My Next Horns

[Zaphod Beeblebrox]

Just for comparison here is the impedance graphs for the Qud 57 and the Martin Logan Monolith.

 

Cheers George

 

Actually, the problem with the Quad ESL graph, is that it doesn't show what happens down at very low frequencies. The Quad ESL57 plummets to far less than 0.5 Ohms at low frequencies. They can kill amplifiers.

[tuyen]

 

 

 

 

 

 

[Owen Y]

Damn, that first spkr system is ugly!  (And I thought my own was no beauty  )

Nice tube amps tho.

[davewantsmoore]

QUOTE OF THE YEAR:

 

Love your sig Mario...   I've got one of his amps right here...   you wouldn't like it though.  Solid state.

[Once was an audiophile]

Love your sig Mario...   I've got one of his amps right here...   you wouldn't like it though.  Solid state.

I know you have one of his earlier amps it was advertised on sna..................

[Once was an audiophile]

Actually, the problem with the Quad ESL graph, is that it doesn't show what happens down at very low frequencies. The Quad ESL57 plummets to far less than 0.5 Ohms at low frequencies. They can kill amplifiers.

I guess a leek 20 valve amp would not be a good match for quad 57?

[damohpi]

Was that a PTP Lenco I saw just before the 7 minute mark???

 

hmm.. sort of! IIRC OMA ripped off the PTP design and produced their own copy

 

http://oswaldsmillaudio.com/anatase

Edited April 25, 2013 by damohpi

[Zaphod Beeblebrox]

I guess a leek 20 valve amp would not be a good match for quad 57?

 

Not necessarily. The poor bass performance of the old Leak would save it from destruction, in the same way old Quad amps can survive the vicious load impedance presented by the ESL57. It's why the old capacitor coupled 303 works so well.

[Ando]

Didnt the original Acoustat X come with a direct coupled valve amp ?

Cheers Mike

[Owen Y]

I guess a leek 20 valve amp would not be a good match for quad 57?

A Quad II could be though...

http://www.quadesl.org/Amplifiers/amplifiers.html

[statman]

So zb will a valve amp work with accustats ?

I've probably built around 400 valve amps, of every description, and a I love stats, and I love horns , to varying degrees, in fact I like all kinds of speakers if they are designed and built with half a brain, but you!d have to have a quarter of a brain to think an OTL would drive stats, no matter how well it was designed. OK, an otl with100 6C33C-B might do the job (slight exaggeration ) but you'd want to live on top of the South Pole.

[georgehifi]

Didnt the original Acoustat X come with a direct coupled valve amp ?

Cheers Mike

That's right Mike, instead of having a 100 to 1 or whatever step up audio transformer, the plates of  high voltage tube amps supplied the high voltage direct to the stators of the esl's, but as you can imagine this was a tad deadly for people with inquisitive fingers, some of these amps were offboad, and this high voltage had to travel along the spearker cable, ouch!!!

 

Cheers George

Edited April 25, 2013 by georgehifi

[statman]

That's right Mike, instead of having a 100 to 1 or whatever step up audio transformer, the plates of  high voltage tube amps supplied the high voltage direct to the stators of the esl's, but as you can imagine this was a tad deadly for people with inquisitive fingers, some of these amps were offboad, and this high voltage had to travel along the spearker cable, ouch!!!

 

Cheers George

Yeah , I built a couple of direct coupled high voltage (2K5V+)tube amps to drive stats directly, using V1505 (212E) tubes, but thought it was compromised , good at some things but ultimately not as good as getting rid of the passive crossovers and going active.

George I disagree strongly with your view on preamps , but I I use ML's too and am old surfer, still kitesurfing , so whatever you say is agreeable with me.

[Once was an audiophile]

 leak 20 tuned for quad 57's 

A Quad II could be though...

http://www.quadesl.org/Amplifiers/amplifiers.html

 

[davewantsmoore]

far less than 0.5 Ohms

 

Wouldn't the clipping performance of ANY amplifier (valve or ss) become important in this situation .... what I mean is that just about every amplifier would be current limited if asked for more than moderate output   ?!?!?!?

[statman]

[img=http://www.stereo.net.au/forums/public/style_images/sna/attachicon.gif] Leak stereo 20.jpg  leak 20 tuned for quad 57's 

Another meaningless grab of misinformation - fancy pix but how about some meaningful info about what your talking about. How have you changed the actual operating characteristic of the amp? Is the technical aspect of the amp changed ( ie does it haves lower output Z or something that makes a real technical difference) or have you just changed a few caps?

Detailed expanation please.

[Once was an audiophile]

Another meaningless grab of misinformation 

I wasn't trying to inform you gave up a long time ago your too good for me.

ps: Its not my leak20 and the owner listens and doesn't care about z

Edited April 25, 2013 by kajak12

[tuyen]

finally moved the bass horns into the room!  woohoo!  

 

[davewantsmoore]

:-D

 

More info?   Sorry if already in previous discussion.     Driver, amp, range covered?

[tuyen]

tuned 50hz exponential bass horn for 15" GOTO UNIT SG-38WN woofer.

 

<60hz                          12" GR Research SW-12-04 Servo Sub Woofer  (Rythmik Audio PEQ-370A plate amp)

>60hz to <350hz          bass horns mentioned above

>350hz to <3500hz      200hz GOTO UNIT S-200B horns  with  GOTO UNIT SG-505TT compression driver

>3500hz to <7500hz    Beyma TPL-150H AMT horn loaded tweeter

>7500hz                       GOTO UNIT S-3000 horn with  GOTO SG-16TT compression tweeter

 

bi-amped,  passive xo designed,built and tuned by yours truly 

[peterstt]

How does the 60Hz-350Hz sound? Do you like it?

[tuyen]

Hi Peter

Not tried yet on my own system. Only just manage to lay out the drivers to take the photo!

Hopefully report back on sound after the weekend

I have tried my woofer on similar 50hz bass horn at friends house before deciding to proceed with building this pair. Much much better than direct radiating/bass reflex solutions. I think the Goto woofer drivers are made for horn loading. The onkens did not work well to my ears. Even the small 125l ported cabs sounded more balanced.

The increase in efficiency by front horn loading improves speed, lowers distortion, better micro and macro dynamics! I guess the downfall with horn loading is the narrow freq bandwidth supported for the physical size. But so worth it!!

The funny thing i find is that even though the mouth of bass horn is very big, when listening to music, you can't tell where the bass notes are coming from the mouth, it just seems to disappear! Kind of like the upper horn channels if setup right. Compared to when using sealed or bass reflex box, if you focus, you can hear the notes radiating from the cone and bass ports. Quite interesting!

What bass cab you using with yours?

Edited April 25, 2013 by tuyen

[Owen Y]

Hi tuyen, Looks interesting...some thoughts...

 

Do you have the bass horns hard against the side walls? (Hornmouth extended by wall/floor.)...Your brick walls will be good for low resonance LF reproduction.

 

Then maybe try having the midhorns closer together.

 

The Beyma TPL-150 have good reports - what's a good source for these?

 

Final thought... maybe in future add a vertical brace across the basshorn mouth.

Cheers.

[tuyen]

Hi Owen

Not hard against wall, there's a gap of a few cm due to the protruding edge trim bit between wall and carpet.

Yeah I'll play around with placement of mid horn after I get it running. I did also plan to create a basic frame of some sort, so that the mid horn sits higher and the tweeter can sit vertically aligned between the mouths. The sato horns will also be something to try when we get round to them.

The beymas are very good. They blend well sonically with the Goto drivers. Being ribbon type of driver, they don't have wide or even dispersion/radiation pattern like the horns I'm used to though. So they don't 'disappear' well IMO. I read a few guys have same thoughts when using the factory beyma horn, but much better when replaced with a tuned waveguide. I got my pair from a friend locally. Have a contact who can get close to cost price if you are interested. Alternatively, there's a pair fs on diyaudio/audio asylum trader section.

I did notice the flex at the edge of the mouth. Was thinking of screwing a metal pole or piece of hard wood on the edge to help straighten up the flexing. Vertical brace would work too, but bit less visually appealing?

Cheers for your thoughts mate

How's your system going? Any further tweaks or happy and been enjoying ?

[Zaphod Beeblebrox]

Wouldn't the clipping performance of ANY amplifier (valve or ss) become important in this situation .... what I mean is that just about every amplifier would be current limited if asked for more than moderate output   ?!?!?!?

 

Just a nit-pick:

 

Clipping is generally regarded as Voltage limiting, not specifically, current limiting. Though, just to confuse matters, most amplifiers that current limit, do so by limiting Voltage output.

 

Anyway, yes, to your question. And, as I stated earlier, 99.999% of all amplifiers will fail to drive the Acoustats, whose impedance curve I presented earlier. SPECIFICALLY, any OTL amplifier would be a spectacularly bad match for such a speaker.

 

That said, amplifiers from companies like Krell, Mark Levinson, ME Sound will operate perfectly satisfactorily with the Acoustats, since they have:

 

* Prodigious current output capacity (Krell , ML, ME).

* Current limiting which is not contained within the feedback loop (ME).

 

The reason why some, well designed push pull triode amplifiers work reasonably well with the Acoustats is because they lack any active current limiting circuits, relying on the respectably low internal impedance of the valves themselves.