Has Anyone Got a Bose Amplifier circuit diagram?

The expensive factory equipment I've seen from BOSE in very expensive cars is just made of:

- Loudspeakers with tiny voice coils, plain poorly-treated paper cones and fragile plastic frames, placed in plastic enclosures or supports.

- Amplifier modules, made with low-cost ST or Philips 12V stereo ICs (no more than 15W/channel), with built-in crossovers and phase shifters made out of TL074 op-amps (12V sinlge supply operated), SMD resistors and lots of electrolytic capacitors.

This makes me think that BOSE just sells boxes filled up of hype.
 

Netlist

Ex-Moderator
2003-01-18 9:50 am
We've got plenty of (open) threads about Bose filled with exotic posts. Let's stick to the original posters question in this one.

/Mod head off

Other then that I must say I can't remember I ever encountered a free Bose schematic on the net.

/Hugo :)
 

PRR

Member
Paid Member
2003-06-12 7:04 pm
Maine USA
www.diyaudio.com
> For years I have heard that Bose is top quality.

Bose has been spending millions of dollars telling us that for years.

> BOSE just sells boxes filled up of hype.

A significant part of the retail price does go to promotion. Everybody does some of that; Bose does it very well.

> Does anyone have a circuit diagram of any Bose

You can't see "quality" in a schematic.

Amir Bose's real genius is in putting together low-cost pieces so that the result is much more than the sum of the parts. There is a lot of art in those products.

And Bose never sold many standalone amps. Most of their amps were made to work as part of a Complete System. The schematic alone would be less than half the story.

> equipment I've seen from BOSE in very expensive cars is just made of:

The average price of a car-audio speaker is like $1.27.

When car-makers assembled their own audio, they would pick the cheapest speaker in the catalog, demand slightly better specs and a much lower price, and get the lower price. Considering the huge quantity and steady demand, it is possible to get a "good sound" for $1.27/speaker. But not very likely. Random selection of parts does not ensure that the total is worth even $1.27, not when a carb-designer or upholstery specialist is re-assigned to sound system development.

That's where Bose comes in. Aside from getting some pay-back for decades of promoting the Bose name, the company is good (better than some spare auto-engineer) at mixing and matching drivers and electronics to give pleasing sound-for-cost.

I myself, an experienced audio dude, made a mistake as bad as Detroit would have. I replaced stock Honda drivers with some Big-name drivers. Because I could not audition all possible drivers, I ended up with ones with low mid-bass efficiency and a complete lack of upper-mids. This suits the market; it does not suit my music. But it does not make sense for me to buy two of every driver available and try them all. But that's something that Bose could do for a million-car deal.

> fragile plastic frames

Also: Bose has a dedicated speaker factory that is bigger than their other products need. And with total control, they can shape the speaker efficiency so monster amps are not needed, fix the un-flat in the TL074 processors. If you left it to Ford/GM/etc you would not even have the TL074s, just a lowest-price SGS or LG chip-amp.

And EVERYTHING made in lots over 1,000 today is SMT.

> lots of electrolytic capacitors.

That's better than not-enough caps, which would be the normal way to go for car-audio.

And it is a car, and a system for the Masses. 99% of people can't hear an electrolytic cap. The 1% who do, take the base or no-radio option and put in their own favorite boxes. The car makers are not selling collectable wine: they sell basic-beer and good-beer. If you want very-very-good beer, BYOB.
 
PRR:

I think that you have not got the point. An additional $2,000 or $3,000 are being charged to the user for those $1.27 plastic drivers and TL074 opamps, and the result sounds just slightly better and not louder than the default no-brand factory equipment that you usually get at no additional cost.

A reasonable price for that stuff would be $200 or $300.
 

tlf9999

Disabled Account
2005-05-25 2:25 am
none
Eva said:
PRR:

I think that you have not got the point. An additional $2,000 or $3,000 are being charged to the user for those $1.27 plastic drivers and TL074 opamps, and the result sounds just slightly better and not louder than the default no-brand factory equipment that you usually get at no additional cost.

A reasonable price for that stuff would be $200 or $300.


but doesn't that point to Bose's talen in maximizing profits? a dream for any capitalist.
 

blmn

Member
2001-02-01 2:43 am
.
Pinkmouse,

Guys, can you only post if you can contribute to the original question please

But he asked something based on it:

For years I have heard that Bose is top quality.

I think he would take some advantage considering the points placed here about the quality of Bose products.

I think they are contributing to the original question...

Anyway I want to see some Bose schematics too...

Regards,
 
Hello Everybody,
By the answers I am reading with my question, someone stated that the 2 Amplifiers driving the small 3 inch speakers were made up of 12volt car audio ic's. To that forum member i ask have they seen inside one of these amplifiers?
It appears that this amplifier is sold more on advertising than what is inside. And that Bose know how to use what they make up their Amps with to the best effect.
Maybe if the circuit inside had something new to offer, someone would have back engineered a Amplifier by now and come up with a circuit diagram as is the case with other designs that have proved to give something more than the average Amplifier.

Lets hope we finally see a circuit diagram and can decide for ourselves if the design is good or not.
 
I don't have schematics. I tried once to get some info out of Bose regarding an older out of production satellite + "sub" system. They responded only with silence. Not even with a "sorry, we don't sdo that". I'm not sure if there is even such a thing as authorized Bose service except by sending them back to the factory. It seems that Bose may be very tight about disseminating any service info. You may find the schematics are simply not to be had.

However, I have to say in all honesty that upon opening up the powered unit, the electronics section appeared to be very well constructed. No commenrt on the circuit topology, just that the PCBs looked to have been manufactured in a very neat, clean manner. I don't remeber the component types except that the output devices were a lot (I mean 10 or more) parralelled TO-220 of some kind, probably choosen because the fet into the space allowed better than fewer but larger devices.


Eva wrote
. . . TL074 opamps . . .
If were selling into the same market as Bose I wouldn't wast OPA4134's on them either:devilr:

All the non-audiophile people I know who have Bose stuff seem very happy with it. If they make their core customers happy IMO they are delivering value for money. A significant part of the product is the intangable part not just the physical. Their customers are buying something more than just objectively (or even subjectively) measured audio reproduction. Think you are too sophisticated for that? Well do you really, really need a Krell?
 

tlf9999

Disabled Account
2005-05-25 2:25 am
none
sam9 said:
All the non-audiophile people I know who have Bose stuff seem very happy with it.


I think that's a very telling statement and conformms to my experience as well.

A lot of customers out there like the Bose kind of sound. for better or worse, that's the market and manufacturers have to cater to that market. In that sense, Bose did a fabulous job.

There is an elitist movement in the audio circle whereby any critism of Bose is an indication of one's profound understanding of quality sound. Much like the undercurrent for back EMF, or no-NFB, etc. - not that I think they are all invalid just that there are people who don't truly understand the merits of what they are advocating but they are advocating for the sole purpose of being different from the mainstream.

As to circuits, they are likely proprietary and Bose has every right not to disclose them. But if you sit back and ask your self to what extend you can reliably tell a LTp input stage from a SE input stage, or a 072 from 324, or even a 741, you will realize just how un-important topology is for daily causal listening.

If you don't think so, just peek inside a professional analog mixing console and I can tell you for sure that 072-class opamps are absolutely the high-end.

After that, ask yourself that if your precious signal has been violated so many times by those "pitty" 072 (or other inferior) opamps, what more damages could have been done by a couple 072s in that Bose?