Warp-1 Amp

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#21
It’s the same as the BTSB Panel Mount Buffer here:
https://www.diyaudio.com/community/threads/btsb-panel-mount-buffer.379030/#post-7040598

Default setting is 6dB on buffer. Amp intrinsic gain is 22dB for total 28dB.

DIP switches are 0dB/6dB/14dB/20dB.

I would say using 0dB for 22dB overall is good if you have a powerful preamp. But I would not go 14+22 for 36dB unless you want to use something like a smartphone to drive it to clipping. Don’t use the 20dB. That’s too much for this amp.

I have more details on which to DIP switch to flip if you can’t make sense of the schematic.

1661703702904.jpeg
 
#30
Hi Folks,
I have been getting some service calls for Warp-1 (several times now) with customer saying that the amp has terrible hum. In some cases, the amp is sent back for warranty repair. Upon examination, nothing wrong with the amp and hum is caused when the amp is connected to speakers, nothing connected to the inputs and power is turned on. The 47k input impedance is enough to pick up mains hum right out of the air if the input is not connected. I connected the “faulty” amp to a source (first go-to source is my iphone dongle and RCA cable) and press my ear to the speaker cone and I cannot tell the amp is turned on. That’s how quiet the amp is. So a reminder, please don’t use your amp without a source connected. Unless you want to amplify in-air EMI hum.

I will update the Owner’s Manual to specifically mention this.
 
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#32
I find it strange that hum comes out of the air, I would think no connection is no sound to amplify. But this is my first power amp, I only had integrated amps before.
Still, if by mistake or by design (by using a switch to switch between Warp1 and another connected amp) there is no connection, the hiss can be frightening to some. As if the possibility exists that your speakers receive full power white noise.
 
#38
Based on the load dependent frequency response, I gathered as much. This is a common trait among the amps marketed by LSA. Not sure why as personally I view it as a flaw when an amp is load dependent. Guess I am spoiled by the design/performance of the Purifi and Hypex products. It reminds me of the 30 year old Tripath class d designs.

The commercial Warp-1 does not have post filter feedback (disabled) in order to get higher output power. With PFFB enabled max power is only 70w.
Click to expand...
 
#39
What other LSA amps are you referring to? I only designed the Warp-1 and HyperDrive-2 headphone amp (Class AB chip amp output stage).

The load variations occur in the upper frequency band so I don’t think it’s an issue. At least not in the critical listening tests by many reviewers.

One can enable the PFFB of course and this dependency will be reduced - or use a new variant of it as described by others on DIYA that’s even better than the TI developed topology. But I submit that not having PFFB makes the amp sound more natural.
 
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