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First Time Build Mullard 5-10 or Williamson

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eldarvanyar

eldarvanyar

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Joined 2008
#1
Hi guys,

Happy Christmas and New Year.

I am thinking of taking the plunge and building a Mullard 5-10 or Williams Amp in the new year 2019. What's the general opinion of which is the best amp to build sound wise for a vinyl front end? Also what views do you have on power transformers sourced from the UK or Europe which would be my preference due to import and postage charges? Am I right in thinking the biggest and most important investment is in the power and transformers? I have seen that Sowter Transformers are very expensive compared to others that are available; are they really worth the extra. What would other alternatives do people recommend? Are there any chassis that are pre-cut available out there? Or, are there any kits that are worth considering. Any other pointers would be gratefully received.

Thanks
 
#4
Either will be fine with vinyl.

First time with valves or on a budget?
Go for the Mullard design. Still plenty of people doing the transformers, more choice, and EL84s are plentiful and cheaper than KT66s or alternatives.

Transformers in the UK (just a list, no particular recommendation):
Primary Windings Building the Mullard 5-10 Amplifier – Primary Windings
Variable Voltage Technology VVT http://www.vvttransformers.co.uk/index.htm
Bluebell Audio sell Hammond transformers Untitled Document

Toroidy Transformers in Poland do a good range too. Power transformers - Internet shop Toroidy.pl

Money not important?
Go with the Williamson design and get the Sowter transformers.

Pre-cut chassis? Not really. There was some one in the UK who sold on eBay and would punch one for you, but not seen the listing recently.
Anyway that's all part of the fun(?).

Kits? Not Mullard, but EL84s try World Designs KEL84 index

The alternative is to buy a Leak Stereo 20 or similar (TL12+ or Heathkit MA-12s) and restore it/them.

Alan
 
#5
A bit late to call Santa, but here's my wish list:
  1. Topology: the Mullard is OK-ish, at least as a starting point for further modifications, building up to something like the Marantz 8, so think ahead and account for Octal power tubes such as EL34/6L6/KT66. I don't like the Williamson's: I attempted to build one when I was 12, and it didn't work 🙂
  2. Output transformer: the most important part of your amp because it's evil. You should throw everything you've got at it. Lundahl and Sowther are good, as well as some Japanese stuff from the Trio/Tango/Sansui family. Ignore anything that's not top of the line, possibly with the exception of the newer toroidal from van der Veen or Toroidy: great price, great spec's, but no independent test that I know; being toroidal, the should have some idiosyncrasies like sensitivity to DC, which should be easy to balance out for a (careful) DIY'er.
  3. Power transformer and choke: recently, I've had great experience with the Chinese stuff: their quality is at least as good as their Western counterparts, at less than 1/2 of the price shipped. Just stay away from the very cheapest junk (hint: look for end bells & screws, ignore the ones with U-clamps). E-I or R-core if you can find them. Be careful about your UK mains.
  4. Cabinet: the Chinese boxes are great. Think BIG, lots of addition will come your way.
  5. Tubes: it's OK to start with some cheap stuff and roll UP after you win the lottery. Think ahead with regards to the compatibility with the output transformer. My fav's are 6L6/KT66, but of course everyone will disagree.
  6. Passive components: electrolytics: Nichicon, Rubycon, Panasonic. Film caps: polystyrene/teflon/polypropylene. Stay with point-to-point wiring!!!
 
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#6
I've been working on an "original" triode Williamson for some time now. I'm using new Gold Lion KT66's and a pair of Peerless 16309 outputs I bought on eBay for $500. The sound is quite beautiful and much better than the PP 300B amp I was struggling with for a long time. I've been meaning to email Sowter and ask if their "Williamson" OPT conforms to the original design. It's very tempting. In fact they make a transformer/choke set for the Williamson that would probably sound glorious. As others have pointed out, the OPT is critical and nowhere more than with a true Williamson design. I prefer it to the Mullard-style topology.

If it helps, here's a list of "blessed" OPTs for the original Williamson--meaning they have the requisite bandwidth and exhibit little or no high-frequency ringing:

Peerless S-265-Q (the best by all accounts but very difficult to find and expensive)
Stancor A-8054
UTC LS-61, LS-63, LS-6L1, LS-6L3

The Stancors and UTCs turn up on eBay and can be affordable if you're patient. ;-)

You might also consider restoring some Heathkit W2's, W3's or W4's. They can often be found on eBay for not much money, in fact less than you might pay for assembling all the parts yourself. Dave Gillespie wrote excellent articles on restoring and improving these at AudioKarma.

If you decide on a "true" Williamson, be sure to read Dave Gillespie's "Regilding the Gilded Lily" article on the AudioKarma forum--it's easy to find. He walks you through the original "Musician's Amplifier" project and has very important recommendations for high- and low-frequency stability. They worked very well for me and improved the sound of my project significantly.
 
#7
The problem with the old Mullard designs 5-10, 5-20 etc. is they have too much gain for most modern systems. Get a hold of "Valve Amplifiers" by Morgan Jones. In the section on power amplifiers he critiques the classic designs of the Mullard 5-20, a Williamson and a Quad II. The 5-10 is very similar to the 5-20 He then offers a modern take on an EL84 amp, of which he has built three. They are quite straight forward except for the requirement of a regulated supply for the gain and phase splitter stages. It can be built with new "iron" or iron from an old Leak or similar. Jones finds 2 of the 3 classic designs lacking.

Steve
 
#8
trobbins said:
KT66's can break your bank toooo.

Do you have speakers to suit the intended max power output and your listening environment?

Do you have suitable test equipment to confirm either of those amps is appropriately set up and performing as it should, and without any instability concerns?
Click to expand...

Thanks for taking the time to reply. I have various speakers I can choose from including some Fostex FE126EN Full-range Speakers. Listening room size will be 12' x 14'.

Concerning the set up, safety and performance, I would seek to have a professional engineer check everything over.
 
#9
and above all, are you familiar with electronics and tube assemblies?
I ask you this because in my case, I come from the transistor that I practice for quite a few years and the tubes have been a shock for me.
so I started with junke box amps bought cheap on ebay to make my hand and understand a little more.
 
#10
Steve Morley said:
... Jones finds 2 of the 3 classic designs lacking.

Steve
Click to expand...

Most of Jones' points are valid strickly within their original contexts. But the beauty of DIY is if you don't like anything, you're free to change them, as long as you know what you're doing. So the topology serves only as a starting point.

Of the 3 topologies discussed, and IMHO, the Williamson has 1 too many gain stage and so the compensation is difficult. Secondly, I've owned quite a few Quad II because I'm a diehard Quad ESL57 fanatic, but I've never been able to extract even a passable sound out of these amps, even after some heavy duty modifications.

That leaves the Mullard. What I would do to it, in no particular order: run the input stage as triode, run the output stage in fixed bias with individual adjustments, use the negative supply to feed the long tailed pair and add AC balance to it, use (MUCH) better filtering in the power supply, etc... You'll end up with something close to a C-J, TVA, Marantz, VTL... You name it.

Of course, if this is your very first build, forget what I said and get a Chinese kit. If you shop around, there's a great chance you find some with most of the ingredients I listed already implemented. And you can still improve on them. Yaqin is a brand that comes to my mind, I think it's even discussed on this board.
 
#13
Zung said:
Of course, if this is your very first build, forget what I said and get a Chinese kit.
Click to expand...
Many newb's have a tough time with their first kit build, even when well documented, and with multiple forum threads. A limited understanding, and lack of tools doesn't help.

A few posters have lamented on the lack of documentation that can come with ebay kit purchases - especially when there are no forum threads specifically on the amp kit being bought, and the marketing info has no technical backup - which can raise the frustration level and perhaps kill-off a new hobby for some.
 
#14
LinuksGuru said:
I have built a Williamson (improved version, google for mods) with reissue of Golden Lion KT88, its not bad but not the best. In your case I would recommend one of the Mullards which design shared on this forum by its members.
Click to expand...

If you're referring to Talbot Wright's "Improving the Williamson," these are very poor modifications, and not only in my opinion. ;-) They rob the Williamson of it's magic. A lot of the "improved" versions, and there were many, get very far away from the original design and sacrifice the musicality of the original design in favor of "lower distortion" or more power.
 
#15
The Williamson (not improved) is a very fine amplifier delivering about 12 watts class A. The Mullard 5-10 delivers a little less power, not class A and has ultralinear EL84's, and does not have a very linear (pentode connected) first stage. It sounds somewhat inferior to the Williamson. Having built both many years ago and quickly discarded the 5-10.
 
#16
Hello, OP's question reminds me my case some twelve years ago. My first ever tube amp was built on a schematic by Mr Tadaatsu Atarashi and was chosen simply because it had written all the voltages on it. Lacking of measurement equipment other than a DMM, I've found that to be a great advantage. I had started with some reading about what is that 6,3V and where it belongs... This amp has seen any kind of modification I happened to come across in the internet. The current version - please don't ask number - is not the result of a straight route. You would have to see it that way to understand it, especially the idiosyncratic psu. I post it here not as a recommendation, just trying to help people to decide what DIY means to them.
 

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#18
MagicBus said:
Hello, OP's question reminds me my case some twelve years ago. <snip>
Click to expand...
Oh great thanks for this. Can you say any more about it and the performance and sound [emoji851]

peteki said:
Having built both many years ago and quickly discarded the 5-10.
Click to expand...
Thanks for replying what type of music did you listen to on the Williamson and Mullard and can you describe the difference
 
#19
trobbins said:
Many newb's have a tough time with their first kit build, even when well documented, and with multiple forum threads. A limited understanding, and lack of tools doesn't help.

A few posters have lamented on the lack of documentation that can come with ebay kit purchases - especially when there are no forum threads specifically on the amp kit being bought, and the marketing info has no technical backup - which can raise the frustration level and perhaps kill-off a new hobby for some.
Click to expand...
I had a look on eBay Douk Store last night which have various kits and built amps for under or just over £200 that I could play with - design, case, components all done and could learn from that as a way of entering into first build or modding.

Douk Audio 6N9P+6P3P Class A Vacuum Tube Integrated Amplifier Stereo HiFi Amp 6434081810014 | eBay
 
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