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Chip Amps Amplifiers based on integrated circuits

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Old 14th October 2013, 05:14 PM   #991
bcmbob is offline bcmbob  United States
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If you are going in that direction, let me suggest a setup.

1. If you are on a PC make sure all the formats are enabled in the sound section of the control panel.

2. If you use JRiver you can select WASAPI to completely eliminate the Windows audio drivers. That cleans things up a bit and your JC-2 pot gets a full-strength straight-through feed.

The same is probably doable on a Mac but I'm not that familiar with Mr. Jobs approach - and the available players
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Last edited by bcmbob; 14th October 2013 at 05:19 PM.
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Old 14th October 2013, 06:15 PM   #992
davym is offline davym  Scotland
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Hi Bob, I tried WASAPI some time last year but I am using a PC/ Musical Fidelity V-Link/V-DAC set up for digital which does not work with WASAPI. It does give the best digital sound quality I've had to date though, it usually makes my turntable sound poor in comparison but I have to leave the PC volume at max for best results. I sold my Rega Apollo CDP after getting this set up working. I still have an old Philips CDR, somewhere in the house, probably the loft. Having boxes of CD's all over the place hacked me off and I had trouble finding CD's I wanted to hear.

Musical Fidelity VLink II USB to S/PDIF Converter

The technoblurb has the same effect that most digital spiel has on me, I feel my eyes growing heavy and concentration wan........

Anyway it seems to work well enough
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Old 14th October 2013, 06:23 PM   #993
davym is offline davym  Scotland
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Quote:
Originally Posted by AndrewT View Post
More probably the source/s need/s a buffer.

That source could be the CDP, or computer, or the volume control potentiometer.
That was my impression, the JC-2 clone has x3 gain but a stepped attenuator fitted to it and left set at roughly 2/3 volume seems to have given me the best solution. It is, effectively, just a buffer now.
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Old 14th October 2013, 06:39 PM   #994
bcmbob is offline bcmbob  United States
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Hey - Whatever feeds the FEs what they're hungry for.
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Old 15th October 2013, 08:19 AM   #995
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by davym View Post
That was my impression, the JC-2 clone has x3 gain but a stepped attenuator fitted to it and left set at roughly 2/3 volume seems to have given me the best solution. It is, effectively, just a buffer now.
times 3 gain is canceled by times 1/3 attenuation, so that the input signal is at the same level as the output signal.

Applying most source levels to most amplifier sensitivities will take the amplifier output to near clipping. It could be over the clipping level, or it could be under the clipping level.
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Old 15th October 2013, 05:53 PM   #996
davym is offline davym  Scotland
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I never run my amps close to clipping. I hear you re the pot position, when I try leaving the pot on the active pre set at or below half volume it sounds dull and lifeless, once I get a bit past the mid point, the sound comes alive, at much over 2/3 volume I am back to having not enough adjustment on the passive pre and it goes way to loud too fast. It seems that roughly x2 gain on the active pre/buffer gives me the best sounding results so far. The new amp will probably not need a buffer at all but I will try it with passive, active and both together to see which combination gives the best results in my setup.
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Old 16th October 2013, 08:08 AM   #997
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by davym View Post
I never run my amps close to clipping. ....................
then you are not using your volume control potentiometer at 2/3rds position.
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Old 16th October 2013, 12:34 PM   #998
davym is offline davym  Scotland
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You have got the wrong impression, i probably confused the issue as usual. I have a small diy passive pre which has an Elma rotary switch for source selection and a 20k stepped attenuator. I have my sources plugged into this. At present this is feeding my active pre which has a 10k stepped attenuator fitted through the back panel beside the RCA sockets. I leave this set at a fixed position to reduce the gain, it means I can still adjust it if needed. The active pre/buffer then feeds the power amp.

I use the passive pre for normal volume adjustment and source selection. I have been trying various settings for the 10k pot on the active pre over the past couple of days, I got the impression that if I left it pre-set at mid way or less, I was losing a certain amount of impact but after a bit more testing, I now believe this was a false impression. As of last night, the (fixed) position for the 10k pot is at just under 1/3 of its available travel. So the passive pre is now used for all adjustments and the active unit it feeds into is just being used as a buffer with no gain. I now get a reasonable range of volume adjustment on the passive pre and have the increased bass weight at low listening levels which I get from the active buffer. A compromise as usual but it gives me decent results. Before I had to reduce the PC's inbuilt volume setting which had a worse effect on the sound than my current arrangement but that did not help with my phono stages output which remained too high for reasonable volume adjustment on the passive pre.

Maybe I can go back to just using the passive pre on it's own with my new power amp, when I get it built.
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Old 16th October 2013, 02:53 PM   #999
AndrewT is offline AndrewT  Scotland
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There is no point in adding excess amplification and then canceling that un-needed gain by using more attenuation.
Have you read?
What is Gain Structure? - diyAudio
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Old 16th October 2013, 04:34 PM   #1000
davym is offline davym  Scotland
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I would normally be among the first to agree. I'll have a read through your linked article later on when I have more time but I am going by what sounds better to me. Without the added buffer my old vinyl is practically unlistenable, really bright sounding with almost no bass to speak of. The buffer makes a better job of the vinyl without making the digital source sound bad. At the end of the day, I have to be able to listen to the system and I have not been playing many lp's of late because of the sound quality. I have been able to enjoy my old lp's again since I set this up. Horses for courses springs to mind.
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