Bose 901 Component Update

[Daniel_G]

I have Bose 901 Series 2 hanging from the ceiling in a 400± square feet room, they sound great with my Tandberg 3012. But I noticed that the amp runs way too hot. It is rated at 100wpc but I am afraid of damaging it.

The thermal protection circuit kicked in the other day, the sound cut out. The Tandberg amp recovered but to be safe I took it offline. Is it likely that the protection circuit prevented any damage? Should I take it to a repair shop?

Also, any advice or a realistic minimum wpc for this size room?

So I am in the market for a 130wpc amp that won't bread the bank. I am opting for new because I have too much vintage gear and I dont want another component that becomes a project too.

I am looking at a newish Teac AX-505 which is supposed to be 130wpc but it is tiny. Could it really power my 901 is a large room? Are all 130 wpc amps created equal. The Teacs size fits my decor needs and I have a similar 50wpc Teac that sounds great.

Another option is the NAD C389.

Any Bose 901 owners who may have some wisdom to share?

Thank you

Daniel

 

[whoaru99]

Is the amp in a cabinet or does it have plenty of air circulation around it? I saw some comments they tend to run warm and need lots of ventilation space.

Is there several inches each side, plenty of space above it, not sitting on carpet or anything that produces heat too?

Does it get hot at low to moderate levels or only when you're blasting?

There really isn't enough info without more info/answer to questions, to determine if the issue is use case or a technical problem with the Tandberg

Also, minimum power is highly contingent on how loud you play the system.

 

[Nkuruma]

Welcome to AK! The amp that Bose designed to go with its flagship 901 was rated at 250WPC. You could get an "inexpensive" class D amp (I.e. Fosi Audio) in the 200-300 WPC range and it'd work really well.

 

[whoaru99]

I have Bose 901 Series 2 hanging from the ceiling in a 400± square feet room, they sound great with my Tandberg 3012 but I noticed that it runs way too hot. It is rated at 100wpc but I am afraid of damaging it.

So I am in the market for a 130wpc amp that won't bread the bank. I am opting for new because I have too much vintage gear and I dont want another component that becomes a project too.

I am looking at a newish Teac AX-505 which is supposed to be 130wpc but it is tiny. Could it really power my 901 is a large room? Are all 130 wpc amps created equal. The Teacs size fits my decor needs and I have a similar 50wpc Teac that sounds great.

Another option is the NAD C389.

Any Bose 901 owners who may have some wisdom to share?

Thank you

Daniel

Normally is not advised to start multiple threads on what is basically the same subject/topic.

FWIW, the difference from 100 to 130W in itself is almost nothing in terms of change in output, 1dB.

And, no, not all amps are created equal.

 

[tadawson]

Note that the almost obscene EQ needed for a 901 (applied by the Bose EQ) really pushes the low end hard (high as well, but nowhere near as much energy needed there), and your amp may well be fine, and it's just the inherent character of the 901 causing your amp to "hit the wall" and run hot.

 

[TPettenati]

Teac AX-505 which is supposed to be 130wpc

From the Teac product page.
Amplifier section
Max output power
130W + 130W (4Ω, 1kHz, JEITA)
90W + 90W (8Ω, 1kHz, JEITA)
Rated output power
115W + 115W (4Ω, 1kHz, THD 0.8%)
70W + 70W (8Ω, 1kHz, THD 0.8%) <--- Probably not much of an improvement

For the same money, this, or a 2125 if you don't listen at high volume.

NC 2250v2 Power Amp

275 Wpc stereo amp with bridged 750 W. THX Ultra2 certified, high-current design, dual speaker outputs, and efficient cool operation—premium power in a compact chassis.

parasound.com

(or a slightly used Parasound A21)

 

[Daniel_G]

Welcome to AK! The amp that Bose designed to go with its flagship 901 was rated at 250WPC. You could get an "inexpensive" class D amp (I.e. Fosi Audio) in the 200-300 WPC range and it'd work really well.

Thank you I will take a look at the Fosi, I love the speakers and hanging them works for the room, but 230wpc is none too common

 

[whoaru99]

The amp that Bose designed to go with its flagship 901 was rated at 250WPC.

Bose also made receivers in the 40 to 100wpc range that were paired with 901.

Not that you said it, but there is a point of comment that the OP's amp with 100wpc isn't inherently the issue that it's "only" 100W because 901s have been used successfully with less and more.

There were some relevant questions in the OP's other thread of basically the same topic, but they've gone unanswered.

Note... looks like three threads going on basically the same topic.

 

[Daniel_G]

My question, more simply stated (i hope), is what integrateds, or what general type, would work with the 901s in a 400SF room at moderally loud volume. Clearly the Tandberg 3012 was getting cooked.

 

[whoaru99]

My question, more simply stated (i hope), is what integrateds, or what general type, would work with the 901s in a 400SF room at moderally loud volume. Clearly the Tandberg 3012 was getting cooked.

Oh, there's no question what your basic question is. It just might be helpful to understand more about the situation if all the questions in post #2 were answered. Rather than just suggestions for different gear.

 

[Daniel_G]

The comments have been helpful so far. I am expecting I will need a more powerful amp. But due to the looping the EQ in seems like a lot of modern amps won't work, at least without jumping through hoops. Just wondering how 901 users deal with what appears to me to be a common and well-known set of details.

 

[whoaru99]

We're on a different page with how to approach. Good luck.

(and yes, have two pair of 901, Series II and Series VI)

 

[Blue Shadow]

Most amplifiers do not care if the thermal shutdown happens. It just turns off the amp letting it cool before allowing the power back on. I have cycled a Crown DC-300a regularly back in the day without problems. More wear and tear on the amp from heat but how that changes its life is unknown. No reason to have it serviced other than to refresh it at this age. If it is hot to the touch the thermal overload system is working fine and protected the amp.

Bose also made receivers in the 40 to 100wpc range that were paired with 901

Owning both the early Series II and later VI, you know the II is a sealed cabinet and very demanding for power. The later receivers were made in the era of the Series III/IV the first of the ported 901s which make them play louder with the same power.

Back to Daniel’s question about powering his speakers. Go ahead and use the Tandberg but make sure the air can flow completely through the heat sinks. First step would be to have the left side of the amp hang out over the edge of the shelf it is on, next would be forced air, a fan. Both will help but neither will stop your amp from overheating if you are listening loud a good bit of the time or very loud.

Recommend you find a preamp with the tape loop for the EQ and as mentioned above a Class D amp of higher wattage. This will allow you to continue the party without thermal shutdown in most cases. The OM shows the power limits are 25 minimum, 275 w amp maximum and 400w peaks for short term. Class D amps use a different type of power supply so they are lightweight and have plenty of power as needed.

but 230wpc is none too common

Maybe that particular number is uncommon but amps from 200-1000 watts per channel of real high fidelity sound are very common now. Class D being the inexpensive choice here. Just google Crown amps and check out Sweetwaters page of these amps, low power to at least 1350 watts per channel for reasonable money. Notice many weigh less than your Tandberg. There are other companies making high or very high powered amps these days.

What you will get with a nice 250-300w amp is less thermal shutdown and a little bit more volume. It takes twice as much power to make it noticeably louder (3dB) and TEN times as much power to make it twice as loud. So watts get burned up quickly as volume goes way up.

I would go with a preamp and a power amp instead of an integrated because of the lack of tape loops on newer gear. The EQ can be put between the pre and power if it must, a tape loop is better. You might find a preamp with a signal processor loop or a tape loop and that would be great with a nice higher powered amps.

 

[Daniel_G]

Thank you for the responses clarifying the details and refining options. I was also looking at a digital EQ from Deer Creek Audio that hard codes several of the EQ curves, this would allow skipping the OEM EQ and outputting directly to an analogue input at the amp. I wonder about fidelity, though. Has anyone had experience with this type of device?