Doc modding Marantz imperial 7

[karatestu]

I have mentioned EPI (Epicure) speakers before in this thread. They sure made some interesting speakers in the 70's & 80's. One model has a woofer and tweeter combo on two sides and the top.

All the models are listed here with links to more information.

https://www.humanspeakers.com/e/epimodels.htm

[karatestu]

I put another section of fence post behind the driver the best I could but it's not optimal as the speaker wires get in the way.

I have listened extensively to all sorts of music and I am yet to find any part of the music annoying or noticeably higher in volume than it should be. There is no boxy sound - if there is then I can't detect it and as such I should be totally ignored from now on

It is so good that it is going to be pursued further. One thing I notice is that runs of bass guitar are more even, there are no notes that disappear or seem louder than the others. Must be something to do with changes in the destructive interference - if the driver is closer to a boundary then it's frequency will have increased from the bass region to somewhere higher up where these things are less noticeable.

It is certainly a highly enjoyable listen and that's what it's all about innit ?

[karatestu]

Some thoughts about time alignment.

You can't do it with a semi omni unless applying delay using some form of digital audio trickery. Not going to happen I tell ya. The sound waves from the up firing mid bass get to your ears many milliseconds after those from the tweeter and they have been through at least one boundary reflection to get there.

Time alignment is said to be good for pin point imaging along with time coherence (remember Roy ?) Smearing happens otherwise. I for one am not that bothered about imaging if it sounds like real music in front of me with lots of detail. Do you need good imaging to eek out that last bit of musical detail ? So far on my adventure I would say no but then how would I truly know.

What prompts these thoughts is trying to work out the best way of positioning the drivers, especially on the top baffle. I have a mid bass and tweeter on top. I have always had the tweeter in front of the mid bass but is this the best way ? The Linn Isobariks have them the other way around (tweeter at the back) and some EPI speakers have them side by side.

Not sure I can be arsed to go through all the different possibilities so am leaning towards moving the mid bass to the front of the top baffle and put the tweeter at the back like the isobariks. But that makes the distance from the mid bass to the wall greater and I am relying on boundary enforcement with this design for some serious bass Also the further away it gets then the more destructive interference from the wall bounce comes in to play.

Choices, choices. I could always dispense with an up firing tweeter but I don't really want to do that. I am a symmetry lover and this is driving my OCD nuts.

[karatestu]

Do certain speakers sound better with certain kinds of music ? I see comments on the tinernet that suggests so. As i dislike most classical music (not all of it) I supose i am biasedd. Why is classical music on the whole so ffffing borring ?

Ok you need a truthful speaker for solo piano and a drum solo (eg take 5 drum solo) but what if you don't listen to that variety of shite ? Am I to be ridiculed for voicing my speakers for my own preferences ? Well no because nobody can be arsed to post on this thread apart from me

[CN211276]

A timely diversion as, having a lot of time on my hands, I have recently played some classical music for the first time in ages. It seemed an appropriate follow up to the synphonic metal of Nightwish. I must admit it sounded quite impressive through the Cube 1s, especially large orchestral works. What really came across was the dynamics and scale. The last time I had played classical music I did not have the system I have now and I was not left with the same impression. I think the semi omnidirectional design is the key factor for me.

[karatestu]

Good work Clive Thanks for posting, this speaker blog is like an echo chamber most of the time.

I was a bit harsh last night (too many sherberts) on classical music. Some of it does move me. Adagio for strings is one such example, absolutely love it.

Maybe I should force myself to listen to more of it at least whilst trying to voice these speakers. But speakers shouldn't have a voice (I hear them cry). Well tough shit, in my house they will sound exactly how I want them so stick that in yer pipe and smoke it.

[karatestu]

Interesting thread here

https://www.diyaudio.com/forums/subwoof ... eters.html

Reading around this suggests that firstly, manufacturers published TS parameters can be quite different to reality and that reliably testing them is very hard to do.

So, are the TS parameters changed by the orientation of the driver ? It is suggested that they are. Lowering of Fs (resonant frequency) seems to be the main one.

I am particularly interested in the effects of mass loading a cone. This can obviously be done by doping the cone like RD did. This increases MMs , Qts and VAS. All this equals bigger box required. But at the same time Fs is lowered which can be a good thing for bass reproduction.

I am only beginning to understand the other way of mass loading a cone and this does not involve adding dope. It seems that firing a driver at the floor for example increases the mass of the air seen by said driver which effectively lowers Fs and increases Qts and VAS. Very interesting as that is what I am doing at the moment with the 5 inchers.

This lowering of Fs may mean that a bigger box is required but the good side effect is that we can possibly get a lot more (good) bass out of these relatively small mid bass drivers. I have never heard a Cube 3 or cubette but I expect they give more bass than they have a right to. Can anyone comment ?

[karatestu]

The thread linked to suggests that the TS parameters are changed by the driver firing up. Dickason mentions it in his speaker cook book. The compliance changes because the suspension is altered by the surround moving due to the weight of the cone making it sag slightly.

I did not put that very well but you might get the gist . Dickason reported that Fs lowered with a driver facing upwards. Interesting stuff Bored yet ? You will be.

[karatestu]

Quote from diyaudio.com https://www.diyaudio.com/forums/multi-w ... vas-3.html

"Generally suspension nonlinearities show up at high excursion, not low."

This would suggest listening at lower levels is good for speaker accuracy. Add more drivers to lower the excursion of each and it's happy days.

"

[karatestu]

Regarding mass loading


"Applied to a speaker, it's different. The moving mass of a speaker consists of the physical moving parts PLUS the air load on the diaphragm. Mass loading thus means techniques which increase the air mass load.

For instance, sticking the speaker on a horn lets the speaker "grab" the nearby air more efficiently. Instead of trying to push all the air in the whole world, the diaphragm is just pushing air right in front of it and can push it more effectively. I suppose those analogies probably aren't technically correct, but useful for thinking.

Now the purpose of a horn is not really mass loading. But some makers put their subwoofer cones facing the floor, or firing into some kind of slot, or facing each other in a manifold. Again since the cone is not trying to grab all the air, but a concentrated piece of air right in front of it, the air mass will be somewhat higher."