umph

Thats far to much those stingrays are terrible amps

[quote name='Mikey R' timestamp='1369340985' post='2088185'] Hey Umph, will post it when Ive got it to hand. The power amp is based losely on the bastard child of a Marshall Major (concertina phase splitter driving a long tailed pair) and a Hiwatt 405 (cathode followers driving the grids of the output valves). I'll add individual biasing for each output valve on the advice of John. Ive recalculated the values using the curves from the Chelmer Valve ECC81/2/3 datasheet, and pretty much followed the recommended operation from the 6550 datasheet for class AB1. If you look at the schematic for the Hiwatt STA preamp, its not so far to change the cathode follower of the ECC83 into a concertina, by splitting the load resistance (100k in the schematic below) between the cathode and anode. If you do this, then, since the ECC81 has such a high input impedance, each grid will see perfectly equal but opposite polarity siginal, therefore you dont need to use different load impedances (33k and 39k in the schematic below) on the anodes. Regarding the layout, yes it was a compromise. I had a choice between orienting either the PT or the chokes at 90 degress to the OT, the only way to have all three orthoganal would be to use a lay down type power transformer and that would have come with its own difficulties. From what Ive read, chokes tend to be noisier than transformers, so they were the critical component to be 90 degrees to the OT. Im not concerned, since the Hiwatts, as well as the big Orange and Matamp chasisse that Ive seen picture of have had their PT and OTs in the same orientation. [/quote] Hmm interesting, I'd be tempted to run a cathode follower instead of the concertina, as I don't think it'll clip well or have enough headroom to drive up your splitter. As to the balance issue a pot will work better as you'll be able to offset the balance in the valve itself. I just foresee issues that could be dealt with using resistors for your ht. With modern caps and proper layout it's very easy to get a quiet layout

Also you have seem to have two phase splitters and a driver in your schematic, any chance I could see your schematic?

Get in touch with fender, their spare parts are very reasonably priced

[quote name='Mikey R' timestamp='1369155853' post='2085588'] There would be quite a bit of current flowing through those resistors, so I wouldnt be happy with the dessipation or the voltage drop. Next one I build probably wont have dual chokes, but this is an experiment in overengineering. [/quote] Chokes don't work right unless they're having the right amount of current being pulled through them. There wont be that much current being pulled from the top rail either. The layout worries me with the transformers like that though

Looks good, just wondering why you went for a choke on both the power supplys? Resistors would've been fine and saved a lot of space.

check out the tube sound fuzz circuit, then spend a bit of time tweaking it

Didn't sound like sabbath to me, sounded a bit nu metal

[quote name='shanefitzy' timestamp='1365889302' post='2045785'] Yeah heavy is a description that fits well . I had it serviced not so long ago so it seems to function ok at test levels . I had 3 given to me a tnb 50 tnb 100 and then this tremolo version . [/quote] lucky get, I'll have the 50 off you if its weighing you down Great little amps these, they do an awesome overdrive sound. quite alot of them came with partridge transformers and mullard caps, so they tend to be fairly reliable aswell

Hiya, I've turned a few of these into preamps etc. They're not normally a plug and play affair but I could turn it into a very nice D.I for you

buy it and sell it for more to a gilmour fan

polyester and paper in oil are the best quality and most linear caps, at the signal levels coming off pick ups it doesn't make much of a difference though

not porn without guts

thats cheaper than an svt

broken valve will give almost no output, best bet is to try swapping it with another, if that doesn't do the trick you can mod it for more gain

[quote name='EssentialTension' timestamp='1363808916' post='2018054'] I realise Hiwatt were premium stuff but the Hiwatt wiring looks easier to do while the Selmer is impossible to follow. [/quote] are you trolling? It's harder to follow because it's a mess! not saying the selmers are bad but they don't stand the test of time like the hiwatts

I'd be looking to go custom, it'll be worth the money and think of the joy you'd get from having a bass that fits you

[quote name='Left Foot' timestamp='1363031649' post='2007381'] Hi guys, When playing long sustained notes i get some crackle/noise that appears when the note finishes or when played too strongly, so im presuming this is noise, as its unwanted sound. Would a noise gate solve this completely without cutiing out anything else? Looking at wiki it days that gates attenuate selected levels of sound, where as this sound appears at both low and high levels. Would a gate work or have i just got a noisy signal that is unlovable? Cheers guys. [/quote] You're overdriving you're amp and something is bias'd incorrectly

[quote name='mbellishment' timestamp='1362961859' post='2006892'] Well then you could say Mozart wrote the heaviest riff ever, and Black Sabbath electrified it. I would find that easier to swallow. I really do understand the influence Sabbath had on the metal genre, and how much they influenced pretty much every metal band going today... I just find saying 'Iron Man is the heaviest riff ever' is an easy answer, with added cool points because you're being retro! [/quote] mars the bringer of war by holst is real heavy and riffy

[quote name='GarethFlatlands' timestamp='1362954484' post='2006812'] I'd love to have been at the hippy fair they did as one of their first gigs and checked out the looks on the faces when this dropped. Still heavy as hell, I need to learn it actually. Also a good one, I do like a bit of Cave In. [/quote] listen to how overdriven the bass is!

[quote name='VTypeV4' timestamp='1362967118' post='2006921'] Cheers Umph, You say 'how it's wound' can you expand a bit more on that? For example, guage of wire, distance between windings, thickness of insulator, density of iron core? [/quote] with guage of wire the thicker it is the better the current handling and thus, low end and power, but obviously you can't get as many turns on so it means bigger transformers. Thickness of insulation is just there to stop interaction between windings and shorts. The quality of the iron used tends to also effect the frequency response mainly in the top end. It's why they use the lower grade in the svt to get rid of the top end to get the svt sound. To go on from what mr foxen was saying, also the way you wind it has an effect on the performance, putting on winding after another often leads to quite big imbalances etc. So its good to interleave the windings to get them more equal. Alot more thought goes into designing a good transformer than you think

basically the output transformer is a bottleneck and how much it limits the response depends on how it's wound. They're normally pretty linear up to the rated wattage in my experience

Your looper is broken, send it back unless you're handy with a soldering iron

no ones mentioned the wizard? for me this is THE heavy riff - http://youtu.be/sO7VP34n2Ps this one is awesome to ;D - http://youtu.be/Yf6XxFOh6tA

They look good if you want to play doom haha