Let's keep a good thing going...

- Official β22 amplifier website
- Official σ22 power supply website

[Edited by amb on 09-21-2007 at 03:02 AM.]

http://www.amb.o...%20set300b4.jpg

thanks

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[Quoting amb]

loop_, I believe that's a Par-metal 20-series 16"W x 12"D x 5"H case (model 20-16125x).

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It is actually 16"x12"X4" (model 20-16124C) clear anodized.

[Edited by set300b on 05-22-2007 at 01:11 PM.]

was wondering, if I get an internal divider plate inside and house my trafo with the psu on one side is that likely to solve hum issues, or is it better to play it safe and house the trafo in another casing?

[Edited by loop_ on 05-22-2007 at 02:27 PM.]

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[Quoting loop_]

thanks. it's looks like a really neat chassis..hope shipping to asia is cheap...

was wondering, if I get an internal divider plate inside and house my trafo with the psu on one side is that likely to solve hum issues, or is it better to play it safe and house the trafo in another casing?

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Shipping to Asia won't be cheap as it costed me ~$15 to ship from East Coast to West Coast.

As for your tranny hum, I don't think an internal divider would solve the issue because the internal dividers are available in 1" height only and secondly, they are not alodined.

Please note that this subject has been discussed extensively on the forum and the best solution still seem to be to house the tranny externally.

This is my 1st DIY project and has gone quite smoothly. My only real problem was putting VR1-3 backwards in all 3 boards. I thought about just leaving them and using them counterclockwise/clockwise instead of normal, but I decided to desolder tham and reinsert in the correction orientation which was a pain. The amp sounds great even with an iPod & Apple lossless files as a source. I really like the K701 & B22 combo.

[edit]The material arrived just one day after ordering it! More importantly the trial was a 100% success. I cut strips of the sheet metal 2" wide resulting in 2" x 4" laminations so that I could test the effect of multiple layers. The source of my buzz is the right channel input on the e22 backplane board. Placing 10 sheets of the shielding material (total thickness = .1") so that the strips were centered on right channel input section silenced the noise. I'm going to play around with how to implement this but I'm pretty darn psyched to know that total elimination of audible noise is possible.

[Edited by n_maher on 06-14-2007 at 05:53 PM.]

We must think alike! I too ordered 10' of the material so that I could experiment. I used about 2' doing my experiments last night but should have plenty left over for the final solution.

If I end up with any substantial leftovers I'll offer them up here if anyone else would like to play around with it.

I just realize that I'm missing 2 Molex KK 0.100" 3-circuit plug for the headphone output: the white plastic part that must be mounted on the cable end (while I have 2 Molex KK 0.100" 2-circuit too much). Probably something went wrong when I ordered them .

I'm wondering if someone here has a couple of Molex KK 0.100" 3-circuit plug left, I will take it over from you.
(Of course I will pay for it + shipment cost). Much appreciation if someone can help me out.
I know that Mouser and Digikey sell these connectors... but placing an order for some Molex connectors doesn't justify the shipment cost to Europe.

3 channel β22 w/ backplane board.
I have jumpered the Rg position on the backplane.
The hiss disappears if I short the input at the board (L or R channel).
Pot is grounded to Input Ground & chassis.

I am pretty sure this is something simple, but everything looks correct to me!

The default gain of 8x is good for most headphones, but if you have a particularly sensitive, low-impedance headphone, you may hear just a little bit of the noise floor at the range of volume control pot range you describe. At minimum volume, the L&R board inputs are shorted to ground by the pot. At max volume, the amp board inputs are also shorted to ground because you have the inputs jacks shorted and the pot is turned "wide open". That leaves somewhere in the upper reaches of the pot travel (but not at maximum) where the equivalent resistance to ground (as seen by the amp) is highest. High resistance = noise.

If your Rg is jumpered, and the pot is mounted the chassis, then the pot body will already be connected to input ground (through the right rear backplane board mounting screw). Thus you don't need a wire to explicitly ground the pot to IG, unless the chassis panels don't make good electrical connection (e.g., anodized panels). The wire might add a second path from input ground to the chassis, which causes a small ground loop and may or may not cause noise. But ground loop noise is usually hum, not hiss.

[Edited by amb on 05-27-2007 at 03:32 PM.]

Thanks for the help!

Shipment cost from ATI Thailand to Europe is not cheap if you buy only one enclosure (can be up to 60-70% the price of the enclosure depending on the shipment method ).

And for my σ22 I use an HiFi-2000 Galaxy Max 283 (230mm x 230mm) with 10mm faceplate. Shipment cost within Europe from HiFi-2000 is very reasonable. They now have a webshop which provides sufficient information about prices and shipment cost.

Nice work on the cases too!

BTW, I snipped the extra ground wire to the pot (it didn't change the behavior).

Thanks for the help! I'll post a picture of it a bit later (mine won't be winning any beauty awards, though).

Thanks,
Andrew

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[Quoting amb]

agreenfi1, what headphones are you using to do the listening with? Can you describe the noise a bit more? Is it like white noise or something else? How loud is it? Also, what volume pot are you using?

The default gain of 8x is good for most headphones, but if you have a particularly sensitive, low-impedance headphone, you may hear just a little bit of the noise floor at the range of volume control pot range you describe. At minimum volume, the L&R board inputs are shorted to ground by the pot. At max volume, the amp board inputs are also shorted to ground because you have the inputs jacks shorted and the pot is turned "wide open". That leaves somewhere in the upper reaches of the pot travel (but not at maximum) where the equivalent resistance to ground (as seen by the amp) is highest. High resistance = noise.

If your Rg is jumpered, and the pot is mounted the chassis, then the pot body will already be connected to input ground (through the right rear backplane board mounting screw). Thus you don't need a wire to explicitly ground the pot to IG, unless the chassis panels don't make good electrical connection (e.g., anodized panels). The wire might add a second path from input ground to the chassis, which causes a small ground loop and may or may not cause noise. But ground loop noise is usually hum, not hiss.

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[Quoting Ferrari]

munchkin, I use an ATI-737U enclosure for my β22... very tight fit as you see:

Shipment cost from ATI Thailand to Europe is not cheap if you buy only one enclosure (can be up to 60-70% the price of the enclosure depending on the shipment method ).

And for my σ22 I use an HiFi-2000 Galaxy Max 283 (230mm x 230mm) with 10mm faceplate. Shipment cost within Europe from HiFi-2000 is very reasonable. They now have a webshop which provides sufficient information about prices and shipment cost.

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Hi Ferrari

what caps are you using? Also, could you tell me how tall your heatsinks are, and how tall you think the heatsinks could go in that chassis? And did you get them to drill your faceplate for you and give you the knob?

thanks!