[David Bardes]

Danny, Hobbs, and associates.

I would love to build a GR research designed speaker kit that would mate well with my 7 watt/channel 300B amp. As I am a demanding kind of guy, I would like bass response down to the mid-30s, a true 8 Ohm impedance, and an SPL of 92 db or better.  Super large speakers won't work in my smallish living room, and of course price is also a consideration.

My current solution is a pair of "barn find" Klipsch KG-4s and they fill many of the checkboxes, a -3db of 38 Hz, a real-world SPL of 92 (the reported 96 db is aspirational once the tweeter is set to the proper level), and my amp seems to be happy driving them.

What would a GR research designed, higher efficiency, perhaps retro-styled speaker look and sound like?

Just a thought experiment.

Cheers,

David

[Early B.]

Danny, Hobbs, and associates.

What would a GR research designed, higher efficiency, perhaps retro-styled speaker look and sound like?

Great question!!!  I'd like to know the answer to that one, as well. Horns, perhaps?

[genjamon]

Tyson and Danny liked the Elekit 300B amp with the NX series of speakers, if I recall. Or maybe that was with the all-ribbon midrange lineup - can’t remember exactly.

[JLM]

Small size, deep bass, and high efficiency violates the laws of physics.  Try picking two.  And forget about low price.  Suggest giving up on the low bass for now and add a subwoofer later.

[dougthebiker]

I drive my NX-Oticas with an Elekit TU-8600S (two 300B's, about 18 watts) with no trouble whatsoever.  It rivals cost-no-object systems.  I do have top-of-the-line tubes in it to get ultimate transparency and dynamics.

[genjamon]

Small size, deep bass, and high efficiency violates the laws of physics.  Try picking two.  And forget about low price.  Suggest giving up on the low bass for now and add a subwoofer later.

Generally true. But he’s only talking about bass into the upper-mid 30’s. That’s rare, but there are a few speakers that go there with all the parameters mentioned. Tekton Lore is an affordable option that does so. Tower design, but only 1 sqft footprint, and goes down to low 30’s. The trade off in that design is not the most solid cabinet build and not the best crossover components, and design is a bit peaky at the crossover point. But if you’re up for opening up cabinet to install no Rez and maybe add some bracing, and pay for crossover upgrades, you can up the performance. And some of the other more recent Tekton speaker designs might get you there too.

That said, Danny’s designs surely have superior, or at least more transparently measured, performance characteristics and refinement. Just not the same single tower full frequency performance.

[Rusty Jefferson]

Small size, deep bass, and high efficiency violates the laws of physics.  Try picking two.  And forget about low price.  Suggest giving up on the low bass for now and add a subwoofer later.

So spot on. And if it's a transformer coupled 300b SET amplifier (high output impedance) you'll want to use speakers that are over 90db sensitivity and at/above 8ohms nominal and easy to drive. Don't know if GR has such a speaker.

SET transformer coupled 300b amps are notorious for poor behavior at the top end and the bottom end, especially if it's a difficult load at the low end.

[corndog71]

X-MTM might be the best option except it’s not retro looking.

[planet10]

SET amplifiers typically have highish output impedance (R_out) which can interact with the loudspeakers impedance to cause FR anomalies, following the speaker’s impedance curve. If the curve looks like a rollercoaster you could well hear it.

while the mantra of high efficiency is what is most often seen, keep in mind that with a SET, flattish speaker impedance can be more important.

So look at the measured impedance curve first. That is fairly straightforward.

Efficiency is a spec that is often from the marketing department not the engineers. For instance, given many tests on many speakers, typically have a  sensitivity 3dB higher than it really is.

Danny builds so many speakers, many are hard to find real impednce curves are, but Danny should be able to supply one for his designs.

Neither of Danny’s speakers mentioned have easily findable impedance curves. I di dfind the XLS Encore. This is an example of one to avoid.



dave

dave

[corndog71]

Most of Danny’s designs are 8ohm loads.

[EdwardT]

I built a set of X-LS and initially tried to drive them with a Decware SE34I.4 which has a max output of around 6.5 watts per channel. The sound quality and soundstage were just so beautiful but the output level was underwhelming. So much so that I sold those LS and attempted to find a good match for the Decware amp, but I couldn’t forget the sound of the GR speakers. Fast forward a year and I’ve built a set of X-SLS, sold the Decware amp and bought a SS/tube pre and a pair of 400w monoblocks…because I think the GR stuff is just that good. Just sayin'

[planet10]

Most of Danny’s designs are 8ohm loads.

That is the nominal impedance, not the real impedance. The first is of only little use. For a SET is hardly of any use.

In the impedance graph i posted is the red line a horizontal line at 8Ω?

dave

[Tyson]

Danny mentions that they are going to be working on a high efficiency speaker at about the 11 minute mark in this video:

https://www.youtube.com/watch?v=b-8GUOXpblc

[David Bardes]

Many of the high efficiency 2-way towers run an 8 or 10 inch woofer as a wide band driver with the tweeter picking just the highest frequencies, and with a single cap as a crossover in some cases. I wonder if the dispersion and overall sound quality would be improved if a lower crossover point was selected, and a steeper slope was used. What would Danny do?

[Danny Richie]

It is funny how the guys are Audio Theory Review post measurements with the scale exaggerated to make it look like the impedance is wild. It is actually pretty smooth and an easy load for most tube amps.

[Speaker Challenged]

It is funny how the guys are Audio Theory Review post measurements with the scale exaggerated to make it look like the impedance is wild. It is actually pretty smooth and an easy load for most tube amps.

Even with that graph Danny I agree that 6.5ohm min would be an easy task for even a low powered tube amp. But to the OP, use a sub as others have said. 

2c.
SC.

[planet10]

Its not the lowest impedance, it is the peak. 26Ω. 4x higher than the minimum. Just under 900k expect a boost with any highish R_out at those frequency. The higher it is the larger the boost.

The one on the bottom is a bit different, but some speakers, expecting a low R_out amplifier might bet a bit/boomy/wooly/uncontrolled bottom.

The higher an amplifier's output impedance the more the loudspeaker's impedance affects the frequency response.

Whether an an is solid state or tubed the R_out of the amplifier is more dependent on whether the amplifer is Single Ended or Push-pull. Not always, but most often. The output transformers on most tube amplifiers do push R_out up adding a big reel of wire to the output.

dave