Altec 838b Carmels

[corbu]

I need a little help getting motivated guys! What would you advise a novice to do with these? A year ago I picked up a pair of Altec 838b Carmels (2- 414z / 806) and gave them a listen w/ both a 30 watt push-pull amp and then a 300b SET. Not impressed. Perhaps my room is too small (12'x14). I have a cheap active crossover....would bi-amping these help? Or should I find someone to freshen up the stock crossovers? Or pull the drivers and go with a different cabinet design (onken?)

Many thanks....Corbu

 

[Zilch]

They are "wrong."

An active like Behringer CX3400 with CD horn boost can flatten and extend the HF response of 806, but they still roll off above ~13 kHz. I never measured the distortion doing that, but boosting them above there would doubtless be untenable in this respect. 806s can not deliver but as mids in 3-way, and getting a tweeter to integrate with 811B mids is difficult drill.

Altec resolved these issues with 802-8G (and ultimately 902) using the requisite high-frequency compensation, extending the response to 20 kHz, in Model 19, et al. You want them to play nice using Altec drivers, replace the 806s with new 902s and build Z19 crossovers for them.

Read up here, where Skywave and I hacked our way through this several years ago:

http://www.audioheritage.org/vbulletin/showthread.php?18913-Altec-9844-8B&highlight=

 

[corbu]

Thanks Zilch. Will do. Suppose I was OK with not playing nice...what would you suggest? Another type of HF driver and horn?

 

[Nat]

I'm trying the Selenium D220ti that shows up a lot on that (incredibly long and interesting) thread in my Valencias -- seems to me more high frequency extension, but I'm not entirely convinced that its virtues outweigh those of the 806. The HF roll off of the 806 kind of encourages cranking up the level control, but that makes the midrange hump more egregious. You can toss in a super tweeter, but of course that doesn't do anything for the midrange. Or you can replace the 806 and the crossover and the woofer and the enclosure, and made a half assed 19, you may wonder if it wouldn't have made more sense, been cheaper and easier to buy a 19 and toss the Carmels in the dumpster. Which is ridiculous.

 

[Tom Brennan]

The 414 woofers have formidable virtues.

I wonder what it is exactly the OP finds unpleasing about the Carmel? If it's the lack of extended lows and highs those problems can be worked on but if the OP dislikes the basic nature of the reproduction between, oh say, 100 to 10,000 cycles he may be better off to find other speakers.

 

[corbu]

Tom,

With the Carmels I am very aware that the speaker is 'there'...no illusion of being enveloped by the music. Sorry for the non-technical explanation.

 

[Zilch]

Thanks Zilch. Will do. Suppose I was OK with not playing nice...what would you suggest? Another type of HF driver and horn?

The next project I'm gearing up in "Flex Your Mettle" is BMS 4555 on PT waveguide with 414 woofer. May get that started this weekend.

I'm trying the Selenium D220ti that shows up a lot on that (incredibly long and interesting) thread in my Valencias -- seems to me more high frequency extension, but I'm not entirely convinced that its virtues outweigh those of the 806.

800 Hz is nearly an octave lower than the recommended minimum crossover frequency for D220Ti. Have others done this, yes. But in my view, even M19's 1.2 kHz is a "push." BMS 4550 is a better option, and you'll find a bunch of threads here discussing upgrading Valencia and similar with that driver.

Let's discuss 811B horns a bit. Ultimately, Altec "conceded" by example that they are 1.2 kHz horns, not 800 Hz. Similarly, 511s are 800 Hz, not 500 Hz. Both have an inherent coloration when run too low. If we take M19, widely acknowledged as Altec's best high-fidelity 2-way effort as example, that points where we need to go with upgrades. Do it with the appropriate Altec or alternative drivers and highpass filter with HF comp to tame Altec's characteristic "shouty" midrange and extend the response to 20 kHz.

Can 811 and 511 horns deliver high frequencies? Yes, but they beam them. Whether that's a significant issue or not depends upon listener preference. They have a pleasant "woody" character (of all things), and I've never heard anyone suggest that Model 19 sucks, despite the fact that few understand how it's supposed to work well enough to optimize the response. I'm saying that half-assed M19s are decidedly better by contemporary standards than whatever they used to be.

[That's my opinion, by no means humble.... :tongue: ]

 

[Tom Brennan]

Tom,

With the Carmels I am very aware that the speaker is 'there'...no illusion of being enveloped by the music. Sorry for the non-technical explanation.

You seem to have a very basic problem with the speaker; an "inherant" one so to speak. It may be they simply aren't your cup of tea and your efforts would be better spent elsewhere.

 

[theebadone]

You seem to have a very basic problem with the speaker; an "inherant" one so to speak. It may be they simply aren't your cup of tea and your efforts would be better spent elsewhere.

I agree with tom, i wouldn't modify a speaker that you most likely, still will not be happy with, after much modification. Someone would surely enjoy those Altecs just as they are, not to mention they might bring enough to fund 2or3 more projects. :yes:

 

[Nat]

Zilch: thanks for the info. I know there is a lot on modifying Valencias -- in fact, the problem is that there is way too much. There are substantially more than 100 pages on the econowave thread, and given that most of the useful input in the thread is by people who know a hell of a lot more than I do, and are interested in all sorts of different projects at once so wander off in all sort of different directions, mostly involving expensive components, its not easy for someone new to horns to orient themselves.
I thought I would try the Seleniums on the 811 because a couple of posters had tried it, and, at least initially liked it. And I figured if I didn't like it, I could always econowave something else. And that may be what happens, but for the moment, I'm listening to them with some pleasure, though I do feel some of the magic is missing -- the Valencias are obviously colored, but they do some things very well, and less obvious coloration at the expense of the things they do well may end up seeming a step sideways. But for now, its interesting to listen to.

 

[GordonW]

My curiosity is such, that if I had a pair of Carmels, I'd consider using the 414s in a 2.5 way mode, with the QSC waveguide and a good horn driver (such as the BMS mentioned above), in an E-wave setup. Could be spectacular- you'd be able to get the best virtues of the 414 (mids) with good bass (since it's 2.5 way), with a very well behaved horn that can perform out to the limits of audibility (20KHz easy). And, by my very rough calculations- in a 5 cubic foot cabinet (total for both woofers), tuned to 38 Hz, with the second woofer brought in at about 75 Hz, you could get bass down to about 35 Hz or so, flat.

Of course, this would be better served with a different cabinet, to "stack" things vertically (horn, woofer, woofer). That means you'd basically ONLY be using the 414s, out of the original Carmel setup. That could be good or bad- the bad is that it's a lot of work- the good is that you would still have the REST of the Carmels, unmolested- so, the 414s could go back into them, and they'd be as-original again...

Regards,
Gordon.

 

[Dan ʕ•ᴥ•ʔ]

You seem to have a very basic problem with the speaker; an "inherant" one so to speak. It may be they simply aren't your cup of tea and your efforts would be better spent elsewhere.

I agree with tom, i wouldn't modify a speaker that you most likely, still will not be happy with, after much modification. Someone would surely enjoy those Altecs just as they are, not to mention they might bring enough to fund 2or3 more projects. :yes:

+2 I'd sell them as is and move on to the next aural adventure.

 

[Zilch]

For some, there's more to this hobby than pickin' and flippin'. Nat's on track to greater pleasures. :yes:

[Member Steve O has been upgrading a pair of Carmels with BMS HF drivers for several years, now.... ]

 

[Steve O]

For some, there's more to this hobby than pickin' and flippin'. Nat's on track to greater pleasures. :yes:

[Member Steve O has been upgrading a pair of Carmels with BMS HF drivers for several years, now.... ]

Yes indeed, I have been doing just that. I replaced the 806 drivers with BMS4550s and worked up my own xover with nec comp for the driver/horn combo.

The project has taken a lot longer than originally planned because I got caught up in indecisiveness regarding:

1. BMS4550 vs 4552 - Ended up with the 4550
2. RCL resonant traps vs RC "T" network for comp - Ended up with the RC network
3. 1,000Hz vs 1,200Hz basic xover F (2nd order LR both) - Ended up with 1,000Hz
4. 2.0 way vs 2.5 way config - ended up with 2 way
5. Std prod L-Pads vs discrete resistor switching - will end up with discrete resistor switching
6. Std design Zobels for the woofers vs modified values for really flat and consistent impedance around the xover F - ended up with mods
7. Verifying the clip leads didn't introduce too much error - they didn't
8. How to mount everything? Plywood, particle board, MDF.... Will end up with everything mounted on 5/8" thick phenolic board w/drilled and tapped holes for inductor mounting, solder lugs etc (no wimpy PCBs here!)

Everything but 5 & 8 was set up with clip leads and listened to for extended periods thus adding more time to the process. The last challenge is getting the crossovers out of clip lead mode and committed to something solid...a challenge made more difficult by my recent decision to go back to school...I should really be studying right now and not messing around on audio fora. :nono:

At this point I'm quite pleased with how it's all turning out. While the present setup doesn't seem to reach much below 50Hz, the overall sound is detailed and extended with a very delicious electrostatic like midrange. Ironically, current power amps are restored QIIs...originally used with my QUAD ESL 57s.

Overall, while I respect Mr Brennan's opinions and his respect for the unmodified Altec sound, based on my experience with the Carmels, I really believe one can modify these particular speakers in the manner I've described for much improved mid and high end performance (subjectively and objectively) while still maintaining the best qualities of the original design. IOW, if one is willing to expend a little effort and a little more $$$, modding the Carmels could be a very rewarding experience. It all depends on ones inclinations. And the expense of upgrading can be partially offset by flipping the 806s since there seems to be a market for these when in good cond (I still have mine for sentimental reasons).

As always and kinda tritely, YMMV.

 

[Zilch]

Heh.

[And I didn't PM him, either.... :tongue: ]

 

[winkun]

I'm watching this thread closely. I also have some Carmels that I'm less than thrilled with. Steve O, is there any documentation yet on the web of your project? Your mention of "electrostatic like midrange" has me intrigued.

 

[Steve O]

I'm watching this thread closely. I also have some Carmels that I'm less than thrilled with. Steve O, is there any documentation yet on the web of your project? Your mention of "electrostatic like midrange" has me intrigued.

No docs re: my Carmel mods other than verbal descriptions here on AK over the last few years. I had begun to put something together in Jan of this year but computer issues put an end to that project and I haven't recovered as of yet. Goal was to present a writeup describing my "journey" and reasoning as to why I ended up with what I did. I also want to get the xovers out of clip lead mode and actually constructed so I have something presentable to go along with the schematic and measurements.

Keep in mind that that everything I've done so far has been optimized for my room conditions and amp preferences (low power PP tube) with zero consideration given to "average" rooms and amps. My room is relatively large @ 24'x26' with a vaulted ceiling. IOW, YMMV. Another possible caveat is the cost of the BMS drivers...German engineering and manufacturing doesn't come cheaply in the US these days.

As noted, my new back-to-school adventure is going to put a damper on formal presentations for the near future but I might be able to post info as I slowly recover it. Stay tuned!

 

[theebadone]

Heh.

[And I didn't PM him, either.... :tongue: ]

LMAO, I'm just suggesting that he doesn't do anything to the Altecs that can't be undone,:nono: those big dual woofer, horn speakers are gettin hard to come by in my neck of the woods, and are commanding top dollar when you do find them. Besides, wouldn't he be better off starting with something a little smaller, in a 12" single woofer 2 way to start with ? And if he likes the results he can modify the carmels, with a little more know how, and confidence. just a thought.

 

[Zilch]

It ain't always about the money.

[This from someone with 414Zs on the test stand at the very moment.... :tongue: ]

 

[corbu]

thanks gordon

... "Could be spectacular- you'd be able to get the best virtues of the 414 (mids) with good bass (since it's 2.5 way), with a very well behaved horn that can perform out to the limits of audibility (20KHz easy)"

Regards,
Gordon.[/QUOTE]

Gordon,

I am located in ATL. Can I PM you to explore this in more detail?

Corbu