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Starke Sound AD4.320 Review (Multichannel Amplifier)

JohnL

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So they claim this thing is capable of 1,280 watts of power??? I would reply and ask them if they could provide a measurement that demonstrated this.

Edit, adding some power loss, this will be at the limit of a 15amp outlet in US can provide.

I asked for measurements…here’s the reply:

John, we are arranging to measure performance of current production units of AD4 and to publish the results along with the analyzer scripts.

We’ll share those with you as soon as they are available.

This has their attention. Hopefully Starke will follow thru and publish here soon. My interactions with Starke on both the sales and service side have been very helpful and professional. Replies are prompt like the one I received from an after hours email today.

It’s too early to jump to conclusions or determine cause. This could be a quality, design, assembly, test, measurement, part, or some other typical manufacturing issue on one amp. It could also be a big issue, who knows. Let’s see what they find.

I have three AD4.320’s built in Jan 2021 and access to low FedEx corporate rates if you want to test more
 

sarumbear

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I asked for measurements…here’s the reply:

John, we are arranging to measure performance of current production units of AD4 and to publish the results along with the analyzer scripts.

We’ll share those with you as soon as they are available.

This has their attention.
Incredible. They are basically admitting that they do not measure the amplifiers they sell. Outrageous behaviour!
 

jrosser

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There seems to be switches for bridging on the back of the box. Could it be that the higher power numbers specified are in bridged mode?

Tom
The more I look at it the more the STD/Bridge mode also feels suspect.

Theres only one heavy duty secondary on the transformer (white wires in post #3) without a center tap, and only one pair of heavy red/black wires from the power board to the amp board, this all points to a single supply rail for the output stages. Practical single supply class-D is realised by bridging two amp channels with idle output set at VCC/2.

Add to that four sets of L/C output filter per amp board, the whole thing smells of 4-channel class-D chip-amp under each heatsink, which would make "STD" mode correspond to "BTL" in Texas Instruments TPA32xx terminology, i.e the outputs are always running in a bridged mode.

The "Bridge" switch could mean "PBTL" (parallel-BTL) in TPA32xx terminology with the 4 amp channels run in parallel pairs to double the current capability with a mono output. The relays on the amp board could easily be re-arranging the inputs/outputs for PBTL mode.

Anyway - from the photos posted earlier of the internals there is the appearance of a single supply, BTL chip-amp. Even the drill-hole spacing in the heatsink and orientation/placement of the reservoir capacitors (positives terminals both at the center of the board) is consistent with this.
 

JohnL

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Incredible. They are basically admitting that they do not measure the amplifiers they sell. Outrageous behaviour!
That is an assumption. It might be true, it might not. There is no way to know if this is intentional or not. I’m giving them a pass because of how responsive they have been to all of my emails. Companies who try and take advantage of customers usually don’t reply to emails

Starke will either duplicate the problem or they won’t. If they duplicate the problem they should implement a fix and allow existing customers to send in for repair. If they don’t reproduce the issue, they should work with Amir to identify the issue. Those are the next steps. (I used to fix problems like this at HP a very long time ago, I need to write a book!)

Anyways, I personally think Amir found a real issue and here’s why. There are no vent holes or slots on the amp. If the amp is 90% efficient it would generate about 128 watts (320 W * 4 * 10 %) and would overheat a closed box which does not happen; it doesn’t get warm at all. But if it generated 50 watts (125 * 4 * 10%) in losses the amp might get warm but won’t overheat. The AD4 runs very cool even when cranked but so far I have only powered 2 speakers at a time. For me it acts like it is running below 50 watts. Is this true? I don’t know for sure and I haven’t measured. It is simply what my gut is telling me. My calculations could be off, I don’t know how efficient the AD4 really is and I’m assuming it is 90%
 

HammerSandwich

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If you push it right to clipping with music, average output will be maybe 10% of peak, probably lower. That average is what sets the temperature, because heat is power * time.
 

voodooless

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Anyways, I personally think Amir found a real issue and here’s why. There are no vent holes or slots on the amp. If the amp is 90% efficient it would generate about 128 watts (320 W * 4 * 10 %) and would overheat a closed box which does not happen; it doesn’t get warm at all. But if it generated 50 watts (125 * 4 * 10%) in losses the amp might get warm but won’t overheat. The AD4 runs very cool even when cranked but so far I have only powered 2 speakers at a time. For me it acts like it is running below 50 watts. Is this true?
Don’t forget that music has a crest factor of 10 to 20 dB, so while you have some dynamics, the average power will be 10 to 100 times less than the peaks. So the amp at rated power would indeed stay only lukewarm playing music.
 

alpha_logic

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Hi - do you think this youtube reviewer got a cherry picked unit or maybe something wrong with the unit tested here? He seems praise the unit especially on the "power" it is delivering. What do you guys think?
Another Edit: The reviewer says he is not pretentious, but might come across as such.


Thank you
Someone needs to review the reviewers; this one in particular has been pushing a lot of garbage lately.
 

sarumbear

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That is an assumption. It might be true, it might not. There is no way to know if this is intentional or not. I’m giving them a pass because of how responsive they have been to all of my emails. Companies who try and take advantage of customers usually don’t reply to emails
How can their declaration "we are arranging to measure performance of current production units of AD4" be understood other than they do not measure their unit before selling them? They are "arranging to measure". If they "had been measuring" they would have said "our measurements".

My comment is not whether they will admit and correct the problem or not, but they have not said they had been measuring them. That is incredibly bad behaviour.
 

Shanman

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Someone needs to review the reviewers; this one in particular has been pushing a lot of garbage lately.
One of his recent reviews had me cracking up because he was polishing the Wharfedale Lintons with orange oil at the beginning of the review. The first thing the manual states is don't put anything at all on the factory sealed finish. Obviously not a details man!
 
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Spocko

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Someone needs to review the reviewers; this one in particular has been pushing a lot of garbage lately.
Because many of the issues and flaws found in measurements are hardly audible unless you know where to listen or have speakers that will reveal these weaknesses - the old adage "you don't know what you don't know" applies here. So if audible tonality issues arise from a mismatch of the speaker impedance (as suggested by the high sensitivity to load measurement of @amirm's review), then you'll only hear it if you know to test it with the "wrong" speaker during the review. I never got started reviewing audio equipment for this very reason and thank the heavens that ASR is here.
 

DuncanJ

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I was concerned that I had possibly overlooked a contender to upgrade my system. A Canadian You Tube reviewer had promoted this amp over the Hpex MC400 monoblocks that I did purchase. You want to make sure that you consider all the possible candidates but clearly this amp was never in the same league.
 

Loron

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I came really close to pull the trigger on two of these…. I am happy I went with.
a Buckeye amp instead!
 

fordiebianco

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That is an assumption. It might be true, it might not. There is no way to know if this is intentional or not. I’m giving them a pass because of how responsive they have been to all of my emails. Companies who try and take advantage of customers usually don’t reply to emails

Starke will either duplicate the problem or they won’t. If they duplicate the problem they should implement a fix and allow existing customers to send in for repair. If they don’t reproduce the issue, they should work with Amir to identify the issue. Those are the next steps. (I used to fix problems like this at HP a very long time ago, I need to write a book!)

Anyways, I personally think Amir found a real issue and here’s why. There are no vent holes or slots on the amp. If the amp is 90% efficient it would generate about 128 watts (320 W * 4 * 10 %) and would overheat a closed box which does not happen; it doesn’t get warm at all. But if it generated 50 watts (125 * 4 * 10%) in losses the amp might get warm but won’t overheat. The AD4 runs very cool even when cranked but so far I have only powered 2 speakers at a time. For me it acts like it is running below 50 watts. Is this true? I don’t know for sure and I haven’t measured. It is simply what my gut is telling me. My calculations could be off, I don’t know how efficient the AD4 really is and I’m assuming it is 90%

Hi John,

any updates from Starke?
 

JohnL

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Hi John,

any updates from Starke?

Checked yesterday. They said next week.

It doesn’t take very long to test output power which is the main issue to me as I have three of these amps. I suspect they found an issue and are working on it.

Most companies know it is counterproductive to ignore bad reviews and comments like this. I hope Starke is actively working on it and not ignoring.

My Moabs with bi-amp connections came in recently and my system sounds best when running the woofers and mid/highs on two different channels on the AD4 versus on one channel which is the second best configuration. I expected bridge mode to work best but that configuration came in is third place. There isn’t a huge change in tone between the configs but there is some.
 

JRaab

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Hi All,

Amirm I love the forums and have made purchase decisions in the past based off your measurements so I really appreciate all your work.

I created an account specifically for this thread cause I have 2 Starke AD4.320 bi-amped to a pair of Totem Hawks and a Totem Rainmaker center (not using bridge mode, just have #4 connection open). I reached out to Starke back on the 28th, when I saw the review, and this was their response.

"Hi Jeff -
Thanks for reaching out. Yeah, we saw the review and are quite disappointed with ASR. Their measurements are misleading and are not the case. All of our published spec's are true and real. Armin’s using some bizarre means of determining peak power output that is constantly running at 1/3 or ¼ of actual power – and it makes no sense to us at all. We're going to publicly release our measurements and the test scripts we used to obtain them so anyone can verify them. We'll have that available in a few weeks time. We'll also have an independent third party perform the same test."

Like John I haven't received an update yet but since it's been 2+ weeks since Amirm's findings and the products been out a year+, they should have had something put together already. The casual tone of the email wasn't great, but least that means a real person wrote it and not some auto-generates PR release.
 
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