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The horn does not properly load the fram down that low, so power handling goes way down, and pattern control issues arise. Bad idea IMHO. If you can get a set of the original 604 horns you might do it.
I always thought 604 bass speaker was a 416, not a 515, so if that were true, then they'll go up to 1,600 pretty easily. But I could be wrong and Old Guy is right if the horn won't load the high diaphragm atbthe bottom, you'll screw it up.
Quote:
Originally Posted by cradeldorf
:) hahhahhah lol
This means that you are missing something ( response-wise ) in your setup. When they sound good, it means that the number being played was not that dependant on the missing portion of the spectrum, and the other way around for the bad sounding days. Assuming that everything about the drivers & the enclosure are standard, it has to do with the xover only. I had suffered similarly for nearly 2 yrs. with my A7-500, and it was finally over for me recently. Ofcourse it ended up with me having kind of a refresher-course in xover designing.
Cradeldrof, what other gear are you running? Personally, I could never listen to my Altec speakers without a graphic equalizer and while alternatly listening to CD's, Youtube videos, and Movie DVD's, am constantly adjusting the EQ not only for each different format, but each different CD, or video. They are all recorded differently and each has to be individually adjusted to taste. It is a time consume task, but is a necessary requirement for listening nirvana. Altec, more than any other speaker brings out all of the flaws in recording engineering.
I don't really know because I don't have one, but I thought that unless you have true 5.1 with a center channel speaker, you will never be able to balance the voices vs soundtrack vs special effects from a video source. I would worry more about how the system plays audio music rather than video. When are they going to split soundtrack voices from the rest of the audio and give us control over how loud those damn special affects and music are on video?
Quote:
Originally Posted by cradeldorf
Yes, OG is absolutely right.
For such a small horn, trying to xover it too low may damage the phram, as the air-mass (volume of air inside the horn) will be too less to prevent it from being over-excursed. On the other hand, the phase-plug as the name suggests, only prevents any phase cancellation from occuring within the prescribed bandwidth, which otherwise can happen as the phram is not a flat surface, and hence the path length from the periphery & the center of it to a point in front of it in space will be unequal. This difference will cause frequency cancellations at different spots throughout the bandwidth. The loading-caps when 'ON' will also prevent the phrams to some extent from being over-excursed, but it usually is the happiest when the pressure/loading on both the sides are similar (linear excursion), which will not happen here for this horn if the xover was too low, even though the caps were on.
Will you pls post a diagram of your present xover/hf-attenuator set up ?Quote:
Originally Posted by cradeldorf
And the DC resistance of the 604 LF/HF sections (it should be ofcourse around 12.5 ohms) ?
Is this a drawing error or for real ?Quote:
Originally Posted by cradeldorf
In the HF rail, the cap should be towards the amp-end & the attenuator should be towards the driver. But here it seems to have been reversed.
This can be very bad for the attenuator and the amp to some extent.
There is no need to worry about negative attitude etc. We all are beyond that.:)Quote:
Originally Posted by cradeldorf
Coming to the subject.....yes the air thru the phase-plug slots is enough to find resistance in the horn pipe. It is also to do with frequency. Actually these drivers are very much like a rugged-ized microphone. Forget about this, think of a 515 in a 825/828, and think of the cone movement...and how little it is !
Yes you are right by saying that you have not yet got the feel of this subject.
It's the unwritten audio law of compromise Cradeldorf. It exists in some form in every step of the audio chain.
Everything we know in our tangible world is confined by basic laws of general physics. Speakers are no exception. In fact, speakers are in some ways a "bridge between worlds" where the laws of electricity meet the laws of kinetics.
Get a 418 guitar speaker run full range and use it as your center channel. Don't you have a left over OB?
Hi cradeldorf,
I know just what you are thinking. I had the same thoughts come back and bite me. Aditya has done a nice job helping to explain the pressurizing thing.
I had made a little boombox with some small Jordan speakers along with vented woofer all in the same box. I didn't worry about the Jordans because there was a vent so how could the woofer cause excess cone movement in the Jordans when there was a great big port in there to relieve the pressure.
Well, long story short, bye bye Jordans, hello new project.
I am now wiser. :)
Hi....thanks for the nice words.Quote:
Originally Posted by cradeldorf
I will suggest you to try out the xover again with the proper connections, but I suggest to use a 10mfd in place of 6.3mfd for the HF. The 1.5 mH coil can remain the same.
Pls try it out and see the outcome.
Yes you are quite right here about the differences between the standard 515 and the one in the 604. Yes, in the case of the 604, it will have a drooping o/p post 1K Hz compared to a standard 515. All the points that you have mentioned will have their influence. But I don't have any actual 'db' figures with me. But i think the combination that the 604 has with the Hf horn, it should be able to match it up. I have listened to them for nearly 2 years, and I am yet to find a substitute to be sounding so good and so full !Quote:
Originally Posted by cradeldorf
Also, I've read that the horn on a 604 doesn't provide loading below 1600Hz. That could be an issue for longevity of the diaphragm / voice coil.
I filed a report with the Speaker Wire Police.:DQuote:
Originally Posted by cradeldorf
If your speaker wire runs don't add enough impedance to impart a negative impact, and can deliver the voltage and current your speakers need to satisfy you, then it passes my litmus test, even if it's household romex or the coily cord from your landline.:)
I got some clear zip speaker wire, at Menards , that only had half the number of strands. So my # 16 awg was in fact # 19.
It was under the Phillips brand.
Don
The 604 was designed keeping studio-monitoring (point source) in view. Any attempt to highlight the lows specifically will create imbalances. Also it can sound boxy pretty easily. So any enclosure careful of this will perform well. OB is definitely a good choice here. Or a BR with an almost IB-ish approach will also do well.Quote:
Originally Posted by cradeldorf
:)Quote:
Originally Posted by cradeldorf
I think the 604s deserve good cables atleast. About the choice part, Bowtie has said it all.:)
Good to hear that. Did you check with the 1.5mH+10mfd combo or the earlier 1.5+6.3 combo ?Quote:
Originally Posted by cradeldorf
Yes, about the attenuator, I think it must have got fried already. Better to get it replaced, at least for dependability sake.
Talking about the xover, you can not (should not) put a cap higher than 10 mfd on the HF side. Yes, you can play with the inductor value.
Another good thing will be to procure a db meter, (the standard 30-8KHz type if not more), and take a real mesurement. B'coz, even with a pair of trained ears, it still gets at times very tricky to tame down things in audio. At least one will know for sure where what is, and then adjust accordingly.
I was actually talking about a pair of 604-8Gs at my friend's place. We both were put up together there for 2yrs, and everyday we used to listen to them in the late evenings. The cabs were BR, approx 12 cu.ft.Quote:
Originally Posted by cradeldorf
Just read about your plans to go for a db meter. I am sure you are going to make those 604s rock. I love their resolving abilities. Good wishes in advance.
I run my 604's at 1250 per what my tech measured? and they sound really good to me, with a little eq. I have GPA crossovers, and that mellowed the sound a bit, and they sounded more like M19's, so I put the original xover that came with the speakers back in. I am glad I have never put more than 3 watts into them after reading this thread.
Apparently ya'll haven't seen Jeff's 604E HF measurements, which should be pretty typical. Ditto his thoughts WRT loading caps [which mirror mine]: Altec Compression Driver Rear Loading Caps
GM
The 16 ohm thing is called as the impedance, which is DCR+reactance. DCR is constant, but reactance varies with frequency, and as a result impedance varies. To calculate xover component values at a particular 'f' one has to know the impedance at that 'f'. The specified impedance (ohms value as you have said) for a driver generally means it to be valid at 1KHz. At other freq it will be different, even may become the same as the DCR. So here comes the 'impedance-graph'. Now just b'coz the graph is in hand does not mean that the computed values will be the workable ones. This is so b'coz, as the graphs are not straight lines, the resultant filter response slopes will be far from what what was calculated. So now comes the difficult part, that is to adjust the values of the components, type of the filters, choice of xover-'f' etc., so that it can deliver the goods.Quote:
Originally Posted by cradeldorf
hahaha ok, if you say so!Quote:
Originally Posted by cradeldorf
Attachment 1481
OK Let us know how they sound! :)
DCR is DC (direct current, or zero Hz) resistance. There is no such term as ohm resistance. If specified as resistance, it is DCR. If specified as impedance, a much bigger can of worms opens. To vastly over simplify, impedance is effective resistance at a specified frequency, an impedance curve is specified at enough points to allow a curve to be drawn between. Impedance is higher than DCR, which is why an 8 Ohm speaker measures less on DC multimeter. 8 Ohm would be "nominal" generally a mean figure. Not to be confused with Sports Illustrated models, who have mean figures of their own.Quote:
Originally Posted by cradeldorf
You know the old saying goes something like this.. "If it Ain't Broke, it Doesn't need Fixing" ? :p
But FWIW Jeff Markwart gave me some great advice.. I have 604-8G's which are a little different then your 604C's. But his 604-8H crossover sounds great with my 604-8G's.. I would check his site and go over the schematic for that network...
http://home.earthlink.net/~jmarkwart...les/604-8h.pdf
http://home.earthlink.net/~jmarkwart...4-8h_gsmpl.pdf
http://home.earthlink.net/~jmarkwart..._8Hpcwmfeq.pdf
http://home.earthlink.net/~jmarkwart/id4.html
The Jeff-xover for cradeldorf will be this one.
Altec Lansing 604B Phase Correct Crossover
This has been modified (16 ohm version) to suit the 604B, and hence will also be good for 604C.
Is the DCR of a 604B/C is at 8.3 ohms ? Jeff's site says nothing about this. Also there is no imp-graph. Only the HF side is there. He only mentions it as a 16 ohms driver. After GM's hint in this thread earlier about Jeff's work, I have been searching everywhere. Finally I found one page from somewhere on the net that I have lost trace of, and it says the 604B to be of 10.59 ohms, and the 604C of 11.10 ohms. The measurements were taken in the yr 1971. The Altecs are towards the bottom of the page.
Attachment 1482
Cradeldorf had got these refurbished at GPA. I think they can confirm about this parameter issue. Otherwise the xover may not match. Ofcourse the best will be to measure them up.
You heard him CD, send them to me and I'll measure them for you. :biggrin2:Quote:
Originally Posted by aditya
There are a few things I wonder about, The first 604 was 20 ohm and had a 2000hz crossover point, the "B" looked identical and it had a 1000hz crossover point, the "C" which has a slightly different horn had a 1600hz crossover point and the "E" which began using the accordion surround had a 1500 crossover point.
In the earlier days, the ohms ratings (impedance) alloted to drivers were very much without any fixed rules. The spec given was purely an assesment of the manufacturer alone. For example, Philips ratings were always the same as their DCR values. But later on the computed values (impedance) at 1KHz was accepted as the standard value.
Though in most cases this impedance value turns out to be 1.25 times the DCR value, this is not the same for all drivers, especially in the case of older and unusual drivers like the 604 types. Here the imedance values can be the double of the DCR value, as their f/imp slopes rise very fast, an indication of their very high efficiencies/sensitivities.
Regarding the varying crossover 'f' choices, I think it was part of the usual R&D stuff. A standard '15 inch' speaker has its toughest task while trying to reproduce the range between around 350Hz to 550Hz, b'coz this is the zone during which its cone's physical limitations start coming into play, and restrict the HF stretch severely beyond 1KHz. Now the HF horn in the 604 is perfect for 2KHz, but limits itself below 1KHz. So this way after trying out both the limits for various reasons, they finally settled for the middle path at 1500 Hz.:)
I'm pretty happy with how they sound they have a real 3dish type of sound. When Avatar is playing all those weird bug noises in the jungle are going off to the side of you and above you It's kinda freaky but cool. I am considering different cabinets again, not because I don't like these but the other day when I switched back to the altec receiver from the marantz I literally made the back panels of these things distort. (they're barely 3/4 thick particle board with no bracing at all,The baffle is the same way) the bass was so much more deep than the marantz that when I fired up the altec and Nady eq the back panels of the heathkits were shaking violently enough to sound like a distorted speaker. I've since tuned them in nicely but when I think of how much power they must be producing to jump the cabinet panels by better than a 1/4 inch I started thinking Butcher block thickness cabinets are in order.
Nice to hear that you are happy finally. I am curious to know....
What is your present xover choice ?
What adjustments did you need via the Nady equalizer in order to make the sound better ? B'coz the reverse of this adjustment is your speaker+xover+amp's response ! Let us know.
That chart is a great find Aditya, I've never come across it in my hunting adventures.
Thanks.
Sounds to me like you need a nice 417 12" guitar speaker in there for a midrange driver. :)
From your equalizer settings, it is very clear that the woofer in the 604C has gone sloppier, I mean the mass-breakpoint has moved downward, and as a result the high-end response of the woofer has suffered badly. This clearly indicates a loss of gap-flux or weak magnets. The HF portion seems to be ok. :)Quote:
Originally Posted by cradeldorf
Remagging is usually done only after the speaker is completely ready otherwise. So the DCR remained the same.Quote:
Originally Posted by cradeldorf
About your meter accuracy, you can always measure a known value resistor, say 10 ohms, and check it.
About the equalizer setting, it is not the left side, it is the peak at around 600 that looked unusual. A 604X rarely suffers here. But however, all these are based only on an assumption that like most people you also like a set up which is tuned to a 'flat' response, b'coz there are no other tangible proof available here. I think it is high time you get these drivers measured up systematically, thru someone more acquainted with the process. Otherwise it will be almost impossible to get predictable results, as the variables are too many, and we even do not know where the 'square-one' is, to go back if needed.:)
'Sounds' like ya'll aren't factoring in the amps used, which were ~matching impedance originally, decreasing down to vanishingly low by the time of the 'E'; so originally, driver impedance was listed as a function of network impedance and the VCs would have been wound to have a DCR/impedance that yielded the desired inductance to achieve the flattest, widest BW over some average power band. As output impedance dropped, the driver's impedance would become increasingly more dominant for a given Qts, power handling.
Note too that compression horns will add enough acoustical loading to raise the nominal impedance up to 2x Rdc over their pass-band, dropping back down when the horn unloads and only functioning as a direct radiator, so with a loading cap I?m not surprised its Rdc is considerably < a woofer?s ~12 ohms for a nominal 16 ohms impedance.
With re-cones though, I?d be surprised if GPA still has period correct coils for the early series or even much choice of nominally 16 ohm coils beyond the ~12 ohm ones for the 416, 515 where inductance should be ~the same, so it seems reasonable these are the ones used in 605, 604 re-cones.
WRT the XO point ?floating? between 1500-1600 Hz with the small horn, I assume this is due to how the XO?s alignment changes with driver VC design between models, which with re-cones may actually work out to yet something different if the original VCs aren?t used.
Short of GPA listing a customer?s options to choose from, one can only measure what one receives, which in some cases we know is well shy of the mark.
This ?E? plot should be in the ?ballpark? from around 300 Hz-up for most of the small horn 604s when driven with a typical SS amp: http://www.lansingheritage.org/image...itor/page2.jpg
GM
Not seeing any EQ setting........Quote:
Originally Posted by aditya
GM
Bracing, doubling [or tripling if 5/8"] the panels are obviously required if they flex and if the rest of the cab isn't made from at least 3/4" no void marine grade, BB or Apple ply with at least one 'X' brace, then it's probably flexing too, or if not, will be when the back has been sufficiently stiffened up to transfer the air load to the next 'weakest link'.Quote:
Originally Posted by cradeldorf
GM
Hmm, I'm logged in and stay logged in even when the forum disappears/reappears unless it's a major update. Anyway, I was looking for a plot, but I now see it's a picture of the sliders. Interesting EQ, mostly the opposite of what a 604 would need.Quote:
Originally Posted by cradeldorf
GM
Cradeldorf, are you using the tone controls on your amp in addition to the Equalizer? If so, what are you adding with the tone controls--any bass?Quote:
Originally Posted by GM
