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I bought a classdaudio.com module...

71.59.73.4
Posted on November 7, 2009 at 06:48:44
Scholl
Distributor or Rep

Posts: 429
Joined: March 8, 2001
 Hi guys,

I received the 2x250 1x500 module last night. I bought this one because it works well with the old Dynaco ST150 chassis that's been on the shelf for 20years because it never worked right. Power supply voltage is +- 50v 33000UF caps.

The module is nicely built on heavy circuit board.

Speaker and power connections were very easy to do and the speaker connectors take 16 gauge wire with room to spare. I had it up and running in less than an hour.

Sonically the web site description is dead on... Bass is tight, full and articulate. It has a pleasant warmer tone. Soundstage is wide and deep. Imaging is precise with larger scale presentation.

I played a large range of music:

Lyle Lovett
Beatles
White Stripes
Metalica
Talking Heads
SRV
Brother Where art thou
Duke Ellington

All reproduced very nicely. At first the highs seem to be a little recessed but I think that's the "PWM amp" signature sound. A Ricky Lee Jones cut with a nice chimey intro came though very sweet.

Speakers were home brew with 4ohm EA TD15s with B&C DE250 on and RCF H100 horn. The 15S are hard to control and the module did a great job. PWM amps and AE woofers are a great combination!!!

Compared to the Panny XR45 I like the Panny mids and highs a little better (the module has 5 hours of break in) but bass on the module is hands down fuller, tighter and more controlled. The power supply for the module is much more robust then the XR45.

The module does have a bit too much gain. An input volume control is a must.

I can highly recommend this for the DIY PWM amp fan who wants more power at a great price point.
Some measurements..., posted on November 14, 2009 at 06:57:33
Scholl
Distributor or Rep

Posts: 429
Joined: March 8, 2001
 As promised I put the amp on the bench with an 8ohm resistive load had no trouble swinging the +-50V rails for a 100v p-p output with normal looking clipping at 100vp-p. That's 155 watts. Frequency response was almost DC to about 70Khz before distorsion set in. Below 10hz the protection lights flickered. Triangle wave looked great, square wave had excesive high frequency ringing.

I scoped the output while listening to music and was able to drive very loud peaks over +-40 Vp-p into the 4 ohm TD15S speakers that's over 200W peaks but the amp did overheat and shut down after a few minutes. More heat sink is needed for extended high power output and maybe required to reach the stated 250watts at 4 ohm rating.

The TD15S 4 ohm speakers are very hard to drive once the cone starts to move more than 1 or 2mm. These require more careful amp matching. Both the pannasonic XR45 and this module run into difficulties with these speakers but both do very well with typical home hi fi speakers with 6 or 8" woofers. I have a large class AB amp that has trouble with these too.

In my opinion all claims are met both sonicly and with output power.

RE: Some measurements..., posted on November 19, 2009 at 02:29:11
roby2k
 Hi Scholl,
I'm Italian.
I have this amp and I am very happy.
In my opinion it's a vary good amp.
Have you measured the input impedance?
I think that it's very low.
I drive it with a 10k pot instead a 50k and now it's ok.
But I think that with a buffer can play better too.
What do you think about?
I hope that you will understand my bad english.

Roberto.
RE: Some measurements..., posted on November 19, 2009 at 03:54:01
Scholl
Distributor or Rep

Posts: 429
Joined: March 8, 2001
 I didn't measure the input impedance but agree with you that it may be low. I tried a 100K pot and sound stage opened up more but bass was less. It's best with a preamp that has low Z and no cpacitor output. I'm looking for a preamp kit with low output Z, any recomendations??

I find the bass "hit" and dynamics at low power very good.

RE: Some measurements..., posted on November 19, 2009 at 08:44:54
wushuliu
Audiophile

Posts: 41
Joined: March 19, 2009
 I also have this amp and I love it. I think it's an outstanding amp for the money. It does roll off the highs on my 4 ohm towers (I believe this is shown by the Frequency response in the IRAUDAMP reference pdf. 8 ohm Frequency response has no roll off), so I reduced tweeter padding a little bit to balance it out and it worked wonderfully.

RE: Some measurements..., posted on November 19, 2009 at 04:12:13
roby2k
 With a 10k pot it's ok , but i'm waiting for a B1 buffer (Nelson Pass).
I think that a buffer without gain it's a good solution.

Regards,

Roberto.

P.S. If you want I write also on diyaudio and Italian forum
http://t-class.niceboard.net/altri-chip-in-classe-t-d-f22/class-d-audio-t3591.htm
There is an american user and you will be welcome.

RE: Some measurements..., posted on November 20, 2009 at 04:38:30
Scholl
Distributor or Rep

Posts: 429
Joined: March 8, 2001
 I saw the B1 schematic, it stil has an output cap so the value has to be considered.

I'm hoping to find a servo compensated circuit board only kit. So far no luck.

Scott

RE: I bought a classdaudio.com module..., posted on November 7, 2009 at 16:26:39
djk
Manufacturer

Posts: 3886
Joined: June 17, 2000
 The power claims for the voltage specified see absurd. No gain level specified, no power vs distortion at different levels.

The ST150 has ±70V available too, I would have considered the higher voltage module.

RE: I bought a classdaudio.com module..., posted on November 8, 2009 at 05:19:10
Scholl
Distributor or Rep

Posts: 429
Joined: March 8, 2001
 Yup..I took a chance but so far so good, I like the sound and bass control is maintaned at low listening levels.

The power for the voltage is right on for the 2x250W module at 4 ohms. Voltage range is +- 45 to 60 which comes out to 126 watts to 224 at 8 ohms if the module can swing the rail voltage.

For the 600W modules they'd have to have a dc-dc converter to make the claim. When I first read though the site I didn't see the higher voltage module rated for 4 ohms so I passed on it. The site does need some work and data is spotty.

On a side note: the modules are manufactured by Team America Technologies who provide opertunities for the disabled.
RE: I bought a classdaudio.com module..., posted on November 8, 2009 at 17:59:48
djk
Manufacturer

Posts: 3886
Joined: June 17, 2000
 Have you actually measued your with a sine wave, both channels driven, 20hz~20Khz?

RE: I bought a classdaudio.com module..., posted on November 9, 2009 at 02:47:12
Scholl
Distributor or Rep

Posts: 429
Joined: March 8, 2001
 No not yet..but I did have the scope on it while playing music and didn't have any problems peaking above 40V. I plan on getting it back on the bench later this week.

RE: I bought a classdaudio.com module..., posted on November 8, 2009 at 11:32:46
passive chappy
Audiophile

Posts: 8
Joined: September 17, 2009
 I had some interest in these products.

Where did you get them?

RE: I bought a classdaudio.com module..., posted on November 8, 2009 at 14:57:48
Scholl
Distributor or Rep

Posts: 429
Joined: March 8, 2001
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