Originally Posted by Musica Amantem (Post 804276)

Then it does matter! What happens if the amp is set with 8 Ohm trannies and I couple it to Soul Superflies?

Originally Posted by Simonatsea (Post 804488)

I didn't want to find out. I know I read about another gent that found using the 8ohm secondaries on his transformers yielded better low frequency performance from his Zu Omen rated at 12ohm.

Originally Posted by Rosco65 (Post 804461)

I think a difficulty many of us face is trying to get high efficiency speakers to do too much. Unless we commit to some some fairly physically imposing speakers, we usually end up in some sort of compromise. High efficiency usually comes at the expense of deep bass; the horn size to produce a true bass wave is enormous, and it is difficult to get a high efficiency direct radiator to move that kind of air.

It is also difficult to make an uncompromised full range speaker. They usually have a rising response in the midband that is hard to match at the top end. Omega speakers are no different in that regard, just better at it than most (I'm looking at you, Fostex). The best way to think about a full range driver is that it is in reality a wide range driver, with compromises on the bottom and top ends of the frequency spectrum. However, this crossoverless, wide range driver can sound really, really good and is a pretty easy load for the amplifier.

Peter has addressed some of these shortcomings by going active: he runs servo-driven midbass subs, actual subs, and upward-facing tweeters on the top. He uses a line-level crossover, cutting the main drivers (Omega Super Alnico Monitors) in above the midbass, probably relieving them of half the acoustic power, letting his 5-10 watt amp behave like a 10-20 watt amp. I'm quite sure he never wants for more power.

I use a couple different pairs of Omega's as well, but am working on a "big rig" speaker. The main driver is an Altec 414C (97dB efficient, 8 ohms, runs without crossover from 40hz to 4,000hz). This driver cover the entire vocal range. Above 4,000Hz, I will use an Altec 802d (nominally 106dB, 8 ohms, but probably about 100dB in the range I will be using it) with a 1st order crossover bringing it in at 6-8,000Hz. The 802 is mounted on an Altec 32A horn - an odd bent horn derived from the WE 32A horn. This bent horn is suitable for use in smaller spaces like studios or listening rooms (in contrast to other Altec horns which were designed to be used in theaters). The enclosure is more or less an Altec 614 of 3.3 to 4 cu ft tuned to 40-50Hz. I don't anticipate using a subwoofer in my small room, but if I did I would go with Peter's choice of Rhythmik servo subwoofer(s).

If that sounds like a lot of effort using expensive, hard to find (and sometimes no longer in production) parts, you could go with Peter's method of efficient single driver with active subwoofers, or you could find a nice pair of Klipsch speakers (Heresy, Cornwall, Forte, Chorus, or LaScala) and update them with nicer crossovers and diaphragms. If you choose Heresy's or LaScala's you'll probably still want bass reinforcement, but you'll never want for power.

Originally Posted by Rosco65 (Post 804461)

I think a difficulty many of us face is trying to get high efficiency speakers to do too much. Unless we commit to some some fairly physically imposing speakers, we usually end up in some sort of compromise. High efficiency usually comes at the expense of deep bass; the horn size to produce a true bass wave is enormous, and it is difficult to get a high efficiency direct radiator to move that kind of air.

It is also difficult to make an uncompromised full range speaker. They usually have a rising response in the midband that is hard to match at the top end. Omega speakers are no different in that regard, just better at it than most (I'm looking at you, Fostex). The best way to think about a full range driver is that it is in reality a wide range driver, with compromises on the bottom and top ends of the frequency spectrum. However, this crossoverless, wide range driver can sound really, really good and is a pretty easy load for the amplifier.

Peter has addressed some of these shortcomings by going active: he runs servo-driven midbass subs, actual subs, and upward-facing tweeters on the top. He uses a line-level crossover, cutting the main drivers (Omega Super Alnico Monitors) in above the midbass, probably relieving them of half the acoustic power, letting his 5-10 watt amp behave like a 10-20 watt amp. I'm quite sure he never wants for more power.

I use a couple different pairs of Omega's as well, but am working on a "big rig" speaker. The main driver is an Altec 414C (97dB efficient, 8 ohms, runs without crossover from 40hz to 4,000hz). This driver cover the entire vocal range. Above 4,000Hz, I will use an Altec 802d (nominally 106dB, 8 ohms, but probably about 100dB in the range I will be using it) with a 1st order crossover bringing it in at 6-8,000Hz. The 802 is mounted on an Altec 32A horn - an odd bent horn derived from the WE 32A horn. This bent horn is suitable for use in smaller spaces like studios or listening rooms (in contrast to other Altec horns which were designed to be used in theaters). The enclosure is more or less an Altec 614 of 3.3 to 4 cu ft tuned to 40-50Hz. I don't anticipate using a subwoofer in my small room, but if I did I would go with Peter's choice of Rhythmik servo subwoofer(s).

If that sounds like a lot of effort using expensive, hard to find (and sometimes no longer in production) parts, you could go with Peter's method of efficient single driver with active subwoofers, or you could find a nice pair of Klipsch speakers (Heresy, Cornwall, Forte, Chorus, or LaScala) and update them with nicer crossovers and diaphragms. If you choose Heresy's or LaScala's you'll probably still want bass reinforcement, but you'll never want for power.

Originally Posted by FloridaBoy (Post 804511)

Musica,

You don't need 104db to enjoy true DHT. I had a 45 driving 98db 12" single drivers and it was plenty. Probably 3 watts with EML solid plates. The speakers were actually too much for my room. If I had a huge man cave....

I think I'm going to give the Omega CAM's a go. There is something special about single driver alnico speakers. At 95db they should work well. What I hope to gain is texture and tone. Louis has a 30 day trial so there is little risk.

Originally Posted by BearCityUSA (Post 804425)

Aercool,

It has been a while and I do not recall your setup. What are your room dimensions, listening volume, primary genre,...? I was seriously contemplating a pair of Zus to mate up with the PSE I have on order from Dennis, though this bit of dialog here of late has me discouraged. I may have some Omega Omnis in my future instead.

Originally Posted by Aercool (Post 804553)

Take a look at the impedance curve on the Zu's. There's a big bump up to around 55 ohms at 30 Hz, and 65 ohms in the curve at about 75 Hz. I can only guess that's what's behind the loss of bass control with the Inspire. I lack the technical expertise to diagnose this.

That's the paradox though - the Zu's are capable of the bass, but the Inspire wasn't.

Originally Posted by Musica Amantem (Post 804547)

6V6 G ST's might yield only 4 watts of power, whereas the 6V6 GT's somewhere around 5 watts with the right rectifiers.

Originally Posted by Aercool (Post 804553)

Hi BC, My room isn't large, approx. 12' wide, 10' from speakers to listening position (another few feet between the speakers and the wall) - but there's no back wall to my listening area - it opens up into the kitchen. Actually quite good for limiting reflections. My genre is mostly Americana, Grateful Dead, etc. No Metallica or speed metal.... ;^) Take a look at the impedance curve on the Zu's. There's a big bump up to around 55 ohms at 30 Hz, and 65 ohms in the curve at about 75 Hz. I can only guess that's what's behind the loss of bass control with the Inspire. I lack the technical expertise to diagnose this. I did re-solder my OPT leads to (first) the 8 ohm tap and then (second) the 16(?) ohm tap at Dennis' direction. Going from the 4 to the 8 ohm helped, but didn't solve the problem. The 16 ohm tap just seemed lifeless. The Zu's are great speakers though - very musical and fun to listen to with the right amp. Don't give up on the Zu's. You might want to do some kind of crossover and hand the bass off to a subwoofer? That's the paradox though - the Zu's are capable of the bass, but the Inspire wasn't. I was using a Inspire LP-2 with the KT-150. I used a bunch of different tubes in the KT-150, even up to some vintage Tung-Sol KT6550's and some nice ECC88 types, but nothing fixed the bass (Track 1, Disc 2 from Lucinda Williams "Down Where the Spirit Meets The Bone" was my pass/fail. The bass on this track would fuzz out and get very saturated and muddled.). Clean and deep bass on the First Watt amps and a ToolShed Amps Transcendence 12 (KT-88's driven by E80F's).