Heathkit W5M versus the Dynaco MKIII

[HiFiCanada]

I have always been a Heathkit fan but I don't own a Heathkit W5M tube amp, but instead I have the Dynaco MKIII tube amps.
How does a Heathkit W5M tube amp match up against the Dynaco MKIII tube amps?
What would be the pros and cons of the two amps?

 

[soundmotor]

I am not a fan of the MKIII nor the W-5M in stock form. The MKIII is unforgiving on KT88's and does not sound all that good w/ the 6AN8 IMO. It does however have the potential to be superb with a great output transformer and a robust power transformer. The W-5M is just the opposite. It starts out sounding good with the stock power transformer but tends to blow it up if pushed. There are also 2 variations of the output transformer. One has the 16309 (lesser) and the other has the 16458 (desirable).

You will never approach the power levels of the MKIII with either however, the +3dB advantage it has is significant. Since you own MKIII's why not mod them if you have not already done so? I see no advantage of the W-5M's over the MKIII's at all. Of course you may just want them, I understand that completely.

 

[Kegger]

I Think? I'm in the same camp as Soundmotor to a degree anyway.

They both have nice iron(get the bigger W5 output), but there circuit and layout
I prefer on the W5 along with the nicer choke, so I find more potential on the W5.
(the W5 being point to point has easier mod potential to me for circuit tweaking)

The MKIII if modding the driver/supply can be pretty sweet, the W5 the supply, I
would also add you'll have more power with MKIII if that's a benefit to someone to.

 

[HiFiCanada]

Modifying MKIII's?

I may be interested in modifiying the MKIII's, got any good links on that?
I am pretty happy with the power, but I am always open for suggestions for better sound

 

[audiodon]

Is the Dynaco MkIII a Williamson circuit?

 

[Shadowdog]

Yes it's a simplified Williamson sometimes called the Cathodyne or Split Phase.

Dynakitparts and Audioregenesis, & classic valve design sell original boards, parts etc.

Classicvalve.ca , tubesfor4hifi, diytube, & triode electronics sell (Mullard 5-20 circuit) boards & kits with and without CCS.

There may be boards out there from some of the other Dynaco ST-70 board suppliers. Their kits & boards are higher priced however.

Nobody seems to make a board with the Williamson type circuit for the Mark III however, Triodes Electronics ST-70 board is based on the original Williamson type circuit in the original Dynaco amps. They have instructions on how to use bigger tubes so it would work for KT-88's. Maybe board could be cut down if that circuit was desired, though you would have to buy 2.

Another option is to take a metal plate and P2P your fave.

http://www.diytube.com/phpBB2/viewtopic.php?t=4443

http://www.diytube.com/phpBB2/viewtopic.php?t=4672&start=0

Randy

 

[GordonW]

The circuit in the Mk III, I'd more refer to as a "Laurent Circuit", after Ed Laurent, who designed it for Dynaco. It was based on the higher gain available from a pentode, which allowed a simple cathodyne phase inverter to work driving larger tubes. It's direct-coupled driver/phase inverter circuit makes it very stable, but it is sensitive to having good 6AN8 tubes (primarily the pentode section) for it to bias up correctly, for appropriate voltage swing to the output tubes. Get that right, and it will drive the dickens out of the outputs, and sounds great.

Regards,
Gordon.