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Post by mazeeff on Jun 28, 2018 5:16:31 GMT -5
I recently purchased a A-300 amp, and am very happy with it. I am considering adding a PT-100, but have a question on volume control. The input sensitivity on the A-300 is 1.2V for full rated output. The line output on the PT-100 is speced at 4VRMS, which seems surprisingly high. With this kind of mismatch, I'll hit the 1.2V input on the A-300 after only around 25% of the PT-100 volume. How many volume steps are there on the PT-100? I am driving a pair of highly efficient Klipsch Cornwalls, and need as much volume control as possible!
Mike
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Post by pallpoul on Jun 28, 2018 8:09:14 GMT -5
With the Cornwall's, u will barely get over 25% before it is super loud with your amp. The volume control is sensitive on the PT-100 and it will work just fine with your speakers. I used it on my Cornwall's w/o a problem.
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Post by mazeeff on Jun 28, 2018 9:00:58 GMT -5
Thanks. What I would like to know, is how many volume steps, I can expect in the first 25% of volume? The PT-100 manual does not mention how many volume steps there are between 0% and 100%. If it is 100, then 25 steps in the first 25% would be fine. On the other hand, if the number of steps from 0% to 100% is only 50, them I would only have 12 steps in the first 25%. That would be a little too coarse for me.
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Post by leonski on Jun 28, 2018 12:52:34 GMT -5
What's in front of the A300 NOW? What' don't you like about it? What DO you like about it?
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Post by mazeeff on Jun 28, 2018 13:10:42 GMT -5
What's in front of the A300 NOW? What' don't you like about it? What DO you like about it? I am using a Windows 10 PC connected to a Schitt DAC, and then on to the A-300. It sounds fantastic, but it is lacking volume granularity. The PC volume runs from 0-100. At a volume of 10, the SPL is well over 100! Having only 10 steps of volume is a problem. I'm hoping that the PT-100 would provide a little more flexibility. |
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Post by leonski on Jun 28, 2018 15:43:56 GMT -5
A passive attenuator MIGHT be what you are looking for.
Doesn't plug into the wall and is just pure attenuation.
Warning: Some can be REAL $$$ which I've never figured out.
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Post by mazeeff on Jun 28, 2018 16:36:41 GMT -5
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Post by leonski on Jun 28, 2018 17:03:05 GMT -5
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KeithL
Administrator 
Posts: 10,256
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Post by KeithL on Jun 28, 2018 17:15:48 GMT -5
It's not "a mismatch"...... Both our hearing and volume controls are logarithmic.
On old-style analog potentiometers, Volume controls use what they call an audio taper, which means that the output is at 1/2 voltage when the knob is about 90% of the way up. Likewise, the dB scale used in most digital systems is also logarithmic.
This means that, if you input a certain signal..... - and get out 4 V with the control set to 0 dB
- you'll get 2 V out with the control set to -6 dB - and 1 V with the control set to -12 dB - and 1/2 V with the control set to -18 dB
- and 0.4 V at -20 dB - and 0.04 V at -40 dB - and 0.004 V at -60 dB
It's set up that way so you have a WIDE range of control with a typical volume control.
Even with Klipsch speakers, you're going to be able to turn the Volume down to almost nothing with no problem at all.... 
I recently purchased a A-300 amp, and am very happy with it. I am considering adding a PT-100, but have a question on volume control. The input sensitivity on the A-300 is 1.2V for full rated output. The line output on the PT-100 is speced at 4VRMS, which seems surprisingly high. With this kind of mismatch, I'll hit the 1.2V input on the A-300 after only around 25% of the PT-100 volume. How many volume steps are there on the PT-100? I am driving a pair of highly efficient Klipsch Cornwalls, and need as much volume control as possible! Mike |
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Post by leonski on Jun 28, 2018 17:45:46 GMT -5
I think the OP is beefing about resolution, not simply being able to 'turn the Volume down to almost nothing'..........
The claimed 10 steps between off and too loud is IMO, insufficient resolution.
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Post by mazeeff on Jun 29, 2018 4:26:40 GMT -5
Thanks Keith. That answers my question. Does the volume step in 1/2 dB increments, and is the range 0dB to -60dB? Leonski is correct, that my issue is one of resolution. On my Windows 10 PC, with the Schitt DAC, I am hitting full volume at a setting of 10 on a scale of 0-100. 7 is a little low and 10 is a little high. That only gives me a volume range of 7-10 or 4 steps!
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Post by garbulky on Jun 29, 2018 9:09:38 GMT -5
Thanks Keith. That answers my question. Does the volume step in 1/2 dB increments, and is the range 0dB to -60dB? Leonski is correct, that my issue is one of resolution. On my Windows 10 PC, with the Schitt DAC, I am hitting full volume at a setting of 10 on a scale of 0-100. 7 is a little low and 10 is a little high. That only gives me a volume range of 7-10 or 4 steps! Though not mentioned, it's possible the PT-100 uses a resistor ladder on a chip volume control like the DC-1. Which "technically" means you don't lose resolution compared to an amp. (That is if it uses it) |
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Post by leonski on Jul 1, 2018 16:34:07 GMT -5
Which defaults the 'loosing Resolution' problem back to the VC on the Confuser. Is Windows 10 AudioPhile Friendly? I guess I'm asking that when the level is reduced, does it loose resolution? I'm still inclined to suggest a Resistor Ladder-type attenuatior between DAC and AMP. www.goldpt.comThe SA-1 passive @344$ SOUNDS like a lot but it is a piece of lasting value. The attenuators are available AlaCarte, so DIY is still a somewhat less expensive option |
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Post by pallpoul on Jul 1, 2018 17:04:38 GMT -5
The pt-100 volume control goes up by 0.5 increments, from 0 to 80. so that gives u 160 steps, not sure if that answers your question.
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Post by mazeeff on Jul 2, 2018 7:39:46 GMT -5
The pt-100 volume control goes up by 0.5 increments, from 0 to 80. so that gives u 160 steps, not sure if that answers your question. Thanks. That is exactly what I was looking for. I ordered one on Friday, and should get it tomorrow. I'm sure that it will work better with my A-300. 1/2 dB steps should give me plenty of granularity. |
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Post by mazeeff on Jul 3, 2018 12:22:24 GMT -5
I received the PT-100 today, and it totally solved my volume granularity issue. Having 160 volume steps gives me the volume resolution that I was looking for. Thanks to all!
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