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Old 17th May 2014, 11:03 AM   #11
fas42 is offline fas42  Australia
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Thanks very much for your feedback, Antonio, and thanks too to abraxalito for coming on board - you'll get plenty of good ideas from there, !

Okay, go straight to the heart of the matter, where you said for the PH, "less grunge and almost not at all mashed over the heavier passages" - this is where to put all your effort, you need to sort out where the PM is going wrong. For example, there may be an intrinsic problem with one of the drivers, a faulty unit, a problem buried so deep in the makeup of the beast that it won't be worth your while trying to get around it - I have a pair of pseudo-Altec PC speakers, and they're pretty terrible, raw, compared to the Harmans - it may be possible to sort them out but I haven't bothered trying.

So, concentrate on where you hear the grunge with the PM - is this a volume related issue, if you turn down the level is there a point where it largely clears up? And similarly with the heavier passage mashing, is this also volume related - can it be largely eliminated by running at a low enough volume?
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Old 17th May 2014, 11:15 AM   #12
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Just to clarify, obviously the goal is zero grunge, zero heavy passage mashing - at no stage should you be aware of the playback 'struggling', and if you do, you need to work out why that's happening ...
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Old 17th May 2014, 03:03 PM   #13
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I’ll give some background on my electronic knowledge just to let know. Not an EE but a Mechanical Eng. With 30 years of DIY audio electronics starting with SS kits from Dynaco and Borbely later went to tackle v. tubes pre and power did from scratch the Manly 150 W monoblocks (4 6550 each) with all transformers built by me (took 2 years to accomplish) built Zen amps and the Aleph 4 (100W class A). Also several speakers 3 ways and FR using raw speakers from Dynaudio, Fostex, Seas, Selenium, Peerless etc Plus fooling around with digital players. Have some test equipment but my Tektronix 7704 died last year so I’m crippled for the moment. - I can walk but a back injury and age keeps me lazy and don’t do much audio projects lately. But this PC audio seems easier for me and since I’m mostly at the computer is a logical little ‘project’.
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Old 17th May 2014, 03:10 PM   #14
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In my experience, PC speakers need as good amplifier as standard hi-fi speakers, if you want to get their best.

I gave to a friend of mine JAMO E600
Jamo : Bookshelf Speakers : E600
to serve as PC speakers.

We found we can get very good sound when we use a good amplifier, not a chip toy. So I gave him one of my older projects
PM-AB1 error correction amplifier

and he has been very satisfied with the result, now for about 4 years.
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Old 17th May 2014, 04:08 PM   #15
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Quote:
Originally Posted by PMA View Post
Frank, do you care about -

1) Flat and wide frequency response
2) Usable SPL
3) Low distortion at higher volume

In case you care about any of those 3 items, PC speakers are not for you. In case you do not care, please go ahead with PC speakers, but please do not convince the others who do care, that PC speakers are satisfactory for high quality sound reproduction.

We will appreciate positive contributions to the thread from anyone. We know the shortcomings from PC audio and we are trying to minimizing them so no need for you to call them. From your posts on the BT thread we know you are a perfectionist at audio so maybe this is not a thread for you dealing with underperforming chipamp audio which are not flat on frequency response.

Thanks for post 14 which is a positive input, I’ll look to your links, I don’t want to be rude to you, nothing personal.

Antonio
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Old 17th May 2014, 07:38 PM   #16
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Quote:
Originally Posted by fas42 View Post
Thanks very much for your feedback, Antonio, and thanks too to abraxalito for coming on board - you'll get plenty of good ideas from there, !

Okay, go straight to the heart of the matter, where you said for the PH, "less grunge and almost not at all mashed over the heavier passages" - this is where to put all your effort, you need to sort out where the PM is going wrong. For example, there may be an intrinsic problem with one of the drivers, a faulty unit, a problem buried so deep in the makeup of the beast that it won't be worth your while trying to get around it - I have a pair of pseudo-Altec PC speakers, and they're pretty terrible, raw, compared to the Harmans - it may be possible to sort them out but I haven't bothered trying.

So, concentrate on where you hear the grunge with the PM - is this a volume related issue, if you turn down the level is there a point where it largely clears up? And similarly with the heavier passage mashing, is this also volume related - can it be largely eliminated by running at a low enough volume?
I guess grunge is an incorrect word trying to explain what I hear, no problems from the speakers. I seldom hear at loud levels, mostly low to mid-levels over this close to ear speakers, about 3 feet.

First let me say that the system is quite musical but it does have a couple of offenders at some points during the performance, one is a peak at mids, to put a number say 800 to 1k Hz, evident in soprano voice. The other would be what I described as Mashy at some point of the WP somewhere at the end of the first movement (8 to 9 or so minutes) and not necessary happening with low frequencies. Seems more like an overload on sustain passages where various notes are played at the same time.

Hope this explanation helps.

Antonio
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Old 17th May 2014, 08:01 PM   #17
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Quote:
Originally Posted by apassgear View Post
From your posts on the BT thread we know you are a perfectionist at audio so maybe this is not a thread for you
This is an open forum, as far as the forum rules are fulfilled, and I have replied on topic.
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Old 17th May 2014, 10:27 PM   #18
fas42 is offline fas42  Australia
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Quote:
Originally Posted by apassgear View Post
I guess grunge is an incorrect word trying to explain what I hear, no problems from the speakers. I seldom hear at loud levels, mostly low to mid-levels over this close to ear speakers, about 3 feet.

First let me say that the system is quite musical but it does have a couple of offenders at some points during the performance, one is a peak at mids, to put a number say 800 to 1k Hz, evident in soprano voice. The other would be what I described as Mashy at some point of the WP somewhere at the end of the first movement (8 to 9 or so minutes) and not necessary happening with low frequencies. Seems more like an overload on sustain passages where various notes are played at the same time.

Hope this explanation helps.

Antonio
That's excellent, and your detailed experience means that you have a very strong feel for what's right and what's wrong.

That overload on sustain passages to me rings clearly that the power supplies are running out of energy reserves when a constant draw is called for, as a simple solution the smoothing caps need far more uF on board. My PC unit has the same problems still, if I feed it the wrong material, so I just back off sufficiently. My approach, in the past, was to over-engineer the chip amp supplies, 95% of the circuitry was PS: comprehensive regulation, then relatively huge local decoupling - zero overload problems.

It is possible that the mains power draw is exacerbating the situation - what I would do, as an experiment, is to feed the PC speakers the cleanest power possible: use a decent power conditioner if possible, and/otherwise devote a house circuit purely for the speakers, nothing else plugged in - so the source component is running off a completely different spur. Does doing this make any difference to the amount, and quality, of the overloading?

It's all about using simple techniques to isolate what is causing the issues - used carefully, it can tell one a great deal.

The soprano voice distortion may be due to the same issue, or it may be something else - I would try and resolve the overload first, and see.

In terms of loudness, it should be able to go substantially above what you listen at - my unit will happily fill the house, provided I don't go silly on the material: classical I can normally run at maximum, without audible problems.
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Old 18th May 2014, 03:49 AM   #19
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Pavel, you are welcome to participate on this chipamp thread. BTW, the schematic you showed looks very interesting but no values. Would be interesting to start a thread on that type of simple amp.

Antonio
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Old 18th May 2014, 03:55 AM   #20
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Frank,
Since we can’t find a definite answer to the maladies I will do what I have done before on upgrading amps like changing caps at the active bypass positions and maybe others on the way while at it with better quality parts. Of course special attention will be given to the PS which is the most obvious as you also suggest. The transformer looks very small so I might also replace it. Wish I had a schematic. - Will see next week what I come with and report back.

Antonio
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