Choke for HRM with 2xEL34

[adamG]

Hi Guys,

Could you help me to choose a choke for HRM 50 with EL34?
As standard, prefarable one for those tubes, acc.to Marshall's circuit is 10H, approx.120mA.
But ,I do not get why that 120mA or more is needed ,when only 3 pcs.of 12A_7 and two screens of EL34 is powered after choke.

Thank you in advance.

Regards,

Dariusz   

[HotBluePlates]

... Marshall's circuit is 10H, approx.120mA.
But ,I do not get why that 120mA or more is needed ,when only 3 pcs.of 12A_7 and two screens of EL34 is powered after choke. ...

EL34 screens may idle around 4-6mA but then rise to 50mA or more during peak output.  See page C1 of this EL34 data sheet.

120mA may be overkill. But what if it's not much bigger/more expensive than a 70mA choke which might be marginal?  Exceeding a choke's current rating may saturate the core and cause inductance to drop to zero.

[drgonzonm]

It is my understanding that the HRM -50 is a clone of one of the 50w Marshall's,

Depending on which Marshall, the choke could condition the entire B-Rail, or could start the conditioning after the O/T.  your comment and HBP's comment suggests its the latter,  If choke conditions the entire B-rail, then the 120ma or a 250ma probably should be used,  if conditioning starts after the O/T. then I would suggest a lighter duty choke.  It is my understanding that you need a minimum current to make a choke active.



Thanks

[tubenit]

It is my understanding that the HRM -50 is a clone of one of the 50w Marshall's

IF I am understanding "the HRM-50" that he is asking about,  it is a Dumble amp and nothing like the 50w Marshall.  I have schematics for both.  Very very different amps. 

With respect, Tubenit

[drgonzonm]

It is my understanding that the HRM -50 is a clone of one of the 50w Marshall's

IF I am understanding "the HRM-50" that he is asking about,  it is a Dumble amp and nothing like the 50w Marshall.  I have schematics for both.  Very very different amps. 

With respect, Tubenit

I saw on the web, that Dumble made modifications,  I also saw that Ceriatone, was selling both kits and completed amps under the HRM-50 name.  There were no schematics posted on this forum's Dumble section nor is there any schematics I could find with a Ceriatone name associated on this forum.  If you can post the schematic, I would appreciate it. I believe others would be appreciative also.   

Returning to question at hand, is a 120ma choke too much?  or should adamG use a 70ma choke?  hopefully, your schematic can provide some help. 

Thanks, 

[sluckey]

Go check out TAG. They have 113 pages of Dumble discussions and 7 pages of Dumble schematics.

[tubenit]

I saw on the web, that Dumble made modifications

. 

It is my understanding that the HRM -50 is a clone of one of the 50w Marshall's

If you are suggesting that Dumble may have modded a Marshall into an HRM-50 ............

No, Dumble did NOT make modifications to a Marshall to make an HRM-50. As I said, totally different amps.

Yes, he did make some mods to some Fender amps from what I understand.


As Sluckey said, the Amp Garage has lots of Dumble info including HRM-50 schematics.

With respect, Tubenit

[drgonzonm]

I did not open the amp garage website, there were several warnings about dangerous downloads, with the site. 
I am not suggesting that Dumble modified a Marshall, lets restate that what I read would be a "Dumble inspired" modification.    this website discussed a Dumble clone of a HRM-50.
http://www.tonymckenzie.com/ceriatone_hrm_review.htm

Ceriatone at  http://ceriatone.com/productSubPages/OTSHRM%20Series/HRMMain.htm,
offers a HRM-50 in its offerings.

Are there more than one amp called the HRM-50? 

Considering that there are less than 500 Dumble built amps, it seems reasonable that the HRM is question is a Ceriaton offering. I ask adamG to chime in.   

I do not mean any disrespect, as I welcomed, the correction. Could we return to the original discussion regarding the choke. 

[adamG]

Dear Guys,

Thank you very much!

I name this forum as my favourite place in the web.

Best regards,

Adam