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Title: 50w OTS HRM voltage help please Post by: rogb on June 03, 2010, 06:01:15 PM Hi there,
I have just finished my C'tone build and it is working pretty good. Sound is coming along as I am burning in and tweaking my trimmers. My main concern is voltages with the Hammond 290DEX (for UK). On V4 and 5 I am getting 470-474V with TAD 6L6 WGC and V1-1 is a bit high at 207V with an old Telefunken. I have tried some different V1 and V2 tubes but it seems about the same. V3 is a Sovtek LPS balanced up at around 298V. I have attached the layout showing where I was told to look at dropping the voltage to V1. I have tried some different values but I can only get the voltage up not down. This is only my second build so I am no expert. I really would like to get the V1 down to 195-200V as this would be a good starting point for tone tweaking. Nobody said this was gonna be easy..... Cool Thanks Rog Title: Re: 50w OTS HRM voltage help please Post by: erwin_ve on June 04, 2010, 05:44:18 AM Try raising the value of the 3K3 resistor to 3K9. Raising the value of that resistor drops the voltage for your pre amp tubes.
Title: Re: 50w OTS HRM voltage help please Post by: rogb on June 04, 2010, 08:44:21 AM Many thanks for that Erwin, I found that I hadn't connected the ground to the FET simulation resistor (220K) on the right :-[ :-[
I now know how to tweak the voltages on the pre amp and that is another thing learned :) Once that was done, I am now getting 194 or so on V1 and 205 on V2, which should do fine. At low level, it sounds fine, hopefully today I will get a chance to crank it a little 8) I have a choke /resistor on a switch, which I can hardly tell at low volume and an HRM lift which really does boost it but I kinda like the HRM sound. PAB on and HRM off turns it really wild :o There sure are a lot of tones in there, I'm loving the clean too, even the Strat sounds really jazzy if you play with the options! All in all I am very pleased with it. I'm just building the head cab today, got to finger joint the panels, no fun, I can tell you! Thanks mate Cheers Rog Title: Re: 50w OTS HRM voltage help please Post by: hywelg on June 04, 2010, 03:48:03 PM All in all I am very pleased with it. I'm just building the head cab today, got to finger joint the panels, no fun, I can tell you! If you are doing that by hand you are a true masochist. Get a router and a jig ;) Title: Re: 50w OTS HRM voltage help please Post by: rogb on June 04, 2010, 04:47:52 PM Yes mate, just come in from the garden, I have done 4 of the edges. I did build a jig and the router is mounted in to a B&D workmate. Just push the panels across the router bit, nice square cuts, move the jig and cut the next one, easy.
The last one I did in pine, and it cut cleanly. This 18mm ply disintegrates as you cut it :'( I have started to cut the vertical cuts with my saw so it doesn't splinter too much. It will all look lovely when it's finished :) and covered in sexy blonde tolex... mmm |