Hi Folks, been lurking for about a year and have finally decided to take the plunge.
What I'm thinking of building is basically a D'lite but modded to HRM. I chose HRM based on all the comments about touch sensitivity and flexibility - it just sounds like my kind of amp - great sound but doesn't hide the playing. Some of the clips on this site are just fantastic!
The plan is to use a Weber Bassman PT and a Heyboer Bassman OT. Boards will all be scratch built from Normster's excellent info using the 16x8 layout.
I guess what I'm asking is - is this a feasible approach?
I've built a couple of other amps but never a switcher.
Sounds like a good plan. I just stumbled through a similar build and was very happy with the resultant amp. I didn't get to the finish line on my own, but with the help of a great friend that frequents here and turned me on to this site. If there is any help that you need, I'm sure you will get it here. This is a great board with many friendly and accomplished amp builders. Good Luck! I look forward to following the build and hearing the outcome!
nickt wrote:Hi Folks, been lurking for about a year and have finally decided to take the plunge.
What I'm thinking of building is basically a D'lite but modded to HRM. I chose HRM based on all the comments about touch sensitivity and flexibility - it just sounds like my kind of amp - great sound but doesn't hide the playing. Some of the clips on this site are just fantastic!
The plan is to use a Weber Bassman PT and a Heyboer Bassman OT. Boards will all be scratch built from Normster's excellent info using the 16x8 layout.
I guess what I'm asking is - is this a feasible approach?
I've built a couple of other amps but never a switcher.
Thanks!
I would forego the Weber PT and just go with Heybour all round. The $20 or $30 difference is certainly worth it. I used a Weber 100W Marshall PT in one of my early OD100 prototypes and it cost me a new fire extinguisher.
It must have had a weak filament winding that heated up and melted the insulation. I had the amp on test for a couple of hours and smelled something, looked over at the amp and noxious black smoke was pouring out of the chassis by the PT. The PT did a huge shellac dump on the chassis.
Just a personal experience, maybe a one off, but enough to put me off.
Since we have here a valve amp expert, it is a good moment to ask the following question(s):
1. What would be a very good PT for a HRM amp that drives 2x EL34? Would it be 345-0-345 with 0,20A or is something like 0,16A (some Marshall PT's for 50W models, presumably 2x EL34) and/or 0,18A (Hammond) is sufficient? Or would we need something like 0,22A? How about voltage, do we need 345-0-345 or would 320-0-320V suffice?
This is ¨price no object¨ type of consideration; looking for a true ¨powerhouse¨ PT that would have lots of guts and ability.
2. How about OT, what characteristics? What would be the best primary impedance, Marshall recommendation of 3,5k Ohm, or something else for D-type of amp. Again, this is a 2x EL34 output section.
3. One more question: if we are seeking studio quiet amp, would we need separate PT for relay supply, and what would its characteristics be (how many mA is sufficient, I suppose little)? Or is it OK to use 5V (rectifier valve supply, usually) winding on the same PT that is used for everything (low noise criteria being considered heavily here)?
'67_Plexi wrote:
I would forego the Weber PT and just go with Heybour all round. The $20 or $30 difference is certainly worth it. I used a Weber 100W Marshall PT in one of my early OD100 prototypes and it cost me a new fire extinguisher.
It must have had a weak filament winding that heated up and melted the insulation. I had the amp on test for a couple of hours and smelled something, looked over at the amp and noxious black smoke was pouring out of the chassis by the PT. The PT did a huge shellac dump on the chassis.
Just a personal experience, maybe a one off, but enough to put me off.
Alan.
Haven't had any problems with Weber before - but, like you, this is on a sample of one so doesn't mean much. I chose Weber because I can get the PT and Heyboer OT from the same source and Weber have been good in the past - they don't offer Heyboer PTs with Aussie/EU voltages unfortunately. I chose Heyboer because of their good reputation and reasonable cost.
On that note - any suggestions on "the best" PT/OT to use and where to get em? I'm not really wedded to Bassman, Heyboer or Weber but do need 240V in for the PT and don't know where I'd ever get to open up 100W (probably 30W if my wife has any say in it ).
Thanks!
BTW - seems like there's an overriding theme of "DOG" across the forum - another reason to like this place.
Just finished a build with very reasonably priced iron from antique electronics. Bassman PT - Prosonic OT at impedance 8/4/2 ohms. Don't know the manufacturer, but very happy with the outcome. It was an HRM in a D'Lite chassis. A clip of the amp can be found on this thread: http://ampgarage.com/forum/viewtopic.php?t=3264
PM me if you'd like the order numbers and details.
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10% of my family's weekly grocery bill is at stake!