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| Author: | Cogito [ June 2nd, 2017, 9:56 pm ] |
| Post subject: | Indentify this |
this is the photo of Altec N-500-D crossover used in VOTT A5 systems. I was using them with 9846 2-way monitors. Could not identify that square white box. Looks like it is made of waxed paper. Attachment: IMG_2609.JPG [ 106.66 KiB | Viewed 27859 times ] Attachment: IMG_2610.JPG [ 98.15 KiB | Viewed 27859 times ] |
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| Author: | SoundMods [ June 3rd, 2017, 10:30 am ] |
| Post subject: | Re: Indentify this |
Altec liked to use coal tar for physical security to keep things in place -- with the side benefit of acoustic damping. The box (I am pretty sure) is a multi-section paper capacitor to go with the inductors I see in the picture to form a second order crossover. |
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| Author: | Cogito [ June 9th, 2017, 2:54 pm ] |
| Post subject: | Re: Indentify this |
yes, it is a 2-order crossover supposed with crossover point at 500Hz. Even if I consider its 2 caps in a single package, they are big. Wonder how the compare sonically to new gen caps. |
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| Author: | SoundMods [ June 9th, 2017, 3:16 pm ] | ||
| Post subject: | Re: Indentify this | ||
When I first got my Altecs on a whim I put them in my system stone stock to see what I ended up with. They were damn good and they had the stock paper caps. But that was then and this is now. You will find that with patience and trial tests with different caps that the Altecs have a lot of quality there that the stock crossover was holding back. I've attached a photo of what I ended up with after the third go at it. The big green "beer can" is Russian hermetic Teflon capacitor. The amalgam of capacitors you see in the picture was not arbitrary but the result of endless ear-testing trials. A combination of polycarbonate, polystryrene, and Teflon caps populate the terminal board for the high pass function, and the low pass was comprised of just polypropylene caps since they were in shunt and not horribly critical. The resistors provided damping to eliminate series L/C resonances (ringing) that could be mistaken for mechanical issues.
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| Author: | Cogito [ June 9th, 2017, 3:52 pm ] |
| Post subject: | Re: Indentify this |
I like the beer can.  Do you have a notch filer between 1k-6k like Jean Hiraga? Spice model of N500-D with 30904 attenurator circuits shows HF is attenuated by around 10dB entire range. Where as Jean Hiraga attenuates about 16dB with a notch filter which lets the freqs above 10k raise to their original levels. Decided to try notch filter like Higara's after N-500D first in place of 30904. Getting the 31 section Behringer Graphic EQ tomorrow to try out various notch filter settings before actually building one. If the notch filter experiment is successful, I will replace N-500D itself. Thinking of getting Erse Air-Core inductors, Jantzen z-supreme caps and Duelund graphite resistors. |
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| Author: | SoundMods [ June 9th, 2017, 7:25 pm ] |
| Post subject: | Re: Indentify this |
Air-core inductors would be a mistake. I tested air-core and flat-ribbon inductors and none of them were better than the laminated-core inductors that Altec provided. Additionally, Wilson Audio just learned that lesson after many years of manufacturing speakers. They now use laminated core inductors. Why? Low distortion and low DCR. Be careful about capacitors. Some can be expensive mistakes. Polypropylene especially typically have "glassy" characteristic that can wear you down. No notch filter required. I modified the horns and the horn drivers. And besides -- a lot of problems seemingly solved with notch filters go away when the mechanicals are under control and the crossover is well damped. And if you really want to know how good horns are just hook them up to a solid-state amplifier and see how well they "amplify" crossover distortion. UGH!! |
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| Author: | Roscoe Primrose [ June 10th, 2017, 2:03 pm ] |
| Post subject: | Re: Indentify this |
SoundMods wrote: And if you really want to know how good horns are just hook them up to a solid-state amplifier and see how well they "amplify" crossover distortion. UGH!! Crossover distortion in amplifiers has nothing to do with whether it's tube or solid state, it depends entirely on the topology of the amplifier.... Roscoe |
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| Author: | Cogito [ July 15th, 2017, 9:16 pm ] |
| Post subject: | Re: Indentify this |
This is the housing of the caps in Altec N-800 crossover (Photo from another forum). What is the purpose of housing the caps in wax? Attachment: IMG_0277.JPG [ 73.76 KiB | Viewed 27596 times ] |
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| Author: | SoundMods [ July 16th, 2017, 9:21 am ] |
| Post subject: | Re: Indentify this |
Potting the capacitors was not a matter of hiding the values as Altec was quite liberal with their schematics. The paper dielectric caps used were not wound as tight as modern film caps and could be effected by air-borne vibrations (sound) especially when they are inside the enclosure where the action is. Potting helps with isolation and enabling better sound reproduction. That's it. No hidden agenda just a goal of providing good sound. |
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| Author: | Cogito [ July 16th, 2017, 10:12 am ] |
| Post subject: | Re: Indentify this |
Thanks Walt. That explains. |
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