tubes 4 hifi
 "the path of least resistance is through a vacuum"

HOME Dynaco ST70 parts Preamp Kits Finished Preamps Amplifiers Tubes4Sale Downloads Site Map

Dyna MK3 mods



Shipping will be billed after purchase unless the item specifically states free shipping

we have duplicated the circuit from our ST70 modification onto a PCB that will fit the Dynaco MK3 mono amplifiers.

(this is the same board used in our M125 monoblocks)


MK3 bare PCBs are $60 a pair
Compatible with Dyna MK3 & VTA M125
includes shipping to the US

a pair of PCBs with parts kit is $95
Includes shipping within the US
NOT including tubes
If you'd rather have the boards assembled
and ready to install,
it's $60 for our labor
total price $155 the pair


NEW 6SN7 OCTAL DRIVER
Compatible with Dyna MK3 & VTA M125
the bare PCBs are $65 a pair
Includes shipping within the US

a pair of MK3 OCTAL PCBs with parts kit is $109
Includes shipping within the US
NOT including tubes

If you'd rather have the boards assembled
and ready to install,
it's $60 for our labor
total price $169 the pair

add an additional $90 for 4 - JJ 12AU7 tubes

add an additional $140 for 4 - EH 6SN7 tubes

add an additional $280 for 4 - EH KT88 tubes

add an additional $120 for 4 - Tungsol 6189/12AU7 tubes

add an additional $200 for 4 - Tungsol 6SN7 tubes

add an additional $300 for 4 - Sovtek 6550WE tubes
four Mundorf EVO oil caps, high-end upgrade for the outputs

four caps for $70
 

optional - upgrade the on board power supply caps
this is 4 - 100uF 400v caps instead of standard 4 - 47uF caps
$15

new 550v quad cap
80-40-30-20 KTL-25
$80 plus $6 shipping

bias meters (replace octal socket) MK3
For use with VTA driver board only

$50 for two pairs KIT

$85 for two pairs assembled/tested


bias test points (replace octal socket) $20 pair
Triode-Pentode switch kit
$30 for two amps

dual speaker posts $16 pair - note these use standard 3/4" spacing
fits ST70 and MK3 only
IN STOCK

new TRIPLE speaker posts $20 pair
note these do NOT use standard 3/4" spacing
and must be used with single plugs or terminals, fits ST70 and MK3 only
IN STOCK

original type Dynaco switch (power, mono-stereo) $4 each (only with orders over $20 total)

here's a review from one of our many customers . . .

Roy,

This is a great-sounding circuit. 
With your circuit, one of the first things I noticed was that different recordings are clearly different, 
indicating to me that the amplifier is neutral, rather than colored. I was surprised by dynamics in music 
that I hadn't noticed before, especially in classical music. 
This circuit seems able to render complex passages and dynamic variations that made the original circuit 
sound sluggish. I am a trained classical pianist, and I also play Hammond Organ, other vintage keyboards, 
and trumpet, so I know what instruments sound like in real space. The original Dyna circuit made acoustic 
guitar sound "good," but also a bit unnatural--as if the player were playing an acoustic guitar that was 
twenty feet wide. With your circuit, it sounds like someone playing an acoustic guitar right in front of me.

Your circuit is especially wonderful for the MkIII, which I've never thought was a very good-sounding amp 
to begin with. It always seemed kind of grainy/grungy even with upgraded parts. 
The new circuit cleans up the highs and gives the midrange both clarity and natural richness.

I did do a little tube-rolling last night. I swapped some Telefunken ECC81s in place of the Mullards. 
It's hard to say which I like best. The Mullards seem more dynamic, the Telefunkens, a bit smoother.

My brother, for whom I built these, was wowed by them. He says he's going to have to get some speakers 
that will do them justice. I'm playing them into a pair of KEF 104/2s that I think are one of the best speakers 
for tube amps. This new MkIII is very well matched to them and drives them with apparent effortlessness.

Best,
David A.

here's a full rebuild I did summer of 2021









here's some photos of a newly built MK3-octal













return to VTA home page

 tubes 4 hifi
 "the path of least resistance is through a vacuum"