Next project?

[Dave the bass]

Well, I'm looking towards the winter and a project/s.

I've got a few lined up to keep me busy over winter but what I'd really like to plan for is another amp build. Having lived with 6B4G and 6EM7 for longer than I've actually used WD88VA I'm looking at possibly selling it and freeing up a bit of cash for the up-coming projects. Does that sound wise? The Rogers speakers too I'm thinking of flogging as I'm enjoying making and listening a lot.

I really like what 6B4G does, especially in combination with the MLTL's and Fonkens so I'm hoping you lot might give me a few ideas on where to go next. 6EM7 is great to have knocking around too but where to next?

As I've said above I like 6B4G a lot. Is that due to the fact its a DHT? I dunno but whatever it is I prefer it over 6EM7 in that it does something to the music 6EM7 doesn't (or is it the other way round, Oh I dunno). Anyway, I'm leaning towards another DHT amp.

I always keep my eye's open for bargains (natch) and today for the huge sum of £6.95 I've snared 2 x UX4 valve bases with 4 Audionote Tantalum 100R humbucking resistors, well...you gotta start somewhere haven't you Too good to just leave so I had 'em.

I'm thinking 2A3/6A3/poss 300B/any others? I'm willing to dissmantle DHTski as C3g seems to be a popular driver and I have huge great toroidal mains TX on him that I could press into service amongst many other bits on him and his PSU.

Thoughts?

DTB

[cressy]

what about pt15s? cool as fcuk to look at and i was impressed with the ones ive heard.

[pre65]

Hi DTB,

if you go with PT15 i will donate the two used ones i have for the project.

I was talking to Steve Cresswell about the possibilities of using PT15 triode mode in a DRD type amp but i think it's a bit complicated for me and i'm now looking at the 300b version.

Not sure how Andrew I is getting on with his PT15 amp,not heard about it for a while.

[Cressy Snr]

Hi Dave

Why not experience the joys of direct coupled amps by building a DC coupled 2a3 or 6B4G amp?

You can go either for Loftin White or Direct Reactance Drive like my PX25 amp.

The thing with these amps is that they are so incredibly simple but fantastic sound quality is available from them. My PX25 has only eight components per channel, excluding the power supply.

There's a grid resistor on the input,
a 5687/E182CC driver valve,
a choke,
a cathode resistor,
a pair of red LEDs
a power valve
an ultrapath cap
and an output transformer

That's it!

The 2A3 might be a better bet if you want to keep things really simple with AC heaters and filaments (2.5V filaments = negligible hum) and a triode strapped C3g might be all you need to drive it. The C3g has a gain of 40 when used as a triode.

Choke loaded in DRD and direct-coupled it'll easily swing 80V pk-pk into a 2A3. And it'll kick some serious current up it as well.

Should make a fab little amp that'll make those Fonkens and MLTLs sing.

You'll need a 450V HT supply for a 2A3, 700V for a 300B.

Steve

[pre65]

Dave-this is the place to see about 2A3,45 or 300b DRD amp circuits.

http://electra-fidelity.com/schematic.aspx

[Nick]

But Dave, what do you "want" to build? Despite your attempt to project the image of a bumbleing fool, I know in your zen nature, there is an amp you
need to build. What valve do you feel drawn to? Lets find that and work towards it...

[Andrew]

I thought you were doing a phono? But then its whatever you want to build, that's point, after all.....

-- Andrew

[Dave the bass]

Hi DTB,

if you go with PT15 i will donate the two used ones i have for the project.

Thats a very kind offer Philip, thanks matey. I'll bear it in mind.

But Dave, what do you "want" to build? Despite your attempt to project the image of a bumbleing fool, I know in your zen nature, there is an amp you
need to build. What valve do you feel drawn to? Lets find that and work towards it...

Ahhh! Out-zen'd by a Zen master Well, yes I do have a little back-burner plan but I didn't know if it made any sense and I fancied seeing in what direction you chaps would advise in going.

My take on it is thus, I like what DHT in SE does, having that smidge of extra power over 6EM7 is handy too, 2 watts or just over seems to be very handy here at Chez Bass BUT deep down I feel I've jumped a step too far in going straight in with a CC DC supply to the 6B4G's cathodes/filaments.

Steve's hit the nail on't head, simplicity, particularly DHT done with AC heating tickles my fancy. I'm feeling very 2A3 right now, yes I know it's close to 6B4G which has more than proved its worth but Mr C's DRD explorations highlights the simple things that make music and that appeals to me.

Now, if only I had 2 UX4 sockets with handy 100R humucking resistors thrown in too.... good lordy... would ya believe it...
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... IBSA:UK:11

I know 2A3 has been done to death but I'm intrigued by it. Saucy EH Gold Grid versions come up on eBay for about £65 and single plates are within easy reach of even an un-sold WD88VA budget, £35 + P+P from Taiwan.

I still don't think I'm ready for 300B yet TBH, I'd like to one day to see what they're like but thats a jump ahead IMO.

I thought you were doing a phono? But then its whatever you want to build, that's point, after all.....

-- Andrew

Deffo doing a Phono amp Mr L, have no worries about that. The mush-master needs replacing and that's on my winter projects list as well. On this thread I'm just putting out 'directional feelers' amp-wise

I've got a TT and arm to play with too as well as possible a pair of Saburo's.

Winter is almost as much fun as summer these days

DTB

[andrew Ivimey]

Oh but you shouldn't wish the summer away!

What was all that waxing down of your skateboard for if not to crown gorgeous golden summer evenings with high flying antics on and off the board?

Simplicity is the ticket, of course, and power we like welly. detail, clarity, imaging and dynamics are essential too. Oh yes, and we want cheepniss with looks to die for; then there is ethereal glows and total absence of hum.

I think that about covers it.

I had a go in a Sinclair C5 last Friday! (Handledbars under the knees indeed; I wonder what kind of world should exist for these to be acceptable as a major means of transport.)

I want my bicycle back

[pre65]

I know 2A3 has been done to death but I'm intrigued by it. Saucy EH Gold Grid versions come up on eBay for about £65 and single plates are within easy reach of even an un-sold WD88VA budget, £35 + P+P from Taiwan.

DTB

I saw some EH Gold 2A3 on e-bay for £65 a pair and noticed they were from a dealer south coast way.Anything to do with Rob Shakespeare Co ?

[simon]

The Rogers speakers too I'm thinking of flogging as I'm enjoying making and listening a lot.

Ah. Hook, line and sinker. You are now a fully paid-up member of the DIY club. There is no turning back, not that you want to. The L plates must go now

Zen amplifiers - I think you need to reach out for your own path of personal enlightenment. If you want to try 2A3s that is the way to go. It would be interesting to try a C3g as a triode - I haven't done that. But there are a number of ways you could drive it, and this is perhaps more interesting than the choice of valve itself. Others may disagree.

To test your resolve to find your path to enlightenment I will throw in a 45. Old stock are available for £15ish each, same 2.5V heaters as 2A3s so you can go AC and have minimal hum. Power output-wise they sit between the 6EM7 and 2A3 - a couple of watts - maybe just enough for you? And with minimal tweaking you can interchange 2A3s and 45s - different cathode resistor and small mod to the PSU potentially. The Bugle I built recently is a really lovely amp and so simple.

But is it time to design your own simple amp yet Grasshopper?

[andrew Ivimey]

They are from somewhere in Brighton; overpriced methinks! Is Rob Shakespeare a Brighton Boy!?

You aren't really going to get any increase in the VOL, with a 2A3 over a 6B4G. 6B4G is really just a twinplate 6volt heater version of 2A3. I believe that going twinplate was a reliable way of getting more power out of a DHT befopre they invented what became 300B. Now, reliable single plate 2A3s like Sovtek and EH, for example, are two a penny, or rather, two for £65. Original 2A3 single plates are soon to be the stuff of legend and people with too much money to spend.

Mind you, the story that Steve has taken us through probably points to more interesting fun and a different implementation giving a very different sound quality. I would guess that more than a few of us well remember how stunned we were with that Bluebell/Shishido Loftin White. If this DRD stuff a la Steve is as charismatic in its own way then it is very worth doing, indeed.

I have this chunky 700-0-700 transformer that was gathering dust ...thinks...opens up a new perspective! My PT15SE is being driven by a C3g, cap coupled with an HT of a miserly 300volts or so.

Let's do ozone!

[pre65]

DRD gets more watts from 2A3 & 300b !

Quote---What does this do? It allows the output tube to be driven to higher levels with lowered distortion. Instead of a measly 1.5 watts, he gets three watts from a 2A3, and 13 vs. 8 watts from a 300 B without stressing the tube. Distortion figure measured at the transformer? Less than 0.5%, mostly second harmonic.

[Nick]

Just because its on the web Phil doesn't make it entirly true. Last time I looked (which was just now) I would expect 3w from a 2a3 anyway, nice way of confusing matters by inventing the 1.5w figure.

I am not so convinced by the 13w from a 300b, to get that with 0.5% would either need some cancelation in the driver or going into A2, which the DRD may help with

[Dave the bass]

Oh but you shouldn't wish the summer away!

What was all that waxing down of your skateboard for if not to crown gorgeous golden summer evenings with high flying antics on and off the board?

Rest assured Mr I that my board is being well ridden this summer, this comming weekend we've got the biggest skate jam Dartford has ever witnessed ....



'DDK' = Dartford Death Kult !!! The toughest/roughest skate gang in the world

Right then, 2A3 looks like a go-er then but... before I get too deep is there anything for me to be gained (other than hum!!) by going AC heating on 6B4G?
Is it the lower voltage/higher current draw on 2A3 that allows folk to get-away with AC heating a 2A3, that appeals that does.

I like the idea of using C3G to drive 2A3 as that already there in DHTski but at the moment I don't think it's triode strapped as the screen grid is held at 150V by an OA2. Triode strapping (apart from sound a bit kinky) is when a resistor is used to join G2 to anode innit?

45, yes Simon, well now... I liked what I heard at Owston, two of the amps that really had my ears pricked were Mo's (ex Phils) 45 Rankin and Will's 45 amp too on that sunday morning session we had but a lot of that was to do with the way Will's whole system worked together, blissfull. Swapping back from 6EM7 to 6B4G showed me why I love it this morning. There's summat in it's sound that is just soooooo clear and yummy. 6EM7 is good, really good with MLTL's at Chez bass but DHT has the edge (I've had Physio on my back this morning and was at home for a while, oooo pain).

Oh, I dunno what to do! 2A3 looks like one of those milestones you have to do on Grasshoppers path-to-aural-righteousness and I've cheated with a CC DC heated 6B4G

DTB