Choice of 515 in a 210 center cabinet

[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

[BoydB]

Well GM, maybe it's my bad. When you said [adjustable DF] , I assumed you meant damping factor. I should have thought [dynamic feedback]

[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....

[GM]

Well GM, maybe it's my bad. When you said [adjustable DF] , I assumed you meant damping factor. I should have thought [dynamic feedback]

I did........... The bottom line though is that we agree that the less nfb there is, the better a speaker's overall performance, so if I'm wrong about how I understand it, then modding an amp for dynamic feedback is another highly desirable 'upgrade'.

WRT damping factor, we want to strike a balance between the speaker's and amp's, so that the sum combined with the Q of any room gain creates a tonally balanced in room response to as low as practical or at least ~40 Hz to cover all of the voice BW and most of music’s.

GM