Sure Class D amps do NOT sound the same

Status
Not open for further replies.
Jump to Latest
F

Flaxxer

Member
Joined 2017
#1
Although aware of Richard Clark's big money offer to anyone who can hear the difference in amplifiers, under his controlled conditions, I know I could pass this one, LOL.

I was using a Sure AA-AB32189 2x100 TDA7498 board in my system, and was really pleased at the rather neutral, with ever so slight sense of body and warmth to my music. Needing more power for my new upcoming speakers, I bought a Sure Electronics AA-AB33511 2x300W+1x500W Class D Audio Amplifier Board - T-Amp board. And any sense of slight warmth went away completely. The new amp sounds good enough, but waaaay more solid state and clean than the 2x100 did. Same exact system. Nothing changed but the amp.

Just curios, if anyone knows if this is the difference in the modules being used .... ie, 32xx compared to 33xx series?

I am now considering an inexpensive tube buffer as a gain control also. Hoping to get a small amount of body back, while needing the attenuation.

Just thought someone may find this interesting.
 
#2
The first amplifier mentioned is based on the TDA7498 chip from STMicroelectronics. A very good chip but more ordinary performance.
I have another board with the TDA7498E and I have nothing to complain about.
The second amplifier mentioned is probably based on TC2000/TC2001 from legendary Tripath with power bridges from STMicroelectronics. Using a modified modulation scheme (class T), the amplifiers using Tripath chips are known to have magnificent sound but sometimes heating issues. Very few are disappointed with class T sound from Tripath.
So, modulators from two different manufacturers but implemented by Sure who picks up any well-sounding class D (or T) chip from IC suppliers.
 
Last edited:
#6
DaveFred said:
What are you using as a source and how are you controlling the gain into the sure amp?
Click to expand...

I'm playing FLAC, WAV, and Hi Rez files from my laptop, into my HiFime Sabre 9018 USB DAC. From there it's to the amp. The only control of gain I have is the laptop volume. The laptop's volume goes from 0 to 100. My speakers are 96db efficient speakers. On the number 2, it is pleasant. 8 or 10 is getting loud. And 30 will hurt you.

So I am thinking a simple tube buffer to reduce the gain into the amp, after my DAC.

It is CRAZY to build amplifiers like this, without any input level sernsitivity control on the boards.
 
#7
Flaxxer said:
I'm playing FLAC, WAV, and Hi Rez files from my laptop, into my HiFime Sabre 9018 USB DAC. From there it's to the amp. The only control of gain I have is the laptop volume. The laptop's volume goes from 0 to 100. My speakers are 96db efficient speakers. On the number 2, it is pleasant. 8 or 10 is getting loud. And 30 will hurt you.

So I am thinking a simple tube buffer to reduce the gain into the amp, after my DAC.

It is CRAZY to build amplifiers like this, without any input level sernsitivity control on the boards.
Click to expand...

Ever measured the signal Voltage coming from the laptop that you are sending to the amp? I am curious to know what 2, 8 and 20 would be.

I connected a variable output dac to a Sure amp on the weekend and burnt up a tweeter. I had the output of the dac very low. I guess not low enough. Max input on the sure amp (mine anyways, AA-AB32195) is supposed to be 2v.
 
#11
Reading the specs on this Sure amp, shows this, "•Fixed gain settings: 28.5 dB, 30.5 dB, 32.5 dB". Would that not imply there is one of three fixed gain settings, via some kind of choice?

My eyes are only so good, and I do not have a magnifying glass I can locate. If anyone is willing, can you see a dip switch anywhere on the schematics, or photos here: Sure Electronics AA-AB33511 2x300W+1x500W Class D Audio Amplifier Board - T-Amp

I would really love to figure this out.
 
#13
Puffin said:
Yes, I bought one and use it with a linear split rail power supply giving about 55vdc. Sound great to my ears. You can bridge these boards. There is a switch on the board. I may get another one so that I can use both in bridged mode.
Click to expand...

Thank you.....Queston besides more power why would you want too bridge them? do you run ribbons?

Thank you

Lawrence
 
#14
I have the answer finally ... After spending 30 minutes on the phone with PE Tech, it has been determined the stated specs of ;

Specifications:
• Power output (with 50 VDC power supply): 500W (3 ohms, THD 10%), 312W (3 ohms, THD 1%)
• Minimum impedance: 2.5 ohms
• Frequency response: 20 to 20,000 Hz (±3 dB)
• Recommended power supply: 24 to 50 VDC, 12.6A regulated
• Fixed gain settings: 28.5 dB, 30.5 dB, 32.5 dB
• Power input jack: 2.5 x 5.5 mm, center-positive
• Dimensions: 6.8" L x 4.5" W x 1.48" H
• Weight: 680g

is not correct for the current model of this amplifier, with reference only to the " Fixed gain settings: 28.5 dB, 30.5 dB, 32.5 dB" line of the specs. Maybe it was the specs before the reputed changing for better cooling of Sure amps.

But this amp does not have any way to control the gain, except one, without buying an external part ... The answer is .... turn down the output voltage of the power supply. That is it. The $10 external digital volume control found here at PE, AA-AB41116 Digitally Controlled Stereo Electronic Audio Volume Control


This will allow you to turn the volume down to a better gain matching level with your source. Leave it where it is best. I was going to hard wire mine to the amp's inputs on the board itself, as an onboard gain.

With full agreement from PE, these ARE the correct answers.

Of course, any kind of buffer, etc is also an option. Just not as transparent as the Sure volume control is.
 
#16
Richard Clark's experiment has a number of reasonable conditions attached. One of them is the EQ. A tube amp with high output impedance certainly sounds different from a solid state. However one can obtain the same sound with a solid state and a PEQ which is indistinguishable from a tube amp (or else you collect $10,000).

Amps have measurable differences. What was claimed was that measurable differences are not necessarily audible, and audible differences could be EQ'ed away.
 
#18
I just did some measuring of sound pressure levels at my listening distance of 9 ft away, with several different recordings. My volume only works in steps of 2. So at the lowest setting of 2, I am getting an average of 66db. One step up to 4, is an average of 73db. At volume 10, it is 83db, and at volume 20 out of a possible 100, I am at an average listening level of 93db.

Very obvious I need a new gain structure. 😀
 
#19
Interesting update ... I haven't been able to find either of my multimeters. 😡 I have been wanting to check my power supply's output voltage. So today, I experimented with a small screwdriver, and the adjustable output pot on my power supply. I first found it set at approx. 30%. I turned it all the way down and up, with music playing, and it made about a 1db difference on my SPL meter.

BUT ... it made a BIG difference in the sound of the amp. With it up all the way, assuming 48 to 50 volts, it sounds fuller, and less "sterile". While it is all meaningless until I can find my multimeters, this would most obviously be due to the better bass and lower mids, immediately noticed. I feel the highs stayed the same. Extremely clean and detailed. But they no longer stand out. I am looking forward to getting the digital volume control, to better take advantage of my gain structure.

But I now feel this amp is even better than the smaller Sure amplifier. It remains less warm sounding. But is now sounding more like what I use to consider some of the very best solid state amplifiers sounding. It kind of reminds me of a really good Pass amp. :hypno1:
This is a BIG amp. It seems to want a BIG load of voltage to sound it's best in my setup.
 
Status
Not open for further replies.
Top Bottom