IcePower module

[Phil Allison]

bitrex bullshitted:
-------------------

The problem with naive class D for consumer audio applications is that
the efficiency is quite good, way better than a linear amp, when running
flat out but nobody uses an amp that way, at normal volume levels the
power efficiency stinks and is not that much better than a class B.


** Hmmm ......

The best *theoretical* efficiency of a class B amplifier is 78%, at full power.

Max dissipation occurs at 40% of full power, where efficiency is 50%.

At 10% of full power, efficiency falls to 24%.

At 1% of full power, efficiency is 8%.

At 0.1% of full power, efficiency is only 2%.

So at low volumes, heat generation is well over 10 times the power output.

Don't think it's anything like the same with a class D stage.



...... Phil

 

On Fri, 20 Sep 2019 19:40:31 -0700 (PDT), Phil Allison
<pallison49@gmail.com> wrote:

bitrex bullshitted:
-------------------


The problem with naive class D for consumer audio applications is that
the efficiency is quite good, way better than a linear amp, when running
flat out but nobody uses an amp that way, at normal volume levels the
power efficiency stinks and is not that much better than a class B.


** Hmmm ......

The best *theoretical* efficiency of a class B amplifier is 78%, at full power.

Max dissipation occurs at 40% of full power, where efficiency is 50%.

At 10% of full power, efficiency falls to 24%.

At 1% of full power, efficiency is 8%.

At 0.1% of full power, efficiency is only 2%.

So at low volumes, heat generation is well over 10 times the power output.

Don't think it's anything like the same with a class D stage.



..... Phil

https://www.dropbox.com/s/3yojvxe4o7iawyi/tpa3255-1.pdf?dl=0


Fig 9. I was agonizing over designing the output transformer ratio,
and had an inspiration of duh: class D efficiency doesn't change much
vs power out, so I may as well step up more than I'll probably need.
The amp won't care.

 

[bitrex]

On 9/20/19 10:40 PM, Phil Allison wrote:

bitrex bullshitted:
-------------------


The problem with naive class D for consumer audio applications is that
the efficiency is quite good, way better than a linear amp, when running
flat out but nobody uses an amp that way, at normal volume levels the
power efficiency stinks and is not that much better than a class B.


** Hmmm ......

The best *theoretical* efficiency of a class B amplifier is 78%, at full power.

Max dissipation occurs at 40% of full power, where efficiency is 50%.

At 10% of full power, efficiency falls to 24%.

At 1% of full power, efficiency is 8%.

At 0.1% of full power, efficiency is only 2%.

So at low volumes, heat generation is well over 10 times the power output.

Don't think it's anything like the same with a class D stage.



..... Phil

Those numbers look right. we should probably agree on what we mean by
"normal volumes" (or I should be more clear in the first place, rather..)

as I recall the efficiency of class D with no "tricks" tends to bottom
out at about 1 watt where in the case of a say 100 watt RMS class B vs
class D amp that the B would still be dissipating 10 times more than the
D at that point sounds entirely plausible to me.

1 watt RMS into 8 ohms is still really fuckin' loud, though!

<https://www.youtube.com/watch?v=MxI491hDMN8>

looks like he's got this 1 watt amp at about 1/3rd volume most of the
time. Your mom is going to tell you to turn that racket down even so.
Play 1 watter flat out if you live in an apt and your neighbor is going
to call the cops

 

[bitrex]

On 9/21/19 12:20 AM, bitrex wrote:

On 9/20/19 10:40 PM, Phil Allison wrote:
bitrex bullshitted:
-------------------


The problem with naive class D for consumer audio applications is that
the efficiency is quite good, way better than a linear amp, when running
flat out but nobody uses an amp that way, at normal volume levels the
power efficiency stinks and is not that much better than a class B.


  ** Hmmm ......

The best *theoretical* efficiency of a class B amplifier is 78%, at
full power.

Max dissipation occurs at 40% of full power, where efficiency is 50%.

At 10% of full power, efficiency falls to 24%.

At 1% of full power, efficiency is 8%.

At 0.1% of full power, efficiency is only 2%.

So at low volumes, heat generation is well over 10 times the power
output.

Don't think it's anything like the same with a class D stage.



.....  Phil


Those numbers look right. we should probably agree on what we mean by
"normal volumes" (or I should be more clear in the first place, rather..)

as I recall the efficiency of class D with no "tricks" tends to bottom
out at about 1 watt where in the case of a say 100 watt RMS class B vs
class D amp that the B would still be dissipating 10 times more than the
D at that point sounds entirely plausible to me.

1 watt RMS into 8 ohms is still really fuckin' loud, though!

https://www.youtube.com/watch?v=MxI491hDMN8

looks like he's got this 1 watt amp at about 1/3rd volume most of the
time. Your mom is going to tell you to turn that racket down even so.
Play 1 watter flat out if you live in an apt and your neighbor is going
to call the cops

I had one of these in college, the Ampeg SS-140C guitar head:

<https://www.musicgoround.com/product/castleton-in/41121-S000028552/Used-Ampeg-SS-140C-Solid-State-Guitar-Head-w-Footswitch?gclid=CjwKCAjw8ZHsBRA6EiwA7hw_sS_SvYAhyZ9rPwfUMSiCbOHNWzTBmWSVxm0c_dOe5Xcui734NAF_KhoCSLUQAvD_BwE>

Found out very quickly it was useless to use in a dorm past 10 pm
because person below me would call security to turn that racket down.
The volume had two lowest settings, no output, and 1 notch up from that
which was security gets called-setting.

I don't recall what happened to it I think I sold it prior to a move at
some point. Hmm, $250 is pretty cheap. It was a very rugged and very
loud amp with a bucket brigade chorus built in. though tube-o-philes
would turn their nose up at it.

 

[bitrex]

On 9/21/19 1:57 AM, upsidedown@downunder.com wrote:

On Fri, 20 Sep 2019 09:16:30 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Fri, 20 Sep 2019 12:07:58 -0400, bitrex <user@example.net> wrote:

On 9/20/19 11:54 AM, jlarkin@highlandsniptechnology.com wrote:
On Fri, 20 Sep 2019 08:28:01 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

fredag den 20. september 2019 kl. 11.23.11 UTC+2 skrev Winfield Hill:
Phil Allison wrote...

just completed repairs on one of these:
http://www.sound-power.ru/files/doc/ICEp

My comment would be, it's nice to have
AC power integrated with the amplifier.

I've been getting class-D amplifier PCBs
from China, very cheap, yet many of them
seem well engineered and well built. But
none of them include a power supply, nor
do they offer a suitable power supply.
But, damn, these high-power supplies can
be more complicated than the amplifier!


not quite china prices but they have a few with psu

http://www.cadaudio.dk/cadpwmmodules.htm

Half-bridge class-D amps are interesting. As they pull power out of
one supply rail, they pump power into the other one.

All those huge-power specs must be some sort of intermittent peak
music thing. There's no way those tiny boards can get rid of much
heat.



You don't think this board can do 100 watts "RMS" into 8 ohms?

http://www.cadaudio.dk/d2050s.jpg

I bet it can just fine

With that big heat sink, maybe so. But they have 500 watt units, and
kilowatt boards, that look scary.

We're designing a 120 watt full-bridge class D amp, and I'm sure going
to have a big heat sink and forced air flow.

So what are the main dissipation mechanism in class D stage ? I can
think of two important mechanisms:

With slow transistors the power dissipated during turn-on and turn-off
transitions can be significant. With constant sample rate PWM, the
number of transitions per second is constant regardless of audio
volume.

The transistor ON state Vce(sat) causes some power dissipation. At
full power, the transistor duty cycle is nearly 50 %, so there is a
single Vce(sat) all the time either in the top or bottom transistor.
However, at low audio volumes the transistor duty cycle is very low
and most of the time, neither transistor conducts and hence the
average Vce(sat) losses are very low.

Any other significant loss mechanisms ?

It appears that the absolute dissipation is worst during full power,
dropping at lower levels, hence if the heatsink is adequate for full
power, it should also be sufficient for low audio levels.

if it's anything like synchronous buck converter design at hundreds of
watts potential losses in the gate drivers probably can be significant,
too.

One of my PCs has a mobo with some questionable part choices it has gate
driver MOSFETs that melt down sometimes, not the output FETs.

 

On Fri, 20 Sep 2019 09:16:30 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Fri, 20 Sep 2019 12:07:58 -0400, bitrex <user@example.net> wrote:

On 9/20/19 11:54 AM, jlarkin@highlandsniptechnology.com wrote:
On Fri, 20 Sep 2019 08:28:01 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

fredag den 20. september 2019 kl. 11.23.11 UTC+2 skrev Winfield Hill:
Phil Allison wrote...

just completed repairs on one of these:
http://www.sound-power.ru/files/doc/ICEp

My comment would be, it's nice to have
AC power integrated with the amplifier.

I've been getting class-D amplifier PCBs
from China, very cheap, yet many of them
seem well engineered and well built. But
none of them include a power supply, nor
do they offer a suitable power supply.
But, damn, these high-power supplies can
be more complicated than the amplifier!


not quite china prices but they have a few with psu

http://www.cadaudio.dk/cadpwmmodules.htm

Half-bridge class-D amps are interesting. As they pull power out of
one supply rail, they pump power into the other one.

All those huge-power specs must be some sort of intermittent peak
music thing. There's no way those tiny boards can get rid of much
heat.



You don't think this board can do 100 watts "RMS" into 8 ohms?

http://www.cadaudio.dk/d2050s.jpg

I bet it can just fine

With that big heat sink, maybe so. But they have 500 watt units, and
kilowatt boards, that look scary.

We're designing a 120 watt full-bridge class D amp, and I'm sure going
to have a big heat sink and forced air flow.

So what are the main dissipation mechanism in class D stage ? I can
think of two important mechanisms:

With slow transistors the power dissipated during turn-on and turn-off
transitions can be significant. With constant sample rate PWM, the
number of transitions per second is constant regardless of audio
volume.

The transistor ON state Vce(sat) causes some power dissipation. At
full power, the transistor duty cycle is nearly 50 %, so there is a
single Vce(sat) all the time either in the top or bottom transistor.
However, at low audio volumes the transistor duty cycle is very low
and most of the time, neither transistor conducts and hence the
average Vce(sat) losses are very low.

Any other significant loss mechanisms ?

It appears that the absolute dissipation is worst during full power,
dropping at lower levels, hence if the heatsink is adequate for full
power, it should also be sufficient for low audio levels.

 

[bitrex]

On 9/21/19 2:57 AM, Phil Allison wrote:

upsid...@downunder.com wrote:

--------------------------------


Any other significant loss mechanisms ?

It appears that the absolute dissipation is worst during full power,
dropping at lower levels, hence if the heatsink is adequate for full
power, it should also be sufficient for low audio levels.


** The Ice Power module, with accompanying pre-amp draws 14W at idle and there is no change with 1W output.

At full output(330W) the power draw is 365W.

The famous Ampeg SVT tube bass head from the 1970s draws 170W at idle, with also no change at 1W since it operates in class AB.

At full output(300W) the power draw is 550W.

So played quietly, the class D amp wins hands down.

At full power, the difference is not nearly so huge.

Interesting.

BTW: the weights

IcePower amp: 3 pounds.

Ampeg SVT: a backbreaking 85 pounds



.... Phil

bring a 50 watt tube amp instead and set a crossover so everything above
~150 Hz goes through the tube amp and put the low end thru a subharmonic
synthesizer into a subwoofer driven by the IcePower.

Serious bass:

<https://www.youtube.com/watch?v=t3UaptsZOQQ>

 

[Phil Allison]

upsid...@downunder.com wrote:

--------------------------------

Any other significant loss mechanisms ?

It appears that the absolute dissipation is worst during full power,
dropping at lower levels, hence if the heatsink is adequate for full
power, it should also be sufficient for low audio levels.

** The Ice Power module, with accompanying pre-amp draws 14W at idle and there is no change with 1W output.

At full output(330W) the power draw is 365W.

The famous Ampeg SVT tube bass head from the 1970s draws 170W at idle, with also no change at 1W since it operates in class AB.

At full output(300W) the power draw is 550W.

So played quietly, the class D amp wins hands down.

At full power, the difference is not nearly so huge.

Interesting.

BTW: the weights

IcePower amp: 3 pounds.

Ampeg SVT: a backbreaking 85 pounds



..... Phil

 

[bitrex]

On 9/19/19 9:27 PM, Phil Allison wrote:

Hi to all my fans,

just completed repairs on one of these:

http://www.sound-power.ru/files/doc/ICEpower125ASX2_datasheet.pdf

Found it fitted inside a mini-size bass instrument amplifier, which the owner had just purchased over the net and failed on him at first power up.

Smelling a rat, I checked the AC switch on the rear panel first - blow me down, it was set to 120VAC and we live in a 240V country.

Reset the switch, then it drew zero AC current - no surprise.

Replaced the blown 5AT fuse in the IcePower module and then the PSU began hiccupping - drawing an amp or two very briefly then shutting off every few seconds.

IME feeding double AC supply voltage to a unit with a SMPS is almost always fatal, sure the AC fuse blows but semis in the HV part of the circuit fail in a fraction of a second. But these must be OK this time because the PSU was hiccupping - ie working but sensing an overload so shutting down.

Soon enough, multimeter testing showed two small power mosfets on the output side of the SMPS tranny were shorted while two others seemed OK. But what the heck are mosfets doing there ?

Well, it's the fist time I have come across seen a *synchronous rectifier* in such an unit. IcePower had certainly gone all out to reduce losses and heat in this module by using a synchronous bridge.

The particular TO-252 fets here are made by ON, number FDD86110 rated at 100V and 8mohms on resistance.

Removing the duds cleared all shorts and after fitting some new ones ( delivered to me by Element14, from their Singapore warehouse ) I gingerly Variaced the unit up from zero.

No hiccupping this time and it began to run normally - after which it passed all my usual bench testing, no problems.

FYI:

AC current draw was 120mA at idle, 2.4A at full power (340W rms/4ohms)

No PFC and inrush surges were about 25A for a few milliseconds.

There was a residual sine wave signal on the audio output of about 1V at 500kHz - no biggie except it makes THD testing a right PITA.

I find it odd the way the SMPS failed, just two mosfets in the secondary rectifier, nothing else. For a brief time, the DC supply to the switching fets must have been nearly double voltage.

Seems the two rectifier fets failed SHORT instantly and protected the rest of the circuitry - remember the power supply is NOT regulated, just a square wave inverter running at 100kHz.

I also feel that supplying an expensive amplifier to a buyer living in a 240V country with the AC inlet set to 120V and giving NO warning is criminal. BTW the amp was fitted with a regular IEC inlet which most of the world uses for 240VAC.

Any comments?



... Phil

Get a big fuck-off sub and power it with the IcePower module. Put the
signal from your turntable thru about 50ms of delay line and then EQ it
into three bands, low, mid, high. Put a stereo compressor on the mid
band and the high band. Adjust mid-band compression and EQ to taste. EQ
the main signal's low end down a bit but first pick off and sum the low
band signal to mono and put it through a dbx subharmoonic synthesizer:

<https://dbxpro.com/en/products/120a>

and then into a third compressor, where its side-chain is driven from a
band-pass filter isolating the kick drum frequencies, coming from the
main signal before the delay, for look-ahead compression on the
sub-bass. Then into the sub. Drive the sidechain of the high-end
compressor with the kick signal too, to make it "pump" a little bit as
well. Then put the highs through a harmonic exciter.

This is how you become awesome-sound DJ.

 

On Sat, 21 Sep 2019 03:20:47 -0400, bitrex <user@example.net> wrote:

On 9/21/19 2:57 AM, Phil Allison wrote:
upsid...@downunder.com wrote:

--------------------------------


Any other significant loss mechanisms ?

It appears that the absolute dissipation is worst during full power,
dropping at lower levels, hence if the heatsink is adequate for full
power, it should also be sufficient for low audio levels.


** The Ice Power module, with accompanying pre-amp draws 14W at idle and there is no change with 1W output.

At full output(330W) the power draw is 365W.

The famous Ampeg SVT tube bass head from the 1970s draws 170W at idle, with also no change at 1W since it operates in class AB.

At full output(300W) the power draw is 550W.

So played quietly, the class D amp wins hands down.

At full power, the difference is not nearly so huge.

Interesting.

BTW: the weights

IcePower amp: 3 pounds.

With such low weight, it makes sense to integrate it into a subwoofer
enclosure. While small, low cutoff frequency boxes will have a low
efficiency requiring a lot of power that IceCube has sufficient power
to drive hard a big speaker element and still make an easily
transportable box.

Ampeg SVT: a backbreaking 85 pounds



.... Phil


bring a 50 watt tube amp instead and set a crossover so everything above
~150 Hz goes through the tube amp and put the low end thru a subharmonic
synthesizer into a subwoofer driven by the IcePower.

In an instrument amplifier, you could set the crossover even higher,
but of course 150 Hz sounds good for a single subwoofer in a stereo or
in a 5.1 system.

Serious bass:

https://www.youtube.com/watch?v=t3UaptsZOQQ

Are those guitars really usable in a band or just as novelty solo
instrument ?

 

[Phil Allison]

upsid...@downunder.com

------------------------

IcePower amp: 3 pounds.


With such low weight, it makes sense to integrate it into a subwoofer
enclosure. While small, low cutoff frequency boxes will have a low
efficiency requiring a lot of power that IceCube has sufficient power
to drive hard a big speaker element and still make an easily
transportable box.

** The Icepower module itself weighs less than 1 pound.

But there is a problem - it needs a small fan to keep it cool when running at high power. See spec sheet, it makes the need fairly clear.

The mini bass amp incorporates a thermistor, screwed onto the heatsink of the Class D stage - it starts a 40mm DC fan running when 50C is reached.

I have also had dealings with some 1kW rated Icepower modules ( type 1000ASP ) that were used in a pro-audio sub cab. They were bolted onto a large, flat, finned heatsink that was exposed to outside air.

FYI:

here is a link to the bass amp:

https://www.aguilaramp.com/bass-amps/tone-hammer-350/


..... Phil

 

[Winfield Hill]

John Larkin wrote...

The fets in the TPA3255 are 85 mohms...

That's typ, 100 max, and multiply that by
up to 2x when the junctions are hot.

The idea behind TO-220 FETs with 5x lower
Ron and good thermal tab conduction, is a
small heat sink, and no fan or forced air.


--
Thanks,
- Win

 

On Sat, 21 Sep 2019 08:57:11 +0300, upsidedown@downunder.com wrote:

On Fri, 20 Sep 2019 09:16:30 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Fri, 20 Sep 2019 12:07:58 -0400, bitrex <user@example.net> wrote:

On 9/20/19 11:54 AM, jlarkin@highlandsniptechnology.com wrote:
On Fri, 20 Sep 2019 08:28:01 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

fredag den 20. september 2019 kl. 11.23.11 UTC+2 skrev Winfield Hill:
Phil Allison wrote...

just completed repairs on one of these:
http://www.sound-power.ru/files/doc/ICEp

My comment would be, it's nice to have
AC power integrated with the amplifier.

I've been getting class-D amplifier PCBs
from China, very cheap, yet many of them
seem well engineered and well built. But
none of them include a power supply, nor
do they offer a suitable power supply.
But, damn, these high-power supplies can
be more complicated than the amplifier!


not quite china prices but they have a few with psu

http://www.cadaudio.dk/cadpwmmodules.htm

Half-bridge class-D amps are interesting. As they pull power out of
one supply rail, they pump power into the other one.

All those huge-power specs must be some sort of intermittent peak
music thing. There's no way those tiny boards can get rid of much
heat.



You don't think this board can do 100 watts "RMS" into 8 ohms?

http://www.cadaudio.dk/d2050s.jpg

I bet it can just fine

With that big heat sink, maybe so. But they have 500 watt units, and
kilowatt boards, that look scary.

We're designing a 120 watt full-bridge class D amp, and I'm sure going
to have a big heat sink and forced air flow.

So what are the main dissipation mechanism in class D stage ? I can
think of two important mechanisms:

With slow transistors the power dissipated during turn-on and turn-off
transitions can be significant. With constant sample rate PWM, the
number of transitions per second is constant regardless of audio
volume.

The transistor ON state Vce(sat) causes some power dissipation. At
full power, the transistor duty cycle is nearly 50 %, so there is a
single Vce(sat) all the time either in the top or bottom transistor.
However, at low audio volumes the transistor duty cycle is very low
and most of the time, neither transistor conducts and hence the
average Vce(sat) losses are very low.

Any other significant loss mechanisms ?

Inductors. And maybe some ESR loss in the big caps.

It appears that the absolute dissipation is worst during full power,
dropping at lower levels, hence if the heatsink is adequate for full
power, it should also be sufficient for low audio levels.

Sure.

 

On 21 Sep 2019 06:01:02 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

John Larkin wrote...

The fets in the TPA3255 are 85 mohms...

That's typ, 100 max, and multiply that by
up to 2x when the junctions are hot.

The idea behind TO-220 FETs with 5x lower
Ron and good thermal tab conduction, is a
small heat sink, and no fan or forced air.

It can make 600 watts, and I need 120. I think it will work.

I have plenty of other issues to deal with, so a done amplifier chip
is great.

I need an overall fan for the rackmount box, so properly locating the
inlet holes puts cooling where it does the most good.

I think I'll put the TI chip on the bottom of the board, with a modest
heat sink. Holes in the floor of the box will blow incoming air into
the heat sink fins or pins. That leaves room in the top of the small
board for parts. Manufacturing says they won't mind doing that. I can
add a test point per pin on the TI chip, so I can scope it from the
top.

In some extreme future application, we could stack a fan over
(actually under) the heat sink; I'll plan for that to be possible.

It's always tempting to design things, but the sensible decision is
usually to not design things.

 

>Some of the wire on those inductors looks absurd for the >specified currents.

Well 12 will carry 30 amps, 14 - 25 and 16 - 18.

 

>We're designing a 120 watt full-bridge class D amp, and I'm sure >going to have a big heat sink and forced air flow.

Nothing wrong with that but the cost. Any heat is developed during the switching period. The faster it switches the more efficient.

Some semiconductors the switching speed degrades with heat, which will then make more heat which will degrade it further. Like thermal runaway in a regular amp.

In a regular amp you have to heat sink because that is how it is, and you have to have the bias track it with temperature. No matter how good a transistor you use the limit for wattage is thermal. Like I could MJ15024 and 023 for a 25 watt per channel amp. Temperature mainly depends on that heat sink. The strong or weak transistor will fail at a certain temperature and it won't be that much different, they all derate to zero Pd at some point. And THE preeminent factor in the temperature is the power versus the surface area of the heat sink.

And those transistor that are rated like 250 watts Pd ? Sure they can if you can remove the heat fast enough. You only get that 250 watts at 25ÂşC..

Bottom line though if you use fast enough transistors you should be able to get away with just using the copper on the board for heat sinking. That's what Icepower does.

 

All those huge-power specs must be some sort of intermittent peak
music thing. There's no way those tiny boards can get rid of much
heat.

Nope, that's the idea of class D - no heat.

Think of it like the light switch on the wall. Power is the product of voltage and current right ? When it is on there is current but no voltage, therefore zero product. If it is off there is voltage but no current so no product. It's the in between that makes the heat.

 

[bitrex]

On 9/21/19 4:54 AM, upsidedown@downunder.com wrote:

On Sat, 21 Sep 2019 03:20:47 -0400, bitrex <user@example.net> wrote:

On 9/21/19 2:57 AM, Phil Allison wrote:
upsid...@downunder.com wrote:

--------------------------------


Any other significant loss mechanisms ?

It appears that the absolute dissipation is worst during full power,
dropping at lower levels, hence if the heatsink is adequate for full
power, it should also be sufficient for low audio levels.


** The Ice Power module, with accompanying pre-amp draws 14W at idle and there is no change with 1W output.

At full output(330W) the power draw is 365W.

The famous Ampeg SVT tube bass head from the 1970s draws 170W at idle, with also no change at 1W since it operates in class AB.

At full output(300W) the power draw is 550W.

So played quietly, the class D amp wins hands down.

At full power, the difference is not nearly so huge.

Interesting.

BTW: the weights

IcePower amp: 3 pounds.

With such low weight, it makes sense to integrate it into a subwoofer
enclosure. While small, low cutoff frequency boxes will have a low
efficiency requiring a lot of power that IceCube has sufficient power
to drive hard a big speaker element and still make an easily
transportable box.


Ampeg SVT: a backbreaking 85 pounds



.... Phil


bring a 50 watt tube amp instead and set a crossover so everything above
~150 Hz goes through the tube amp and put the low end thru a subharmonic
synthesizer into a subwoofer driven by the IcePower.

In an instrument amplifier, you could set the crossover even higher,
but of course 150 Hz sounds good for a single subwoofer in a stereo or
in a 5.1 system.


Serious bass:

https://www.youtube.com/watch?v=t3UaptsZOQQ

Are those guitars really usable in a band or just as novelty solo
instrument ?

The Chapman Stick is a more practical invention if you wanna get into
many-stringed instruments.

<https://www.youtube.com/watch?v=2rLsSfd67qE>

$2500 for a base model, new, not cheap but not ridiculously priced as
far as pro instruments go.

 

[bitrex]

On 9/21/19 4:54 AM, upsidedown@downunder.com wrote:

With such low weight, it makes sense to integrate it into a subwoofer
enclosure. While small, low cutoff frequency boxes will have a low
efficiency requiring a lot of power that IceCube has sufficient power
to drive hard a big speaker element and still make an easily
transportable box.


Ampeg SVT: a backbreaking 85 pounds



.... Phil


bring a 50 watt tube amp instead and set a crossover so everything above
~150 Hz goes through the tube amp and put the low end thru a subharmonic
synthesizer into a subwoofer driven by the IcePower.

In an instrument amplifier, you could set the crossover even higher,
but of course 150 Hz sounds good for a single subwoofer in a stereo or
in a 5.1 system.


Serious bass:

https://www.youtube.com/watch?v=t3UaptsZOQQ

Are those guitars really usable in a band or just as novelty solo
instrument ?

I'm pretty sure that is just an expensive novelty. 5, 6, 7 string basses
are pretty common but AFAIK you generally don't get more than 1 extra
low string (B below the 41 Hz low E on a bass guitar) and the rest go on
the top.

The lowest strings on that one are like guy-wires. They just flap around
mostly by the look of it

 

[Tauno Voipio]

On 22.9.19 09:17, bitrex wrote:

On 9/21/19 4:54 AM, upsidedown@downunder.com wrote:

With such low weight, it makes sense to integrate it into a subwoofer
enclosure. While small, low cutoff frequency boxes will have a low
efficiency requiring a lot of power that IceCube has sufficient power
to drive hard a big speaker element and still make an easily
transportable box.

Ampeg SVT:  a backbreaking 85 pounds



....  Phil


bring a 50 watt tube amp instead and set a crossover so everything above
~150 Hz goes through the tube amp and put the low end thru a subharmonic
synthesizer into a subwoofer driven by the IcePower.

In an instrument amplifier, you could set the crossover even higher,
but of course 150 Hz sounds good for a single subwoofer in a stereo or
in a 5.1 system.


Serious bass:

https://www.youtube.com/watch?v=t3UaptsZOQQ

Are those guitars really usable in a band or just as novelty solo
instrument ?


I'm pretty sure that is just an expensive novelty. 5, 6, 7 string basses
are pretty common but AFAIK you generally don't get more than 1 extra
low string (B below the 41 Hz low E on a bass guitar) and the rest go on
the top.

The lowest strings on that one are like guy-wires. They just flap around
mostly by the look of it

The real bass is <https://en.wikipedia.org/wiki/Octobass>

--

-TV