Reprint my sound system: (2) HiVi DIY3.1 bookshelf speaker kit transformation process

Preface: fancy Huiwei DIY3.1, is completely its elegant and leisurely and compact appearance, no other, compared to my old speaker that has been used for many years, it is inevitable to see a little strange thinking Although my old speaker is not bad: 6.5-inch three-unit main speaker + subwoofer, the use is also Huiwei old speaker, the cabinet is customized, the power amplifier is electronic four-way 8 channels, (see the previous part “My Audio System: (1) Electronic Four-way Power Amplifier DIY Production Process and Technical Concept”), with a key to switch “pure post-stage” and “merger” “The function of conversion, the crossover point is 800/5000Hz, the cutoff frequency of the subwoofer channel is 150Hz, usually used is no attenuation, direct drive main speaker and subwoofer a total of 8 speakers, no waste of performance, all made of personal DIY; Can be with me for many years, there must be its highlights, one is busy life, ignoring the crazy bees and butterflies, falling flowers and flowing water around me, the other is often auditioned in the audio store and compared to the same kind or even more high-end, my audio sound quality is not inferior, not to belittle others, but to have their own favorite sound style, just like that, a blink of an eye is more than ten years.

Idle, full of lust, the so-called lust, desperate, although there is no specific information on DIY3.1 performance indicators, there may be problems such as matching with the amplifier in the future, but there are always more ways than difficulties, martial arts people, see the tricks, there are always insidious means to subdue this mysterious object.

This confidence comes from experience. Although I am a major in electrical automation, but audio is a layman, the first power amplifier made in the youth era is based on the “three-channel electronic crossover amplifier” published by the predecessor Mr. Li Yingkai in the early 80s in “Radio”, systematically deepened the understanding of pre-amplification, equal loudness, tone, line buffer amplification, electronic crossover, OTL, OCL, stabilized power supply, etc., the broken and yellowed circuit diagram, as a memorial, is still preserved.

Looking back, Lucky’s own threshold for starting back then was very high, and of course it was my wise choice; At that time, electronic parts were very expensive, and there were not many varieties, it is no exaggeration to say that accidentally burned a 3DG12B triode, a week’s breakfast money is gone, but therefore also cultivated a cautious and steady character, every time I encounter something important, I will remind myself: “If you want to eat breakfast, be careful, beautiful boy.” “I really sigh that the juniors who are learning electronic technology now meet the good times, the network information is developed, the electronic components are varied, and the quality is high quality and low price, which is really envious of the predecessors.”

At that time, the production, from corroding circuit boards, drilling, transformers, speakers, to soldering parts by part, to debugging, all of them were hands-on, getting unlimited fun, while knowing the innate advantages of electronic crossover in personality freedom, over the years DIY several amplifiers and speakers, only once did power crossover, due to performance consumption, adjustment troublesome and difficult to accurate, since then abandoned.

These are all my strength to grow old and flower.

First, the model specifications of new and old speaker speakers:

1. DIY3.1 kit:

Isomagnetic band treble (RT1.3-B), 6Ω, 20W,

4″ dome midrange (DMN-B), 5Ω, 120W,

6.5″ mid-bass (L6-4R), 4Ω, 60W,

Another useful information for me is the crossover point curve, which is not very clear, and the visual crossover point is about 1100/5200Hz;

2. Huiwei old speaker of the old speaker:

4″ dome tweeter (SS1II), 5Ω, 30W,

5″ dome midrange (DMA-A), 5Ω, 150W,

6.5″ mid-bass (SS6.5R), 5Ω, 120W,

In actual use, the sensitivity is not far off.

Second, the new and old speaker comparison test:

In order to have a clear idea, first compare the timbre of the old and new horns.

The left and right channels of the electronic crossover amplifier are connected to the old and new speakers of the same frequency respectively for real-time comparison tests, and the results are intuitive:

1. Bass contrast: the new speaker bass is thick and refreshing, and the old speaker is defeated in all directions, and it surrenders unconditionally;

2. Alto horn: the old melodious and pleasant, the new one is more calm, decent, no characteristics;

3. High note: the sound of the old dome is relatively uniform; The female mid-treble part of the new horn is severely deficient, and it is estimated that the Huiwei crossover assigns these to the midrange unit; The vertical directivity is narrow, but the performance of metal percussion instruments has a different style.

Third, the overall comparison of new and old speakers:

Connect the amplifier and drive each speaker directly without any attenuation:

1. Old speaker: the sound is melodious and transparent, the midrange peak is prominent, and there is a bold smell, which may be a wonderful chemical reaction between the power amplifier and the midrange speaker;

2. New speaker: insufficient brightness of the treble, hyperactive midrange, thick bass, estimated impedance and sensitivity of each speaker, the overall lack of highlights;

The feeling after comparison: It can be imagined that even if the new speaker uses the original power divider, or adjusts the crossover point and attenuation of the amplifier to match, the timbre style is not my dish.

Momentarily at a loss, I drank a glass of frozen water to calm down, and I felt completely cold, just like my mood.

4. New speaker modification:

On a whim, create a speaker with adjustable timbre:

1. The old dome tweeter replaces the new belt type, the panel diameter is the same, and it can be directly replaced and installed without affecting the beauty;

2. The midrange speaker cannot be replaced due to the size difference, so I have to continue to use the new midrange unit;

3. The belt tweeter is installed on the custom-made U-shaped bending acrylic external frame, and then fixed in the position closest to the mid-range speaker for external tweeter;

4. The three-speed switch conversion on the external rack can select 3 different timbre trebles:

*1st gear, using the dome treble in the box, suitable for vocals;

*2 gears, using an external belt tweeter for playing light music;

*3 gears, the dome is the main treble, and the external band type is a combination of super treble, suitable for pop songs, rock, even classic old songs with poor sound quality, etc., have good performance;

5. Connection method of tweeter: power amplifier tweeter output to the input jack on the external shelf, external rack output to the terminal of the speaker tweeter, if no external belt tweeter is used, the amplifier tweeter output is directly connected to the speaker tweeter.

* Negligence: The external tweeter should be equipped with 2-3 frequency selection switches to facilitate the adjustment of different super treble according to different music. This is a mistake and a regret.

5. Passive subwoofer cooperation:

For increasing the diving and fullness of the overall bass, many years ago, referring to the BOSE leisurely No. 5 three-chamber structure of the subwoofer, enlarged and customized according to the proportion of the original size, modified into two outlets, equipped with two 8-inch rubber-edged woofers, left and right channels independent channels, can be used flexibly:

1. According to the placement of the subwoofer, you can choose positive or reverse phase connection, adjust the principle, and the overall bass is cleaner and softer;

2. Excessive ultra-low bass, or excessive low-frequency standing wave reflection, will destroy the spatial three-dimensional sense of the sound field, and cause the sound and image shift, at this time, only the subwoofer can be used all the way to the speaker;

3. It can block a sound outlet to reduce the output of subwoofer, and can also connect attenuation resistance in series, but it is not advocated;

4. Some streaming videos and audio bass is insufficient, or various situations such as dance parties, or watching blockbuster movies, can be adjusted by using the above known methods to add atmosphere;

5. If it is not needed, it can be not connected, and it does not affect the inherent technical indicators of the power amplifier and the main speaker.

6. The mixing process of matching the amplifier and the speaker:

1. I prefer the timbre of Beats headphones, rich in details, clear layers, and open personality, which is very suitable for pop music, rock, etc., in order to achieve similar effects, an external belt speaker is specially installed in the main speaker for super treble;

2. Use the original genuine Beats headphones to play Cai Qin’s “Ferry” and Wang Wen’s “Love for You”, pay attention to the drum sound in the song, the string sound of the guitar, the voice of the singer, etc., and the proportion of their loudness in the song, and use this sound effect as the standard to adjust the speaker;

3. The power amplifier is debugged in the “pure post-stage” mode to avoid the influence of the pre-stage’s sound coloration, so it has the smell of the monitor speaker; Repeatedly compare the sound effect of the headphones, the machine super bass only uses one way, to avoid the overall bass is too heavy, the belt type is used as a super treble series 6.8uf capacitor; the volume of the midrange is too loud, noisy, the method is to debug different resistors in series on the midrange speaker line, and finally determine the attenuation resistance of 20w2.5 ohms, so as to balance the proportion of the sound component of each channel unit.

4. The power of the attenuation resistor should be above 20W to avoid the change of resistance value caused by heat generation, which will affect the overall sound quality;

5. To balance the proportion of sound of other channel units, the correction method is the same;

6. Taking into account various factors such as pre-stage use, different sound sources, music types, equal loudness, listening distance, common volume, cabinet resonance, personal preferences, etc., modify the frequency division point of the main speaker of the amplifier to 800/5000Hz;

7. After this adjustment, the overall timbre is about 90% similar to the headphones, mainly because the listening environment of the two is different; As a super tweeter, the belt horn performs well in sound details, and is on par with Beats, showing its full advantages;

8. Due to the limited space in the living room, a hanging boom is installed at the center of gravity of the speaker, hanging horizontally on the wall, and three pairs of horn lines are covered up with fake flowers and plants, I believe that no one dares to be so rude to Huiwei DIY3.1. Brother Huiwei, sorry, sorry!

* Communication: I personally believe that three-way or above speaker tuning, under the framework of scientific theory, should also be carried out with the power amplifier, the speaker has the best performance, such as “pure post-stage” and “merged” are two different sound quality styles, or different brands of front-level, the sound spectrum is also different, there should be two different sets of crossovers, but it is not realistic for the product, so when buying more high-end speakers, pay attention to the power amplifier recommended or demonstrated by the business, casually matched may not have good results, some brands of power crossover speakers, There are attenuation adjusters with midrange and treble that serve as a balancing sound. Two-way speakers are easier to match because there is only one crossover point and the influencing factors are limited.

VII. Conclusion

The supreme state of DIY is to make pickles with roasted goose flavor and enjoy themselves, nothing more.