Jensen-22, built by Goran
Copyright 2010 Troels Gravesen

Hi Troels!
I have a valve amplifier, ''DYNACO ST120''. What is impedance of speakers ''JENSEN 1071'' for use with valve amplifier? 4 or 8 ohm, or maybe something between?
I send you one picture:22W/8851T00,18W8531G00 and D2905/9900, the crossover is the same like yours. Mid cab is 22 liter/ 37 Hz and bass cab is transmission-line. I never heard unbelievable sound like this!
Thank you for everything and best regards from Goran.

Hi Goran. The Jensen speaker is a 4 ohm speaker with a minimum of 3.5 ohms at 300 Hz.
I really like the idea of a transmissionline for the bass driver. I have no doubt it sounds great. Based on simulation the original Jensen crossover should work fine with your 22W bass driver. To other builders I have to say that I cannot guarantee the crossover will work perfectly as intended due to the minor changes to the front panel dimension, but as the front panel only appears to be ~2-3 cm smaller than specified, the impact on sound may be minor.
Regards Troels

Hi Troels!
One more thing:In this cabinet ,bass is free of coloration from 20Hz,deep,natural and fast. Reason for triangular transmission line port is that there is a "attenuation or suck out" of the line's frequency response near 120Hz.Triangular port adjust the maximum upper impedance fH more broadly and reduces the effect of the 120Hz suck out.
Regards Goran

Download cabinet drawings used by Goran by clicking image.
Damping can be seen here.


Comments from Radomir:
Hi Troels.
Just saw your newest speakers corner. I must comment your Jensen project. I've been invited by Goran who built your Jensen with TL bass loading. Goran wanted to bring with me mine SET amp 2x11W no nfb. I was reluctant to try set on such big loudspeakers thinking that there will be no chances to drive Jensen. First we listened Jensen with Denon 1520 solid state 2x120W, then we connected 6C33c set and after 20 minutes of warmup we pressed play; well, I was totally surprised, sound was fantastic, everything was better compared to SS amp, even bass was deeper, Jensen simply disappeared, nothing was missing, full flat spectrum, no dips or peaks. That is testimony of excellent xo design I guess. Goran, owner of Jensen, was very, very happy. Even spl was high enough on good recordings, it seems Jensen proved to be good match even for SE amp, even with no nfb. Goran is working on upgrade of his Dynaco pp so we have not listened to PP, latter we have one drink in your name. One more thing Jensen with se amp played female vocals briliantly while with Denon ss such vocals were very, very unpleasant. Wishing you only the best in new year, good health and new projects. Rgds Radomir.