ALTEC 604 E in small enclosure...

[Guglielmo]

OB in my case...

Then I realize that the available space in my living room for BR cabinet is not suitable for a proper 604E fitting... For that I would insist in the OB project avoiding too limited enclosure size and relevant bass frequency lacking response. Nevertheless the baffle shall be maximum 35" x 21" and positioned on the longer side on the furniture shelves at more than 80" height (like in studios control room). I fear anyway a bass lacking even if this OB shall be close to the rear wall. For that I am seriously thinking about an helper woofer like in this Jamo model

http://www.jamo.com/speaker-types/fl...ding/?sku=R909

The allowed space on the baffle is just sufficient to host my 604E and another 15" woofer. Then to stay in the Lansing family I would an Altec vintage woofer, may be a 416B in Alnico. What do you think? If this could be a good approach how do I have to connect the woofer? Consider that I will drive the Duplex sections directly from bi-amp set up with active Xover and two power amps (SS for bass and tubes for high). Shall I have to "cut" the bass response of this helepr woofer may be around 100 Hz like a sort of subwoofer or connect directly to bass amp leaving the mechanical frequency cut which is much more high?

I very appreciate your skilled help!

Guglielmo

[Alien_Shore]

It doesn't sound like you have enough room for an enclosure for a "helper woofer" that will give you the low end that your OB/604 setup will need for adequate reinforcement (realizing of course that my definition of adequate is completely inside my head, not yours!). You really should look at a separate sealed subwoofer you could tuck up next to your coffee or end table. Did you look at the bucket subwoofers? They are actually very impressive with their output and the low-end they produce!

[cradeldorf]

I would go with something like the 6 moons MLTL if I was in your shoes. Greg (GM) Had a large part in this design.

http://www.6moons.com/audioreviews/altec/dream.html

[GM]

I guess I?m still confused as your baffle only has room for one woofer, so not sure why the reference to the Jamo.

Anyway, since you?re limiting your choice so much to ?60s era Lansing woofers, yes, the 416B is as good a choice as any AFAIK.

Since these will be very near a back wall, just wire the 604?s woofer and 416-16B in parallel to the SS amp and use some form of EQ to flatten it in-room down to wherever it best overall blends to the room?s gain curve. If the room is small, tight enough, none may be required since the dipole will roll off ~1^st order down to the driver?s Fs.

That said, all these drivers were designed to be driven with a high output impedance, so the norm when bi-amping with tubes/SS would be to drive the 604 with tubes and SS for just the ?helper? woofer and use digital EQ to boost/cut it as required to blend it to the 604 and room gain curve.

GM

[Guglielmo]

GM,

thank you for your suggestions. Yes, the woofer will be very close to the 604, actually the two cones shall be very nearby, like in a JBL C50 Olympus, just to get an idea.

The 416B may be also a later version with respect to my 604E period namely Seventies, just to simplify the research and to optimize the performaces being these Alnico woofers more efficient in the more recent versions. Correct?

I will consider to connect in parallel the woofer to the bass section of 604 and leaving the natural roll-off on the higher frequencies to work. Anyway I am always in time to cut the upper threshold in some manner, passive or active, choosing the best possible mix of the two bass drivers.

Guglielmo


P.S.: I forgot a question: is the 421A also suggested like helper woofer or is it just for musical purposes? I ask this because I found a nice pair of the same 604E period. Anyway I fear that the bass response would be lesser but being in Open Baffle... ?

Thanks again!

[GM]

I compared a then just released 421-8H and 416-8B in ~20 ft^3 cabs and not surprisingly the 421 went non-linear at very low power, though still pretty loud by most folk's standards, so in a suitable vented cab it might be fine for apt. or similar HIFI/HT app that limits usable power to maybe 3 watts, though the dust cap needs to be damped with rubber cement or felt or a paper one attached to it as its shrillness is much too sharp except to the hearing impaired.

Consequently, IMO it's totally unsuitable for any high SQ OB, IB or the higher SPL required to meet THX reference or even deal with pipe organ symphonies without some form of EQ to severely limit excursion down low.

Limit it to ~80 Hz in a sealed cab though and the 421 series [with damped DC] makes a ferocious HT mains or similar two way monitor 'on the cheap'.

Yeah, with OB there's no such thing as having too much displacement, so either a very high Xmax and/or multiple drivers is desirable unless close to a corner, but then it's no longer an OB, but some 'flavor' of vented alignment.

GM

[Guglielmo]

Thank you GM, I've understood that the 421 is not an ideal mate for a 604E in OB... I guessed this being a "musical" speaker design. I found also a nice pair of 418B with no-metal dust cap (restored?) as in annex here below. Do you think that also this type is not suitable for my purpose? By the way these 418B seem of the same period of my 604E comparing the frame grey-white color...

Or, I doubt, I have to stick on the 416 which is the true bass performer needed as helper woofer to reinforce the low end lack in OB set up.

Thanks

Altec 418B.jpg!

[sanhanul]

This just isn't a speaker that is going to perform well in a small enclosure. Mine didn't sound good in a sealed alignment even as large as 200 liters. Once I got up to about 250 liters in a vented alignment, the woofer really started to sound good.

Hmm,,It means I need 612 cabinets or 620 at least. (My 604s are in 614 cabinets- little bit over 100 liter- now)
I have to think about it again.

[GM]

Thank you GM........Do you think that also this type is not suitable for my purpose?

You're welcome!

I never bothered to learn about the design details of the various drivers since I lived only a 'stone's throw' from Altec's Southeastern USA distributor that had its own in-house system design and repair facility, relying on them to tell me what I needed and why, etc., but from dim memory of what's been posted here over time is that all the MI woofers were designed to 'sing' [distort], i.e. virtually no Xmax; so while they might be able to be re-coned with 416/whatever diaphragms, their respective VCs and/or spiders might not be usable.

They might still be fine in most HIFI/HT apps due to their high efficiency, but will audibly distort in any app that requires more than ~ a mm of linear excursion.

In short, unless old guy, bowtie or others more knowledgeable say otherwise and why, I can't recommend any of them for any potentially high excursion app whether re-coned to look like a 416 or not.

GM

- - - Updated - - -

My 604s are in 614 cabinets-

Yeah, a 614 is fine for a true PA [public address], AM broadcast or similar app where the bass is rolled off below ~125 Hz, but enough bass to potentially sound ‘full’ in room will require a net Vb that’s a significant percentage of the driver’s Vas.

GM

[sanhanul]

Yeah, a 614 is fine for a true PA [public address], AM broadcast or similar app where the bass is rolled off below ~125 Hz, but enough bass to potentially sound ‘full’ in room will require a net Vb that’s a significant percentage of the driver’s Vas.

GM

You guys are way up too high for me.