OPTs and power for bi-amping

jnb · 4th June 2007, 06:15 AM

Hi,

If the spectrum is split 50/50 (like 300-400Hz) using two identical amps, is it easier to drive the highs because the amplitudes are lower or not.

Does a 45 sound powerful enough at 1.5 W for the highs if I split at 1500Hz? My speakers are not that sensitive <90dB.

I have some various sinle ended OPTs from unsalvageable old radios and TVs. The iron is typically 5cm^2 (2' x 2') can it handle the power of the 45 at those frequencies if I can find one with the right inductance and ratio?

Thanks

ErikdeBest · 4th June 2007, 11:38 AM

HI JNB

I do not know if your first sentence is a question or a statement, but here is an article by Broskie that may shed some light on it.
http://www.tubecad.com/articles_2001...s_and_Filters/

Just a personal opinion on the combi tube + OPT you are planning. It may work well, but I expect the 45 tube to be 'to good' for the OPT's you are planning to use - at least the 45's are too expensive. Personally I would sell the 45s, buy some better iron from the money and run a a SE amplifier with a cheaper valve as a EL84 in triode, which will give the same power (I think), but probably much better due to the better OPT (much people consider OPT to be the weakest link in an amp...) But this is just my humble opinion!

Erik

jnb · 5th June 2007, 07:46 AM

The reason for my question is because I read that there is 70% of the music power present below 1500Hz.

If this is true, I figure the 1.5W amp will compromise the system if I try to run it louder than what a 5W full spectrum amp would go. In other words, it seems that any more than 3.5W for the bass amp and the tweeter amp will distort first.

Or am I wrong?

4th June 2007, 06:15 AM	#1
jnb diyAudio Member Join Date: Dec 2006	OPTs and power for bi-amping Hi, If the spectrum is split 50/50 (like 300-400Hz) using two identical amps, is it easier to drive the highs because the amplitudes are lower or not. Does a 45 sound powerful enough at 1.5 W for the highs if I split at 1500Hz? My speakers are not that sensitive <90dB. I have some various sinle ended OPTs from unsalvageable old radios and TVs. The iron is typically 5cm^2 (2' x 2') can it handle the power of the 45 at those frequencies if I can find one with the right inductance and ratio? Thanks

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4th June 2007, 11:38 AM	#2
ErikdeBest diyAudio Member Join Date: Mar 2003 Location: Itoculo	HI JNB I do not know if your first sentence is a question or a statement, but here is an article by Broskie that may shed some light on it. http://www.tubecad.com/articles_2001...s_and_Filters/ Just a personal opinion on the combi tube + OPT you are planning. It may work well, but I expect the 45 tube to be 'to good' for the OPT's you are planning to use - at least the 45's are too expensive. Personally I would sell the 45s, buy some better iron from the money and run a a SE amplifier with a cheaper valve as a EL84 in triode, which will give the same power (I think), but probably much better due to the better OPT (much people consider OPT to be the weakest link in an amp...) But this is just my humble opinion! Erik

5th June 2007, 07:46 AM	#3
jnb diyAudio Member Join Date: Dec 2006	The reason for my question is because I read that there is 70% of the music power present below 1500Hz. If this is true, I figure the 1.5W amp will compromise the system if I try to run it louder than what a 5W full spectrum amp would go. In other words, it seems that any more than 3.5W for the bass amp and the tweeter amp will distort first. Or am I wrong?

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