Choice of 515 in a 210 center cabinet

[Altec Best]

I haven't had a trashed driver yet that came within 150 of the cost of a new driver. And since you cannot buy a new driver that says "Altec" on it, and i prefer drivers that say "Altec" on them, i would still pursue this venue to a few bucks beyond the break even point.

I would think a true "Altec or nothing" guy would feel a sense of loyalty to the name as well as a degree of responsibility to preserve what can be saved.

C'mon B . A frame that is cut all the way into the accordion ? Really ? We are talking about this particular woofer at the moment aren't we ? That was started in this thread. Sure I'm an Altec guy first,always have been. And the Altec purist that I am I would never consider cutting into an Altec product ever.I would be more apt to mount something that already fits.You can warp an intact frame just by over tightening the screws.How easy would it be to do that with cut frames ? Just to fit them in an A4..I would be more apt to drop 15" 515B's or any other 15" Altec designed for the job in them, instead of breaking out my hack saw. Try reselling those cut woofers and see if you get your return out of them.

This isn't a justification for cutting woofers to fit in your A4's is it ? Personally I would like to see this practice of butchering perfectly good Altec woofers to end and not advocate it ! That's how I'm going to try and save them..


Just my ?.02

[GM]

As I was reviewing the literature for the 515 16G, I saw that the bass response of two of these drivers extends father down than I thought, maybe to 35-40 Hz.

Would switching these drivers into the 210 give me a better sounding set up than the current 515s, or would I be losing something from the midrange? I do have a pair of JBL 4685 subs for low end reinforcement.

What do yours measure? In theory there should be virtually no audible difference down low until the original begins distorting, which will happen at much lower power than the Gs, so as to whether to 'upgrade', I guess it boils down to how loud down around/at the cab's ~35 Hz tuning you need them to go and even then I recommend using 15" frames.

Excluding the 'G', which I've no 'hands on' experience with and is supposed to be a modern day version of the original 515 AlNiCo WRT horn cab loading, mids/HF extension, the rest of the 515s trade some mids/HF 'snap' for LF extension. Back when I could hear pretty good, the difference was subjectively about the same as between the 416A, B and the mid '50s 515B series I compared them all to [~20 Hz Fs, 20 ft^3 Vas, 0.2 Qts].

Also, the electronics can make a significant difference, i.e. system impedance and whether or not tubes.

GM

[analog addict]

What do yours measure? In theory there should be virtually no audible difference down low until the original begins distorting, which will happen at much lower power than the Gs, so as to whether to 'upgrade', I guess it boils down to how loud down around/at the cab's ~35 Hz tuning you need them to go and even then I recommend using 15" frames.

Excluding the 'G', which I've no 'hands on' experience with and is supposed to be a modern day version of the original 515 AlNiCo WRT horn cab loading, mids/HF extension, the rest of the 515s trade some mids/HF 'snap' for LF extension. Back when I could hear pretty good, the difference was subjectively about the same as between the 416A, B and the mid '50s 515B series I compared them all to [~20 Hz Fs, 20 ft^3 Vas, 0.2 Qts].

Also, the electronics can make a significant difference, i.e. system impedance and whether or not tubes.

GM

I don't have the gear to measure the freq response. Maybe I can get Pano to make a trip out this way. Last I looked, I couldn't find a spec sheet on the original 515 either. I also forgot the 15" vs 16" issue, which prolly seals the deal.

I'm running the center on a PP 7189A powered tube amp, one channel for the highs, one channel for the lows. This should put out somewhere around 15-18 WPC, and the SC-ASR-433 does have a 16 ohm tap, which is what I'm using.

[GM]

I also forgot the 15" vs 16" issue, which prolly seals the deal.

I'm running the center on a PP 7189A powered tube amp, one channel for the highs, one channel for the lows. This should put out somewhere around 15-18 WPC, and the SC-ASR-433 does have a 16 ohm tap, which is what I'm using.

It would for me as long as I didn't need PA SPL output.

The tap rating is normally just that, so isn't an indicator of an amp's damping factor/output impedance. PP amps typically have a relatively low output impedance, so require a bass tone control [adjustable DF] to get it up to a ~matching impedance, i.e. DF = unity [1]. Say yours has a DF = 10, then 16/10 = 1.6 ohms of output impedance, which isn't going to effectively 'weaken' the motor much [raise its Qts] whereas as a DF = 1 would nearly double it, dramatically reshaping the speaker's response to a much more pronounced [mid] bass response relative to the mids.

You've got such a rare [and to my ears, superior performing] system that getting either a ~period correct amp with a bass tone control or having a tube amp whiz add one to yours seems a better overall 'upgrade' to swapping out woofers, unless of course it's to go to a custom 515 field coil that allows one to tonally dial it using a cheap adjustable power supply.

Anyway, hop you can get some driver, speaker system specs, measurements for posterity/frame of reference.

GM

[BoydB]

You've got such a rare [and to my ears, superior performing] system that getting either a ~period correct amp with a bass tone control or having a tube amp whiz add one to yours seems a better overall 'upgrade' to swapping out woofers, unless of course it's to go to a custom 515 field coil that allows one to tonally dial it using a cheap adjustable power supply.
GM

If you instruct your "tube amp whiz" to add to your amp a means of playing with the damping factor, go the extra step and have him/her add a pot for variable negative feedback. Having variable negative feedback allowing you to dial-it-in can do wonders for horn loaded woofs powered by PP tube amps.

[GM]

I know little about amp design, but I thought that's what you're doing when adding a bass tone control to a tube amp, varying the nfb to vary its output impedance.

GM

[analog addict]

It would for me as long as I didn't need PA SPL output.

The tap rating is normally just that, so isn't an indicator of an amp's damping factor/output impedance. PP amps typically have a relatively low output impedance, so require a bass tone control [adjustable DF] to get it up to a ~matching impedance, i.e. DF = unity [1]. Say yours has a DF = 10, then 16/10 = 1.6 ohms of output impedance, which isn't going to effectively 'weaken' the motor much [raise its Qts] whereas as a DF = 1 would nearly double it, dramatically reshaping the speaker's response to a much more pronounced [mid] bass response relative to the mids.

You've got such a rare [and to my ears, superior performing] system that getting either a ~period correct amp with a bass tone control or having a tube amp whiz add one to yours seems a better overall 'upgrade' to swapping out woofers, unless of course it's to go to a custom 515 field coil that allows one to tonally dial it using a cheap adjustable power supply.

Anyway, hop you can get some driver, speaker system specs, measurements for posterity/frame of reference.

GM

Thanks for the nice comments. The ASR-433 has separate channel bass and treble controls, so that this is a non issue for me. The bigger issue is the balance of the two main channels and the center. Now, confounding this is the fact that I'm running the big Simplex/M19 stack in the corners, and the 604-8G/828s closer towards the center. I've been fiddling with the level of the center channel to maintain the soundstage and to not overpower the right and left channels. Plus, the current amp for the Simplex stack and the 604s is a brand new 2A3 I just finished building, putting out all of 2.5 WPC....

[Altec Best]

Agreed !