How did it start

I had a dream for a long time - to buy the legendary S90 and modify it with a file to make a budget decision for the envy of everyone. While monitoring various flea markets for a long time, I bought a 35ac-212 “Radio Engineering” S90 on one column, which is 1981 release (my peers;)).
The state of the outside on a solid 4, inside the crooked paws, no one was picking. There was only one minus - the bass from one speaker was killed, which I was honestly informed about, well, I really didn’t like the fact that both woofers were painted with silver (it’s good that the paint is not deep paint, that is, the diffuser mass increased only slightly).
Over 1000 p. I bought a set for creativity.
We will refine.
Oh, I feel strong controversies between supporters of improvements in Soviet acoustics and supporters of her to dig in completely and without turning.
Immediately I apologize for the quality of the photos, because at the time of completion, and now I do not have a digital camera other than a phone.

We get inside

After listening decided to disassemble each column for compliance with the insides column passports. As it turned out, 10GD-35, MF-15GD-11A are in high quality, and 35GD do not remember low frequencies (something), but with a rubber suspension that does not dry out.
First of all, I rewound the woofer.
The restoration of the dynamics for me was not a problem, because I did it very often in my youth for denyuzhku. Unfortunately, I didn’t have a mandrel of a suitable diameter, but the need for invention is cunning and I went with a caliper in my pocket to the nearest construction worker. As a mandrel, I bought some kind of plumbing pipe for about 20 rubles. I sawed it along (this is necessary because after winding it would be practically impossible to remove the coil from the mandrel).
Let's add another 20 minutes for winding and centering and a day for drying the speaker. Everything, the speaker began to play without extraneous overtones and just as untouched.

Let's start with tweeters

After listening to the result and reading the great Internet, I began to think further on how to make the sound even better. Basically, all types of improvements are reduced to replacing the HF, replacing the MF and damping the body.
HF really does not sound very. There are unpleasant overtones on HF and lack of ringing at midrange. In the HF link, speakers are used by domes of some plastic / polyethylene. I put for comparison 10 watt speakers with silk domes, the high-frequency sound became much more transparent and the overtones disappeared, which simply cut off the ear. As a result, these rootless speakers of about 500 r per pair remained in them. I bought them for a long time and the marking on them is not readable, but I do not remember what was written on the price tag. You can use speakers and 10GDV with silk domes.

I note that at first I made one speaker and compared the sound on test discs with the sound of the original speaker. After listening, I decide to leave the mess or return everything back. Everything was done on my favorite rumor that seemed to never let me down.
')

Body refinement

Then I decided to do the bass, i.e. body refinement. Batting was bought for ridiculous money, 38 r per meter in length and 2 meters wide with something. Just looking at the manufactured filters listened to the advice to change all the wiring in the columns.
Dismantled all the speakers from the speakers. Removed the filter and switches. Wires can be safely cut as they are all the same for replacement.
Then I cut out the necessary piece of batting, took a furniture stapler from a friend, and began to sheathe them inside in 2 layers.


The phase inverter tube is placed on the sealant and is also covered with batting.


The next thing you need to do is modify the filter.

The filter scheme is simple

I completely disabled the switches, since they are completely unnecessary. Unnecessary elements are removed from the filter board.
We change all the fine conductors in the filter to normal copper wire.
Here is a filter before rework.

This is a copper wire about 4 squares used for almost all connections.

As a result, converted with cleaned dividers and regulators

then install it in the case and close the batting.
Also batting close all midrange box outside.

Mid link

In principle, after such improvements, the sound changed for the better, the bass became clearer, the upper frequencies became “more transparent” and “lighter”, but I still didn’t like the middle aids and the upper middle was not enough. There was not enough ringing in the vocals.
Rummaging in their reserves found two 4GD-8E in excellent condition. I put one speaker and compared the result for a long time. I liked the result. In one blues record I heard blows of brushes on the main drum. Before that, I did not distinguish them.
But these speakers stood in acoustics for a long time.
After listening to the weekly refined speakers came to the conclusion that the sound began to tire me.
Probably, all this is caused by the fact that 4GD-8E dynamic heads have a very high Q-factor and, in a closed box, have a very rugged frequency response. Unfortunately there is no normal microphone to take measurements. Yes midrange speakers were equipped with PASS of foam rubber covering the rear holes in the speakers. The midrange box itself is filled with fluffy "eye" wool.

On the Internet, they often wrote about 5GDSh-5-4 and 6-GDSh-5, about the fact that they, after installing the PAS, give out excellent MF. Walking through the neighboring radio stores I bought a pair of 6-GDSh-5 4 ohms for 110 p. As far as I understand, they are installed in consumer electronics. I sealed the windows in the diffuser's basket with thin batting and set them instead of 15-11, since the installation dimensions are completely the same. There is another way to refine the midrange speakers - impregnation of the suspension with a mystical gerlen mixed with the blood of the conductor of the orchestra with acetone and applying a thin layer on the back of the diffuser. But I understand it so rarely that in construction men they just throw their hands on it. It would take an experiment because 110 p for a couple of new speakers is not a pity.

After all the operations we collect all the acoustics and enjoy the new sound. I tested the sound on a self-made amplifier of high fidelity to Sukhoi (I'm afraid the true Hi-Fi connoisseurs will spew diarrhea rays in my direction) I also collected it myself, with minor modifications to the nutrition and played it for more than a dozen years, but that's all in the same kind of engineering sample. Connect it all to Sb Live! Losing flac special discs such as audio doctor. And just wav and flac disks that are specifically recommended for testing the audio path.

Total

Costs 1000 p. acoustics itself
500 r tweeters
110 p midrange speakers
rubles 150 batting, glue staples for the stapler screws and other trifles
Total 1760 p.
What did we get?

Here's a nice acoustics


Next is just my opinion and the opinion of my friends who have done it.
I don’t remember a friend of the jbl model Napolnikov, but they cost about 20,000 for one Yamaha receiver, he clearly agreed that after revision the S90 replay its kit.
I sound completely satisfied. Walking through different salons with acoustics and listening to it, I understand that such a sound is cheaper than 15 000 r. for one speaker does not buy.

Threat Now they are playing in conjunction with the Humel Simple amplifier and explosive pre-amplifier Sukhoi. All connected to the same sound SB Live! and it works like a front to 4.0 sound for watching movies on the LCD panel 37 ". Realism in disaster films is more than enough. I don’t even think about adding a subwoofer.

PS All this is written by a sersad man who, well, can’t get to habr. And he will be very happy to invite him. In this case, he could continue to further his articles and respond to all your comments.

That's the way his article 1 article 2 .

UPD Thanks for the invite!