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 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

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It is currently 18 Apr 2021, 16:33

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 Post subject: Let's Stuff Again !
PostPosted: 19 Feb 2021, 17:15 
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Joined: 03 Jun 2020, 11:06
Posts: 118
Location: France
Let's Stuff Again ! :confused: ;)

I decided that my KLIPSCH Heresy I "HBR" (1983) were in need of some additional stuffing, in order to smooth her bass and low-midrange response...

As most of you already know, the Heresy I is a sealed enclosure with two horns and a 12" woofer, without any stuffing or damping inside the cab, made from 3/4" plywood :

Image

In the past, after correcting the E-2 crossover for smoothing the tormented impedance curve in the Midrange region, I added a small damping mattress on the back panel, using a Monacor MDM-3 natural sheep wool :

Image

It was just to tame a bit the internal resonances : certainly not enough, but after all, the original design of the Heresy has NO stuffing...

That said, the situation changed when the Heresy II were issued, where a simple mattress like mine was factory added. The Heresy III saw an improved stuffing, and the Heresy IV is even no longer a sealed enclosure, but a bass-reflex with inernal stuffing and back firing rectangular port.

So let's go - the goal is to lower the Qtc, damp the low-mid resonances, improve the transients, and extend somewhat the bass response :

Image

Verdict : yes, it works as expected, at least by ear, and its obvious : frequency response is smoother in the mid-bass range and the bass extension is met, just like described by Vance Dickason in his well-known "Loudspeaker Enclosure Cook Book". 8-) 8-) 8-) .

I should made some measurements to evaluate and qualify the improvement - when my measurement rig will be operational again... I'm somewhat lazy ! :|

-tbln.

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 Post subject: Re: Let's Stuff Again !
PostPosted: 03 Mar 2021, 12:41 
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Joined: 03 Jun 2020, 11:06
Posts: 118
Location: France
I quickly refinished the cabs by radiusing the edges at R : 6mm with my router, applied a coat of matching tint and some wood sealant locally, all this in order to cancel the edge bump suffered from previous owners... :|

Image

The result is not premium, but at least is acceptable... And by the way this is not worse !

The original Klipsch E-2 Xover Heresy I impedance curve :
Image

My modified Klipsch E-2 Xover Heresy I impedance curve :
Image

My modification :
Image

-tbln.

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