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Review of the Audio-GD FUN - A modular Dac / Headphone amp / Preamp - Page 6

post #76 of 1242
2/27/10 at 2:00am
Quote:
Originally Posted by Currawong View Post
If you dislike the 627s, get the Earth. The Moon (due, I think, due to stereo crosstalk, going by RMAA measurements someone did) has recessed mids, which gives the illusion of greater soundstage. It doesn't sound like 627s to me at all. I was just trying the Pacific Valve config, with Sun and FET stage, and it's more 627-like with rolled-off treble. The standard A-mode config + Earth sounds right to me with all my headphones.
I second the Earth HDAM striking the right balance (A config with DIR9001/AD1852 modules). It is the most consistent performer of the 3 and I always seem to end up going back to it after a short while with the Moon or SUN V2's. Of the 3 flavors I use the Earth 90% of the time (in every piece of my gear an HDAM can be used in).....FWIW.

Peete.
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post #77 of 1242
2/27/10 at 5:48am
Great, I can't wait to try it out now BTW kingwa is excellent to deal with. Answered all my emails within minutes and after I ordered it yesterday, he shipped it today!

A question about burn in of the hdams and the fun... Do you guys just leave it playing for 300 hours? or should I let it rest/cooldown?
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post #78 of 1242
2/27/10 at 7:07am
Thread Starter 
Personally, I used to burn-in new equipment 24/7 without interruption.
However, Pricklely Peete mentioned somewhere that it is better to let components cool down and do the burn-in in cycles. It is probably a better solution that what I used to do.
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post #79 of 1242
2/28/10 at 10:01pm
Correct slim.a, for these two reasons. Thermal seating of the fresh heat sink grease needs heat up and cool down cycles and any suspect parts/solder joints will be exposed by the thermal cycling process fairly quickly although 100 hours of QC before shipment should sort out the the latter by a fairly high percentage (likely 98%).

I used to just run stuff 24/7 for weeks but found if I rested the gear once a day for an hour or so the thermal seating of the heat sink grease brought overall temps down much quicker. At first power up for the RE1 for instance it ran quite warm for the first week or so until I had cycled the power a half dozen times or so. The case temp then dropped a few degrees C overall once the grease was fully seated. I used to use the same thermal compound when I worked in the Industrial PC field (as a service department bench tech) back in the early 80's (the cheap white stuff) and I remember it needed a number of cycles to be become fully effective. I have some idea why but I have found the high performance stuff (like Arctic Silver) is really quite effective from the get go but it also needs a few cycles to reach optimum efficiency. Anyway Penchum and I discussed this very thing quite a awhile ago (via PM) with both of us coming to the same conclusions. A good number of heat up/cool down cycles during burn in is beneficial.

Peete.
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post #80 of 1242
3/1/10 at 2:46am
Great, thanks for the advice!

Another question if anyone knows... What does the gain switch do and does it affect the preamp section?
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post #81 of 1242
3/1/10 at 3:03am
Not sure how to explain what the gain switch does, but it helps to raise the gain when you use higher impedance headphones like HD600. It should affect the preamp output - at least, it does on my older Compass.
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post #82 of 1242
3/1/10 at 4:06am
Thanks, so with powered speakers I don't need to use it. I was just checking out the audio-gd fun site and kingwa recommends to leave it off. He also recommends to keep the volume between 10 and 2. I wonder if that applies to the acss gain model also?
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post #83 of 1242
3/1/10 at 6:54am
What power cable do you use with the FUN?
Do you think the Audio-gd power cable are worth buying or do you have something else to recommand?
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post #84 of 1242
3/1/10 at 10:23am
A gain switch controls how quickly it gets loud when you turn up the volume. Since headphones have wildly varying impedances, it can be hard to choose a good gain setting. For example, you might have very low impedance phones and a high gain in the amp, so when you turn up the volume, it's already quite loud by the time the dial is at the 9 o'clock position. On the other hand, you might have very high impedance phones and low gain in the amp, so you hit max volume with quieter classical music, which isn't very good either.
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post #85 of 1242
3/1/10 at 6:10pm
Quote:
Originally Posted by Currawong View Post
A gain switch controls how quickly it gets loud when you turn up the volume. Since headphones have wildly varying impedances, it can be hard to choose a good gain setting. For example, you might have very low impedance phones and a high gain in the amp, so when you turn up the volume, it's already quite loud by the time the dial is at the 9 o'clock position. On the other hand, you might have very high impedance phones and low gain in the amp, so you hit max volume with quieter classical music, which isn't very good either.
Agree that a gain setting for the amp is a very clever and useful feature. Currently I'm using Maverick Audio D1 but the gain is a bit too high (barely pass 9 o'clock for most of my sources). The mod would involve a soldering of two resistors which I rather avoid doing.
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post #86 of 1242
3/1/10 at 7:52pm
Well thats good to know, since I'll actually be using my headphones and my speakers with the audio-gd fun. Since it has an output switch. It was too cumbersome with the maverick to do that since they removed the preamp/headphone auto mute.

The thing is I don't really need an amp for my headphones. They're normal pc gaming headphones (steelseries) and I just like the convenience of not having to change my pc output since creative cards seem to like to freeze when I switch between spdif and analogue out. There shouldn't be an issue with using regular headphones through a headphone amp?
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post #87 of 1242
3/1/10 at 7:55pm
BTW I emailed Kingwa about the volume on the audio-gd fun. On the website it says to use the Fun with the volume between the 10 and 2 positions for the best quality. This doesnt apply to the acss version (version a).

Does anyone know where I can find some literature of how acss works/what it does?
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post #88 of 1242
3/1/10 at 9:18pm
Re a power cable - someone recommend the Cryo Sonikleer (around $45 on Ebay) somewhere else on this forum. I am very happy with that + FUN. YMMV.
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post #89 of 1242
3/1/10 at 9:20pm
Some of the pages for other Audio-gd gear have information about ACSS. Shotgun summary: Audio signals are fluctuations in voltage. Quality amplification requires quality components that behave in the most linear way with rapid voltage fluctuations. Some clever person in the '60s figured out that if you switched the signal to be fluctuations in current, then the result was much better, with components degrading the signal less in this state. Krell uses this kind of system too, calling it CAST.

The volume control in a regular amp is connected to the input signal. However, according to the Audio-gd site, an ACSS volume control is connected to the output of the current gain stage.
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post #90 of 1242
3/1/10 at 9:40pm
Great, thanks for the laymans answer! All I googled was gibberish to me
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