Duplex 604E in a backloaded Horn?

[GM]

Did one ages ago with a 20hz flare rate, but neither me nor the owner much cared for the backhorn 'sound' and we wound up putting them in scratch built 825 cabs. Due to the high DF tube amps used (MC-60s), we wound up sealing them up to keep them from being so 'boomy'.

In this configuration with the HF attenuated, they were right impressive, going much lower in-room than the ~equivalent sized horn.

That said, if a lower DF amp was used, and knowing a bit more about horn design today, then with a DF around 3 and a 5-6hz flare rate, it might work if long enough to get to at least 40Hz and let the room do the rest.

GM

[klausesser]

Hey GM!
Well, the GRF or similar, not really ;-) long foldings go to max. 50Hz. But that?s enough if it?s cean and "fast" (bass isn?t fast, i know but it feels like that).
I heard the Tannoy 15" Monitor Gold in BR for years in my home . But the GRF-folded backhorn impressed me very much, so I?m looking for plans for the 604E.
At the moment I?m using an AudioResearch D76A and I like it. Future plans are to try an DIY Pass Aleph. Who needs damping-factor with really good drivers :-)?
best to you, Klaus

[klausesser]

Hi!
Did anybody try a 604E Super Duplex in a backloaded horn? I?ve heard a Tannoy GRF some weeks ago and was faszinated by the kind of bass it perfomed. Not very deep but very, very clean and swift. Mids and highs come definitely better with my Duplexes but the bass . . . ok, maybe it?s a bit deeper from the 820 cab, but it?s not as clean as it is in the GRF which is a backloaded horn.
I remember having seen a drawing of a folded horn, which i think looked like a sideboard and had a Duplex in the middle and horn-mouthes left and right from it - was it a dream ;-) or a real but swift rememberance?
I think the cleanness in bass affects deep mids and the lack of box-shape seems to me positively to avoid standing waves more effectively as it is by damping.
best from Germany, Klaus

[GM]

Without the DF, the flare rate is impossibly low and requires more HF extension, ergo more BW to comb filter with the driver's front radiation, not a good plan IMO.

GM

[klausesser]

Right! I see.

best, Klaus