Doc Mod - Knowledge Compendium

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Ithilstone
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Doc Mod - Knowledge Compendium

Unread post by Ithilstone » Thu Apr 13, 2017 9:52 pm

Please do not reply to this post! If you want to something added or ask a question please PM me

With Doc's blessing ;] and hopefully with help of this Forum
I will try to gather as much knowledge about Doc Mod Drivers and speakers as possible from depth of archives.

Anyone with knowledge and experience with with Doc Mods is invited to chip in as they feel fit, from corrections and gap filling to photos or diagrams
please post replies here or PM me and I will correct and/or update main post

I would like to make it only about " why and how" and no opinions as opinions always bring heated responses :mrgreen:
pure knowledge and "know how's"

I will start digging in the archives to build compendium based on most common questions then we can go and start answering those not so common ones.
I am sure I will have some questions myself so Doc and other more knowledgeable users can help.

It will be mostly copy and paste but to make it usable
I will follow this simple index:

Index

Why

Keep it simple - judge by ears - learn

As Doc once said ( or more than once actually ) If you find a problem you look for solution on how to remove its cause, and not on how to correct effects the problem caused.

The point of Doc Mods is to remove all possible filters from the signal path, even the wadding is a filter. Doping is to take away the need for electronic component filters on the drivers. It is as though the driver had been designed and built properly in the first place, so needs no electronic crossover. An electronic crossover is bad because the components sit in the signal path and pollute the music. That loses information, things that are in the music you no longer hear. Worse they introduce timing errors into the music, and timing is the very essence of all music. Filters introduce phase lag and phase lead depending on the filter design, 1st order the least and worse as you go up through the orders, so more complex filter destroy the music timing and communication more.

P/S Racks are evil, crossovers are from hell :mrgreen:

[placeholder]

How

Modding used or new speakers

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Preparing cabinets - material used etc

- Glue to use
http://www.bison.net/en/products/642-co ... bison-kit/
Where to buy info http://www.cyanotec.com/bison/

- screw hole problem - Don't screw - glue drivers in with Bison Kit

- how thick should I apply the glue for the steel plates - As thick as you want. Honestly trust your own judgement and learn.

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Modding driver units (or buying Docs ready ones)

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Putting it all back together

[placeholder].

Advice on set up and positioning

About racks
- Racks are evil

Speaker positioning
- The full process. Put the speaker flat on as near to the wall as possible, listen. Move away from the wall until the tonal mix is as you prefer. It will be thicker nearer the wall and thinner the further away.

Then toe in in degrees until you get the image you want. More angle = deeper.


Added From: karatestu

Something to add here if i may.

When doping the driver yourself - the volume of bison kit shrinks quite a lot as it dries. I thought i had put on a healthy dose but it shrunk in depth and i will need to add more. I assume any air and volatile substances escaped whilst it dried.

This is ok, the Doc has said that this is a process of adding more layers until your ears tell you that you have the correct amount. Don't be scared and trust your own ears. It is sad that a lot of people would rather trust the ears of some one else over their own.

Padding resistor - one may be needed even if the original design did not have one. If keeping the original tweeter its sensitivity does not change whereas if you are doping the original mid bass driver, its sensitivity will drop and the tweeter will become exposed.

Above all else have FUN :dance: :dance: :dance:
Nothing to see here...

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karatestu
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Location: North Yorkshire
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Re: Doc Mod - Knowledge Compendium

Unread post by karatestu » Wed Sep 13, 2017 9:17 pm

Something to add here if i may.

When doping the driver yourself - the volume of bison kit shrinks quite a lot as it dries. I thought i had put on a healthy dose but it shrunk in depth and i will need to add more. I assume any air and volatile substances escaped whilst it dried.

This is ok, the Doc has said that this is a process of adding more layers until your ears tell you that you have the correct amount. Don't be scared and trust your own ears. It is sad that a lot of people would rather trust the ears of some one else over their own.

Padding resistor - one may be needed even if the original design did not have one. If keeping the original tweeter its sensitivity does not change whereas if you are doping the original mid bass driver, its sensitivity will drop and the tweeter will become exposed.

Above all else have FUN :dance: :dance: :dance:
Naim, Linn & Harbeth fanboy

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Ithilstone
Posts: 354
Joined: Mon Jun 01, 2015 10:54 am
Swaziland

Re: Doc Mod - Knowledge Compendium

Unread post by Ithilstone » Wed Sep 13, 2017 9:37 pm

Jeez I compliantly forgot about it I might sit on this post tomorrow - thanx karatestu for reminding me!
Nothing to see here...

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karatestu
Posts: 1198
Joined: Sun Jan 08, 2017 4:40 pm
Location: North Yorkshire
Great Britain

Re: Doc Mod - Knowledge Compendium

Unread post by karatestu » Wed Sep 27, 2017 8:38 am

More to add here.

When doc modding 3way speakers the level of bass may to be too high compared to the mid and high frequencies. This was evident in the case of my 3 ways all with the docs doped Kevlar drivers. Certain bass frequencies (low bass notes) were overloading my room and reverberating like hell.

The good Doc recommended a padding resistor in series before the bass driver (4, 8, 12 or 16 ohms to taste) to attenuate the very low frequencies and I have tried 8 ohms with much success. I need to go a bit higher though I think. It is important that the mid is wired in parallel to the bass driver when using this padding resistor approach on the bass driver.

Having any capacitors and resistors on the outside of the cab in the experimenting stage has really made it easy to tweak component values without having to open up the cab / remove drivers every time.
Naim, Linn & Harbeth fanboy

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