"In my opinion , Class-G does the commutation more linearly than Class-H ......But it uses More Devices whereas in Class-H the Switching element may be a high power Mosfet with lower RDS , and is much cheaper to implement then Class-G...what do you think....."
Yes, that is why I mentioned the cost difference between the two.
"The Spikes originating from the switching phenomena might have their impact on the sonics what are your views....."
The noise is largely a function of the switch (diode) used. Existing designs do not use the best available diodes, they consider them un-needed for PA.
Carver used an ordinary fast diode with a snubber, and sounded quite good.
Crest made a special version of one of their 4000 series amps just for HF use. It was class AB rather than class G, which indicates some users must have objected to the sound of the class G amps on the HF drivers. I have about eight various Crest CA series amps. The smallest of which (CA4) is class AB. The end users (this is for rental use) prefer the AB International 600 for sonics. A similar class AB amp, it does sound better for HF use.
The design of the AB 600 is virtually identical to the v4.0 Leach. Since both the AB and the Crest are class AB amplifers with very similar EF type output stages, it must be the front end and the overall execution of details. I've been meaning to try a v4.5 Leach with an added class G output stage just to hear for myself what can be done with class G.
A newer design commercial class G stage:
http://patft.uspto.gov/netacgi/nph-...,387,876.WKU.&OS=PN/5,387,876&RS=PN/5,387,876
Yes, that is why I mentioned the cost difference between the two.
"The Spikes originating from the switching phenomena might have their impact on the sonics what are your views....."
The noise is largely a function of the switch (diode) used. Existing designs do not use the best available diodes, they consider them un-needed for PA.
Carver used an ordinary fast diode with a snubber, and sounded quite good.
Crest made a special version of one of their 4000 series amps just for HF use. It was class AB rather than class G, which indicates some users must have objected to the sound of the class G amps on the HF drivers. I have about eight various Crest CA series amps. The smallest of which (CA4) is class AB. The end users (this is for rental use) prefer the AB International 600 for sonics. A similar class AB amp, it does sound better for HF use.
The design of the AB 600 is virtually identical to the v4.0 Leach. Since both the AB and the Crest are class AB amplifers with very similar EF type output stages, it must be the front end and the overall execution of details. I've been meaning to try a v4.5 Leach with an added class G output stage just to hear for myself what can be done with class G.
A newer design commercial class G stage:
http://patft.uspto.gov/netacgi/nph-...,387,876.WKU.&OS=PN/5,387,876&RS=PN/5,387,876
Hi Kanwar,
The switching in class H is visible on an oscilloscope when looking at the output waveform. You can hear it as well.
Carver changed to class G for some later amps for that reason. They later developed the "down converter" as an efficient type of power control that emulates class G. I am impressed with the performance of the original Lightstar for that reason.
The Lightstar is a real animal (for North America). It's rated at 300 W 8 R, 600 W 4R and 1200 W 2R. That's per mono channel. It has a dual mono design, two power cords.
I think the technology has proved itself. We even had failures due to the feedback resistor burning out (someone should be slapped).
-Chris
The switching in class H is visible on an oscilloscope when looking at the output waveform. You can hear it as well.
Carver changed to class G for some later amps for that reason. They later developed the "down converter" as an efficient type of power control that emulates class G. I am impressed with the performance of the original Lightstar for that reason.
The Lightstar is a real animal (for North America). It's rated at 300 W 8 R, 600 W 4R and 1200 W 2R. That's per mono channel. It has a dual mono design, two power cords.
I think the technology has proved itself. We even had failures due to the feedback resistor burning out (someone should be slapped).
-Chris
djk said:
Hi DJK,
That's the Peavey patent, its very similar to the Yorkville amps of Canada http://www.yorkville.com/downloads/servman/smap6020.pdf
...So Class-G wins over Class-H interms of Sonics in HF region.....
anatech said:
HI CHRIS,
Yeah I had an Access to QSC RMX1850HD , Seen the Waveforms...Glitched during HF reproduction....
So Class-G is more accurate than Class-H but Costlier.....
To DJK & ANATECH,
Why Pro amps [QSC,CREST&others]are rated like this:
500W 8R, 800W 4R , 1200W 2R.....
is there anytype of limitation in term of Supply sagging , or limited power....
meanwhile We rate 500W 8R, 950W 4R , 1800W 2R
Rail sag is just 6Volts Max and output peak voltage Swing is within less 1 V max than VCC
Or there are any other circumstances involved...
Thanks Very Much
regards,
K a n w a r
Hi,
The Lightstar has an active power supply. The specs are published ratings that the amps will exceed. Therefore, the actual power output will show some sag in the supply.
We also have 110 ~ 125 VAC supplies. That will limit the power output to below what you can get on a 220V system depending on the current fusing.
Considering that this is an amplifier aimed at the home market, the output power is excessive anyway. Imagine needing two circuits at 15A, 120V for one amplifier.
-Chris
The Lightstar has an active power supply. The specs are published ratings that the amps will exceed. Therefore, the actual power output will show some sag in the supply.
We also have 110 ~ 125 VAC supplies. That will limit the power output to below what you can get on a 220V system depending on the current fusing.
Considering that this is an amplifier aimed at the home market, the output power is excessive anyway. Imagine needing two circuits at 15A, 120V for one amplifier.
-Chris
Hi Arif,
Good question. Never had a problem with this. My guess is the supply control looked at the peak (held) signal amplitude. The output was filtered so there was no residual RF in the output.
If you ran a 10KHz, high amplitude signal in, the supply would probably lock to the required voltage and not follow the waveform anymore. It would track lower frequency waveforms as in real music.
-Chris
Good question. Never had a problem with this. My guess is the supply control looked at the peak (held) signal amplitude. The output was filtered so there was no residual RF in the output.
If you ran a 10KHz, high amplitude signal in, the supply would probably lock to the required voltage and not follow the waveform anymore. It would track lower frequency waveforms as in real music.
-Chris
That is what I gather as well... however, personally I never liked the Sunfire in the treble area... (Actually 2kHz and up). Can't explain it. I sold the Sunfire I had the next day back to the dealer (actually it was a 600wpc Sunfire signature) and got a Krell KAV-250a for the same price... Still have the 250a after 8 years. 
Hi Arif,
Could be the op amps that Bob loves to run the signal through. I used to joke that Bob Carver wasn't happy unless he could run a signal through at least 10 op amps per product.
The Sunfire was a less expensive unit than the Lightstar. It only had one set of down converters for both channels that I know of. I'm not familiar with the entire Sunfire line. Having said that, I haven't seen a Lightstar series two either. I was selling the business in that time period and the Canadian distributor was going out of business (deserved).
-Chris
Could be the op amps that Bob loves to run the signal through. I used to joke that Bob Carver wasn't happy unless he could run a signal through at least 10 op amps per product.
The Sunfire was a less expensive unit than the Lightstar. It only had one set of down converters for both channels that I know of. I'm not familiar with the entire Sunfire line. Having said that, I haven't seen a Lightstar series two either. I was selling the business in that time period and the Canadian distributor was going out of business (deserved).
-Chris
Hi Arif,
I used to converse often with the engineer that designed the Lightstar Series 1. It may have been Bob's concept, but not his design. The Sunfire design was later, by a different team. The Lighstar series 2 was designed to compete with the same supply.
The Lightstar 1 had two power cords. A dual mono design. Two power transformers. Each amp was independant from the other. The Sunfire had but one power cord and could only pull power from one circuit.
There is no way to compare the two, not even for brute power.
I have no clue which one sounded better. As I said, the Lightstar was the best sounding Carver I ever owned. Wasn't too bad. There is no way I could justify the power, but it looked soooo cooool. Touch switch and all.
-Chris
I used to converse often with the engineer that designed the Lightstar Series 1. It may have been Bob's concept, but not his design. The Sunfire design was later, by a different team. The Lighstar series 2 was designed to compete with the same supply.
The Lightstar 1 had two power cords. A dual mono design. Two power transformers. Each amp was independant from the other. The Sunfire had but one power cord and could only pull power from one circuit.
There is no way to compare the two, not even for brute power.
I have no clue which one sounded better. As I said, the Lightstar was the best sounding Carver I ever owned. Wasn't too bad. There is no way I could justify the power, but it looked soooo cooool. Touch switch and all.
-Chris
Here's the paper...
http://www.vxm.com/21R.69.html
Read the middle of the paragraph titled: Fast Forward 13 years...
Seems like Bob has a differing recollection than your Carver Engineer buddy... I am not taking sides . LOL he also defends his use of OP-Amps.
A better version of the whitepaper (with Diagrams) can be found at the Sunfire website.
http://www.vxm.com/21R.69.html
Read the middle of the paragraph titled: Fast Forward 13 years...
Seems like Bob has a differing recollection than your Carver Engineer buddy... I am not taking sides
. LOL he also defends his use of OP-Amps.A better version of the whitepaper (with Diagrams) can be found at the Sunfire website.
Hi Arif,
Interesting paper. Bob is almost always thinking outside the box. I do fully agree with him on the bipolar vs mosfet thing.
Can you imagine Bob and Workhorse discussing amplifiers!
As you know, Sunfire / Lightstar do get warm. I suspect the 95% done thing is a stretch. The last 5% was all the detail stuff. Bob did design the Sunfire and that's why they are different.
He didn't always force op amps into class A either, but that's okay. I have enormous respect for him whether I personally agree or not. He does have way more experience designing amps than most people do.
-Chris
Interesting paper. Bob is almost always thinking outside the box. I do fully agree with him on the bipolar vs mosfet thing.
Can you imagine Bob and Workhorse discussing amplifiers!
As you know, Sunfire / Lightstar do get warm. I suspect the 95% done thing is a stretch. The last 5% was all the detail stuff. Bob did design the Sunfire and that's why they are different.
He didn't always force op amps into class A either, but that's okay. I have enormous respect for him whether I personally agree or not. He does have way more experience designing amps than most people do.
-Chris
anatech said:
I Wish , If Bob Carver could be our Forum member, then i would really showed him the superiority of Present day Mosfets & ofcourse their SOA, in the Paper he is talking about the mosfets [hexfets from IRF] which are worse than their present day counter parts....for example IRFP250 is an older version , IRFP250N is newer version with improved characteristics...
K a n w a r