About possible Babelfish J interest

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#461
Since I’m never satisfied, and always looking to improve I have a couple of questions.

I built these amps to be built into my console project. I’ve tried out a couple different arrangements of drivers in the speaker portion and have decided I can’t live without a larger speaker. So I’ve decided to shorten the console down to eliminate the amps and speaker portion.

So I am going to build proper cases for the amps. Part of the rebuild will include a little more heatsink.

Long story to get to my questions, sorry. Since I’m going to be rebuilding I was wondering what else I could improve on? I didn’t match the mosfets, do you think matching would matter? What resistors would be considered in the signal path? Maybe a benefit to use nudes there?

Thanks as always for your time to reply.
 
#462
Matching the output mosfets will lower thd so I think you will benefit from this.
If you want to use bigger heatsinks you can also try to increase output stage bias, it helps a lot in lowering thd if you use low impedance speakers (4ohm)
The last but not the least you can try to play with r27 which will shape your thd profile and that is making the amp have more or less single ended character(more or less h2).
Good luck with the tweaking

Ps. Don’t forget to let us know your findings about sound and how do you like it.
 
#463
schultzsch said:
Matching the output mosfets will lower thd so I think you will benefit from this.
If you want to use bigger heatsinks you can also try to increase output stage bias, it helps a lot in lowering thd if you use low impedance speakers (4ohm)
The last but not the least you can try to play with r27 which will shape your thd profile and that is making the amp have more or less single ended character(more or less h2).
Good luck with the tweaking

Ps. Don’t forget to let us know your findings about sound and how do you like it.
Click to expand...

Thanks much for the reply!

In my project I’m using 4 daughter boards per monoblock (12 IRFP240’s) so match in groups of 6?
 
#464
just two things you can do better:

-match mosfets (upper group matched , lower group matched , no need of matching upper with lower group) ....... but that was Conditio Sine Qua Non from first train station ........ 🙂

-fiddle with Aleph AC gain to please your ears
 
#465
Finally received amp and cap bank pcbs, took a while to go through France 🙂) The boards look amazing, like the black color, nice work ZM:
An externally hosted image should be here but it was not working when we last tested it.


Anyways, this is my first amp build and I am quite a noob at this so appreciate any help given. I've read through most of this thread and I must say, wow, some of the builds look pretty impressive :bigeyes:

I've been trying to get all the pieces required for the build and so far I feel like little :wchair: at the location where I live, where there is quite little options to choose from 😡

Here are some questions I have :

  1. I am going to use bridge rectifier for the build. Having in mind that I have 2 x 250VAC (2x18V / 7A) transformers, I will need 4 x ~15-25A, 100V peak voltage bridge rectifiers. Does this sound alright? Any recommended manufacturers I should be looking for?
  2. For the cap bank, I already have bunch of EPCOS 33mF/25V caps. Any suggestions for R1/R2? I have CL-60 for NTC. Anything I should be aware of when stuffing/wiring it?
  3. as for amp pcb components -
    C4 is 220 to 1000uF , decent quality 16V minimum , C7 is 220 to 1000uF 16V minimum and that one need to be best quality you have
    Click to expand...
    I kind of messed up and didn't see that these are in critical position before buying. I got panasonic 470 µF, 35 V, FC Series and I also have same from NHG Series. As far as I understand these must be better than panasonic ? 😀

Oh and BTW, I received the dissipante 4u 400mm case with baseplate as well 😀 didn't expect it to be that heavy, looks solid though 🙂
 
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#466
1. any 25-35A , 200V or more , will do the job ; they're pretty much all in same price range , so no skimping in voltage needed

2.if you're asking for resistors in CRC , just buy 0R1/5W square wirewounds .... besides polarity of caps , nothing really much to take care of
you can use doubled wires going to and from PSU pcbs ; side with NTC is output side ; you can use there physically smaller NTC than CL60 , any resistance between 10 and 20R

3.I have no opinion about difference between these caps you mentioned; in my book they're both good enough for task ...... except that NHC are somewhat sharper looking :clown: ; besides , you got 1uF MKC as bypass for that critical position , so any difference is minimized , if there is any
 
#467
Sounds good, that saves me some time and money looking for these C4/C7 caps - I can just use the FC ones.
Talking about wires, I was browsing through the forums to find the information on optimal thickness for the wire used. I also looked at your build photos but it's hard to tell. What should I use for 1) mains, 2) bridge rectifier -> psu, psu -> amp, 3) amp -> banana connectors?

Also, is this just a simple mains connection through thermistor? Looks bit different than terminal block in F5 guilde.
 
#468
input signal wire - tiniest solid core you can fight with , twisted

mains - stranded 1.5 sq. mm as minimum

DC side - stranded 1mm sq. , or 1.5mm sq. with few strands on end cut , to squeeze it in hole .... but observe that everywhere are holes for two wires for same thing, so practically doubled

pic- I'm using one CL60 (or equivalent) per Donut , being dual mono

also each channel's GND connected through dedicated CL60 to chassis
 
#470
well, even when you want to play with Lego , or with puzzles ..... and you have a picture of thing you're building ...... one need to engage a brain 🙂

so , first thing first - do you know how to build PSU .......... considering that you get two PSU pcbs , it's completely logical to go dual mono route

if you need schematic , just say so ....... 🙂

btw. when you see green/yellow wire going from Donut to chassis , that's always so called static shield - blind winding/screen between primary and secondary .......
 
#471
well, the psu looks simple enough for me to understand, but schematics would useful in any case..

and yes, forgot to mention, I am going with dual mono approach 🙂

also, forgive my ignorance, i'm learning a lot of new stuff right now, but i hope the pieces of the puzzle will come together soon and it will be much easier to get around without asking dumb questions 🙂
 
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