HP-41C HiFi PAC Part I

[plore90]

Hi everyone.
Here I am again to present you a package of programs that I developed for the HP-41C/CV/CX for the HI FI project of a BAFFLE for LOW FREQUENCY drivers. The idea came to me while leafing through one of my Italian magazines from the 80s, Micro&Personal Computer, precisely No. 1, where a HI FI PAC for HP-67/97 sold by HP Italia was reviewed. Let me start by saying that I am not an expert in HI FI and therefore, being new to the HI FI world, I tried to read up online and fortunately I found enough documentation. There are many PC software online that help you build a speaker both in pneumatic suspension (BAFFLE sealed) and in BASS-REFLEX (BAFFLE Vented), but I have not found any software developed for programmable calculators, much less for HP calculators. Trying to understand the technical terminology (Thiele / small parameters) I decided to write this first of 2 PACs and precisely for the project of a Seleaded BAFFLE for Woofer. The program is divided into various subprograms, each usable via menu keys. The program requires a total of 268 program registers and 45 DATA registers, and the memory of the 41 requires a SIZE 46. The program after being loaded into memory is executed via XEQ "CCLOSED". The "A" label which is mandatory as soon as you run the program from the beginning asks for the insertion of the mandatory driver (Woofer) parameters which can be measured in the laboratory or obtained from the Woofer manufacturer's DATA-SHEET. Once loaded the driver data you can choose to calculate the characteristic acoustic parameters of the BAFFLE Seleaded up to the net empty volume using the "C" key. Or you can choose to start from a given net empty volume and calculate the acoustic parameters of the BAFFLE backwards using the "c" key, always in USER MODE set at the beginning by the program itself. It is possible, ONLY after having made one of the previous two choices ("C" or "c"), to calculate the final volume of the BAFFLE and its acoustic parameters by simulating the filling of the net volume of the BAFFLE with a percentage (usually from 70 to 90 %) of absorbent material using the "D" key. Finally, the program can calculate the gain in Db of the low frequency response from 20 Hz to 500 Hz of the driver (Woofer) in BAFFLE Seleaded with or without absorber. Both calculated for a single input frequency, and automatically from 20Hz to 500Hz for normalized third-octave center band frequencies. You can load the parameters of a new Driver by pressing the "A" key. It is clear that the program requires a certain knowledge of the meaning of the various Input/Output parameters in the Hi Fi context but in addition to documenting the program listing in the most detailed way possible, I have attached, in addition to the program in ready RAW format to be loaded as widely as possible onto the 41C, a series of basic documents for using the program itself. As usual, I used the basic and simplest method in writing the program lines at the expense of size but making it as comprehensible and simple as possible. If I notice a certain interest on your part, the development and publication of the second part (BAFFLE project in BASS-REFLEX) and the third and final part (CROSS-OVER filter project) will follow. I tested the program with various examples. driver and the results were excellent, but there may be some hidden BUGS. I would be very grateful if, upon discovering this, you would let me know so that I can intervene. Changes and improvements are welcome by all. The function that calculates the frequency response G(F)Db is under the Label "RFREQ" and since I deliberately did not use the data registers 00 to 11
you can use the PRPLOT routine inserted in the HP-IL module to obtain the frequency response graph from 20Hz to 500Hz.
Thanks
Plore90
P.S.
I had to upload the CCLOSED.zip file to OneDrive because it weighs almost 6 Mb.
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https://1drv.ms/u/s!AsglEsK1WR5eliCTCS9g..._?e=JB3dFv

[Ángel Martin]

Nice application, I've put it together in a ROM format and its now attached.
Will a part-2 follow soon? There's room available in the same ROM should that became available...

[plore90]

Hi Angel,
thanks for your interest, yes, I'm starting to "porting" to the HP-41C/CV the second part of the HI-FI PAC, BASS-REFLEX Vented Box project, of which I have just published the version for the HP- 97/67 always on this forum. As soon as it's ready, I'll put it on the forum...
Best regards
Paolo Loretoni
plore90

[Ángel Martin]

(04-13-2024 04:52 PM)plore90 Wrote:  Hi Angel,
thanks for your interest, yes, I'm starting to "porting" to the HP-41C/CV the second part of the HI-FI PAC, BASS-REFLEX Vented Box project, of which I have just published the version for the HP- 97/67 always on this forum. As soon as it's ready, I'll put it on the forum...
Best regards
Paolo Loretoni
plore90

Great, I'll add it to the ROM when ready.
In the meantime I've put in there your ACC program as a place-holder.
See my previous post for the ZIP

Cheers,
ÁM