Something stirs in the Undergrowth

[IslandPink]

Quick update Chris, did try the tweeter alone last night with 2.2uF and 3.9uF cap. Interesting - the 2.2uF sounded nicer , had more tone - which you'd not expect purely from a bandwidth comparison - more the other way, 3.9u should have more 'going on' & be a bit fuller. With the 3.9uF on there it wasn't really harsh-sounding, but the tone was a bit grey and less interesting than with the higher crossover. So it looks like you were right - I was pushing my luck a bit with 3.9uF and nothing else. Will confirm either today or tomorrow by trying the 3.9uF with a choke to pull it down quicker below 2kHz.

[IslandPink]

Another thought - I wonder how the Fostex T90A compares with the TPL-150 or G3?

First - any ribbon or bullet tweeter will outclass anything other than a low-mass mid/FR driver where it crosses - the FE208Ez works as although it's a little bigger as it has a big magnet ( very low Qt ) and moves very quick. Also low Rms helps ( as on this and old-school drivers ) as these tweeters work cleanly at very low signal levels.

I saw Ron Clarke ( reading a lot from him, Dallas, A166 etc BLHorns ) post that he didn't get the T90 to gel with his FE208Ez, used a Fountek ribbon. Not sure how bad the mismatch was, though... too late to ask him.

[simon]

I saw Ron Clarke ( reading a lot from him, Dallas, A166 etc BLHorns ) post that he didn't get the T90 to gel with his FE208Ez, used a Fountek ribbon. Not sure how bad the mismatch was, though... too late to ask him.

Do you have a link?

[IslandPink]

Lost it damn ! - read it about an hour ago. Quite a short post - there are a few repeat posts where he advises people on the Fountek ( Neo2.0cd ? ) for the FE208Ez but this one did mention the T90 as being not successful ; 'course searching 'T90' by REC1 doesn't find it Was on DIY Audio FR section.

Currently listening to 3.9uF > 0.82mH to ground, to G3 ribbon. Very very nice - definitely better than last night, maybe better than 2.2uF alone - so Chris was right. It will take more detail listening to get decide exactly on cap value ( or tests ) might be 3.3uF or 2.7uF eventually. But it just sounds great on Rendell/Carr's 'Dusk Fire'. The flutes are real, in the room ; brass is great , soprano sax. I love ribbons

Stop Press - got it now -
http://www.diyaudio.com/forums/full-ran ... ost1682008

[andrew Ivimey]

You will remind me what a G3 is.

[andrew Ivimey]

I was not impressed with T90.

[IslandPink]

You will remind me what a G3 is.

Sir yes Sir !
Aurum Cantus G3 ....
Are you familiar with the 'Dusk Fire' Andrew ?
I was enthusing to Thomas about this album, the second-best UK Jazz album, to me, after 'Under Milk Wood' by Stan Tracey & Bobby Wellins ?
Oh Shit just found out Bobby Wellins died another one gone.

[simon]

You will remind me what a G3 is.

Aurum Cantus G3 ribbon

http://www.aurumcantus.com/aurumcantus- ... r%20G3.htm

[simon]

Couldn't see anything saying the T90A didn't work well with the 208Ez, not that I'm disputing it.

There's some interesting comment in the linked thread, and doesn't particularly align with my experience. I started with just a 1uF cap and when I brought the horns to Owston once there were a number of comments about a hole in the treble. I subsequently lowered the crossover and think I ended up around 8kHz.

But the Fostex datasheet recommends a second order crossover and I'm currently using a cap and choke with an Lpad for level. Can't remember which values off the top of my head but I was aiming for 8k IIRC. I'm happier with the sound now than I ever have been. I expect the G3s or Beymas are somewhat better.

[andrew Ivimey]

Ta.

Haven't heard no - interested though.

Autumn q of course, sorry.

I thought the t90 was going to be a marriage made in heaven but couldnt get it right. Heils work with anything over 4mfd - takes yet choice but I felt the back loaded horns weren't right for the 208E sigmas. Never got any further so they're up in the attic with 6dn7 amp and the telly, none of which get much use!

[IslandPink]

Couldn't see anything saying the T90A didn't work well with the 208Ez, not that I'm disputing it.

There's some interesting comment in the linked thread, and doesn't particularly align with my experience. I started with just a 1uF cap and when I brought the horns to Owston once there were a number of comments about a hole in the treble. I subsequently lowered the crossover and think I ended up around 8kHz.

But the Fostex datasheet recommends a second order crossover and I'm currently using a cap and choke with an Lpad for level. Can't remember which values off the top of my head but I was aiming for 8k IIRC. I'm happier with the sound now than I ever have been. I expect the G3s or Beymas are somewhat better.

Sorry - correct - Ron said he "never worked with the T90 " - not the same as 'it didn't work with the T90' !

edit : however, from AA Heff forum - "http://www.madisound.com/neocd2.0.html
208e sigma with my own design BLH.(Dallas)
I just prefer the ribbon over the horn and no attenuation necessary.
ron"

[IslandPink]

but I felt the back loaded horns weren't right for the 208E sigmas.

I've spent a lot of time reading about 'Dallas II' horns & all of Ron Clarke's work, lately - been bombarding SimonC, JamesD and Nick with stuff on email. He designed these with heavy duty fluid-dynamics (CFD) software as that was part of his job. He had specific technical observations about the Fostex 208 horn and the Jericho horn ( and the Hedlund ) about what was wrong and why they didn't work very well ( lack of bass acoustic loading, blending of TL/horn action , baffle step etc ) . It does seem very interesting and the reports of the Dallas II and A166 do seem extremely positive. I believe he most likely died in 2009 and it seems like we lost one of the guys who could have taken speaker design to the next level.

[chris661]

Currently listening to 3.9uF > 0.82mH to ground, to G3 ribbon. Very very nice - definitely better than last night, maybe better than 2.2uF alone - so Chris was right. It will take more detail listening to get decide exactly on cap value ( or tests ) might be 3.3uF or 2.7uF eventually. But it just sounds great on Rendell/Carr's 'Dusk Fire'. The flutes are real, in the room ; brass is great , soprano sax. I love ribbons

Glad you like it.
FWIW, the monitors I have here use a ribbon tweeter of some kind, and use a 4th order crossover at around 3.4kHz. Ribbons are great at what they can do, but they do have a way of complaining if you drive them too low.

No idea if this'll be of interest to you, and it might well be heading towards diminishing returns with regards to complexity, but it might be worth putting a big cap in after the inductor, heading towards third order. It might be another step in the direction you've just come, giving the ribbon the easiest time possible and letting it shine where it can. I'd try something big like 10-20uF, so the first cap is still defining where the slope starts, and the inductor and second capacitor give a steep rolloff down low.
Might be worth a try, might be too far. Could be worth a go if you're running on clip leads and have the parts to hand.

Chris

[IslandPink]

Well I must say my week has ended on a much brighter note than it began ( at someone's funeral ! ) -
Just received a PM from Scott confirming that ( my ) rumours of Ron's death have been greatly exaggerated. Apparently he's alive and well and still corresponds with Scott from time to time
I've never been happier to look a bit silly !


re. third-order, Chris, I'll put it on the list ... extra cap in signal path ... hmmm.

[Ali Tait]

Is there a good place to buy G3's in the UK?