900W H-class PA Amp with Limiter

[Kagz]

Load 2.667 ohms. 3 8ohm speakers in parallel. Is there a way of making the stepper to switch to the higher rail even when the preamp is at low volumes? Mine only switches when at maximum volme, i.e almost where the signal starts to clip. It's like first it exhausts or rather exploits the lower rail completely up to
audible clipping then it starts climbing to the high rail. This is usually the time i hear and feel the way a car engages the other gear for the speed climb. The speaker starts to get some extra power. Can this phenomena be harnessed before the amp reaches higher volume dial? My preamp is at its max gain. I mean i only require 279 mV of input to drive amp to its full power. Are there components i can change to make it more sensitive sir Apex?

 

[rohin]

Load 2.667 ohms. 3 8ohm speakers in parallel. Is there a way of making the stepper to switch to the higher rail even when the preamp is at low volumes? Mine only switches when at maximum volme, i.e almost where the signal starts to clip. It's like first it exhausts or rather exploits the lower rail completely up to
audible clipping then it starts climbing to the high rail. This is usually the time i hear and feel the way a car engages the other gear for the speed climb. The speaker starts to get some extra power. Can this phenomena be harnessed before the amp reaches higher volume dial? My preamp is at its max gain. I mean i only require 279 mV of input to drive amp to its full power. Are there components i can change to make it more sensitive sir Apex?

amp cann't clip without high rail if you use apex clip circuit and hv rail switch near 30v so no chance of clip before rail switching to hv. something wrong.

 

[pallab]

H900P

sir,
will you please share H1200 details??

 

[rohin]

sir,
will you please share H1200 details??

hi"DIY 1.5KW Bipolar Class-H"

 

[pallab]

hi"DIY 1.5KW Bipolar Class-H"

Thank you sir.

 

[isidore kanerusine]

hi guys may I have files for H900 Apex amp, ie, PSU, soft start, clip indicator, amp and protection PCB in PDF format.

 

[stewin]

2 tier based on waso step up and apex vas input . please check for errors.

three tier based on the above tech loading...............
after i finish with two tier

 

[Kagz]

@Stewin

Have you tried the TL071 tranny stepper combination that you have posted mr Stewin? Was just trying a phonic stepper clone but dont know how it would behave with voltages more than +-90Vdc. What i like about it is the low component count. Stewin, do you know where i can buy an oscilloscope in Nairobi? Where do you source your parts especially BAV21 diodes? Lack of components in Kenya is what demoralizes me. Can someone help me how i can add H900EF another tier to make it three n reduce its dissipation for a 2ohm reactive load to achieve 2kW please? Say at 130 _90 _45 _0_-45_-90_-130?

 

[stewin]

Have you tried the TL071 tranny stepper combination that you have posted mr Stewin? Was just trying a phonic stepper clone but dont know how it would behave with voltages more than +-90Vdc. What i like about it is the low component count. Stewin, do you know where i can buy an oscilloscope in Nairobi? Where do you source your parts especially BAV21 diodes? Lack of components in Kenya is what demoralizes me. Can someone help me how i can add H900EF another tier to make it three n reduce its dissipation for a 2ohm reactive load to achieve 2kW please? Say at 130 _90 _45 _0_-45_-90_-130?

hi kagz . i have never build a class h before but i have been following this thread .
seeing the reliability of commercial h amps and the many people who have build them ,i decided to give class d a break , until i have enough skills and components to make a robust class d.

any way i will post details of my class h development here, i am very greatfull for apex and this forum.

concerning components you can order at ali express , ( i have not ever used ali express but was advised that it is good ) . concerning buying componets locally just whatsapp me on +254 722862970

 

[rohin]

2 tier based on waso step up and apex vas input . please check for errors.

three tier based on the above tech loading...............
after i finish with two tier

tlo71 step driver nothing in front of ir 2117 because ir fast and produce less heat to mosfet .discrete step driver good if cannot source ir .good luck for your project.

 

[stewin]

tlo71 step driver nothing in front of ir 2117 because ir fast and produce less heat to mosfet .discrete step driver good if cannot source ir .good luck for your project.

Hi rohin , have you ever tried the transitor version or tl 07xx at high volumes with low impedance loads??

 

[stewin]

The 47 pF caps on each rail switch keep the slew rate under control. It increases the switching time - but not enough to make it ineffective at audio frequency. Switching losses will be noticeable at 20k, but are you going to put that much into your compression drivers? It helps reduce the commutation noise, as do the .1uF/2.2 ohm snubbers. The other thing that slew limiting does is reduce di/dt - to the point where TO-247 package and typical PCB inductances are practical. Too much inductance combined with too fast switching and you get spikes across the PCB traces that last only a few hundred nanoseconds but are deadly. These commutators are the variation of the QSC switch that I use on some of mine. Uses the 311 - so they're an option in places where the IR drivers are difficult to find. The basic amp schematic that I use is similar to Apex's (with the opamp in the input stage and EF outputs).

Corrected from post 246. Anyone doing class H should be able to figure it out, but...

hi diyers
greetings hows this step anyone made it
warm regards
andrew lebon

tlo71 step driver nothing in front of ir 2117 because ir fast and produce less heat to mosfet .discrete step driver good if cannot source ir .good luck for your project.

hi rohin discreet or lm311 as gate driver which is better with this class h design

 

[Kagz]

Mr Rohin, you were correct. Amp was clipping b4 rail started to switch bcoz i had put very little capacitors on the lower rail rectifier. Was working with 3300uf by 100V x2. I didnt think that a classH needed as much filters as a class AB. I thought I could miser it on everything and save some costs and get better results than from AB, after all its more efficient than AB, right? Wrong. I was very wrong. I had to add it more in parallel n the problem disappeared. Wow!

 

[Kagz]

The clip LED by Apex never came on and I always wondered why while the sound was distorted at high volumes. The problem was the capacitor banks. This beast needs a robust power supply to perform.

 

[rohin]

The clip LED by Apex never came on and I always wondered why while the sound was distorted at high volumes. The problem was the capacitor banks. This beast needs a robust power supply to perform.

much is better then less.if we use much powerful component said then no problem if use less then we are near the trouble.i love to help other diyers because i am too.

 

[rohin]

these step driver good if anyone can clone this to work .lm 311 step driver can work well .as my concern i checked my pa h class amp i want to clone but i leave the idea to clone because there is always some little patch or spike in waves when amp switch. i love to clone mixer only.

 

[stewin]

hi all i have settled on discreet mosfet driver using mmbt 3904&4403 as gdt, and three pairs output bjt.
on the two tier version. the three tier one i will use lm 311 . my choices are based on availabillity of materials.

it shall be a two tier class h, the voltage maxx shall be +/-45 , 90 vlt dc
the fets i will use either irf ,z44,z46,z48, 1010, 1407 e.t.c

please all check if there is any errors on schematic or what can be improved to the schematic. thanking you all in advance diy stewin

 

[rohin]

hi all i have settled on discreet mosfet driver using mmbt 3904&4403 as gdt, and three pairs output bjt.
on the two tier version. the three tier one i will use lm 311 . my choices are based on availabillity of materials.

it shall be a two tier class h, the voltage maxx shall be +/-45 , 90 vlt dc
the fets i will use either irf ,z44,z46,z48, 1010, 1407 e.t.c

please all check if there is any errors on schematic or what can be improved to the schematic. thanking you all in advance diy stewin

 

[sownel]

Hi sir,rohin
this apex discrete stepper is not working properly,negative side suddenly increased rail

 

[stewin]

Hi sir,rohin
this apex discrete stepper is not working properly,negative side suddenly increased rail

please post clear photos of your project.