audio-talk

I also have two 10mh @ 5A Hammonds (159ZJ). :wink: Those'll be yer input chokes for whatever greedy fil valves you have lying around . Should be easy enough to do your own if you can find some surplus unvarnished mains transformers . Even pulling apart , gapping and using the secondaries can you ne...

63mH for what exactly ? If those chokes are the £5 a pop ones from Ebay , don't expect much , they're more suitable for the isolation choke rather than input use .

cheers

Nic

All that complexity and sand ;) I just use a pair of laminated chokes (one input, one in series with the filament) , pair of caps and schottkys in an LCL supply for directly heated types . For the medium mu thoriated types which need a very quiet supply , such as 3C24 , I use an LM1084 sries reg fol...

When I used 5894 (very similar to 829) , the solder connections on my home-made topcaps melted and went crispy . Eventually I modified the guts of screws terminal blocks and used heatshrink to insulate . I'm not sure these ceramic caps will fare very well with soldered connections , I have some the ...

Did you use the new 15k Lundahls for the output transformers ? I must admit I had a lot of fun with the A2 valves , these all had the coated anodes which glowed cherry red in use

cheers

Nic

I wonder if any one as used ECC32 valves in there valve amps either in the front stage or as a phase splitter, if so how did you rate them, they are supposed to be a very good sounding valve. Acorn I have one somewhere but to be honest with you for octal double triodes a Sylvania VT231 or Brimar 6S...

I thought I'd better prove that I do build things having just joined the group! Not new (infact, much modified over the last year or so!) Basically it uses TZ40's. in A2 with 6L6's (Cathode follower) driven by E83F's (Pentode) The original Japanese design used 5693's but my 'experimental 'chassis h...

Hi Nic, Thanks, I should have said I also tried the D3A, but it was an unfair test as I hadn't bypassed the cathode properly and lost bass as a result. I do think the 300B is quite a bit harder to driver than the D3A and that although you can do it with a single triode, I'm beginning to think for a...

I'm using choke loaded triode connected D3A DC coupled to a 2A3 at present . I'm very impressed with the D3A and prefer it to E280F and EC8010 (in terms of high gm valves) . 99% sure the same situation will work with your 300B . Price to pay is 550V HT assuming a 350V op point on the 300B . Gets you...

For a 2 hour lashup this amp measures very well . With unoptimsed layout and AC fils on the 2A3 there is 6.1mV and 6.5mV hum at the speaker terminals . Power output 3.6w at clip . With one channel's inputs shorted and signal in the other , there was slight crosstalk but nothing major . Into a resist...

It's AC heaters and AC filaments at present although I much prefer the clean sound of LCLCL DC fils on a DHT . I'm not 100% convinced regarding the 36 ohm cathode bias resistor , will need to do some hang some test kit off the amp when I get a chance and see if there's much of a signal at the E280F ...

This one's going in a box :) Got this one up two days ago , made a few tweaks and it's now sounding very good , just need to tame a bit of bass bloom . Can run with E280F or D3A triode strapped with no changes , no electrolytics anywhere and also no sand devices of any kind . Plate chokes for the dr...

I did a SRPP 6C33 amp a number of years ago and burnt up numerous NOS teflon septar sockets . Whatever you do , try to source some decent ceramic (not Chinese) B7A/septar sockets before considering anything else . 6C33 get very hot and the heat conducts through the pins making the contacts crisy and...

Everything works ! I can't quite get to 14V bias, at the moment I'm on 13.2V and it sounds "big" and "nice". :lol: I think the bias needs a slightly smaller resistor (from 1.5K to 1K perhaps) and a bigger value pot (from 1K to perhaps 2-5K). Will have a listening session now. :w...

Here is how I made the driver stage to provide variable bias for my 3C24 breadboard . Please ignore all the gubbins on the output stage which used a modified mains toroid with a tertiary cancellation winding added . HF was excellent , LF all over the shop (not enough inductance , mixed in with dampi...