Quote Originally Posted by Panomaniac View Post
... I also need to pull out a lot of energy around 220Hz with EQ. It's a notch of -9dB and a Q of 2.2. Without that EQ there is no way I can get the box flat. But pull it out and tune the port right and the box plays right on down to where a big box should play.

If I measure the box 1 meter from the front, it does not play so low. But back where I sit it does, and is nice and flat. Must be room gain making up for it.
I don't know if this 220Hz peak in common in this box, but both mine suffer from it. If you have some method of EQ, I suggest you try this.
Dear all,

This is my first participation to this forum and I need to introduce myself. I am 54, French but living in Cologne, Germany. I am passionate by Aviation, music and photography.

When I discovered this thread, I suddenly realized that I was not alone anymore! I went through the same journey with the same loudspeaker and despite the thread has been quiet for a while, I could not resist to post my contribution.

Like Panomaniac, I did the bracing and dumping of the horn and I found by testing that reducing, but also tuning the port was improving a lot the bass response.

I am using a different loudspeaker (GPA 515-8G) and a passive crossover (Wonderful serie crossover, I will create a post on this crossover). Despite that, the attached impedance curve is very similar to the one posted by Panomaniac (Sorry, attachement not possible before 3 days).

I am also facing the problem of the 10 db bump at 220 Hz, which seems to be common to all VOT. I would like to avoid the EQ as I am using an integrated amplifier (Accuphase E-530) and still listen a lot of vinyls.

- Is there a possibility to reduce this bump with some internal modification (dumping…)?
- Has somebody established what could be the best modern loudspeaker for this cabinet (Vas, Qms, Qts…)?

I wanted to post images but I will not be authorized before 3 days. Sorry...

Thank you in advance for your participation!

Dominique Tanguy