Thanks RWBadly, I will pass on your advice to my friend. I think he will still eventually try to design his own crossover and employ a compression midrange because he is convinced that both the woofer and tweeter are rough at there crossover points and a midrange horn will help.
Then it wouldn't be a coaxial type speaker anymore. The whole point of a coaxial is that all the sound comes from a point source. Instead of doing that, just going with the woofer (416 etc) and a 511/802 with appropriate voicing, the entire audio band can be very well reproduced with just those two components. These can still be placed close enough to each other to become a semi-point source.
Yes, with a midrange it won't be coaxial. But, neither of us are very religious about things having to be of a particular design. I've heard massive horn systems with drivers spread over huge baffles and compression drivers offset from the woofer by the many feet of horn throat length, and they still image beautifully and manage to deliver a coherent sound. This would be sort of just an experimental project anyway (as was the GP 604 in the first place). My friend currently has the 604 in a large, conventional bass reflex cabinet that was specifically built for this driver, although he did toy with the idea of a Jensen Onken cabinet (the cabinets designed for this driver are massive and heavy in Onken configuration). He has experience with building crossovers so experimentation would be endless.
Ampexed, the use of the woofer with a wide range horn for midrange and highs might be an interesting approach. I would go with a WE713a, but my young friend probably could not afford that choice. He sort of likes 802s, particularly the 802b, and he owns a single YL 500 series compression driver (practically hopeless looking for a matching driver).
Just keep in mind that there are few fundamental concepts with horn speakers, and a couple of them are that 1) keep the voice coils of the drivers on the same vertical plane (time alignment), and 2) keep the horn cluster as tight as possible (driver integration). Whether you choose to ignore these is up to you, but you're leaving performance on the table if you ignore them.
I wonder how others keep the voice coil of a woofer in line with that of a compression driver which is coupled to a horn with a 4-5 ft. long throat. My own horn is mercifully not that long (WE KS12025) so I can keep the compression driver and the woofer voice coils reasonably close in distance to my ears.
As long as the horn mouths aren't both attached to a common flat baffle then it's easy. My A7-500s do this by mounting the woofer on a short horn so the voice coils the two drivers naturally line up vertically.
There are lots of great sounding new speakers today. To acquire the vintage sound is = $$$ That's why I'm just resurrecting an old speaker cab so I can get rid of the "in your face sound". I bought a set caps from Madison after I dial the crossover to the sound I'm targeting on. Maybe next week it'll be all here and we'll see if its gonna get better.
Oh boy, looks like I have 35 pages of reading to do. Mentioned in an a7 thread, I may be able to get some 804a’s, but not sure I’m ready to open that door considering I know nothing about vintage Altec anything lol
Been on a bit of an adventure with the Altec parts that I picked up and wasn't sure what to do with. Still on the journey but should be finishing up this week and then putting them into my system to see how they sound. The two cabinets these came in - one with the 515b and the other with the 605a were mismatched, so I tore apart the 605a cabinet and reconstructed it to match the one containing the 515b. Used all the original wood except for making a new baffle and putting new backs on both cabinets. I've never done any woodworking before but did some reading up and youtube watching on veneering and decided to try and put walnut veneer on both cabinets with a hand rubbed oil finish. Made a lot of mistakes and they are far from perfect, but I think they turned out OK. I probably should have started my veneering experience with something smaller! I sold the 605A and used the funds to track down another 515b and sent both 515b's to Bill at Great Plains Audio for a reconing and restoration. Fed ex lost my shipment and then finally found it after several calls and my filing a claim. It took 6 weeks for them to deliver the drivers, but glad they finally tracked down the package and got them into Bill's hands. I just got one driver back from GPA yesterday and the other is scheduled to be delivered tomorrow. In the meantime, I painted the horns and came up with a stand for them to sit on top of the cabinets. Not sure I'll stick with this but it'll do for now I just finished putting new grill cloth on and mounting the 515b in one of the speakers and will do the other tomorrow. I also bought a big roll of 2" cotton batting, so need to line the insides with that. My last step is to watch some youtube videos on soldering because I need to hook up the N500C's. Never soldered before, but bought a cheap soldering iron and a roll of pure copper wire and hope to figure it out. I mounted a speaker terminal plate on the back of the cabinet, so will be installing the crossover inside. It's been a learning process over the past couple of months and I made a lot of mistakes, but glad I took this on regardless of the eventual outcome. Just can't wait to hook them up and give them a listen!
These finished cabinets look fantastic! I have we very faith that they will live up to your expectations. My main A7 cabinets are not a factory matched pair. They were obtained by the guy who restored, reinforced and upgraded them. I don't worry about little things like this.
I experimented with a new pair of Klipsch . I wasn't happy with them. I found a pair of JBL L250's and I am extremely happy.
Looking at the N500C networks to figure out the wiring and need some help - this is all new to me. Below is an image with the current wires that I need to desolder and put new wires on. From what I could find online, it seems simple enough - my positive wires go on the Input, LF and HF terminals and all the negative wires go on the Common terminals. But from the current wiring (if the prior owner used the brown wire as positive) it seems that he reversed polarity on the HF. Anyone know if I should be reversing polarity on the LF or HF hook up? Also, I see a note on the Altec networks sheet off GPA's website stating "because of the extreme overall efficiency of the 802-type high frequency driver at least 3 db of attenuation must be provided if used with the N-500C network." I see the attenuation terminals on the network, but have no idea what to do with them and how to "provide 3 db of attenuation." Doesn't seem like the prior owner did anything. Any advice much appreciated - I keep digging online but know there are some real experts here and I don't want to damage anything by mis-wiring this all!
I've been thinking about the Forte IV's. What didn't you like about the new Klipsch and what model did you experiment with?
The HF needs to be reversed in polarity in relation to the woofer, however this is assuming the regular VOTT low frequency cabinet which you are not using, where the woofer and HF driver are vertically in the same plane. I would try both ways and keep the orientation which gives smoothest response at the listening position through the crossover region of 500Hz. The HF is already attenuated within the N500-C network to match the efficiency of the woofer. See the graph in my profile which shows the response of the N500 network, along with other Altec information. The attenuation on the network is for adjusting to preference.
Thanks so much - knew you'd have the answer! Another quick one for you - do you have a recommendation for another crossover that might work better in this configuration than the N500? All these drivers are 16 ohm.
Honestly, I'd go with active crossovers. You can dip your toe into it quite cheaply using a DSP crossover and an additional power amp, and this works very well especially if you have a digital front end since it's a complete preamp also. If you have an analog one, the DSP crossover can identify crossover slopes, voicing, and time alignment optimizations and be replaced by an analog active crossover later. Passive crossovers are wasteful, inflexible and far from optimum when driving reactive loads such as speaker drivers. Aftermarket passive crossovers are simply better looking lipstick on the same pig - virtually nobody here agrees with me on this, but then again I worked for Altec, and they didn't. A USB microphone like the UMIK-1 and Room EQ Wizard are highly recommended to sort things out. You should pay attention to the information I give regarding Altec horns in my information page having to do with voicing and damping the HF 511 horn etc.
Hooked up the Altecs this morning and pleasantly surprised! The horns sound amazing. The highs and upper mids are clear and detailed. Very impressed. But I'm getting a low level static present in the horns - not an issue when playing music but would like to figure out what is causing it. Also not getting the bass I would like out of the 515b's. I may need to reposition them. I wonder if I need to add more insulation into the cabinet (see pic below). I also have a pair of subs and will need to adjust those settings. And one of the 515b's seems to have some distortion. Hoping the voice coil did shift around in shipping. It was not packed that well when sent back by GPA and fed ex did a number on it. Fed ex seems to be getting worse and worse. I hesitate to use them anymore. Need to do some tweaking before deciding whether these will stay in my system or not, but finally got a set of horns to listen to!
You're not going to get thunderous low frequency extension from any speaker with very, very high sensitivity such as the 515s. You will need subwoofers if low bass is your thing. I run four 18" subs with my Altec A7-500s (response graph in my profile).
As for the "static", check to insure all connections are tight. The matting in the speakers apparently need to be on at least one side of two facing walls, so as there is none on the front where the speaker is mounted, you should probably stick some to the back panel. The key is to avoid standing waves. In my A7's I glued and screwed 1"x2" beams on edge in irregular patterns, (4, not X, as two X's across from each other have triangles in which standing waves can form. I then packed the voids made with the irregular runners with wool felt (can't stand fibreglass). Altec do not go real low, but low enough for me (and I would bet sub-woofers would not sound as immediate as the Altec's). I will include a link to mine playing a jazz song with some bass, so you can see if deep enough for you before you buy subwoofers.
I started with two 18-inch subwoofers but found that they did not have the same impact as the A7 cabinets. I added two more and that brought the subwoofers up to the same level of impact as the Altecs.
Thanks. I do have matting covering the back panel. Maybe I'll add some additional but first want to figure out what's going on with the one 515. And I do have dual 16 inch subs in cabinets behind the Altecs. I used them with my planars and will be making some adjustments to fill in the base. Should be fine! On the horn static, I'll check all connections. But it's equally prevalent on both sides. Maybe I need to check some of my tubes out - would horn be more sensitive to tube noise from worn tubes than the ribbon on my planars?
