The Amp Garage

Gentlemen (and gentlewomen), Anyone ever work on (or play) a Jim Kelley Line Amp? I've always wanted one, and recently found a guy who might be willing to part with his, however it looks to be modded a bit: the slaved power section appears to have been converted from triode operation to pentode.. bu...

It's used as inductor in series with cathode bypass cap. HAD did something like this in his Manzamp. Not quite the same implementation though. Note that the LC element(s) in the POW are actually connected to both the cathode and plate (roundaboutly). It's my understanding that out-of-phase nature o...

I didn't see it mentioned, so I will add the one small piece of SSS info that I know about. One of these amps was owned by the Canadian guitarist Colin James, who was apparently turned on to them via his SRV connection. I remember seeing it listed for sale in the Rocket (Seattle area music 'zine) in...

Hi! Is there a reasonably easy way of making the OD channel of a Ceriatone HRM Bluesmaster sound more like the OD channel of a regular Ceriatone HRM? All while not changing the sound of the clean channel! Cheers Es What I do is change the boost so that it is of the old "treble-lift" type (which is ...

Why not just jump across the socket to connect to the first stage plate? Or even from the pin 6 plate to the pin 2 grid stopper at the terminal strip? Retaining the grid stops at the "standard" values is odd too, as a large grid stopper on a CF doesn't do much for HF roll-off with its less-than-uni...

I don't know what to think about the CF hypothesis, it certainly sounds plausible, and a measurement showing a large Rk would confirm it. Still, that green grid wire that crosses to the other triode emerges from the goop exactly where the OD entrance trimmer would be. I agree with you Martin re: wh...

I don't think there is a CF stage here since the two triodes have separate plate, grid, and cathode leads. The drive control does not replace the OD entrance trimmer since the lead from the Clean output to a V2 grid stopper is the same as usual. Here's another possibility that is consistent with th...

Overdrive entrance pot on front panel? Cathode follower V2? I don't think so. All knobs are accounted for by the usual ODS arrangement, and V2 has separate plate, grid, and cathode leads on both sides. Looks like a ripper to me. The lack of an OD entrance trimmer, and the "crossed" inputs to the OD...

The 20V is in error due to the meter's input impedance upsetting the bias point. I suspect that Charlie measured it in the same way. Check it at the bottom of the 4k7 for a more accurate result. I'd expect a bit under 43V. The grid leak on the PI has to be a 1M, even if the third band does look a l...

jelle wrote:I just did a voltage test for you:

V2: 218V NA 1.53V, 265V 20V 45V.

The junction between the 56K and 33K reads 15V.



Jelle

Thanks, Jelle!

-chris

The resistor is yellow/violet/brown=470 ohms. I might have made a mistake on the NFB resistor but I am pretty sure on this one. CW Hi Charlie, I'm a little late to this thread, but many thanks for the cool info on this amp! A question for you (and others though): in going over the cathodyne PI valu...

Added a PDF file with my notes on the Opal to my original post.

Cheers!

chris

I had a few questions about the Opal and other two rocks. Is there a schematic for the Opal? Is this the only model that is both HRM and bypasses for non-HRM? How difficult would it be to mod the Opal schematic for 100 watts? In a related note, is there circuit info for the TS-1? Anyone been inside...

I did something similar on one amp (Chris actually played it). Chris it was that snakeskin amp. At that time, the amp had 5881's installed. It was a Bluesmaster front end into a non-HRM OD section with 150K/100K plates. It actually sounded quite nice. No loop on V1B btw. Standard BM boost, with gai...

Hi, This week a friend of mine is gonne bring over his d-clone. Non-hrm skyline(sorry I'm not into the new namings). The plan is I'm gonna mod it to a Bluesmaster pre-amp with a non-hrm overdrive section and standard PI/power amp with 6L6. Obviously it will take some time to get things right, but I...