Sound Quality Vs. Measurements

[john dozier]

The THAT chips are used on some of ClassD Audio's amp modules. I use their amps and find them superior to $5k tube amps. I am not the only one with these findings. I suspect the quality of the input chip is at least partly responsible for the excellent SQ. The price of the amps is very attractive-$600. regards

 

[a.wayne]

John,
5k Toobs , dont tell me anything , any Names ..?

How are they vs other SS amps, my last outing with class-D didn't make me a believer, big cinder block SS amps are still at the top of my list, the little class-D amps (belCanto) had good speed and dynamics , but was pretty grungy sounding by comparison ...


Regards ,

 

[john dozier]

They are ASLs. I suggest you actually listen to the amp-its the Spiral Groove mastering amp-there is a free home trial and the price is right. Be a sport and listen first then denigrate. Regards

 

[a.wayne]

They are ASLs. I suggest you actually listen to the amp-its the Spiral Groove mastering amp-there is a free home trial and the price is right. Be a sport and listen first then denigrate. Regards

I did listen to the Bel Canto, as stated above , I gave you my observation, the spiral groove amp is too small for any of my current application.

 

[john dozier]

To my mind, "grungy" is a term of denigration. I was suggesting that you listen to the ClassD audio before making any judgement. All class d amps are not alike. The ClassD can be strapped for mono for additional power if needed. Regards

 

[a.wayne]

Fair enuff, maybe using the term "edgy" would have been less so i guess.


The Bel Canto's are highly rated and are not "inexpensive", The same for the Merrill Audio, they offer Class-d for a lot , but i have not heard it and missed the opportunity to do so, others who have tried the even more expensive Rowlands or ML's tell me the same vs other top tier Linear SS amps.

Many are of the opinion it's the SMPS why they fail to sound superior....(ML uses one)

Regards

 

[john dozier]

The ClassD Audio amps all use linear supplies. Regards

 

[dvv]

I don't believe the NPN is matched to the PNP (it would help if they showed curves of Vbe with current, but note they say excellent matching of transistors of the same gender). Base spreading R is pretty low but there are lower. Beta is not very high. Someone there told me once that they tried making beta higher but the breakdown voltages got too flaky.

For some applications, especially those that require good log conformance, like translinear circuits including analog multipliers, they should work very well.

If there were packages with more pins you could have eight independent devices, and they will sell the chips if you want to manage the packaging yourself.

Actually, Brad, there is such a package, I didn't make a note of the designation, but I did see an 8 transistor package.

On curves, I agree - we really could use them.

 

[dvv]

The THAT chips are used on some of ClassD Audio's amp modules. I use their amps and find them superior to $5k tube amps. I am not the only one with these findings. I suspect the quality of the input chip is at least partly responsible for the excellent SQ. The price of the amps is very attractive-$600. regards

I agree with that assement. In my view, most amp issues are resolved at the input and the output stages, not many get the VAS wrong, but many "save" on the outputs.

 

[qusp]

The ClassD Audio amps all use linear supplies. Regards

I thought they were linear class AB amps too, with a silly name ...

 

[jan.didden]

I was holding my breath to see who would drop that one first - haha!

jan

 

[dvv]

I was holding my breath to see who would drop that one first - haha!

jan

Well, you sure didn't have to wait long, did you, Jan?

It can't fail to come up.

 

[bcarso]

Actually, Brad, there is such a package, I didn't make a note of the designation, but I did see an 8 transistor package.

The 380 is mentioned as a "bare-die" array, but only 14-pin packages are shown on the 300 datasheet. Having all eight devices independently available, plus a substrate connection, would require 25 pins.

 

[nigel pearson]

Some suggestions to use instead of That's corp transistor chip . Noise date is hard to find . BC850/860 2N4403/1 seem to be unavailable in dual ? A noise figure of 1.9 dB/1.6 dB seems OK coupled with 65 V . From memory a little bit better than old BC series ( 4 dB ? ) .
http://www.nxp.com/documents/data_sheet/BC846BS.pdf
http://www.nxp.com/documents/data_sheet/BC856BS.pdf

Also useful ready made current mirrors BCV 61/62 . The 30 V rating is usually OK as they are protected by the next transistor in the chain ( VAS ) . What is better than usual is the ability to work at the sometimes 0.6 V VAS base to rail voltage of a VAS . Discrete mirrors often show imbalance when so close to the rail . There is even enough headroom to use emitter swamping resistors . The very best matched transistors I tried were noticeably inferior on mirror balance . One can fit a VAS emitter resistor as a cure or Darlington VAS . The resistor degrades loop gain . 24 R would do enough usually ( 8 mA ) .

http://www.farnell.com/datasheets/45933.pdf
http://www.farnell.com/datasheets/45935.pdf

 

[Pano]

why? because if we didn't use measurements we would be in stone age as far as audio quality is concerned...

Yeah, but you know - those guys rocked!

 

[qusp]

I was holding my breath to see who would drop that one first - haha!

jan

Well, you sure didn't have to wait long, did you, Jan?

It can't fail to come up.

indeed one couldnt hope for a better opportunity to drop that one. its one of the more harmless things to be said ... but it depends, there are 2 companies with this name, this could be the second, USA based one; which actually does appear to make Class D amps

 

[john dozier]

These are the good guys! All American made in California! Uses THAT chips and niobium caps. Regards

 

[qusp]

yeah, seems good, but there does appear to be some, erm.. 'problematic' feedback on their website

 

[john dozier]

Please point out the "problematic" feedback. Regards

 

[qusp]

the older reviews on their site seem good, but the 2 most recent (which is 2 years ago) not so much ...

from here

kudos for leaving them there I guess, if theyve seen them

Bad customer service Review by Oscar
I sent two Amplifier boards, one for repair and another for warranty replacement since last November (2010) and I still have no answer. I've sent several e-mails but I get no response.
(Posted on 8/1/11)

Some problems I did not expect Review by Hase
Yes, I was very happy as I found a company, who is building amps with the TAS5630 . So becaus I am in Germany, I had to wait a little bit for shipping. I got 2 amps, but one had a broken capacity conection in the output, and the balance was very bad between the chanals. The other worked nice at a lab test with 30VDC. I sent the one amp back and after 3 month I got one back, but again with problems: The balance is bad between the channals, the less power channal makes a big switch in noise and it sounds if it has no input-signal like 50 or 100Hz. It would be very nice, if we could find a way to have good working amps.
Remark: The second amp, which worked nice at lab build, did not start at all after half a year staying in the plastic bag and controlling before mounting in the housing. This was a very blue day. (Posted on 1/16/11)