Noob Here - Altec Valencia 846B Question

Just bought some minty Altec Valencias from the original owner; eBay; $850. Everything on them is original and only the foam from the grilles and one badge are missing. The veneer is almost perfect.

I fired them up and the drivers all work, but even at high volume with the bass turned up, the woofers aren't doing much; I'm getting very little bass.

I know the crossovers tend to "wear out" and I've looked at the threads about rebuilding them or replacing them, but right now I just want to get these speakers operating to their original specifications before investing in upgrades. I want to hear how they are supposed to sound, in other words.

So, two questions:

(1) If I rebuild the N800K-8K crossovers to the attached specifications, can anyone tell me exactly which parts I should order from Parts Express, and which parts they replace? I know I need caps and inductors and maybe L pads, but I would love to have the exact values and brands if anyone can steer me right. Please pretend (yeah, right) that I'm a complete idiot who knows how to solder and fix things but has no clue on electrical component values. I just need to be told which part to solder where. I may also send this schematic to Parts Express and ask them to make me a shopping list. For each unit, would I want two 1.75 MH air core inductors, one 21 MF capacitor and an one 8 MF capacitor? (The L Pads seem OK.) Which brands and models?

And (2) how would bad crossovers kill the bass? (I hope I'm looking at the right culprit, here.)

Thanks!

PS Is this the right schematic?

Thanks! They're the Bs, and the woofers are original. In fact, the cabinets have never been opened (and the surround spooge is oozing). And I mean very little bass, period; not just below 40 Hz. At high volume with the bass turned up, I can hear and feel little bass. The heartbeat on Dark Side of the Moon (MFSL CD) barely makes them vibrate at high volume, where my sub (also connected to the amp's speaker-level outputs) is shaking the house, when I turn it on. My uncle had some Valencia closes he made with the same components, and they used to make our house groan with that recording; the woofers would visibly pump.

I ran my iPhone frequency generator through them and the output seemed to drop off in the 100 Hz range and below. (I think; I'd have to check again.) Compared to my B&W 802 Series 80s they have less bass, and those speakers aren't noted for their powerful bass; in fact, they roll off around 50 Hz. The voice coils are not rubbing or burned out and the woofer's are definitely operational, just weak. The midrange is clear, imaging is good, soundstage nice, but vocals are a bit metallic to my ear.

My amp is an NAD C272; solid state, about 150 WPC with soft clipping.

I'm really confused, here, and this is killing my buzz in a big way. Could bad inductors do this? Is there is a 21 MFD cap in the LF circuit above?

Thanks again!

Update: Now having played with the levels and the HF knob, I'm coming around to the view the speakers are working properly, but have less bass than I recalled from the set my uncle used to have. Right now we're playing them and my whole family is enjoying them, so I guess it's all good.

By the way, I pulled one of the baffles (it was a virgin) and it looks like the sides and top and bottom are solid walnut!

Didn't know if you had this sheet or not. I don't have any experience with Valencia cabinets, but the drivers and crossover I have out of a set of 846A's are very clean sounding. The woofers themselves barely move. Too get the deep, window shaking bass, I use a subwoofer. Also, make sure you rotate the woofers to get that goop to spread out again, 90deg at a time. Then, once the stuff is spread back around the surround, rotate periodically to keep this from happening again. If all that goop is in one area, it can make the VC rub and you may get some buzzing on certain frequencies. You can also use clear pvc pipe cleaner found at hardware stores to help soften it and spread it back out evenly, just being careful not to get the solvent running down the cone.

As far as the mid being a bit metallic on the vocals, I've heard of people placeing a baggie of sand on the top of the horn to help reduce it or even wrapping with insulation.

Thanks, DN! I have seen that sheet, but the rest of the tips are new to me. Very cool. I may put some Damplifier (like Dynomat but cheaper and, in my view, better) on the horn, too. I do notice that the woofer is barely moving. I have dialed back the horn and turned my Velodyne F1200 sub back on for the lower bass.

Right now I'm cleaning the veneer carefully, then I'll sand and/or fill a few nicks after I color match some filler, then on to light sanding (400+), oil and wax. And I need new grill fabric, too.

Eventually I may upgrade the crossover to the Model 19 Zilch is making, and get a better compression driver, too.

Fun, fun!

I have thoroughly documented the shortcomings of Valencias all over the internet since Jackgiff and I investigated them in the "Babies" thread in Lansing Heritage forum and here on AK. Solutions have evolved over the intervening years, and we are now very close to having an ultimate answer, based upon this work:

http://www.audiokarma.org/forums/showthread.php?t=328530

I am sending Jack the requisite parts for that solution, and he is prototyping a PC board to implement it. They should be generally available in a matter of weeks here, so sit tight a bit longer. The comprehensive solution effectively converts Vals into quasi-Altec-Model 19s, and Jack will be fully documenting the process here on AK.... :yes:

........but have less bass than I recalled from the set my uncle used to have.

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It's all about the room. If you're not listening in the same room as you heard your uncle's in, then you shouldn't expect the same results, especially below 100hz where room interaction is significant.

.............and it looks like the sides and top and bottom are solid walnut!

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It's plywood or MDF, much of the furniture grade cabinet stock was sourced veneered on both sides. Solid wood is generally a poor choice in materials for cabinet construction.

Thanks, Bowtie. Yeah, I figured that out about the veneer; it was just weird seeing it inside the cabinet. I'm now gently cleaning the outside preparatory to filling a few small dings, then lightly sanding, oiling and waxing it. I need new grille cloth, too. Color is still an open question.

As to the bass, yes, I think it was about the room and my expectations. Also (embarrassing confession time), I started out running them through my sub, which has a passive 80 Hz high-pass filter. But even after I connected them directly to my amp they still weren't putting out as much bass as I expected.

Bottom line is, they have less bass than I expected, but now they seem a lot more "normal," if you will, at the bottom end. I think I'll keep my sub in the picture.

Zilch, I think that is so cool about all the work you guys have done. I've been going back through those threads and it's weird to think that I seem to have I bought my speakers at this time, just as your M19 work is finishing up.

Oh, and here's a lousy Hipstamatic photo; I was too lazy to take a decent one last night. My cherry B&W 802 series 80s are next to them. My brother may be taking them off my hands. Merry Christmas to me!

I've rebuilt quite a few of the 846B crossovers, I don't think any ever helped with the bass.

Neat - O! Lovely photos! Can you tell me what the types and values are of those caps? Where did you get the inductor "clamps?"

I realize now also that I was reading the L Pad wrong; I thought 10 meant loudest instead of quietest. The woofers got a lot more audible when I turned the horns down properly.

Zonker92 said:

Neat - O! Lovely photos! Can you tell me what the types and values are of those caps? Where did you get the inductor "clamps?"

I realize now also that I was reading the L Pad wrong; I thought 10 meant loudest instead of quietest. The woofers got a lot more audible when I turned the horns down properly.

Click to expand...

Those clamps are nothing more than noninductive electric conduit clamps, attached by nonferrous aluminum retainers. The extra 8 ohm resistors and 20uf caps are for the Zobel to stabilize the woofers impedance. I believe I went with identical Solen 12uf caps, and 18 awg 1.5mh coils, Dave.

can someone explain how a 2way speaker using an 8 ohm woof and an 8 ohm tweet are yielding an effective 8 ohm cabinet? as is seemingly the case on the 'B' model ?

the only way i know to get an 8 ohm cab is to wire two 16 ohm drivers in parallel....so the standard altec 2way (or any other 2way) that uses a 16 ohm woof and 16 ohm tweet wired togetether in parallel to the speaker jack, is the only way i know to yield a 8 ohm cab . and therefore use the 8 ohm tap on the amp, and therefore use a 8ohm crossover ...so how did altec use two 8 ohm drivers and still all this an 8 ohm speaker ? if one uses two 8 ohm drivers in a cab, the only possible yields to the speaker jack are - 4 ohm (parallel) or 16 ohm (if drivers are wired in series) ...no?

so the way it works is that the 2nd order crossover allows for these 8ohm drivers to yield 8 ohms and a 1st order would not? or would the 1st order do this as well? the problem with the crossover calculator is that I can't see what magic its doing to achieve this - i dont doubt its doing it, just wondering how....

it must be a property of the inductor and caps obviously, as they effectivel manipulate the resistance ,I just am not getting how the end result can be called an '8ohm' crossover or a '16 ohm' crossover.....if the speakers cable coming off the crossover to the amp where measured with a meter, would an 8ohm crossover measure 5-6 ohms (8ohm)?

I know that the general advice is that if one wants a '8ohm' 2way cabinet, then one uses both drivers of 8 ohms and if one wants a '16' ohm cab, then use two 16 ohm drivers...but there are altecs that use one 16 and one 8 for example...how is the crossover magic determining whether the end result is a 8 or 16 ohm crossover/speaker? and is the crossover designer in control of this, or is the calculator/past physics in total control of this outcome?

.I assume the valencia, like all other 2way altecs are using the drivers wired in parallel with one another? or are the drivers in series to yield 16 ohms and then the inductors resistances wired in parallel knock them down towards a ending 8 ohm cab?



maybe the answer is...its complicated
https://speakermakersjourney.blogspot.com/2016/12/crossover-basics-impedance.html
https://www.calsci.com/audio/X-Overs3.html

Linkwitz-Riley Crossover
thanks much for the info. will take some time to try and digest...one of the particular questions that I need to ascertain is whether a standard first order (one cap and inductor) would 'maintain' the 'speaker system impedance' ? when you say, most good crossovers maintain that, I assume that a simple 2way with 16 ohms for tweet and woof, wired in parallel (8 ohms) is the 'speaker system' and that the standard first order crossover would yield 8 ohms - and so that is what the amp would be set to? I have 16 ohm taps as well if needed... Also, if one just uses high pass cap and no inductor, is that a 'good crossover' that would also maintain the impedance in the same above two way 16ohm driver/8ohm final cab load? those two scenarios as well as a standard 2nd order are the three scenarios for my altec 2way and ultimately , just trying to determine what each would yield as the final 'cab' impedance so I'd know which amp tap to use.....Need to read and think about the info and links given, but first glance suggests that all three scenarios may yield the same 8 ohm total load (assuming drivers are both 16 which they are in my case)

the links are quite confusing,,example :
"If a series and parallel crossover are compared using a suitable resistor in place of the speaker, they are almost identical. However, loudspeaker drivers are not resistive,.....drivers are reactive,....... a parallel network requires impedance compensation. Without it, the final frequency response is a lottery, and it certainly won't behave as expected. The impedance correction involves a notch filter for the tweeter, and a Zobel network for the woofer. Without these, the response will be highly unpredictable (and rarely good). Other effects will also have an influence as detailed below. A parallel network has a lower overall impedance, mainly due to the compensation circuits (a compensated parallel version using the same drivers has an average impedance of about 4.5Ω between 400Hz and 10kHz)."


So when this talk of 'impedance compensation' is mentioned. it is in respect to fine tuning the slight impedance of the system, and not the global/grand impedance I am seeking the answer to (8 vs 16 ohm amp settings) ? The issue with alot of the info I come upon is confusing because the examples used are, or may be, complicated 3way or 3rd order situations, and all im needing to figure is is 1st order or at most , a bone stock basic 2nd order...Have heard about the zobel, but that addition would be the most complicated detail if I decide to try.....



here's another confusing paragraph - I get that drivers are not even close to static impedance. but....The info below and in this search, seems to indicate that because drivers are so varied in their impedance, that crossovers can sometimes either be intentionally - or unintentionally (bad design) made to turn two 16 ohm parallel drivers into a total '16 ohm' load (in terms of how close one is to 8 or 16 in terms of the amp setting), when a 'good crossover' would 'maintain' the system and yield an effective '8 ohm' load.... Since im just using basic first or 2nd order situations, I am assuming this bad design would not end up as a problem,? but the info below seems to be relevant, and yet makes very little sense so far...

"If the two drivers remained at exactly 8 ohms at all frequencies, the impedance curve is almost dead flat. There will be a small dip at the crossover frequency, but for two 8Ω (nominal) drivers it falls to 6.3Ω at 2.4kHz, with a very gentle slope (the 'notch' is 8kHz wide!). The impedance curve was produced using the same values as all other examples, and the only significant points are the resonant frequency of the two mid-bass, and the impedance peak roughly half-way between the tweeter's resonance and the crossover frequency. The impedance was measured using the same equivalent circuit for each driver as shown throughout this article. With an impedance such as that shown, no known amplifier will be at all stressed."

the system im using is altec 414drivers and old altec or jbl tweets. all 16 ohms...have spent months learning, have got the cabs built and it's sounding good. But now am at the crossover stage and this is quickly getting complicated...right now have been using with no inductors and just high pass caps, but I have not even yet determined whether that simple situation is an 8 or 16 ohm load, so have been trying both on the tube amp...Also been trying inductor on the 414 (still first order) and if am able to wrap brain around impedance, may venture into the basic 2nd order.....









"Next time you put a small speaker system together, try the series 6dB/ octave network. It's highly unlikely that you'll be disappointed. "

?

so, Linkwitz-Riley Crossover . apparently .linkweitz first order uses series drivers and 2nd order linkweitz has them parallel? it seems. whereas all first and second order butterworths have them paralelled? so this author is suggesting the first order likweitz is the most worthy.

still do not see how two 16 ohm drivers in series (32 ohms) can be corrected down to 16 or 8 with caps and inductors though.....




so here is a linkwitzriley calculator and is does not allow for entering impedances for each driver..it only has allowance for 'ohms at crossover' ? what is that I wonder

http://www.mh-audio.nl/Calculators/SLR1.asp#calc1

and here is the answer !!

http://www.mh-audio.nl/Calculators/MLC.html

oh my. All I have is a radioshack DMM !

dgwojo said:

Эти зажимы представляют собой не что иное, как неиндуктивные зажимы для электрических кабелепроводов, прикрепленные фиксаторами из цветного алюминия. Дополнительные резисторы сопротивлением 8 Ом и конденсаторы емкостью 20 мкФ предназначены для Zobel для стабилизации импеданса низкочастотных динамиков. Я полагаю, что я использовал идентичные конденсаторы Solen 12 мкФ и катушки 18 AWG 1,5 МГц, Дэйв.

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good day!
please tell me how the zobel is displayed on the sound? and could you draw a diagram with the zobel so that it is visible where it is connected. thanks

From DGwojos post, this is the Zobel network that was added

An example of where it is in the circuit

Has anyone installed this zobel? Is there any improvement in sound?

The zobel was part of this add on network. I’ve never installed it on an existing crossover. I did build a variation of the 9849 crossover shown above, and it sounds great.

Most people just add the 30923 HF section.

factory crossover. has a 20 μF capacitor on the midbass.
if you add another zobel, then the total will already be 38 μF. which strongly appears on the frequency response. and the midbass will be cut off much lower.
are you sure that the zobel is installed additionally? or just add an 8.2 ohm resistor to the existing capacitor?