The original card-based Fortran IV program was coded in 1969. I punched and validated the cards myself 🙂.
"You wouldn't remember the model, would you? "
Guess, IBM 360?
https://en.wikipedia.org/wiki/IBM_System/360
Guess, IBM 360?
https://en.wikipedia.org/wiki/IBM_System/360
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Sorry, I can't recall the specific system model number. Each cabinet / suite of cabinets had a different designation depending upon its function. The computer was definitely older than the System/360 though. I do however fondly remember the very first digital computer I had access to - an IBM 1640. I had to get up at three o'clock in the morning to be able to use it for half an hour at a time 🙂. It was in service 23 hours a day, with the other hour allocated to maintenance. Although the computer room was air-conditioned, the amount of heat generated by the machine meant that it was always very warm when working in the data processing area - even in the wee small hours of the morning. It had a magnetic core memory. Those were the "good old days"...
Correction - should read IBM 1620 not IBM 1640. There was however an Amstrad PC 1640 🙂.
I came across FastBEM so I checked DIY to see what people's opinion was after a bit of experience with it.
And this is the only post, have you tried it yet?
Best wishes
David
Hello,
I have been reading a lot of different topics and I think maybe this one is the most appropriate and is to be resurrected.
I bought a JBL 5024540 PRX735 waveguide for my 165mm BC md38 driver but the throat is only 100mm and I think the effective cone diameter is around 130-140mm
I first thought I would just cut it to get the desired diameter but after reading on multiple entry horns I think it is not necessary.
I think I could use a box with one or two BC 6md38 and connect it to the waveguide.
But how ?
The mid horn would be used between 400 and 1600-2000hz
Then there is a faital cd on sth100 horn...
Below there is a 15" BMS.
I decided to use a waveguide for look and to throw less energy to the room. I built a prototype in wood and sand I got good results but I made throat equal to SD.
Below there is a 15" BMS.
JBL has used compression cone driver which apparently in the beginning were mods of an Audax pr170mo ( 165h) with a phase plug and a back chamber.
Of course I won't have a phase plug, but as I am not willing to reach very high frequency it might work without any.
To calculate the back volume, do I simply simulate a sealed box ?
I also have a phl 1140 in my custom waveguide, also an upgrade of pr170mo.
Thanks for your help.
I have been reading a lot of different topics and I think maybe this one is the most appropriate and is to be resurrected.
I bought a JBL 5024540 PRX735 waveguide for my 165mm BC md38 driver but the throat is only 100mm and I think the effective cone diameter is around 130-140mm
I first thought I would just cut it to get the desired diameter but after reading on multiple entry horns I think it is not necessary.
I think I could use a box with one or two BC 6md38 and connect it to the waveguide.
But how ?
The mid horn would be used between 400 and 1600-2000hz
Then there is a faital cd on sth100 horn...
Below there is a 15" BMS.
I decided to use a waveguide for look and to throw less energy to the room. I built a prototype in wood and sand I got good results but I made throat equal to SD.
Below there is a 15" BMS.
JBL has used compression cone driver which apparently in the beginning were mods of an Audax pr170mo ( 165h) with a phase plug and a back chamber.
Of course I won't have a phase plug, but as I am not willing to reach very high frequency it might work without any.
To calculate the back volume, do I simply simulate a sealed box ?
I also have a phl 1140 in my custom waveguide, also an upgrade of pr170mo.
Thanks for your help.
Attachments
I would use hornresp for your rear chamber question.
Making the throat the same size as the cone isn't always the preferred choice.
Making the throat the same size as the cone isn't always the preferred choice.
Thanks, I think it is possible to load the parameters for hornresp on a website.
But never used that software. What kind of waveguide do you think this JBL waveguide is ?
But never used that software. What kind of waveguide do you think this JBL waveguide is ?
It looks fairly regular, might just extend the mid directivity a little in the frequency range. Like others this has a short narrow vertical section which ought to be extended beyond the flat mouth mounting surface but usually isn't. It is popular for trying to get closer spacing but this can be a false economy.
Every situation is different. In any case, I've written a little about it here - https://www.diyaudio.com/community/threads/when-to-use-an-asymmetric-waveguide.375799/
I read your topic with interest.
This is also a very interesting article by JBL about cmcd horns.
This is also a very interesting article by JBL about cmcd horns.
Apparently JBL uses no waveguide for prx735 prx835
They use a waveguide for
AM4200/95 using JBL CMCD-61H - CONE MIDRANGE COMPRESSION DRIVER
the cone driver in this compression driver is looking like an Audax or phl driver of mine.
I think they are looking at high efficiency and output because with a 1.5" HF cd they cross at more than 2.5khz !
So I am hoping that for home use and crossing below 2khz, phase plug could be avoided.
Anyway if someone knows where to get a spare phase plug, please keep me updated.
Otherwise I will try to 3d print something which could be ok.
They use a waveguide for
AM4200/95 using JBL CMCD-61H - CONE MIDRANGE COMPRESSION DRIVER
the cone driver in this compression driver is looking like an Audax or phl driver of mine.
I think they are looking at high efficiency and output because with a 1.5" HF cd they cross at more than 2.5khz !
So I am hoping that for home use and crossing below 2khz, phase plug could be avoided.
Anyway if someone knows where to get a spare phase plug, please keep me updated.
Otherwise I will try to 3d print something which could be ok.
Yes, pulling the cross down is a priority. A lot of the pro waveguides will be too small for that.