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Kannan

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I was running a 4-way active setup with two Pioneer 944 amps in my Indica.
But after 14 years the car started to show its age and was not able to take the high load from the two Pioneer amps which were pushing a 10 inch subwoofer, a pair each of 7 inch mdbass, 4 inch midrange and tweeters.

So I had to remove the two Pioneer amps and instead tried to see the possibility of using any of the numerous low profile Class D amplifier boards available.
From what I read and gathered, the ALLO Volt+ amp was the most promising, both is quality, power needs and integration.

These ready built boards perform well at 20 volt input and push out around 30 to 35 watt RMS at reasonably low THD levels and another good thing is they are stable with 4 ohm drivers. Another good thing is the current draw is only around 4 amps, so that was hardly any load as compared to the two Pioneer amps which were drawing close to 100 amps.

Now the need was for a DC to DC booster which could provide a clean output. Picked up two such mini boards from amazon. But these produced high interference and DC noise through the speakers when powered with the ALLO.

So out went these boards and in came Laptop adapters. The output was clean, no noise or interference.
Now the need was for a good 12 volt to 220 volt converter to power the laptop adapters.
I had purchased a good one several years ago to run my laptop in the car. It was rated for 300 watts, 40 amps, so that was no issue with these laptop adapters which draw less than 5 amps.

The 12/220 investor, the two laptop adapters, two ALLO boards giving 4 channels of amplification and a power strip were added to the boot on a MDF board behind the passenger seat.
I ran a 12 volt line with a 50 amp fuse direct from the battery to the 12/220 investor with a switch near the driver seat to control the input. The stable common ground was tapped from the boot section itself.
I will be adding a fan to keep the ALLO boards running cool.

The ALLO amps are driving a pair of Dayton 7 inch midbass and a pair of Dayton Reference 4 inch wideband.
The midbass is playing from 63hz at 18db slope to 315hz at 12db slope and the midrange from 315 at 12db slope to 20khz. The source is the 3-way active head unit Eclipse CD7200mkii and the Kenwood KOS-300 is used for USB integration.
The setup is without tweeters or a subwoofer at the moment.

The ALLO amps are able to,power the midbass quite well, and of course the wideband as well.



 
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Kannan

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Today added a circuit to trigger the 12 volt line going to the 12/220 volt converter as it is directly wired to the battery.
I used a 40 amp Relay to do the needful.

I had to do this for two reasons:
1. To ensure that converter automatically shuts down when ignition is off to prevent draining of battery.
2. To control the switching on and off of the ALLO amps from the head unit.

Had to do this as ALLO amps do not have an onboard remote turn on circuit like normal car audio amps.
Since the ALLO amps are powered from the converter, I used a 5-pole Relay to trip the 12 volt line going to the conveter.
The trigger current to the relay is provided by the head unit's remote turn on lead.
In effect when Eclipse head unit is powered on, the converter will switch on, and will switch of when Eclipse is powered off.

This diagram explains it in a simple way:



 

Kannan

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The Nichicon and Panasonic capacitors, four 3.3 and four 2.2 micro farad caps were received today.
It throws open a wide option of crossover points.

Since I have two pairs of AMT 8 ohm tweeters, yet to decide whether to go with one pair of tweeters or two.
I can get 4 ohm, 8 ohm and 16 ohm configuration with these two pairs.

Also dabbling whether to run it off directly from the midrange drivers or get another dedicated ALLO amp board for the tweeters as it offers me additional option of stepped attenuation for gain matching.

caps low size.jpg
 

eapen

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Kannan, instead of converting 12vDC to 220vAC & then 220vAC back to 20vDC couldn't you have used a direct DC-DC boost converter from 12vDC to 24vDC ?

Having a multiplug 230v extension box in a moving car I believe is a fire hazard.
 

Kannan

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Kannan, instead of converting 12vDC to 220vAC & then 220vAC back to 20vDC couldn't you have used a direct DC-DC boost converter from 12vDC to 24vDC ?

Having a multiplug 230v extension box in a moving car I believe is a fire hazard.
Yes..that is what i used first, but it produces excess interference and noise. Even tried implementing a noise filter but that too did not work.
 

manniraj

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MaSh

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Wow how did I miss this thread. This is a great and compact way of powering the speakers.

MaSh
 

Kannan

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How about using a capacitance multiplier like this http://www.diyaudio.com/forums/solid-state/297921-jumas-easy-peasy-capacitance-multiplier-35.html#post5322959? I think many from the diyaudio are using the same and happy when used with DC-DC boost small PCBs even with higher DC voltages of 40+ eliminating the noises. Simple and easy solution I feel but never used. Even Allo has one which is fully built one and I think can be used in your setup.
Thanks. Will give it a read.
 

Kannan

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Wow how did I miss this thread. This is a great and compact way of powering the speakers.

MaSh
Yes....It is working very well. I later cleaned up the install with a dedicated enclosure made from a hardboard jewel box. Now am planning to make a full wood enclosure for both the amp and powers section as metal fabrication is a bit expensive.

jewel box 4.jpeg

jewel box 3.jpeg
 

Kannan

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How about using a capacitance multiplier like this http://www.diyaudio.com/forums/solid-state/297921-jumas-easy-peasy-capacitance-multiplier-35.html#post5322959? I think many from the diyaudio are using the same and happy when used with DC-DC boost small PCBs even with higher DC voltages of 40+ eliminating the noises. Simple and easy solution I feel but never used. Even Allo has one which is fully built one and I think can be used in your setup.
Oh..I forgot to mention. the ALLO Volt+ already uses capacitance multiplier.
 
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Kannan

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Rejigged the amplifier inside a wood enclosure that came with an analogue multi meter.
Also carpet wrapped the amp to match car decor, cooling is with a fan mounted on top of the amp.

Three Allo Volt+ amps (TPA3118D2 boards) and one mono amp sourced from Aliexpress. The mono is based on TPA3116D2 board and can output around 70 watts at 21 volts, 2 ohm at around 0.1% THD. The Al
los do around 20/25 watts at 20 volts/4 ohms.
The ALLOs power the Dayton miniAMT tweeters, Dayton RS100-4 midrange and Dayton RS180-4 midbass while the mono powers a isobaric subwoofer made with two Dayton RS180-4 midbass drivers.

The subwoofer is a push pull isobaric front ported design with two woofers mounted on the same baffle with facing cones. They are wired in parallel with the outer woofer is out of phase. A sample
vented-cone-to-cone-isobaric.jpg


IMG_20180131_001946.jpg

amp5.jpg

amp4.jpg

carpet amp 1.jpeg

carpet amp3.jpg

The Isobaric push pull configuration Subwoofer:

isobaric subwoofer.jpg
 

Dr.Lakshay

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Rejigged the amplifier inside a wood enclosure that came with an analogue multi meter.
Also carpet wrapped the amp to match car decor, cooling is with a fan mounted on top of the amp.

Three Allo Volt+ amps (TPA3118D2 boards) and one mono amp sourced from Aliexpress. The mono is based on TPA3116D2 board and can output around 70 watts at 21 volts, 2 ohm at around 0.1% THD. The Al
los do around 20/25 watts at 20 volts/4 ohms.
The ALLOs power the Dayton miniAMT tweeters, Dayton RS100-4 midrange and Dayton RS180-4 midbass while the mono powers a isobaric subwoofer made with two Dayton RS180-4 midbass drivers.

The subwoofer is a push pull isobaric front ported design with two woofers mounted on the same baffle with facing cones. They are wired in parallel with the outer woofer is out of phase. A sample
View attachment 25609


View attachment 25603

View attachment 25604

View attachment 25605

View attachment 25606

View attachment 25607

The Isobaric push pull configuration Subwoofer:

View attachment 25608
Nice. But the box looked better with wooden look IMO.
So from what I understand, isobaric is a means to achieve greater spl by using a small box when you are constrained on space. Is there any other benefit? Like going lower into the frequency spectrum?
 

Kannan

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Nice. But the box looked better with wooden look IMO.
So from what I understand, isobaric is a means to achieve greater spl by using a small box when you are constrained on space. Is there any other benefit? Like going lower into the frequency spectrum?
It was optimal for my needs. I already had a pair of RS180 midbass with me and I also wanted a simple one amp solution. The TPA3116 is stable up to 2 ohms, so I could wire the two drivers in parallel to offset the 3db loss is efficiency. it has worked out very well and I am getting very good output.
The design will not make the driver play lower, there is infact no change in F/s, by the way the port is tunes to around 35hz, but I had to compromise a little on the port length, but I have done a dual flange (flange at both ends) to minimize ringing.
 

Kannan

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With carpeting, the amp blends into the decor and nothing is visible to any prying eyes
 

Kannan

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A sample of ALLO amps playing in my car. It is a 4-way active setup and I have three used three ALLO Volt+ amps powering the main speakers and a mono TPA3116 mono board powering the sub.

 

VSTEREO

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A sample of ALLO amps playing in my car. It is a 4-way active setup and I have three used three ALLO Volt+ amps powering the main speakers and a mono TPA3116 mono board powering the sub.

This is one of the best active setup that I have listened so far. Whoever wanting to try active with limited budget, this is the best I would suggest.
 

captrajesh

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I had visited Chennai a few days ago met FM Kannan and was able to sample his Car Audio System. I truly appreciate the passion and enthusiasm with which he explained the technicalities. I'm truly flabbergasted that a Car Audio System can sound so good; Of course, I admit that I've not really sampled too many custom installations but whatever little I saw was bass heavy or bright systems that made me cringe longing that the ordeal was over. As for this system, it was a revelation as to how good a Car Audio System can sound. I'm truly hooked on and look forward to taking tips and advise from Kannan on setting up an Audio System if and when I buy a new Car.

isobaric is a means to achieve greater spl by using a small box when you are constrained on space. Is there any other benefit? Like going lower into the frequency spectrum?
On the contrary, AFAIK, isobaric systems are 3 dB down from the one of those drivers with double the box volume. Isobaric configuration is resorted when there are space constraints as the box size is reduced to half.
 
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Kannan

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I had visited Chennai a few days ago met FM Kannan and was able to sample his Car Audio System. I truly appreciate the passion and enthusiasm with which he explained the technicalities. I'm truly flabbergasted that a Car Audio System can sound so good; Of course, I admit that I've not really sampled too many custom installations but whatever little I saw was bass heavy or bright systems that made me cringe longing that the ordeal was over. As for this system, it was a revelation as to how good a Car Audio System can sound. I'm truly hooked on and look forward to taking tips and advise from Kannan on setting up an Audio System if and when I buy a new Car.
It was a great pleasure meeting you sir. Thanks for the time spent even though you had a long drive ahead of you.
Also thanks for you words of encouragement, especially when it comes from such a senior member of the forum and an experienced audiophile, it vindicates the hours of toil that went into the setup.

Thanks once again and hope to meet you again.
 
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