I am nearing completion on a double build & thought I would post the builds with a bit of the build story.
A old friend of mine was out visiting from the UK. We jammed together in our student days. I showed him some of things I had been building, one thing led to another & I agreed to make him an amp. I can't charge him, we'll probably argue that one. I decided on an orange one for myself. I started the cabinet builds while researching & sourcing parts.
I settled on the following configurations:
-
I've powered them up & am really happy with the sound. I'm still testing. I need to sort out the MOSFET mounting. The insulating washers I have are too large. I've also ordered bigger spec MOSFET's - NTE2377 & will stick those in when they arrive.
There is one big problem: The tremolos do not work at all. The speed & intensity pots do absolutely nothing. I have been through the wring & parts a few times can see nothing out of place. My initial checking against Richies voltage chart looked OK. I'll check it again in the week. The real issue here is that I don't know what to look for. Call it inexperience.
A old friend of mine was out visiting from the UK. We jammed together in our student days. I showed him some of things I had been building, one thing led to another & I agreed to make him an amp. I can't charge him, we'll probably argue that one. I decided on an orange one for myself. I started the cabinet builds while researching & sourcing parts.
I settled on the following configurations:
-
- Both would have the traditional trem channel. I settled on "Richies improved layout" (as in Richie & Dana Hall brothers that do the Hall VVR)
- Both would have VVR. For the scaling pot, I replaced the power switch with a CTS push/pull switched pot. I could only find an audio pot @1 meg. The power scaling is not exactly even& gets pretty sensitive @ 8 & more. I'm deciding whether or not I can live with it. Its possibly an acceptable quirk. I got some VVR kits but decided to use a more familiar on-the-turret-board configuration.
- On the orange amp I've replaced the 12AX7/ECC83's with 6n2p-ev. These are old Russian valves. I bought 14 on eBay for $20 +$11 for shipping. The shipped from Siberia & took a few weeks to get here. The "-EV" is one of the military versions. They are low noise & long life. The heaters are different & only wire pins 4 & 5 instead of [4+5] & 9. I think they sound pretty good & are way superior to JJ's. For the price, they are worth a look. You can also get adapters to make them plug&play in a 12AX7 socket. I have gotten hold of a few of these & will try them in my JTM45.
- I bought 2 Tayden "Great Brit" speakers last year. They are ideal for what I'm looking here. They have big 'ol magnets & are quite similar to the G12H, only much cheaper. They made in the UK.
- On Ewald's recommendation I got the chassis, faceplates, PT &OT from ValvePower in the UK.
- A lot of the components came from a wholesaler in the US & Tubedepot. I bought a lot of components from eastern suppliers via eBay. I am liking the "free shipping" that you see more & more from China / Hong Kong
- The pilot lights are temporary while I wait for the Chicago Miniature ones from the ZA RSonline. I have been waiting > 3 months since ordering... They are very close to the original round amber indicator & I really want them. - This is my only local online order. Go figure.
I've powered them up & am really happy with the sound. I'm still testing. I need to sort out the MOSFET mounting. The insulating washers I have are too large. I've also ordered bigger spec MOSFET's - NTE2377 & will stick those in when they arrive.
There is one big problem: The tremolos do not work at all. The speed & intensity pots do absolutely nothing. I have been through the wring & parts a few times can see nothing out of place. My initial checking against Richies voltage chart looked OK. I'll check it again in the week. The real issue here is that I don't know what to look for. Call it inexperience.
