Bossobass Mini GTG Thread

[chrapladm]

I wont be buying yet. I more than likely will be looking at a 220 A-14K-R for my first amp purchase. I was thinking of multichannel amps and was curious on the A 12K but it is overkill for my purposes. When it comes time to buy I will send an email anyways to make sure I get what is needed.

 

How loud are these fans Bosso on the 14K?

 

I dont recall anyone commenting on the fans before.

[Infrasonic]

They indirectly note that they are not quiet by suggesting "for remote installation".

 

I'd be surprised if Dave and Paul couldn't change them but maybe it's for the best for proper cooling. I don't know but I know the clones have loud fans stock.

[chrapladm]

I think I remember Bosso commenting on fans before about them perhaps being loud but not sure what the exact words were. BUT thanks Scott. If they are loud I may just have to build a small AV cabinet for them.

[Bossobass Dave]

Firstly, we're talking about multi-KW amplifiers. The Class A/B or B output stage is 60% efficient. (Amplifier efficiency is a complex subject, so the numbers cited are a bit arbitrary. Ours is an average number based on several data inputs). Simple math shows the potential amount of heat that may be necessary to dissipate. The huge increase in heat sinks and the addition of a 5th cooling fan to the so-called "clone" platform should be telling enough regarding whether or not we think the fans can be rendered silent for a fanatic who might be known to stop listening and track down a fly whose buzzing is annoying him.

 

Selecting the +10dB BOOST option with NO HPF option in a Raptor system gives maximum extension. That's because the native low end response of the system is altered to work with typical room gain to provide flat-to-5 Hz response at the seats. To accomplish this, the lowest frequency content of murderously difficult soundtracks like "9", X-Men First Class, Battle:LA, How To Train Your Dragon, et al, are boosted by a factor of times 10.

 

So, imagine the playback level set to achieve peaks of 120dB. That would mean transients requiring, say, 1,000 watts. BUT, the extreme low end is boosted times 10, so they require bursts to 10,000 watts. And, those watts are being applied to amplify frequencies from the Netherworld, where audio enters another dimension previously unknown to humans.

 

Switching from volts to amps of current at impedance minimums to reproduce incredibly dynamic source that includes single digit frequencies that are dredged up from the depths of dimension 'X' means a few things must be coped with that normally can be ignored:

 

1. The efficiency of the amp (that means ANY amp, class notwithstanding) drops when the impedance of the load drops.

2. The heat rises... QUICKLY.

3. The output transistors heat rating can be exceeded faster that the modified cooling apparatus (read: fan mods) can prevent the problem.

 

Seaton mentioned in the SP amp thread that:

 

 

No amplifier is the perfect solution, as they all still need to pull the power from the wall and the cost can creep up quickly searching for ever more output, but when you consider the ability to run predominantly without a fan, and be nearly bulletproof into any low impedance, the SpeakerPower torpedo family of amplifiers deliver quite a bit for the money spent.
 
As an example of the low impedance tolerance/stability, the in-house burn-in step at Speaker Power uses a near short circuit heating element mounted to its own heatsink in order to get the amplifiers to heat up in a realistic time frame.  This tests thermal stability and protection.  That sort of burn in and robust protection is part of what makes for the premium cost of the amplifier vs. the cheaper amps produced in China.

The "housekeeping circuitry" is handled by a custom programmed micro-controller.  There is different programming for each power model, rack vs. plate, and even some differences between those sold to the home vs. heavy duty pro use like those doing EDM shows.

 

So, "no amplifier is the perfect solution", "robust low impedance protection circuitry costs $$" and "protection is handled by a custom programmed micro-controller" that address "even some differences between those sold to the home vs pro use".

 

We agree.

 

The A Series amplifiers are meant to bridge the gap between three to five RU 100# plus amplifiers whose max output sits at around 5KW and the latest class D, non-bridgeable low end amplifiers that can't keep their spec while reaching into the Netherworld and the SpeakerPower/Powersoft class of amplifiers, cost-wise. If fan noise is such that you can't relocate or adequately sequester the amp and fan noise is a deal breaker for you, buy the SP/PS amps and call it a problem solved with extra $$. On the low end side, we hope that no one will buy one of those offerings and delude themselves to think they perform equally, but life is what it is and we can't influence that.

 

Every physical operational noise reduction scheme modification we attempted to implement on the A Series amps... every one... ended in premature amplifier failure. As a results of our tests, instead of reducing the cooling efficiency, we increased it.

 

Now, let me be clear here. Most people who build a sealed , horn or ported subwoofer do not apply the sort of signal shaping boost we and others DIYers use to mate system and room gain to achieve full bandwidth playback. This is a whole nuther ballgame, thus some other random posts about fan mods being successful. No frequency response, no signal chain data, no playback measurements, etc. We're not saying no one could mod fan noise and get away with it. We are, however, saying that any failure associated with modifications made to the A Series amplifiers is not covered by warranty.

 

In my theater, I have 2 A-14K amsp, a Marathon MA-5050 and three QSC RMX amps, all installed in a dual-console:

 

 

I always leave the doors open enough to allow adequate air flow to the amps, so they aren't actually isolated in another room, like Adam's are, but maybe Adam can chime in here and comment on the fan noise in my HT as he's been there a couple of times watching movies. I don't find it a problem and if only one A14K was running, I doubt I'd ever even think about it, but... that's me.

 

Sorry for the long answer, but it's an important subject to address in detail.

[Infrasonic]

Hey. No complaints here, Dave. The question arose and I looking into the details of your product and posted about it.

 

Many of us are unlucky in that it is required for our gear to be in the same room. Hence the importance of quiet fans even at the expense of maximum performance.

[Bossobass Dave]

Hey. No complaints here, Dave. The question arose and I looking into the details of your product and posted about it.

 

Many of us are unlucky in that it is required for our gear to be in the same room. Hence the importance of quiet fans even at the expense of maximum performance.

 

Understood and thanks for the input.

[NWCgrad]

Nice explanation Dave...what one wishes for is seldom feasible in reality (i.e. dead silent, low cost, and capable of accurately reproducing a 3 Hz signal boosted by a LT signal shaper).

 

Looked at your line of amps today, must say I may become a customer once I get further down on my project list.

 

-- Military Man aka Steve

[chrapladm]

Huge thanks again Dave. I might have a problem with fan noise but that is because I only sit about 2-2.5m away when listening to movies. I changed my fans out on my current amp because at low cooling stages the fans were annoying. More so the extremely bright lights are annoying but I just place a card in front of the lights. So I was able to be "silent," after the mod but I am not anywhere pushing my amplifier with L/T's and everything else yet. The fans dont whine anymore either at any volume of air being moved. So while not completely silent these fans can move a lot of air but do so without the annoying whining sound. I also believe it had to do with the fans maybe aging.

 

Anyways I am not saying I need complete silence I am just looking at what to expect is all. I will most likely have my amp in a very similar location as yours also. But after factoring in budget and everything else that is needed for my subwoofer system I dont mind some noise.

[EndersShadow]

^With regards to the lights bugging you, they do sell small adhesive tint you can use to put over that kind of stuff.  My wife has similar problems with LED's so we bought some for our DVR box, Security system and even our clocks.  You can buy it in a small kit with diff size circles, squares, etc, or just in a sheet you cut to size.

[EndersShadow]

Having trouble editing my post, but here is a link to what I bought...

 

 

https://www.thinkgeek.com/product/eeb6/

[lukeamdman]

 

In my theater, I have 2 A-14K amsp, a Marathon MA-5050 and three QSC RMX amps, all installed in a dual-console:

 

Oh my...does this mean that 6 months later you still have 8 Raptors in your HT?...

[chrapladm]

^With regards to the lights bugging you, they do sell small adhesive tint you can use to put over that kind of stuff.  My wife has similar problems with LED's so we bought some for our DVR box, Security system and even our clocks.  You can buy it in a small kit with diff size circles, squares, etc, or just in a sheet you cut to size.

Lights are known to be stupid bright because the design. I have known about the tints and other things I could do to cover them up but I always have a hard time modding anything. BUT thanks for the suggestion either way.

[Madaeel]

Honestly the best endorsement I can give is both times I've been to Dave's house I never thought about the amps. Just forgot they were there. Even during the quietest scenes and Dave always had the doors open. The fans only spool up when demanding scenes hit anyway and no chance you'll hear it. For all the guys with projectors they are a good bit louder than any of those amps. I do have my 14k in the closet but that was only because I don't wanna see my equipment. Though sometimes I wish I kept the amp out so I could see my VPL lights for uhh "spirited" sessions.

[Madaeel]

Oh my...does this mean that 6 months later you still have 8 Raptors in your HT?...

He still had 3 systems in there.  

[lukeamdman]

He still had 3 systems in there.  

 

I was referencing something earlier in this thread where Dave was trying to convince us that he's somehow different than everyone else and didn't really enjoy the extra bass in his room    He made it clear that the extra Raptors were leaving never to return

[Bossobass Dave]

There is not 3 systems in there. Adam's breaking balls. There is "only" a single System 3 running. That's because one side is an original prototype stack in which I originally used D2 drivers, so it's a nominal 4 ohms. The other side is with MKII drivers that I switched to D4 VCs to get the loads right to run both systems from the same amplifier (one stack = 8 ohms nominal and wiring 2 stacks parallel is 4 ohms nominal).

 

If I wire the existing 4 ohm stack to the 8 ohm stack in parallel it comes out to <3 ohms and I don't want to run a single bridged amp into that low a nominal impedance. Wiring the stacks in series yields 12 ohms nominal and that's not ideal either. So... I run one amp bridged into 8 ohms and the other amp bridged into 4 ohms.

 

Honestly. I did 16 x 15" a long while back when just to test the results. At reference level, 8 x 15" had plenty of headroom, so going to 16 x 15" at reference level made no difference on the SPL meter or on SpecLab.

 

Topping 135dB is doable with a System 3 (8 x 15"), but not in full bandwidth mode. I'd have to engage a curve that includes the 18 Hz HPF. Now, if you want to exceed 135dB at full bandwidth with the usual suspects demo scenes, you need 16 x 15" in my room.

 

In fact, I just got around to re-calibrating the system yesterday. I set the subs to flat with the OPPO SW trim at -5dB. That way, I can run the subs as much as +5dB hot without worrying about the stupid OPPO gross distortion when exceeding '0' SW trim level. I also affected a -3dB Hi-Shelf from 4k Hz and up to trim the top end a bit.

 

Sounding pretty darned good.

[Infrasonic]

But is it properly reproducing what is on the disc?

 

[Madaeel]

There is not 3 systems in there. Adam's breaking balls. 

Sorry man but you did have pics of 3 systems in there. Plus it hurt to see that HST just lying around not being abused.

[Bossobass Dave]

Yes, I had pics of 3 systems. Only 2 were fired up for the GTG. My actual system, which has been in the corners all along, was not connected.

 

When you were here I had my system 3 connected. The 3 modules that were still in the room were from the shootout, one with the Raptor BHT-15 drivers, one with the LMS-R drivers and one with the HST-15s. None of those were connected.

 

Every system I've had in the HT since 2003 has accurately reproduced what's on the disc.

[chrapladm]

Bosso I thought you had a room layout posted but I couldnt find it. So how far do you sit from your amplifiers?

 

And if EQ'ing two different sub systems is it best to have a pair of Dash V's?

 

Looking at finishing my "Seagull," system but may add some smaller subs in the main towers. So I was looking at needing two different EQ setups for the different systems. So that would be a pair of 11/12's in the towers and the other Seagull system will have the 15HST's. Hope this make sense.

 

And what is the biggest difference between the  A14K and A14KR?

 

As long as they deliver the same, still have the amazing FR and deliver at 2ohms then I am happy. Just trying to see if I am missing anything is all.

[Madaeel]

Yah *I* know what was connected I just like to tease you sometimes. I enjoy it immensely.   Two Raptors in your room would be silly since just the one is coasting 90% of the time. San Andreas was loud enough with one that's for sure.

 

I do wish I got a chance to see those HST's dance a little though. 

[SME]

Congrats on your web page improvements and new product offerings.  I must say, the amps on offer are a killer value.  I'm probably one of the few willing to step "up" to a SpeakerPower amp to avoid the fan noise.  If I didn't have a lot more spare money than time right now, I'd probably see about buying and installing one of these in my hall closet.

 

It does deserve mention that the importance of a low noise floor in the listening room is definitely underrated.  The problem with noise is that it doesn't have to be annoying to affect sound quality.  I definitely notice a difference in my room depending on whether the HVAC fan is running.  In the summer months, I tend to leave the HVAC fan running full-time for comfort.  It's not that loud as far as HVAC goes, and with it running, (IIRC) my noise floor SPL lingers in the 40s (C-weighted dB).  With it running all the time, I often don't notice it at all, even when the room is otherwise dead silent.  Of course, I do hear it if I think about it, but I don't think about it much.  However, if I A/B audio or music with it off versus on, the difference is very apparent, even if I *can't* otherwise hear the fan against the sound of the music.  In other words, even if you can't hear a sound, it can still mask details in the sound you *are* listening to.

 

When I installed my first room treatments, the difference became even more apparent.  The biggest impact the noise floor has seems to be on the imaging.  A secondary impact is on the perceived dynamics.  Without the HVAC noise, the imaging has a lot more definition and dynamic stings and slams tend to hit harder.  It also deserves mention that the impact depends a lot on the SPL of the playback.  The louder the playback level and content, the less the noise floor tends to mask that content.  Likewise, I would expect that once the noise floor is reduced below some SPL (say 15, A-weighted?) that further reductions don't yield any more improvement with real-world material.

[Bossobass Dave]

Bosso I thought you had a room layout posted but I could find it. So how far do you sit from your amplifiers?

 

And if EQ'ing two different sub systems is it best to have a pair of Dash V's?

 

Looking at finishing my "Seagull," system but may add some smaller subs in the main towers. So I was looking at needing two different EQ setups for the different systems. So that would be a pair of 11/12's in the towers and the other Seagull system will have the 15HST's. Hope this make sense.

 

http://data-bass.ipbhost.com/index.php?/topic/22-the-data-bass-member-equipment-list/?p=9979

 

I sit 10 feet (3M) from the amps.

 

When sending the multiple subs an identical mono summed signal, that is the signal that should be shaped. It makes little sense to split the signal and affect it's shape separately. Separate subs in mains towers is something I'll leave you to tell me what is best as I have no experience with the scheme.

[chrapladm]

OK thanks Bosso. I figured if all the subwoofers were the same then the signal  and EQ should be the same. BUT when eqing different size subwoofers I wasnt too sure on that. Although I could adjust levels and be fine. Wont know for some time but trying to get my ducks in a row is all.

 

I see you also have a Stewart amp.lol I had one of those also when I had my bass setup in the US before I moved. Accugrove cabinets, a pair of Stewart amps and my Demeter pre was one setup I enjoyed for a while. Then of coarse I changed it out for a few other options. Someday I need to get back into playing bass guitar.

[Bossobass Dave]

Congrats on your web page improvements and new product offerings.  I must say, the amps on offer are a killer value.  I'm probably one of the few willing to step "up" to a SpeakerPower amp to avoid the fan noise.  If I didn't have a lot more spare money than time right now, I'd probably see about buying and installing one of these in my hall closet.

 

It does deserve mention that the importance of a low noise floor in the listening room is definitely underrated.  The problem with noise is that it doesn't have to be annoying to affect sound quality.  I definitely notice a difference in my room depending on whether the HVAC fan is running.  In the summer months, I tend to leave the HVAC fan running full-time for comfort.  It's not that loud as far as HVAC goes, and with it running, (IIRC) my noise floor SPL lingers in the 40s (C-weighted dB).  With it running all the time, I often don't notice it at all, even when the room is otherwise dead silent.  Of course, I do hear it if I think about it, but I don't think about it much.  However, if I A/B audio or music with it off versus on, the difference is very apparent, even if I *can't* otherwise hear the fan against the sound of the music.  In other words, even if you can't hear a sound, it can still mask details in the sound you *are* listening to.

 

When I installed my first room treatments, the difference became even more apparent.  The biggest impact the noise floor has seems to be on the imaging.  A secondary impact is on the perceived dynamics.  Without the HVAC noise, the imaging has a lot more definition and dynamic stings and slams tend to hit harder.  It also deserves mention that the impact depends a lot on the SPL of the playback.  The louder the playback level and content, the less the noise floor tends to mask that content.  Likewise, I would expect that once the noise floor is reduced below some SPL (say 15, A-weighted?) that further reductions don't yield any more improvement with real-world material.

 

Thanks for the kind words. It means a lot after the hard work.

 

IMO, a listening space is either one for critical listening of music or HT. They are two completely different animals. For example, one would never invite multiple listeners into a space and have them site randomly, as in a HT situation to view a movie, and suffer under the delusion that everyone in attendance will be able to critically listen to music.

 

There is only one seat in which one can enjoy a proper sound stage. In fact, there is one very specific placement for one's head while sitting in that seat.

 

Movie viewing at reference or near reference levels, which is assumed when the owner of the HT space is considering a 14,000 watt amplifier to power his subwoofer system alone, makes fan noise irrelevant.

 

If I listen critically to MC SACD (I don't listen to 2 channel CDs at all, ever), I also listen at average levels of around 90dB with 100dB plus peaks. The only time fan noise is an issue is if I want to ride the end of a tune that happens to have a very slow fade to 0dB. Of course, in that case, any fan noise will override the music at some point in the fade to zero.

 

Again, if critical listening of music were the goal, I would not need 14,000 watts of amplifier on an 8 x 15" subwoofer system. I would simply use the Stewart fanless class D 1200watt amp or similar connected to a single Blackbird module when music only listening.

 

A Critical listening NC-15 room is a relatively rare item. It has it's place, but in a HT with state of the art sound, not so much. As Adam noted several times on these boards, a typical projector has quite audible fan noise when no media is playing.