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seroxatmad Member Joined: Nov. 13, 2005 |  Message [#220] posted on: 01-10-2007 05:06 PM CST (US).   |  |  Hi all Ref the 1455 hammond case. In the UK i will be ordering from farnell - but find i can have an all black case (with either plastic or metal ends), or silver with silver ends. On the hammond website they have pics of a silver case with black ends. This is what I fancy, i can then have a silver control knob and matching silver phone jack. The problem is the separate black ends are sold as spares/options. Anyone know where they can be bought as most suppliers do not seem to sell the options available for the cases. John P.S Amb do you have any pics of your unit wired and housed? [Edited by seroxatmad on 01-10-2007 at 05:09 PM.] |
tomb  Headphone Council Joined: Mar. 1, 2006 | Message [#221] posted on: 01-10-2007 05:53 PM CST (US). | | Mouser definitely sells the ten packs of the 1455 endplates. It's not a standard stocked item, so they quote a minimal delay of 7-10 days, I think, or perhaps less. The last I looked at it, the delay seemed quite reasonable. The only reason I didn't order them is that I followed Mister X's advice and called Hammond directly. They sent me out a couple of replacement plates in just a couple of days. The Hammond drawings have the part numbers listed in the title block. Input one of those numbers for the endplates into the Mouser search, and you'll get their results. Calling Hammond directly is OK, too - but I gather that they're more interested in serving customers who've bought a case and screwed it up - like I did. Anyway, it's possible that Farnell or others do the same thing. A lot of you guys tell us that Mouser is not very friendly with overseas shipping costs. [Edited by tomb on 01-10-2007 at 06:05 PM.] |
(They were no charge!)| dave_m HeadWizer Joined: Jul. 1, 2006 | Message [#222] posted on: 01-10-2007 06:22 PM CST (US). | | Rapid sell hamond cases with the metal end pannels. Here you go... http://www.rapid...&moduleno=74372 If it has BL in the name, it is black. |
amb Headphone Council Joined: Apr. 1, 2004 | Message [#223] posted on: 01-10-2007 07:50 PM CST (US). | |
I'm in the process of re-casing mine into a Hammond 1455Q1602BK and relocating the toroid into a Jameco wallwart case, so everything is taken apart. Also, My front/rear panels are not finished yet, so I haven't taken any pictures. I'll post pics when I'm done. |
| seroxatmad Member Joined: Nov. 13, 2005 | Message [#224] posted on: 01-10-2007 08:29 PM CST (US). | | Hmmm my tracking number still shows them americans as having my pcb's at 1410 on the 08/01/07! Will have a look at rapid as really like idea of a silver case with black ends (either plastic or metal) and silver control knob etc.
Regards John P.S Was after mine in 1 case to site next to my mission cyrus one amplifier. [Edited by seroxatmad on 01-10-2007 at 08:33 PM.] |
| dBel84 HeadWize Fanatic Joined: May 5, 2006 | Message [#225] posted on: 01-10-2007 08:53 PM CST (US). | | @seroxatmad, mine is housed in a single case with the transformers separated from the pcb by a simple shield plate. All the wiring is shielded and I have 50R resistors between the amp and output. That said it is dead quite and I am still occasionally wow'd by the sound of this amp..dB |
| amb Headphone Council Joined: Apr. 1, 2004 | Message [#226] posted on: 01-10-2007 09:35 PM CST (US). | |
That's the way USPS Global Priority Mail works... their online "tracking" doesn't really show anything useful except that the package has been accepted at the post office. If you're lucky, it might even show that it's left the USA, but other than that, there is usually no further info.
Spectrum analysis shows that there is still a small amount of EMI when the toroid is in the same case (and it varies depending on the orientation of the toroid -- turn it a bit and there is a significant change). Even though I can't really hear any hum or buzz through my HD600s, I want my build to be as good as it can be, so that any test results that I publish can really be considered a reference, I decided to separate the toroid into a separate box. [Edited by amb on 01-10-2007 at 09:36 PM.] |
raromachine HeadWize Fanatic Joined: Apr. 15, 2005 | Message [#227] posted on: 01-11-2007 02:19 AM CST (US). | |
I've seen a amp build where the builder has placed a metal sheild between the transformer and the circuitry. Is this a feasible way to sheild the components from EMI or jsut for show? |
| amb Headphone Council Joined: Apr. 1, 2004 | Message [#228] posted on: 01-11-2007 02:26 AM CST (US). | |
It may help a little or not at all... magnetic fields are tough to shield. You'd need to contain the transformer within an enclosed can made of ferrous material to shield effectively. A dividing wall between the PSU and other circuitry is sometimes used to shield against RFI (e.g., which may be radiated by a switch-mode power supply), but EMI is a whole different beast. |
| raromachine HeadWize Fanatic Joined: Apr. 15, 2005 | Message [#229] posted on: 01-11-2007 03:07 AM CST (US). | |
Thanks - the few sheilds I've seen have been thin material, so just for show I guess Is there any way to guage the range of the EMI generateed by a transformer of a certain size? I'm imagining it as a field. And! - I can't find the dimensions of the PCB - how big is it? |
| amb Headphone Council Joined: Apr. 1, 2004 | Message [#230] posted on: 01-11-2007 03:25 AM CST (US). | |
I'm not sure there is an accurate way to calculate/predict this. The construction, size and orientation would all affect it. I only have empirical experience from testing different amps. It does seem that the bigger the transformer, the stronger the field. The recommended Amveco TE62033 toroid isn't too bad. At a distance of about 2.5" from the amp board, the spectrum shows only very small spikes at the AC mains frequency and some of its harmonics.
http://headwize....=6605&pid=56455 |
| raromachine HeadWize Fanatic Joined: Apr. 15, 2005 | Message [#231] posted on: 01-11-2007 03:29 AM CST (US). | | Thanks! |
| dave_m HeadWizer Joined: Jul. 1, 2006 | Message [#232] posted on: 01-11-2007 10:46 AM CST (US). | | I wanted to add that aluminium will be very ineffective at blocking EMI and should not be used. If you cannot hear any noise through the headphones from the trasformer, then I wouldn't worry about it. |
| seroxatmad Member Joined: Nov. 13, 2005 | Message [#233] posted on: 01-11-2007 12:34 PM CST (US). | | Hi Dave I guess we will be the last 2 to build our amps Are you using 1 case or sticking the transformer in another case? Can i ask which sides of the PCB is 120mm i.e with ref. to the output transistors. John |
| amb Headphone Council Joined: Apr. 1, 2004 | Message [#234] posted on: 01-11-2007 03:19 PM CST (US). | |
The side with the output transistors measures 120mm. |
| randytsuch Member Joined: Sep. 9, 2002 | Message [#235] posted on: 01-11-2007 09:28 PM CST (US). | |
Why do you say that? I have been to more than one EMI lab for tests, and have seen Aluminum foil used as an effective EMI shield. Magnetic fields are a different story. Randy |
| amb Headphone Council Joined: Apr. 1, 2004 | Message [#236] posted on: 01-11-2007 09:55 PM CST (US). | |
EMI = electro-magnetic interference. Aluminum is not effective for shielding against this. It is good for RFI (= radio-frequency interference) shields. |
| seaside Member Joined: Aug. 16, 2005 | Message [#237] posted on: 01-12-2007 01:24 AM CST (US). | | I am currently working on my own BOM and will order parts soon. But before placing order, I want to know if I can use those parts I already have in my drawer. Here's some questions for you guys and amb. According to amb's BOM C3,C4,C12,C13 4 1000uF 16V electrolytic 647-UPW1C102MPD - Regarding C3~C13... I know the space is tight, maybe not enough for 1000uF/25V though... is 16V safe here at this position? - Regarding C37,C38... is really 35V cap needed at this position? I got some 220uF/25V in my drawer, and wondering if I can use them. - Regarding C19~C24, Any specific reason why they are 50V bioplar type? Can we use regular 25~35V rated eletrolytics here or not? - Regarding C25~C32, it looks like stablizing capacitor used with diode bridge. Looks like 10pF ceramic could do the job here... do we absolutely need MKT 100nF quality at this position, or its recommended because they are simply better? And few more questions - Any alternative for 2SK170BL/2SJ74BL that is easily found at US? - Regarding the case, which sized hamond 1455 would be used if I want the PCB, transfomer, and all connectors together in the same enclosure? - Is there any particulary essential part that has to be of very high quality... in order to ensure great sound quality? Thanks a lot. [Edited by seaside on 01-12-2007 at 01:45 AM.] |
| randytsuch Member Joined: Sep. 9, 2002 | Message [#238] posted on: 01-12-2007 01:42 AM CST (US). | |
But EMI starts with an E, for eletro. The "EMI" tests I have run include Radio Frequency bands, they go from 150KHZ up to around 6 GHZ. I don't normally associate magnetic fields with EMI, but I think it is semantics, so I won't make any more off topic posts. Randy |
| amb Headphone Council Joined: Apr. 1, 2004 | Message [#239] posted on: 01-12-2007 03:56 AM CST (US). | |
Yes.
25V is fine, however the 35V unit in my BOM has the correct lead-pitch (5mm) and diameter for the board layout. Your 25V cap will probably have 3.5mm pitch.
These are for the DC servo. Since the DC offset could stray either direction (positive or negative), the capacitor needs to be bipolar or it might "see" reverse voltage.
10pF is probably too small. The optimal value depends on the specific diodes you use. If you use the 1N4004s as listed, then the 100nF is probably appropriate. If you use fast recovery diodes then a much smaller cap could be used, such as 100pF. It doesn't have to be MKT. Multi-layer ceramic caps are also good. Just be mindful of the lead pitch and capacitor size.
You can get 2SK170BL/2SJ74BL pre-matched from me, or unmatched ones from B&D Enterprises. Both are in the US. I don't recommend substituting with something else.
Hammond 1455Q2201 (metal end panels) or 1455Q2202 (plastic end panels), add BK suffix for black anodized.
You won't go wrong if you use the recommended parts in my BOM. [Edited by amb on 01-12-2007 at 03:59 AM.] |
| dave_m HeadWizer Joined: Jul. 1, 2006 | Message [#240] posted on: 01-12-2007 05:12 AM CST (US). | |
You are thinking along the right lines. I looked it up.. RFI and EMI are names for the same thing (see Wikipedia). I think then that transformers don't emmit any EMI, they just have a magnetic field that leaks out.
What's the rush? You still need to order the parts to build? That will take a couple of days. The longer you have to wait, the better it's going to sound I'll have the transformer in the same case, I don't like external PSUs much. Make sure you earth your case properly if you do the same! [Edited by dave_m on 01-12-2007 at 05:19 AM.] |
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