1 Watt - World-Designs-Forum

andrew ivimey · #1 7th January 2007, 11:48 AM

USing 6DN7 and 6EM7 I cap coupled, I direct coupled, I ni-cadded the cathode and I used resistor and cap. I varied pretty much every component that might produce improvement and I varied the HT from 250 - 400volts, and then thought I'd leave well alone.

I'd like to see The improvement on Paul's 6EM7, but this is tehone I played with over December.

No croc. clips

Andrew · #2 7th January 2007, 12:40 PM

Tell us more....a spud by the look of it.

cheers,

A N Other

Martin213 · #3 7th January 2007, 05:10 PM

Yes,i must agree with Mr Other,please tell Andrew........

andrew ivimey · #4 7th January 2007, 08:43 PM

Strange, when I uploaded the picture I added text but no text appeared. That happened with my previous pic; the mess. So, what I said was something like this ...

Throughout December I tried 6EM7 and 6DN7 in quite a few different ways; direct coupled, cap coupled, messed with cathode bias, ni-cads too, tried HT from around 250volts to 450 or so. Made the amp very loud indeed but no dynamics, just flat out! and then returned things to normality.

For normality read Bottlehead's SEX amp Mk2.

Didn't try anode choke nor interstage ... shoulda done.

I'd like to see Paul's 6EM7 version or Gerry Kaufman's, if it is an improvement.

6EM7 and 6DN7 are very similar. As amps, using same PSU and output transformers I couldn't say which was better valve.

Nice spud.

Dave the bass · #5 10th January 2007, 10:26 AM

I've only just seen this thread. Great looking little amp Andrew. Are those the TX's from 'hardwareshop' you mentioned the other night?

DTB

andrew ivimey · #6 10th January 2007, 05:32 PM

Yes Dave they are, and he has put the price up since I bought them. IMHO you get what you pay for with output transformers. I dream of a 'bargain' but haven't found lucky nirvana yet.

Having said, when I first built a 6DN7 amp from Bottlehead forum I used (and still use) Fender Champ output transformers. They were about $13 each, plus postage. they are quite small. They sound lovely. I still have this amp with the luxury of valve rectification (for looks) too.

The same chap does a pair of 5K trafos for Â£19-95 which I used with EL84 and 807 (for a while). They suit the EL84s very well indeed, but the ones in the 6EM7/6DN7, well, I was lured by 'c core' n.b. single not double c core.

Harwarehouse, or whatever his name is, is fast, beautifully packed and meticulous in detail. He sends a bunch of email photos to you to show exactly what you are getting and how each individual item is packaged.