A BRIEF DESCRIPTION

The Boodo Khan is one of the most famous models of the whole walkman range. It was also one of the firsts models to include bass amplification , and the first one to have a dynamic one (not static, like an EQ).
SONY developed the DOL (Dynamic Optimun Loudness) system and integrated it on some of their top-level HI-FI products on 1986 (amplifiers and equalizers) and decided to include for the first time on a walkman, so they can compensate the typical poor bass response on portable players. The DOL system was the first attempt and after it many came, like the famous Mega Bass, and almost every brand on earth copied the idea under different names: DSL, Super Bass, Extra Bass, Bass boost...

This system amplifies not only the bass but also the highs, but in an dynamic way, so the intensity is maximum at low volume and weak at high output. It powers the bass (between 20-100 Hz) up to 9 dB and up to 3 dB the highs (from 10 kHz and up).

The mechanics are derived directly from the DDII and the DC2, but externally it has a closer look to the DD30.

The "Boodo Khan" (formerly, "Budokan") name refers to one of the most famous indoor arena of Tokyo (see it on Google Maps). This place is commonly used for martial arts competition, but sometimes it's also used as a concert hall. Because of its excellent acoustics, many important artists and groups has performed concerts or recordings there, like Bob Dylan, Brian Adams, Pearl Jam, Avril Lavigne, Quincy Jones, Deep Purple, Blur... and so it gained many importance as a music hall.
Because of that, Sony decided to give this name to the top player on that year, and to improve it, they accompanied the player with a pair of good closed headphones. (seen at the Wikipedia)

The Budokhan indoor arena, at Tokio. (from Wikipedia)

The DD100 came with a big headphones supplied. They really are the SONY DR-S3, but in this case they were renamed to DR-S100 and got the Boodo Khan logo stamped. Contrary to the general trend, the big, closed headphones supplied targeted this legendary player towards the audiophile, not the teen or casual listener.

CONTEXT

At the time when the DD100 was released, only Panasonic had one model with a similar feature, called "Ultra-Phonic", but SONY went far with its DD100, and the DD100 simply started a new cathegory on portable cassette players, so we can say that there was simply no alternative to the customer.

The Panasonic RX-SA80 was the world's first walkman to have a bass amplification system, but it was not dynamic but fixed. I mean: like a preadjusted EQ, that always equalizes the same way.

Panasonic RX-SA80, the world's first walkman with bass enhancement.	Detail of the green switch "Ultra Phonic".	The RX-SA80 and the Boodo Khan.

Dynamic bass amplification works by amplifying much more at low volume than at higher levels, because of the way the human ear works. It's an automatic variable EQ: the lower the volume, the stronger EQ. SONY's DOL and AIWA's DSL dymanic bass systems were also implemented in HI-FI systems, but no portable player had yet integrated. Until then.
However, AIWA was preparing a groundbreaking player, the PX101, which also had a bass amplification (DSL) and many sophisticated features, that was released a few time after the DD100.

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This model is one of the most special ever released, and every serious collector has normally one of them in his collection. The luxury, elegant design combined with the closed headphones and the extremely powerful DOL system has placed it in the olympus of the walkman age.

As with many DD models, the base sound quality is excellent, with very low wow&flutter. The Dolby B system, however, as with many other models, doesn't allow to get the maximum from it. A good Dolby C, like the one present in the WM-DC2 would be excellent.

The DOL system offers a huge bass amplification. The first time I heard it I was simply blowed out by its power. Itsn't common to feel such power of bass frecuently. I have to say that I like so much powerful bass on music, and the headphones I use on daily basis offer such an excellent response: the Sennheiser HD280 Pro, a headphones used on studio reference, that offer a plain response over all the range and excellent noise isolation. The bass is very powerful, but not distorted at all.

Then I tested the same with the original SONY DR-S100 headphones and felt that the bass was a less powerful, much more balanced, so I believe that those headphones were really finely adjusted to the Boodo Khan (or the DOL system was adjusted to those headphones).
So if you have a goo pair of modern headphones with powerful bass, I commit you to not use it with the DOL system or you are in serious danger to be blowed out by the huge bass of the DOL system.

Overall score
Sound quality*
Sound w/Dolby
Ecualization
Features
Design
Build quality
Overall

*: Without Dolby and without any ecualization or sound processing.

For rating the sound quality, I use a pair of high quality Sennheiser HD 280 Pro studio reference headphones, and a test tape (Maxell XL-II) with a high quality recording made with a SONY D6C portable deck. However, this is a personal opinion and it's not intended to be a precision rating.

Before rating this model, it was taken to a professional technician for examine, repair and fine adjusting. Remember these are old machines and internal belts stops working properly after some time. Of course, head and rollers have been carefully cleaned before testing.