The "Elsinore Project" Thread

[Joe Rasmussen]

Hi Guys

Sorry if I have been somewhat incognito for a while. Lots of other distractions and I wear many hats - in fact amplifiers have been my focus of late as well as digital playback and upgrading Oppo players.

When the weather gets a little warmer, will get my head around the Hamlets.

Yes, the question is whether they will be 16 Ohm nominally (but actually 12 Ohm - which means by convention 0.707*Z cannot be rated as 16 as that comes out 11.3 minimum Z).

But if we go for 4 Ohm, then it will actually be 3 Ohm. Again the same convention applies and 4 Ohm Z is allowed a minimum of 2.83 Ohm.

If the latter, the voltage sensitivity will be close to Elsinores, but it will draw the twice the current - hence efficiency will be exactly half.

But if we go for 12/16 Ohm, then the voltage sensitivity will be low, but efficiency will still be the same as 3/4 Ohm.

Hence we can see that sensitivity and efficiency are not the same. Whichever way we go, they will have the same efficiency, but one will be -6dB lower sensitivity.

Which way to go? I am open to a consensus onion.

Cheers, Joe R.

[Joe Rasmussen]

Re proposed Bolser mod, if they are to be tried, then this is the way I would implement them.

This will take a series of postings, so please bear with me. I won't respond to other postings till I completed them.

But personally I would prefer things as they are - for the time being.

Here is the Bolser changes - but not as I would see them, but do them differently in a number of respects and why.

[Joe Rasmussen]

Let us take it one step at the time.

What effect will adding the 33R resistors across Voice Coils?

In fact very little difference in response. Take a look below, Red is without and Green is with.

Note this is 15 degrees OFF axis.

Note that there are two scales shown, my usual 5dB scale. The difference is easier when 1dB scale, but it looks uglier.

It won't sound brighter that for sure.

[Joe Rasmussen]

Now let's look what happen to the Z.

Other than it being lower, it still keeps it overall shape well.

Is some feels that is better, then OK by me.

Maybe the 1.8uF (which I use) for the Tweeter, its value could be increased slightly to correct the balance if you find it a little duller.

[Joe Rasmussen]

Now for the electrical phase.

Again as for above examples, Red is before and Green is after.

Again, flatter in the bass and not bad elsewhere.

[Joe Rasmussen]

Now for adding the LCR before MidBass drivers.

This is what the Bolser mod is aiming at.

But not only adding the LCR plus parallel resistor for series choke, he omits L5, R3 and C4 conjugate filter.

The effect it has on the response:

[Joe Rasmussen]

Let us now take a look at the electrical phase, and here I have some problems that I would like to see addressed.

Red is original, Green is parallel 33R resistors only, and Blue is the whole hog, caused by the 33R resistors, additional parallel resistor to choke and LCR plus omitting conjugate.

[Joe Rasmussen]

What if we re-engage the conjugate?

Here it is:

[Joe Rasmussen]

Clearly the conjugate is out of whack.

By changing the conjugate we can end up with the following.

Here Red is way back to the original and Green will be with the Bolser mod further modded. Basically retuning the conjugate:

[Joe Rasmussen]

The end response will end up as per Bolser, but with a flatter Z and to me even more important, a flatter electrical phase.