Doc modding Marantz imperial 7

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Daniel Quinn
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Re: Doc modding Marantz imperial 7

Unread post by Daniel Quinn »

Thanks a lot Steve, you piqued my interest. 😄 But at the moment I'm preoccupied with fixing my amps with 1 hand. In fact there must be a reason why a full range driver takes 2 hands to do it properly 😉

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karatestu
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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

I am currently listening to my speaker set up with the smaller cabs on their backs with mid's firing inwards and the tweeters up firing :o The speakers are resting on books on top of the big isobaric cube so i can get the speaker leads plugged in.

I wanted to get a feeling for what the tweeter sounded like firing up (See my infinite baffle thread ). I accept this is nothing like it would be with all the drivers mounted in the floor and up firing but it sounds good, no way as bad i expected it to. For sure it is lacking some sparkle and there is a bigger sense of "wall of sound" but is a lot easier to listen to :think: Maybe i need a bigger padding resistor on my tweeters ?

I am now going to take the small cabs off the big cabs and put them on the floor in front. The big cabs are down firing sat on 6" legs. I am in danger of confusing myself even more but getting the tweeter down near the floor will help me see more of it and be more like it would if mounted in the floor.
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karatestu
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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

Right. Got the little cabs on the floor now. Tweeter firing up, 5" firing inwards.

That is a bit better. It is completely listenable. A little more very high frequencies when compared to being on top of the big cabs.

Now i will try tilting the up firing tweeters towards the listening position a little so they are firing at the ceiling about half the distance between me and the speakers.

What would Doc say to such faffing about. I don't know but i found this quote aimed at me

"Enough already, or we will never see anything finished. You need a pair of these, you are like a shaggy dog hanging out a car window- ooo look at that, no that is better, perhaps if - bright eyed tongue hanging out."
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karatestu
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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

Listening now to the small cabs on the floor with the back edge resting on books so the tweeter is tilted towards me.

This is even better than the small cab on the floor firing straight up. I don't think i will be able to live with a tweeter at ground level firing straight up so it will have to tilted to some degree or other.

Also i think getting the little cab off the big one has improved things. There is considerable vibration from those isobaric 12 inchers and the cabinet is only made out of the crapest chipboard with no bracing apart from the partition which divides the volume in two.
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karatestu
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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

Still got my little cabs on the floor tilting toward me a little. I very recently removed the 12R resistor in series with the tweeter to counteract the high frequency fall off that occurs when not having the tweeter on axis.

Very interesting :epopc:
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karatestu
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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

Resistor needs to go back in (or some resistance) . Even with tweeter firing straight up i have a headache .
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karatestu
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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

Now trying a shield in front of the tweeter so i can not see any of it (still no padding resistor)
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Latteman
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Re: Doc modding Marantz imperial 7

Unread post by Latteman »

Hi Stu, I tried an interesting version that I still have on ‘trial’
Instead of a tweeter I used a small coned full range- car type speaker - with the cap to positive as usual.
Interesting that I liked the sound.
The full range are 4” but will source some smaller and trial
I’ll put up pics later
Analogue Source -
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karatestu
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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

Latteman wrote: Wed Oct 30, 2019 2:28 pm Hi Stu, I tried an interesting version that I still have on ‘trial’
Instead of a tweeter I used a small coned full range- car type speaker - with the cap to positive as usual.
Interesting that I liked the sound.
The full range are 4” but will source some smaller and trial
I’ll put up pics later
Excellent work :clap: Just trying things out sometimes you will stumble across something that has potential.


I have had to put the 12R resistors back in. Even with tweeters up firing and a shield in front of them it was painful to the point i could not listen to anything except old recordings with limited high frequency content. Also too much overlap with the 5" mid bass.
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karatestu
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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

Interesting link to semi omni speaker HERE
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