Altec Bolero 890c experiment incoming

I wasn't really planning on doing this, but as fate would have it, these empty cabs showed up here a few weeks ago. I think I have T/S parameters for the 406-8Y around here somewhere....View attachment 37788
I've got this so far...purportedly for the 8Y. I've never measured T/S before. I understand it's not terribly difficult... I've either got, or got access to, the hardware to do it.

Pic from an old diyaudio post from 'GM', who went on in the thread to recommend a 7 cu ft TL enclosure for the 8Y.
 

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Through the years, I've experimented with double LF drivers (755E x 2 and 414A x 2) in a mono set up. Each time I was disappointed. In spite of the gains in scale, low frequency extension, dynamics and higher SPLs, I couldn't live with the muddled midrange and lack of overall purity. But that's just a reflection of what I want out of my hifi set up and my preference to keep things simple.

If I were in your shoes, I'll bypass the Heppner horn, run the -8Y in wide range mode in the original box w/ passive radiator and mount the RCF horn combo on top using the M15 XO as a starting point. The RCF H3709 is a nice horn! If mounted free standing, it might (?) need a bit of damping since the metal used was relatively thin. Since it's a straight horn, make provisions for greater attenuation vs. the 90 degree bent Altec 32 horn.

My gut feel is the 406Z and 406-8Y will give more bass in a bigger box like the 614. Something I've been wanting to try.
Ditto on the RCF H3709 horn - it’s a real sleeper. Plus you have to respect RCF for emulating a classic.

As for the horn ringing, surprisingly the ringing isn’t too bad when free standing. I am rotating between two sets of speakers, the one shown below as well as an OB design with the H3709 mounted to the baffle. I’m not bothered by any ringing or shouting, and that’s something that makes me run straight out of rooms at audio shows.
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je2a3

Senior Member
Ditto on the RCF H3709 horn - it’s a real sleeper. Plus you have to respect RCF for emulating a classic.

As for the horn ringing, surprisingly the ringing isn’t too bad when free standing. I am rotating between two sets of speakers, the one shown below as well as an OB design with the H3709 mounted to the baffle. I’m not bothered by any ringing or shouting, and that’s something that makes me run straight out of rooms at audio shows.
View attachment 37877
I agree, beautiful cabinets!👍

The H7309 aren't easy to find, but your RCF experience was a nice read!
 
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StevenZ

Pending Gold Star Member
I’m using PIO motor run with film caps paralleled to adjust value/crossover. You can see a picture of the back of my speaker at the end of the 802/32/414 pinned thread. Not married to any flavor of caps, at this point, with all films the next step at a slightly different value (measured value). I work slow...listen to music more than I change things. I’m not sure of the crossover frequency...I’m using a online calculator with 8 ohm on high pass and 16 ohm on low pass, then adjust frequency until I match cap value.

My goal is simplified...nothing between wide-range 414z and the tube amp but wire. And no resonator box to tune therefore the open back. I’m bringing the 32c/807 in slowly to help the top end, but not to step on the 414z. I’m using the less sensitive Altec CDs thinking they would be a better match to the 414z without the need for a L-pad. On bottom, I’ve got the same goal, but haven’t done much critical experimenting. I’m using a 605B in a H-frame cabinet with only the woofer powered by some plate amps with crossover fq at 40hz. Really like the sound of bass guitar and drums with this setup. MiniDSP may be the best solution here, but then, I got to learn how to use it. I have a Nakamichi TA3A with Nelson Pass designed stasis amp I would like to use here.

je2a3 is the man for help. His blog got me started down this road.

I almost forgot, I bought 2 pairs of 414Z’s to do the dual 414 thing, but one pair arrived damaged. Your thread has me thinking I need to get the damaged one repaired and....a never ending road!! But it’s fun
Sorry for the detour but I also have a Nakamichi TA3A and I think they are absolutely excellent, especially when Stephen Sank does his mods to them. Their already great performance gets brought up a few levels. The mods are very cheap as well. Definitely worth doing.
 
I haven't forgotten about the Bolero experiments - just slowed by my 3 month old daughter.

I've also been distracted playing with a pair of Cetec Gauss HF4000 large format compression drivers I got for next to nothing.

I'll start a thread on those soon.... suffice it to say I'm a fan and I'm planing a 2-way or maybe even 3-way Westlakeish build around them.

Anyhow - I'm about to fire up the RCF N480/ h3709 combo on the Boleros. I've wired them such that I can run the 10" full range or through the recapped Bolero crossover, which rolls it off around 2k.

More to come.
 
Just got the RCF N480 (phenolic)/RCF h3709 combo hooked up on the Boleros, and wow... very impressive.

Whether through the stock network or with the 406-8y run wide open, this RCF iteration retains the characteristic big Bolero sound, while adding a lot more HF information and energy.

The RCFs make the Bolero even more reminiscent of classic Altec designs I've owned, without ever sounding edgy. I haven't measured the RCFs in this setup, but I'm guessing they have good extension out to 16k or so.

Presumably because they're more efficient, the RCFs have greater output than the stock horn drivers, the -3db cut switch put them right about where they should be. Definitely going to roll in the Model 15 networks next. They have a much more sophisticated HF section compared to the Bolero for better fine tuning of the HF section.

Given their very low cost, these old RCF N480 compression drivers have great sound. More polite and hi-fi sounding than Altec drivers I'm accustomed, but still with a nice solid midrange. They're my only experience with phenolic diaphragms - I'm really enjoying them.

I got my n480s for next to nothing - attached to the h3709 horns.

If you're interested in picking up the h3709 horns or the RCF N480/481, search in the usual places for EAW drivers/horns. I don't think it's a fluke these two sound great together....EAW used this combination used on several of its studio and 'cinema' designs in the 1990s. ( FR253, CF350).

I think part of why the h3709 is so hard to find is that few people (sellers included) know the model name. I found mine on the auction site sold as 'EAW horns.'
 
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