Altec 604G Markwart xover (1st attempt)

[Elitopus1]

I got all the parts for one channel of my crossovers laid out on a board. Components are just ty-wrapped on for now. Eventually I will use nicer boards and find a cleaner way to attach. Maybe RTV under each piece?

What do you guys think about the layout? The caps, coil, and resistors on the left side are for the HF section. The cap and coil on the right side are for the LF section. What do you think about the coil placement? I have a picture that shows how to put coils in relation to one another. Maybe they are just talking about iron core. IDK.

See any obvious placement issues?

[GM]

Looks fine as is and yes, inductors are inductors regardless of construction, so orientation matters, though yours are probably far enough apart to make it moot since they're air core.

Ty wraps are fine, though prefer to do a bit of component vibration damping as well as system damping via mass loading, especially if they're exposed in/on a speaker.

How and with what do you plan to wire it up? wiring everything to a proper cold weld terminal strip is superior to soldered joints and allows quick/easy testing/parts swapping.

GM

[Elitopus1]

The xovers will sit on top of the speaker cabs for now. When I switch over to the 620 cabs I might put them inside. I could mount them with RTV and then maybe use some duct seal to deaden it more.

I plan on using regular 12 awg copper wire. Basically the same as lamp cord. I was going to solder it all together but I could use a terminal strip instead. The caps are going to remain the same value but the resistors might change. I am using a resistor instead of the L-pad. I was told to use between 10-15 ohms. I am starting off with 10 ohms because from what I have read this xover is a little soft on the HF.

[GM]

FWIW, me and many other DIYers that use[d] passive XOs dial[ed] in the 'best' sound with a [cheap] pot, then measure[d] it to find the exact resistor value. In theory, baffle step is 6 dB, but in room it can be as little as none, though this low is rare, but still a lot of resistor size range if just a dB or two and the higher the XO point the more likely one can hear relatively minute differences, especially between speakers, so not a good plan to automatically assume that they will need identical shelving unless your room, layout is in essence like the Onkens posted the other day.

Ditto vent tuning in some cases, a point I periodically post, though to date [going on 21 yrs on the BBs/forums now] don't recall anyone doing it.

GM

[Elitopus1]

Yes my room setup is definitely more difficult than the Onken setup. That makes sense about the speakers possibly needing different HF shelving. I had not thought of it before. It does seem like with my current crossovers that one horn is loader than the other.

I really appreciate the input. Thanks

[GM]

You're welcome! Looking forward to what you wind up with. If folks with any non basic speaker/room layout [mirror image] would treat each speaker/location like it was a mono system, then they'll most likely 'chase your tail' to ultimately [at least somewhat] unsatisfactory results before giving up; though some folks are really stubborn; to wit: on a HT forum long ago, an electrical engr. from a well known engr. school and been tutored by an equally well known horn designer had some serious issues with his cone/dome [3] way, which BTW had been designed by said horn designer that numerous DIYers had built/measured to great results.

Anyway, long story kind of short, one speaker was in a corner by a large entrance way and the other at a corner to a long hallway going to the rear and after 'x' [many] number of XO permutations, outboard EQ fiddling, returned everything to 'stock' and finally tried it the pioneer's/my way to audio nirvana within the limitations of being in an apartment and SWMBO. If nothing else, the thread exposed a lot of folks buying/upgrading homes how to go about choosing/designing an audio/HT room back before it and much more on the subject got added to the WWW.

IIRC it was the one that took a side step into tall pipe [aka ML-TL] sub design, specifically sonotube [cardboard] subs, helping to 'spark' a huge fad with a couple of the posters going on to form SVS, though sadly I had little luck getting folks to understand that many of these weren't simple vented alignments and the long vents typically used had audible consequences, etc., until the requisite simware became available.

GM

[LowOhms]

The xovers will sit on top of the speaker cabs for now. When I switch over to the 620 cabs I might put them inside. I could mount them with RTV and then maybe use some duct seal to deaden it more.

I plan on using regular 12 awg copper wire. Basically the same as lamp cord. I was going to solder it all together but I could use a terminal strip instead. The caps are going to remain the same value but the resistors might change. I am using a resistor instead of the L-pad. I was told to use between 10-15 ohms. I am starting off with 10 ohms because from what I have read this xover is a little soft on the HF.

Hello,

I suggest you use a higher quality hook up wire than 12 AWG lamp cord, assuming you seek quality results.

Biggest bang for the buck I know of in wire is to use Mil Spec M22759/11 , readily available at good prices, surplus from Apex Jr, Steve, on eBay ( be selective there ). 12 AWG is OK at $0.50 a foot, and 14 AWG at $0.40 a foot. Multi stranded copper, silver plated, teflon jacketed, very high quality in materials and construction.

I used double 14 AWG to wire between all my components on the crossovers. I cut the leads off of a inductor, just as it comes out of the winding, and use double 14 AWG for that span, much nicer if all else is executed properly, which many fail to do..

I also find several other EASY to obtain performance enhancements can be had on ALTEC VOTTs :

(a) I run the M22759/11 14 ( 14 AWG) to my 802s, directly from the crossover, use a 57 1/8th inch run.

(b) I run TWO paralleled 57 1/8th inch runs of Mil Spec 12 AWG, to each woofer polarity of my 515Bs, crossover to woofer. Very nice.

(c) I use Robert W. Fulton wire lengths ( or multiples thereof ) in all my speaker wiring, its 57 1/8th inch.

(d) another large sonic improvement comes by soldering this Mil Spec wire ( Carefully ) DIRECTLY to the 802's diaphragm terminals, and directly to the 515B woofer terminals, . This totally eliminates all the crummy-sounding push-to-fit stock ALTEC speaker-wire connectors. Nice sonic results ensue. A great thing to do.

(e) Oil caps are middle of the road in quality, and today, we have far better sounding and measuring caps, at industrial,, not commercial prices, than oilers.

All caps in the crossover require multiple bypassing for the speaker to sound its best, in all cap locations. Suggest you use a GOOD 0.68 film, values like maybe a 0.033 and 0.01 uF film, in parallel, equal lead lengths on bypass caps, use bare Wonder Wire ( Percy ) or 18-19 AWG pure silver.. ( Percy , Cardas, etc. ).

Have fun, my A7-800s are starting to really perform, and all of the above I did to them, carefully, listening to changes, in 2016.

Of course, amps for the ALTEC is always from my experience, the weakest link, once you have properly wired the crossover and speakers internally, and employed proper wire from the amp to the crossover.

Have Fun, I am.

Jeff Medwin aka Low Ohms

[Elitopus1]

I actually like the sound of oil caps. Same for the lamp cord. Maybe its because thats what I grew up listening to

[Elitopus1]

Other caps seem to make the VHF harsh sometimes. With the oil caps its always smooth. They don't make the horns roll off any sooner either.

Just my experience with my own Altecs and other systems I have heard.

These crossovers were built with exactly the parts I wanted to use. They are sounding pretty good so far

[bowtie427ss]

I actually like the sound of oil caps. Same for the lamp cord. Maybe its because thats what I grew up listening to

You may eventually find that your preferences and/or sonic observations have not yet reached their full maturity or resolution.

I find it an interesting venture to sometimes re-visit gear and combinations of gear that i was highly endeared to 10, 20, even 30 or more years ago. Sometimes, it can be an eye opening shock when what once sounded so good, so perfect is rendered outright bad once subjected to your frame of reference which has continued to develop and refine over the last decade or three.

Other times, that same frame of reference will show you how good some designs were, and how they continue to stand the test of time. Things like Altec drivers, Hegeman designed tube circuits and so on.

Once upon a time, i thought Cornwall was the cat's ass, and couldn't conceive how another loudspeaker could by any margin sound better. Cornwall hasn't changed. But, my frame of reference certainly has.