The Amp Garage

I have an AirBrake and have compared it to the VVR in the same amp. While both sounded quite good, the VVR sounded better to me at higher levels of attenuation. Cool...thanks so much! Anyone else? Same situation (18-watt Lite IIb w/ VVR and airbrake). Same result. The airbrake is definitley one of ...

Another ditto for marstran. I've got a full set of PT/OT/Choke in a JTM45 and they're great. He seems to be out of stock at the moment though. Another option is the Hammond 1750N. It's $80 from angela.com, but I've never used one personally so I can't speak directly to it's quality. The MM Tone Clon...

Hi people, I have a question that maybe some of you can help me answer: I built a JCM800 preamp (actually there´s a post here about that), and I was getting hum (rectifier spike hum specifically). Eventually I solved the problem but when I was doing research about how to solve it, I read somewhere ...

There are 2 things that I have a VTVM for that can't be done with a normal DMM: Sorting through 1-Ohm resistors to get exactly 1-Ohm. Measuring the grid voltages on a Long-Tail-Pair Phase Inverter. A normal DMM really screws that one up. The better DMMs have a higher impedance (10M-Ohm for the Fluke...

I picked up a Harmony H-306 that wasn't working from a pawn shop for $50. I knew that the speaker wasn't a guitar amp speaker because of the massive chrome-covered hole-in-the-middle magnet in it. I got it home, pulled the speaker out to see what it was. Someone had put in a 1000-Watt automotive sub...

Thanks for the tips Phil. So what transformer specs should I be looking for to provide rectified 330VDC, and enough juice to power a 12AX7 in the preamp, a 12AX7 tremolo tube, and a 6V6GT power tube? For a center tapped tranny, something close to a 275-0-275 will get you 330VDC with the 6X4 rectifi...

Thanks Matt - I saw that page, which gave me the idea. Does a hybrid rectifier require a centre tap? I see at the top of the page he says a bridge rectifier needs a non-centre-tapped transformer, but it's not so clear with the hybrid. Forgive my newbiness! I'm still trying to dredge up what little ...

Thanks for your replies to these threads, Phil. On closer examination, and after doing as you suggested, it's clear that this is a "found" transformer that someone has installed to get the amp working on 240VAC mains power. There is NO centre tap for the HV secondary, only for the filament supply. ...

It sounds like someone tried to convert it to a half-wave rectifier. I'm not sure what pin 2 on the 6X4 would do as it doesn't look like it hooks up to anything. That setup would probably push B+ up into the 450V+ range. And it would hum like nobody's business. Where is the center tap for the HT win...

Thanks sky. Where did you come up with the 418vdc figure? I thought 300v ct off of the pt would put me in the 320-340 vdc range. Great doc from hammond: http://www.hammondmfg.com/pdf/5c007.pdf 300VAC * 1.4 = 420VDC That's for silicon rectifiers. If you wanted 320-340V, run it with a 5Y3: (300VAC * ...

Everything I read suggest that a pair of 6v6's in class AB1 would want to see a plate to plate load of 8K on the output transformer. could I assume that a Vibrolux OT of 4K into 4 ohm would equal a 8K load into 8 ohms ? I see that Fender used 6.6K load on a Blackface Deluxe reverb, is that the same...

Thanks all for the suggestions. Right now, I'm leaning towards the rivnuts. That's what I use also. (That, and industrial strength velcro occasionally) Call around to some sheet-metal places. I've found one or two here that do rivnuts for not too much. I had them do one chassis then bought my own r...

Tonegeek wrote: I wonder if he has gut shots of that amp not that I care

http://ampgarage.com/forum/viewtopic.php?t=5874

Why are the larger caps a good idea here. What exactly do they do in this spot. ange They're just filter caps for the bias circuit. Since there isn't much in the way of current there, the caps don't need to be very big. 8-10µ is pretty standard, but I've used 160µ on at least one build because that...

DAaaaannnngggg! :shock: :shock: I wish my last amp (my 10th) looked anywhere near that good. I usually throw mine in a pine box w/ some expanded steel in front to protect everything. I haven't even gotten to what would be considered my first 'woodworking' project. That is one nice looking amp. What'...