND frontend is superbbb!
Cheers
The chassis looks great!
Thanks Jeff. Had enough for now in cutting with a jigsaw and filing everything square on 3mm alu 😀 but I am glad It came out good. I have also calibrated the old Sifam VU meters. I mounted those little flat white leds on sticky tape inside the meters. Works good. The sound betters my NAD 214 and even Lateral mosfet amp which itself is very good. I am really not biased towards the Slewmaster as it is a new build, It just's really sounds better . My true observation.
Have any of you build the vindicator cfa circuit?
Are there else anything new about the vindicator circuits Os worked on here earlier?
Are there else anything new about the vindicator circuits Os worked on here earlier?
Dear Vrystaat,
Please post the final Schematics as done for reference please !
--gannaji.
Anyone know something about the schematic in post 9094 have there been made any real or even a PCB?
post9763 has a link like this...........forums/solid-state/248105-slewmaster-cfa-vs-vfa-rumble-490.html#post5068198
http://www.diyaudio.com/forums/solid-state/248105-slewmaster-cfa-vs-vfa-rumble-490.html#post5068198