Burmester 218 - Reviewed amp buzzes

[MAB]

Odd review of one of Burmester's obscenely expensive amps:

Burmester 218 power amplifier

As much as I tinkered with a little crystal radio as a child and started reading stereo magazines in high school, it wasn't until my early 30s that I half-stumbled into the higher end of the hi-fi sphere. As I progressed from used Advents to used Spicas and began to experiment with speaker...

www.stereophile.com

They are $50k each.
At least they are powerful and not too bad looking. They lack handles to make moving around reasonable.

Page 1 of the review is utterly content-free prose.
Page 2 starts off with the reviewer worrying about placement, how to get the amps onto ad hoc amp stands, and the fit of the amp stands, and the existential desire to keep the amp off of the bamboo floor due to vibration concerns, potentially "putting them at a disadvantage to my reference and other amps."

At this point the amps started intermittently malfunctioning:

During my time with the 218s, one of the amps began to buzz. Sometimes the noise was low, sometimes it was a bit louder, and occasionally both amps buzzed. Changing power cables made no difference. Plugging them into other receptacles didn't help. I do not hear this noise with my reference amps. Regardless, even when it was present, the noise never interfered with listening, and the amps sounded so good that I doubt anything serious was wrong with them.

Rather than contact the manufacturer to ask about why $100k worth of amplifiers broke, he gets sage advice elsewhere:

After I told Jim Austin about the buzzing emanating from the amps, he suggested I try different power cords, including those supplied by Burmester. In the process of retrieving those Burmester cords from the shipping boxes, I slipped while dismounting a storage crate and crashed to the floor. Nothing was broken, but my left foot and back ordered me to delay switching power cables until I could twist and bend without adding insult to injury.

Wow, HiFi cables are hard work. Glad he was good enough to finish the review, real champions fight through the pain and make power cable comparisons. Too bad he never got the buzzing fixed, apparently it sounded too good on the amp stands to worry about. Maybe he thought it was an even-order buzz?

 

[digitalfrost]

Do you suggest lowly standard power cables would be good enough for these amps?

 

[Alexander Gödde]

I had to comment on the article:
"
Stereophile reviewers consistently claim that everything should be done to ensure the lowest possible noise floor in a system. Measures to this end which are recommended include separate power supplies for digital and analogue stages, power conditioners, "cryogenically treated" cables or special equipment racks. The cost of these in many cases substantially exceeds that of an entire system that most people can afford, and the effects are often below what can measured - yet are claimed to be clearly audible and beneficial.
Yet when two separate units of a 50,000 USD (!) amplifier both develop not just measurable, but clearly audible buzzing it is claimed that "even when it was present, the noise never interfered with listening, and the amps sounded so good that I doubt anything serious was wrong with them".
So apart from the fact that 50k gets you either bad engineering or shoddy quality control, it also appears to move the goalposts for what constitutes great audio - just not in the direction one would expect.
"
Of course, a comment further down is more concise and equally apt:
"
I will not be baited into posting a predictable rant about a review of an amp like this. I give up. Stereophile wins.
"

 

[Mikig]

So apart from the fact that 50k gets you either bad engineering or shoddy quality control,

Talking about poor engineering or poor quality control seems out of place to me.

It happens in every sector and with any man-made device. Simply a component failure is enough to have a buzz.
We don't know if it was an amplifier that has been around half the world between fairs and editorial offices or maybe it took a bad hit in transport or maybe just a component misfired.
It happens even though components are now made in an ultramodern and industrial way...

I would rather not have reviewed it and sent it back.
There are two ways:
1) in the review you mention this problem and therefore you don't continue with the test. You only write a page.
2) you send it back, you have another unit sent to you. If the problem still exists on the second unit, you declare that the machine in question presents this aspect. If it doesn't, you simply declare, for the sake of truth, that the company gave you a second device because the first was defective.

What seems most anomalous to me is that a buzz does not disturb. If it is perceptible enough to be noticed and you write it, clearly it cannot be a non-disturbance, otherwise you would not notice it....since you have good ears to hear the differences between power cables.....not being disturbed by a buzz while listening.....well....

 

[Alexander Gödde]

Talking about poor engineering or poor quality control seems out of place to me.

Agree if it had been a single unit, however the reviewer heard buzzing from both units under review, so I assume more of a systemic issue. (Could, of course, still have been e.g. transport damage to both units.)

since you have good ears to hear the differences between power cables.....not being disturbed by a buzz while listening.....well....

Or maybe, just maybe, Stereophile reviews have a heavy bias based on how many pages of ads a company buys.

 

[Matias]

For 50k one would expect perfection. To have it buzz, and allowing this experience to be publicly reported on a review, is a failure beyond words...

 

[restorer-john]

Typical ASR pile-on without considering what is potentially going on here.

The amplifiers use very large toroidal transformers. They are susceptible to assymetric distortion/DC offset on the mains. The fact the physical "buzz" was not consistent suggests the reviewer should invest in, or at least investigate, a decent DC-blocker.

 

[GXAlan]

Typical ASR pile-on without considering what is potentially going on here.

The amplifiers use very large toroidal transformers. They are susceptible to assymetric distortion/DC offset on the mains.

I have one of those Emotiva DC blockers which work great to solve buzzing toroidal transformers.

That said, when I think about $50k amplifiers, I think of stuff like Halcro or the ML 33’s which integrate the AC line conditioning into the unit.

That is, the DC blocking should be integrated into the box…

 

[amirm]

The amplifiers use very large toroidal transformers. They are susceptible to assymetric distortion/DC offset on the mains. The fact the physical "buzz" was not consistent suggests the reviewer should invest in, or at least investigate, a decent DC-blocker.

If it needs a DC blocker, then it better be in a $50K amplifier!

 

[Chrispy]

LOL

 

[Somafunk]

Typical ASR pile-on without considering what is potentially going on here.

The amplifiers use very large toroidal transformers. They are susceptible to assymetric distortion/DC offset on the mains. The fact the physical "buzz" was not consistent suggests the reviewer should invest in, or at least investigate, a decent DC-blocker.

View attachment 396640

Buy this amp but you will also need a dc blocker is not quite the “gotcha” I imagine you were after

The sooner this “esoteric” hifi crap is f****d off into the weeds is all the better for consumers

 

[GXAlan]

The sooner this “esoteric” hifi crap is f****d off into the weeds is all the better for consumers

Esoteric hi-fi itself isn’t a bad thing if it delivers. It’s when you have problems like humming transformers when the company clearly was not constrained by BOM.

 

[AndrewC]

Once again Stereophile proves why they've lost all credibility.

 

[restorer-john]

Not sure what is going on with @John Atkinson and his dBW numbers...

DBW is decibels with reference to one Watt. Since when was dBW only a reference to 2.83V@8R? That makes no sense.

His 4R and 2R dBW numbers in the review are incorrect in my opinion.

 

[Doodski]

Typical ASR pile-on without considering what is potentially going on here.

The amplifiers use very large toroidal transformers. They are susceptible to assymetric distortion/DC offset on the mains. The fact the physical "buzz" was not consistent suggests the reviewer should invest in, or at least investigate, a decent DC-blocker.

View attachment 396640

The manufacturer's featured power supply impedance path being so low seems a overstatement. The manufacturers specs do not indicate that and the Stereophile measurements are about the same as the specs.

 

[restorer-john]

@Doodski What's the point you're trying to make?

The amplifier is capable, well built and ridiculously expensive.

 

[Doodski]

@Doodski What's the point you're trying to make?

The amplifier is capable, well built and ridiculously expensive.

It seems they are bragging about a power supply impedance when it cannot maintain power output as the speaker impedance drops. Many other amps can do this for less money. For the expense of this amp I expected a bit more from it than a claimed statement of power supply impedance resulting in better power output. Am I being too fussy?

 

[restorer-john]

Many other amps can do this for less money.

Many amplifiers "appear" to do that, usually by down grading the 8R continuous and 4R specs to look like they might "double down". It's a ruse that's been going on for decades.

Even if your power supply was fully regulated and maintained perfect voltage rails under all current draws (fiction, but hey), you still can't get away from the IxR voltage losses in the devices/emitter resistors in this class of amp. More current- more loss of voltage- more power dissipated and not getting to the load.

Am I being too fussy?

Yes.

 

[Doodski]

Many amplifiers "appear" to do that, usually by down grading the 8R continuous and 4R specs to look like they might "double down". It's a ruse that's been going on for decades.

Even if your power supply was fully regulated and maintained perfect voltage rails under all current draws (fiction, but hey), you still can't get away from the IxR voltage losses in the devices/emitter resistors in this class of amp. More current- more loss of voltage- more power dissipated and not getting to the load.



Yes.

All good points. Just for theoretical conversation; by increasing the amount of output transistors and increasing the amount of emitter resisters then that would reduce the power outputs current gain stage losses significantly? Is there a point where it becomes not effective? I see some amps with a lot of output transistors and wonder if this is why?

 

[restorer-john]

All good points. Just for theoretical conversation; by increasing the amount of output transistors and increasing the amount of emitter resisters then that would reduce the power outputs current gain stage losses significantly? Is there a point where it becomes not effective? I see some amps with a lot of output transistors and wonder if this is why?

They are minimising the losses and providing for much greater continuous current, better linearity etc.

But all those devices need bias current, which means a more capable driver stage, more idle losses, more expense, etc.

I think the manufacturers, on the whole, do a good job. It's pretty hard to destroy a set of outputs even with a full power short in a modern amplifier with decent protection.

There was a period in the early 80s where a lot of commercial (and DIY) high power designs sailed a bit too close to the wind in SOAR. But speakers were less reactive, more efficient and of a generally higher nominal impedance than they are in 2024.

The Class Ds render most of this moot as they have such incredibly low RDS(on) and consequent device losses are minimal.