Watts and Valves

This may be a stupid question. Most transistor amps are rated at last at 35w p/c upwards. Most valve amps are rated much lower - esp SET designs. I've been wondering about dipping my toe into the world of valve amps (probably WAD) and was wondering how this power rating difference translates into real world volume / headroom for transients. My speakers are rated at 89 db/w @ 1m so is 15 - 20w really going to cut it. What else do I need to consider? Am I missing something here? As usual, any help appreciated...

= John

 

It will be plenty, in reality watts has very little to do with actual percieved level. Two watts into 89dB can be enough in some cases (depending on impedances and so forth).
In case you didn't know, WAD isn't actually WAD any more, they are World Designs. Same sort of stuff but different management etc. Seem to be better so far.
Do you have any particular model/circuit in mind?

 

I guessed it would be - but that begs the question as to why so many mass market integrated amps are in the 50 - 100w range?

Yeah - they seem to be pretty upfront about the changes and their forum is quite active. I was considering the basic KEL84 integrated kit (15w/pc into 8 ohms). Nothing too complicated, just an introduction.

 

I think you'll be pleasantly surprised if you go for a WA amp. I had a KEL 84 several years ago and loved it - it lacked a little in the "thwack" and ultimate detail department but was a great improvement over the transistor amps I was using at the time.
When I sold it I moved to DPA transistor amplification which was very nice indeed but currently have a 'modded' WAD KIT 88 ~ 35 watts per channel. I can't see me wanting much more from an amp these days than that delivers.

 

I have an Emille tube integrated which puts out 70w. Into my previous speakers pmc OB1's, which are 87db I barely had to turn the volume knob to reach a room filling sound.

Rod

 

Kel 84 is a good starter, beats the Leek 20 imo. Not bad out the box but worth doing all the bits and pieces detailed on the wd forum, particularly the bridge rectifier mod. Make sure you listen to a proper SE amp when your looking for something better though, PP just doesn't cut it next to a good SE amp.
Actually, my kel 84 will be going spare in a few weeks- I recently moved and my phono stage and board built SE amp didn't fare too well in the move so need to order spare bits but if you want it and can collect from NW London, its yours. All you'd need is to buy a new set of tubes (the ones on there are a bit old tbh). Its a bit scruffy (it has an external psu and I never got round to tidying it up properly or fitting sockets- they're attached to each other by the multi-core cable) but its full working order and I've done a fair bit of work under the hood so its a decent amp ans not hard to tidy up if you feel the need.

 

It depends on your timing Jon.

Nick at hifi collective is in the process of doing a prototype EL84 based amp.

It will have more power than the WAD, and knowing Nick as I do (and owning one of his amps), I am confident that it will kick ass.

Design will be again be by Andy Grove.

 

That is the deal of the century

If it was offered to me I'd be all over it like a rash. GO GET IT!!!

 

Agreed, start running now!

 

Ant if John doesn't want it your second in line. I want it to go to someone that will use it rather than sit in my cupboard as its brought me a lot of pleasure.

 

errrrr can I be third?

 

Ok some one can correct me ......

the reason small watt valve amps sound good and are able to drive 89db speakers is the output transformer this is a resovoir of energy ...solid states do not normally go this route as output transformers are very expencive. So the solid state needs to derive its power from somewhere ...ie in sheer output device grunt.

valves are a very good move .....!

 

I think the real answer is that for "normal" listening levels in a domestic setting, we only need a couple of watts..if that!
The rest comes down to quality issues.. decent powersupplies, class A, etc.
My usual listening level is probably less than 85db peak, my speakers are a fairly easy impedence load and 89db-ish sensitivity.. I could probably get away with a 1/2 watt amp.. The 10 watts that my amp is capable of is probably overkill=)

 

Really?

 

That's a very generous offer! Unfortunately, there's no way I'm going to be able to get to London in the forseeable future. Even ATP has been moved to the west this crimbo (the only time I ever head south as a rule). I do occasionally head back to Norwich - but that's a 5+ hr drive from here, so a detour isn't really possible.

Form a disorderly queue folks.

 

Anex you are a gent.PM me the detials and I'll come over.

I live in Orpington or Bethnal Green (gf's place) and work in Canary Wharf so should be able to get over quite easily.

Believe me it will get used, modified and generally looked after.

 

Woah woah woah, hang on a sec.
John: Are you going to ATP? If so, that would be a perfect place for a hand over and gives me plenty of time to sort out my knackered SE.

Otherwise I'll contact Ant when the SE is working again.

 

I am indeed going to ATP (Stooges AND Gang of Four! It's a no-brainer). If you are happy to carry it down to Minehead, then that would be brilliant and I will have the opportunity to buy you several pints. I'll be driving down from Bangor so getting it back safely won't be an issue.

= John

 

Ok, shouldn't be a problem. Only thing it I may need to seperate the amp from the psu. I have a 3 phase plug and socket which you can have but since moving to London I now lack any access to power tools so I can put the plug onto the umbilical cable for you and I will try to wire up the socket to keep things tidy inside but I have no way of actually mounting the socket in a useable fashion so you will need to cut a hole in the back etc. (won't take you long) or alternately just solder the cable back up again, whatever suits. Or I'll just cut the cable and give you the plug and socket, depends whether I remember to do it properly or not Either way I will give you a good clear diagram and make sure you check, check and check again with a multimeter that each wire goes to the correct place. I have loads of paper work for what I have changed inside which you can have to and if you get stuck at any point, give me a bell or pm or something.
For tubes I'd look at 4 Sovtek M (M for military) EL84's and 2 Mullard ECF80 (Langrex are usually good for stuff like that, pretty cheap too). Mullard made tubes for lots of people so don't worry if they turn up with GE or Valvo or something written on them.

Only thing I ask is that you pass it on to someone else when you no longer have a need for it (that is in no way rushing you to upgrade/pass it on etc. just don't let it go to waste ). When the time comes, if Ant still wants it then he should be top of the list but again, I'm not rushing you to be upgrading, use it as long as you need.

 

Sounds like a deal. If I like the sound, I'll almost certainly upgrade and I'll have a whole pile of resaleable Cyrus gear to finance it.

Wasn't quite sure what you meant about the plug - why 3-phase? I'm sure all will be clear when I see it. Did you add some kind of outboard PS? I can run it past the electrical engineering technician in the Chemistry department here if I have any doubts.

Cheers - I'll PM you nearer the time to sort out a meet at ATP.

= John