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Old 26th October 2011, 04:09 PM   #501
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Default Some additional thoughts on the L2 trap inductor

A quick additional follow up on the trap inductor, L2.

The 19 ga. Pano called out in his Bill of Materials (BOM) can work. It has the obvious advantages of lower cost and size. However, with it's higher resistance of about 0.9 ohms, an adjustment in the R2 pad resistor would be required to retain the tonal balance of the system as well as the desired Vifa crossover high pass slope. R2 would drop to around 3.5 to 4 ohms to compensate for the higher L2 resistance.

Per standard theory, the higher resistance could slightly degrade the Vifa's performance, but from a practical standpoint, I wouldn't worry too much about it. Just my $0.02 worth.
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Old 26th October 2011, 04:37 PM   #502
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Hi John,

I think the challenge to find a reliable driver on specifications is very hard.
Have you test European brands ? beyma, 18sound, rcf ?

US SPEAKER - 18" Speakers - 18" speakers by Eminence Speaker, 21" woofers, JBL, EV, RCF, Beyma, Peavey, Celestion, P.Audio, Ampeg, Crate, Jensen, Fane and Pyle. 18" bass speakers & 21" bass speakers. Find the right 18" woofer here.
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Old 26th October 2011, 05:00 PM   #503
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What about two slsīs paired with the FA22RCZ. About 96-97dB spl at 2,7V...
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Old 26th October 2011, 05:16 PM   #504
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The true efficiency of the current version of the SLS is about 89 DBW. Add in cross over losses and a bit of power compression (it is a long throw woofer) and then add back in the 6 db when operating a pair of them in electrical parallel, and you end up around 93 dbw. This set up would result in a 4.7 ohm load. Not as SET friendly as a single 8 ohm 18".

So, you could use a parallel pair of SLS's, padding the Seas 8" to match. This assumes a third order electrical crossover on the SLS and other crossover tricks. 20" wide baffle and so on.

A single 18 with an Xmax around 6 MM peak will have very little power compression and should be able to provide a true 97 db or better efficiency like the discontinued Eminence woofer I currently use in the HE prototype.
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Old 26th October 2011, 05:19 PM   #505
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Quote:
Originally Posted by John Bsuch View Post
A quick additional follow up on the trap inductor, L2.

The 19 ga. Pano called out in his Bill of Materials (BOM) can work. It has the obvious advantages of lower cost and size. However, with it's higher resistance of about 0.9 ohms, an adjustment in the R2 pad resistor would be required to retain the tonal balance of the system as well as the desired Vifa crossover high pass slope. R2 would drop to around 3.5 to 4 ohms to compensate for the higher L2 resistance.

Per standard theory, the higher resistance could slightly degrade the Vifa's performance, but from a practical standpoint, I wouldn't worry too much about it. Just my $0.02 worth.
Thanks for the summation John. Spending a total of $40 more for the low dcr inductors might not be in keeping with the "inexpensive" part of the project.
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Old 26th October 2011, 05:24 PM   #506
vaughn is offline vaughn  United States
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thanks for the replies Pano and John, those Sigma 18's look pretty good. Hopefully they work well in the HE design.
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Old 26th October 2011, 06:26 PM   #507
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Quote:
Originally Posted by John Bsuch View Post
The true efficiency of the current version of the SLS is about 89 DBW. Add in cross over losses and a bit of power compression (it is a long throw woofer) and then add back in the 6 db when operating a pair of them in electrical parallel, and you end up around 93 dbw. This set up would result in a 4.7 ohm load. Not as SET friendly as a single 8 ohm 18".

So, you could use a parallel pair of SLS's, padding the Seas 8" to match. This assumes a third order electrical crossover on the SLS and other crossover tricks. 20" wide baffle and so on.

A single 18 with an Xmax around 6 MM peak will have very little power compression and should be able to provide a true 97 db or better efficiency like the discontinued Eminence woofer I currently use in the HE prototype.
Ahh. alright, I see. Good luck with your search. always exciting too se how "simple&good" these sets turn out

BTW, how would the vifa driver handle 2sls`s?
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Old 26th October 2011, 07:02 PM   #508
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The Vifa is about 84 or so DBW up in the freq range we use it. Add the 6 db rear radiation and allow for trap and rear reflection losses and you end up around 88.5 or so usable before we pad it to match the single SLS. This is well short of what the 2 SLS running in Electrical parallel will provide per my prevous post.

The Seas 8" FR is around 94.5 dbw plus 6 db rear radiation less it's trap & reflective losses, so it could work with dual SLS or the efficient 18" with the proper pad and crossover.

All of these efficiency values are quasi 1/2 space.
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Old 28th October 2011, 01:11 AM   #509
vaughn is offline vaughn  United States
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I'm wondering if I really need to go with the HE design...

My room is fairly small and I am using an Eico HF-81 (around 15 watts). I don't know if this would be enough power for the standard Manzanita or not. If not, would a 30wpc Sansui 1000A do the trick?
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Old 28th October 2011, 01:44 AM   #510
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Default Manzanita power requirements

This has been a curious topic from the beginning. Most of the time these days I drive the Manzanita with a KT88 SET that I operate in Pentode mode. About 12 - 15 watts max per channel.

Assuming the baffle face is 40 inches or so from the rear wall, 8 - 10 foot listening distance and general musical formats, the Manzanita is quite good. If you really want to rock, you can hit the Manzanita with 100 + watts and it will respond accordingly. A pair can deliver 100+ db peak clean output down to about 40 Hz.

Many people have listen to it driven with a 8 watt "T" amp during some of my LSAF and RMAF demonstrations and have found it surprisingly listenable with that limited of power.

As usual, it gets back to personal need. And how you listen to, and what you listen to music wise.

Just for the record (no pun intended), 15 honest watts per channel will support an upper 80 db output level at 8 feet with a 6 db head room on most music in a small to medium residental environment. For a majority of users, this should be adequate.
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