Doc modding Marantz imperial 7

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karatestu
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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

Latteman wrote: Thu Jul 15, 2021 6:36 pm
karatestu wrote: Mon Jul 12, 2021 3:20 pm Having listened to quite a few albums I can find nothing not to like about this experiment with tweeter pod directly above the mid bass. :dance: It certainly is not ideal because I have tweeters held in with tape that is wrinkled a bit, the tweeters are not all flush with the ring of the cut out at all points and the crappy wire cradle is not helping.

Even so it sounds bloody good. There are some changes that at first I could not get my head around. I don't know what is exactly going on but there is more fine detail on offer and spaciousness. No harshness at all that I have tuned in to yet but there are many more albums to test it with yet. It is a slightly more energetic presentation but not too far the wrong way.
Although our systems are very different I implement some of the ideas u post- I will agree placing tweeter pods over the mid bass does energise and promote the mid bass.
Hey Peter. So what have you done exactly ?
DIY inspired by Richard "The Doc" Dunn RIP

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Re: Doc modding Marantz imperial 7

Unread post by Latteman »

Moved the holding bracket forward to edge of the mid bass

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CycleCoach (Thu Jul 15, 2021 7:34 pm)
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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

Latteman wrote: Thu Jul 15, 2021 7:01 pm Moved the holding bracket forward to edge of the mid bass

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Very good Peter but you NEED to get them tweeters in a sphere :epopc:
DIY inspired by Richard "The Doc" Dunn RIP

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Re: Doc modding Marantz imperial 7

Unread post by Latteman »

Was thinking half sphere- the capacitors are in the tubes too- quite heavy for what it is
Analogue Source -
Diy Turntable ,- Thorens Td321 donor
Diy tonearm- Well Tempered clone,
Benz Micro Silver
Hitachi HT-660, Ortofon vivo blue
Phono 1 (160va) & Ortofon MCA10
Digital Sources- MF M1 Clic, Diy IDE cdp, iPhone 6s.
Amplification 2x Nva A20; A30 mk2; AP10H; Khozmo passive pre
Speakers- Diy ‘Bipolar 5.25” in bamboo sphere ; Ls6/3
Dc blocker to Nva mini BMU

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Re: Doc modding Marantz imperial 7

Unread post by Latteman »

Found this
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antonio66 (Tue Jul 27, 2021 2:06 am)
Analogue Source -
Diy Turntable ,- Thorens Td321 donor
Diy tonearm- Well Tempered clone,
Benz Micro Silver
Hitachi HT-660, Ortofon vivo blue
Phono 1 (160va) & Ortofon MCA10
Digital Sources- MF M1 Clic, Diy IDE cdp, iPhone 6s.
Amplification 2x Nva A20; A30 mk2; AP10H; Khozmo passive pre
Speakers- Diy ‘Bipolar 5.25” in bamboo sphere ; Ls6/3
Dc blocker to Nva mini BMU

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Re: Doc modding Marantz imperial 7

Unread post by Fretless »

Those speakers are staring at me.

:shifty:
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Re: Doc modding Marantz imperial 7

Unread post by Grumpytim »

Fretless wrote: Mon Jul 26, 2021 12:13 pm Those speakers are staring at me.

:shifty:
It's worse than that, their eyes follow you around the room.. :o

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Re: Doc modding Marantz imperial 7

Unread post by savvypaul »

Grumpytim wrote: Mon Jul 26, 2021 12:36 pm
Fretless wrote: Mon Jul 26, 2021 12:13 pm Those speakers are staring at me.

:shifty:
It's worse than that, their eyes follow you around the room.. :o
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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

Not seen these cute little things before. Never heard of Davone Audio before either. Typical Scandinavian design.

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Some very interesting designs by this company https://www.davoneaudio.com/index.html
DIY inspired by Richard "The Doc" Dunn RIP

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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

Nothing much done here lately, harvest is upon us.

I have been faffing with the drivers themselves. There are a few things to do with these cheap drivers that might improve them but without measurements to prove there might be no way of knowing. So why bother. They make sense to me in my head.

I removed all the soft mounting strips which are attached round the outside of the rubber surround where the mounting screw holes are located. These drivers must have been intended to be mounted from the inside of a cabinet via a removable panel. The strips looked like they could be touching the rubber surround which is not good.

After pulling the strips off it was evident that too much adhesive had been used and it was actually on the surround in several places on all the drivers. Luckily the black coloured adhesive is removable by rubbing ones nail up and down a few times and moving gradually all the way around the driver. These mounting strips are not really required so no loss and in my case I aim to make some domed aluminum rings like donuts slides in half that help blend in the driver to the curve of the spherical enclosure.

I have done a lot of reading regarding every aspect of speakers over the last few years with some of that time concentrated on doping and the drivers themselves. It became apparent that the surround can have a big effect on the operation of the driver especially the resonant frequency (Fs). Lower Fs gives the potential for the driver to produce lower bass frequencies and putting stuff on the surround raises Fs which is not what I want to do.

So anything on or touching the rubber roll surround is bound to modify the behaviour. Getting these strips out of the way and removing the excess glue which got squeezed out on to the edge of the surround can only be good imo. The original 5.25" doped drivers I got from RD before I started doping them myself had plastidip sprayed over the surround as well as the cone. Well I don't think that was a good idea so on all the drivers I have doped I masked off the surround.
DIY inspired by Richard "The Doc" Dunn RIP

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