Looking for an Altec 846A Valencia dividing network sch.

[TerryE]

HeathKitPat,

Got it. Thanks. I'm embarrassed to say that I thought an L-Pad was a simple variable resistor - so much for 4 years of an MIT education (I was a biology major!). After a little research based on your reply, I now see that I'm wrong. I had already ordered the same L-Pad you mentioned in your reply, so I should be good to go. Note that this L-Pad is 8 Ohms, not 16 Ohms as you mention in your post. Is 8 Ohms okay here? And, I will eliminate the 20 Ohm fixed load. Finally, you used a solid core conductor for L2 in the original schematic, and an open air conductor for L1, right?

Thanks again for your help.

Terry

[HeathKitPat]

Terry, your LPad should be 16ohm. I used a solid core inductor for L2, however were I to do it again I would go with air core. The iron core is more economical, however more chance of saturation.

[TerryE]

Thanks to HeathKitPat and everyone else who replied. The crossovers are now built and installed.

HeathKitPat - I've read of saturation of solid core inductors - what does the saturation sound like?

Thanks again,

Terry

[HeathKitPat]

Thanks to HeathKitPat and everyone else who replied. The crossovers are now built and installed.



Terry

Well tell us how they sound? Do you notice an improvement? I sure did.. I think the two best things I did to my Valencia's was to rebuild the crossovers and change the HF driver to a new GPA.. I think the stock drivers cut off way too soon. With the new drivers and crossovers installed I also found that I had to run the attenuators almost all the way down to tame those horns! If I had kept my Val's, spraying some sort of damping like rubberized undercoating on the outside of the horns was next in line (there is a ringing that at times isn't audible but my ears ringing later in bed after a listening session were proof positive that those big horns were working)... Those 811 horns are beasts but they can be tamed.

[cradeldorf]

Terry, your LPad should be 16ohm. I used a solid core inductor for L2, however were I to do it again I would go with air core. The iron core is more economical, however more chance of saturation.

I preferred the iron core on the LF side, I felt it gave richer bass.

[TerryE]

Well tell us how they sound? Do you notice an improvement? I sure did.. I think the two best things I did to my Valencia's was to rebuild the crossovers and change the HF driver to a new GPA.. I think the stock drivers cut off way too soon. With the new drivers and crossovers installed I also found that I had to run the attenuators almost all the way down to tame those horns! If I had kept my Val's, spraying some sort of damping like rubberized undercoating on the outside of the horns was next in line (there is a ringing that at times isn't audible but my ears ringing later in bed after a listening session were proof positive that those big horns were working)... Those 811 horns are beasts but they can be tamed.

Overall, the sound is much improved. However, this was expected because the previous owner had replaced the original crossovers with one of his own design that were shoddily built. I'm still troubleshooting a small amount of midrange distortion coming through the 416 of one channel. I can hear it some but not all of the time. Any thoughts there?

Terry

[Alien_Shore]

I'm still troubleshooting a small amount of midrange distortion coming through the 416 of one channel. I can hear it some but not all of the time. Any thoughts there?

Terry

Hey Terry,
Some simple things to try (not trying to insult your intelligence!). First you should isolate the cause of the distortion:

• move the cable between the amp and the crossover to the other channel of the amp
• attach the 416 to the other LF crossover on the other channel
• use a different cable from the LF crossover to the 416
• if you have a tone generator, run a sweep on the 416 (direct, bypassing the XO), to determine the frequency range where the distortion is noticeable
• listen for vibrations in the cabinet - is the distortion truly coming from the driver or possibly from the cabinet?