More 2-way Altecs

[ICTWoody]

If you are still stuck on the PP vs SE question, @ICTWoody, perhaps you could split the difference and look into PP DHT amplifiers (e.g. PP 300B). Maybe something like this: "Fatboy" 300B Push-Pull Amp

I'm not really stuck on it. I've owned plenty of SE amps. I owned the Redboy Built EL84 SEP's, I have my Dennis Had Inspire SE amp, I had the Larry Moore 300B amps, Icon Audio MB30SE's etc...

Right now its more lower watt tubes vs. big ballsy Mac SS just cause I have never tried a bunch of power on the Onk's. I'm very happy with the A&S amp... but for fun... since the MC2205 is just sitting there about 20ft away. :-)

- Woody

 

[RPMac]

All DHT...the next frontier.....

 

[Jim Hodgson]

Right now its more lower watt tubes vs. big ballsy Mac SS just cause I have never tried a bunch of power on the Onk's. I'm very happy with the A&S amp... but for fun... since the MC2205 is just sitting there about 20ft away.

It might also be a matter of zeroing in on the right amplifier damping factor. Onkens and other bass cabinets with Ultraflex genes are especially fussy about output / source impedance. If your Onkens were built “by the book,” then they’re probably sized/tuned suboptimally for those passive crossovers and tube amps (especially single-ended). For starters, they want to see a very low total series resistance on the order of ~0.1R. (Apparently, this is something that got lost when the original articles were translated from French and condensed—or so I’m told by people who know French.)

Here’s some (different) forum discussion I found once and took a screenshot of—original source is lost:



Your MC2205 seems to be in the ballpark:



Finally, here’s a classic implementation:
lecleach.htm

 

[Ronw]

The ringing is not mechanical, it is acoustic, caused by reflections within the horn. There are a lot of discontinuities and sharp breaks in that Altec design. Each creates a pressure variance which can literally reflect sound energy.

You mention JMLC. His work was focused on reducing one of the worst of these problems, the reflection from the mouth back to the driver due to imperfect termination of the horn mouth. See how the L'Cleach horn mouth continues way around the bend, so to speak.

There is probably a benefit to having the horn in a baffle independent of any mechanical ringing considerations.

I know people like those horns OK but I can't do it. I'm going by the way I feel when listening as much as "sonic" criteria. I find the 811 and 511 very fatiguing and mind-scrambling to listen to. The WE/Altec 31A is a large format horn that does the same thing, even with a WE 594A on it! Really bad horn.

This damn 50s JBL DLH175 potato masher I have here is even worse.

I suppose there is a large element of what one listens for and what one has heard built into our reference frameworks.

So if you ain't hearing any this, just ignore what I say!

Any suggestions for minimising the ringing in the JBL

The ringing is not mechanical, it is acoustic, caused by reflections within the horn. There are a lot of discontinuities and sharp breaks in that Altec design. Each creates a pressure variance which can literally reflect sound energy.

You mention JMLC. His work was focused on reducing one of the worst of these problems, the reflection from the mouth back to the driver due to imperfect termination of the horn mouth. See how the L'Cleach horn mouth continues way around the bend, so to speak.

There is probably a benefit to having the horn in a baffle independent of any mechanical ringing considerations.

I know people like those horns OK but I can't do it. I'm going by the way I feel when listening as much as "sonic" criteria. I find the 811 and 511 very fatiguing and mind-scrambling to listen to. The WE/Altec 31A is a large format horn that does the same thing, even with a WE 594A on it! Really bad horn.

This damn 50s JBL DLH175 potato masher I have here is even worse.

I suppose there is a large element of what one listens for and what one has heard built into our reference frameworks.

So if you ain't hearing any this, just ignore what I say!

Any suggestions for taming the dlh175? If so thank you very much for the info!
Ron