I do not fully understand the concept of chokes. when I am looking on digikey they were asking me about the dc resistance and current. Which parameters would be ideal for removing hum/buzz in a tube amp? the audio stage, not the power.
Would a 120ohms be appropriate? I read that amongst these forums. However all digikey items are rated down to 10mA which I really doubt thats enough.
Thanks!
Would a 120ohms be appropriate? I read that amongst these forums. However all digikey items are rated down to 10mA which I really doubt thats enough.
Thanks!
Hi,
The parameter good for removing buzz is the inductance (in henries). 10H is a good general start.
The gague of wire and length used determines the resistance. The smaller the core, the more turns needed for given inductance, hence the higher the resistance and lower the current rating.
Digikey does not have power supply chokes.
What you're looking for is a supplier of Hammond chokes, as they will likely be the best bang for the buck.
The cheap overseas chokes half the time aren't gapped for DC and are woefully overrated (I have some here common as dirt sold as 90mA DC that aren't gapped at all and wound with 36AWG [good for 36mA continuous] wire!!!), so you want to avoid those.
Cheers!
The parameter good for removing buzz is the inductance (in henries). 10H is a good general start.
The gague of wire and length used determines the resistance. The smaller the core, the more turns needed for given inductance, hence the higher the resistance and lower the current rating.
Digikey does not have power supply chokes.
What you're looking for is a supplier of Hammond chokes, as they will likely be the best bang for the buck.
The cheap overseas chokes half the time aren't gapped for DC and are woefully overrated (I have some here common as dirt sold as 90mA DC that aren't gapped at all and wound with 36AWG [good for 36mA continuous] wire!!!), so you want to avoid those.
Cheers!
Geek said:
Actually, they do.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=154G-ND
So does Mouser
http://mouser.com/Search/ProductDetail.aspx?qs=NRA9IjDEzh2JFrKrtnBU2w==
Neither generally have great prices, though the difference is often lower than the shipping from elsewhere if you are ordering other stuff. That is, if you need lots of Digikey/Mouser stuff and only one Hammond piece, you are often better off getting it through Digikey/Mouser than paying the additional shipping elsewhere. Neither have that many in stock, though I think Mouser is better in this regard.
athos56 said:
Radiodaze.com might be better, and you don't have to deal with Angela shipping weirdness or attitude.
Also, Handmade is closing out their Hammond and you might find a deal: http://www.hndme.com/productcart/pc/viewCategories.asp?idCategory=107
dsavitsk said:
Well, I'll be darned.
Showing all non-stock here. Best to get at another place unless he has an account.
dsavitsk said:
Fellas, notice his location.... suggesting Mouser is bad: FedEx + Canuck = $$$$$$$$$$ brokerage
Though if he can find a dealer to ship USPS, then that would be cool, as he can get it cheaper than up here even with the extra postage
Cheers!
would I be looking for something like this?
http://www.hndme.com/productcart/pc/viewPrd.asp?idcategory=107&idproduct=348
thanks for the headsup on the deal though, I'd probably get a pair of their output transformers too
http://www.hndme.com/productcart/pc/viewPrd.asp?idcategory=107&idproduct=348
thanks for the headsup on the deal though, I'd probably get a pair of their output transformers too
actually solely for cost reasons, im trying to stick to them because their output transformers are on discount =P I figured the hammonds are better than those 18$ ones mentioned else where on this forum. im not sure what you mean azazello with mkf.
thx
edit: btw! whoowhoo! im outta probation =)
thx
edit: btw! whoowhoo! im outta probation =)
If you are talking about Edcor as the $18 ones, then you might want to check out this page Tubelab tests hammond and edcor transformers . Edcore is good value for money.
Ah, just realised your the same guy asking questions about power transformers and Simple SE. What you want is a Hammond 193H 5H 200mA or 19J 10H 200mA. I see most guys are using the 10H choke. I am one of the first builders of this, my amp is the first one on the builders amps page on the tubelab site. I used the 193H 5H choke and get zero buzz or humm.
The Edcor transformers I listed on the other page are very good. I suggested the GXSE (guitar transformer) or CXSE. The simple SE I am listening to now uses the $20 XSE transformers and it absolutely sings, however, I have an active crossover pulling the sub 80Hz frequencies to dedicated woofer units with solid state amps. I have purchased the GXSE for other projects and Tubelab himself now recommends the Edcor CXSE above the Hammond I think, he just likes the sound.
The Edcor transformers I listed on the other page are very good. I suggested the GXSE (guitar transformer) or CXSE. The simple SE I am listening to now uses the $20 XSE transformers and it absolutely sings, however, I have an active crossover pulling the sub 80Hz frequencies to dedicated woofer units with solid state amps. I have purchased the GXSE for other projects and Tubelab himself now recommends the Edcor CXSE above the Hammond I think, he just likes the sound.
".....Cap 1-2 mkf paralell to the choke ...."
"...what does Cap 1-2 mkf parallel to the choke?..."
The capacitance and inductance form a resonant circuit . In this case resonance at the power supply frequency where the impedance of the parallel circuit is very high at resonance. This means a higher series impedance at mains frequency is formed compared to a plain inductance , resulting in lower hum on the final dc supply.
eg. 1uF and 10 H will resonate at 50.3 Hz .
The circuit is not an ideal resonant circuit because of the series resistance of the inductor. Any spice simulator should give you a quick comparison between the two circuits .
Cheers.
"...what does Cap 1-2 mkf parallel to the choke?..."
The capacitance and inductance form a resonant circuit . In this case resonance at the power supply frequency where the impedance of the parallel circuit is very high at resonance. This means a higher series impedance at mains frequency is formed compared to a plain inductance , resulting in lower hum on the final dc supply.
eg. 1uF and 10 H will resonate at 50.3 Hz .
The circuit is not an ideal resonant circuit because of the series resistance of the inductor. Any spice simulator should give you a quick comparison between the two circuits .
Cheers.
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