My first Altecs - 604-8H

[Toph]

Just got word from Bill that they are finished and will be shipped today!

The total price was about $300 which included New Diaphragms, Remagnetization, and shipping both ways.

I'm totally content with that pricing and can't wait til they arrive!!

[GM]

What substance should I use to clean? De-Oxit?

De-Oxit or similar is fine, just extremely pricey, so historically I've used PB Blaster or similar chemicals I could buy in bulk for cheap at the local electrical contractor distributor emporium.

GM

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I'm totally content with that pricing and can't wait til they arrive!!

I'll say! My last invoice in '86 to re-cone, drain/re-zap a pair of 515Bs came to $208.11 and this was just a minor round trip delivery to Greenville, S.C.!

GM

[Altec Best]

I also like CRC Electra-Motive and it comes in a much bigger can than the De-Oxit..YMMV

CRC Electronic Parts Cleaner, 20 oz Can - G1352145 at Zoro

[GM]

Yeah, any of the electrical motor cleaners I've tried work well enough, though they have no lubricating chemicals.

I've historically used these and Brakleen for cleaning Mass Air Flow sensors also, but I noticed that lately my old 2k Toyota Tundra has been a bit off, so cleaned it with no obvious improvement. Bummer, I need a new one since plugs, et al, look fine, but my friendly local NAPA dealer of 50+ years says gamble $8 on CRC's MAF cleaner first and lo and behold! It's running like new again, so not just a new label on an old chemical!

Anyway tried it on some really corroded PC boards from an early mega $$$ Sony HT receiver 'curb queen' I recently snatched up for its huge caps, heat-sinks and it ~ 'spit shined' them, so another to add to the list of good cleaners only.

GM

[Toph]

Got some de-oxit- that solved the problem with the button! Thanks!

Next question:

One of the L-Pads rotates all the way around instead of stopping at Min or Max. I opened the back the bad one and a good one but couldn't determine what exactly is malfunctioning to cause this.

Any ideas?

[Alien_Shore]

The LPAD has a resistive coil inside of it and a wiper that is connected to the external knob. The wiper hits a mechanical stop at both ends of the coil, which provides the "min/max" settings you're used to feeling when operating it.

Usually when the LPAD won't stop at min or max, some knuckle-dragging trog has forced the knob to the point where the wiper jumps over the stop, or breaks the stop off entirely, or bends the wiper up where it just glides right over the stop (and the coil). This can be fixed depending on the damage. Take a look here for a pretty good inside look of a high-quality LPAD.

[Toph]

Hmm. I opened up a good one, but did not see a mechanical stop like the one in the link you sent me. Maybe the mechanical stop is internal/not visible?

If it's not repairable, does anyone have any recommendations for a replacement?

[Toph]

Would this be the appropriate L-Pad to replace the broken one?


Speaker L-Pad Attenuator 100W Mono 3/8" Shaft 8 Ohm


Will there be sonic differences from the others? If so, should I replace them all instead of just the 1?

[Toph]

Well! they've been playing music for a few days now, and I can definitely say I am loving them.

The duplex design is presenting imaging that I do not hear in my JBLs - there was a period of 30 minutes last week where I sat with my eyes closed while listening to Spirit of Eden by Talk Talk. These speakers have some magic that my JBLs lack.

Two things I am noticing that I'd like to try to work out:

The midrange is a bit overpowering and the detail of the highs seems to be lacking. I've been dialing in the crossovers and trying to hone in on solving those issues, but I can't seem to get there with the stock networks.

I've read many other places that Jeff Markwart's 604-8H crossover solves both these issues.

I'd like to explore that.

I would love to pay someone to build the crossover for me - but if thats not possible...

I was wondering if anyone has a step by step guide? a parts list? I'm looking for more than just the schematic, because I do not know how to read the schematic.

[juniper]

Glad you are hearing the 604 magic!!! with mine its all about the recording and whats up stream. I would look into replacing the caps, and I don't know if it applies, but the M19 has a very similar crossover design and there are issues with the lugs needing to be ground. Hopefully someone can confirm.