Hafler'a "Dyna 120"

0 Members and 1 Guest are viewing this topic. Read 1448 times.

Bobzilla

Hafler'a "Dyna 120"
« on: 21 Jun 2017, 09:43 pm »
What are the possibilities of using this design but substituting a driver board from tubes 4 hifi to use triodes?



dB Cooper

Re: Hafler'a "Dyna 120"
« Reply #1 on: 22 Jun 2017, 04:02 am »
I'm sure someone could design that type of input stage but.... The really hard part would be finding an output transformer good for 120W. This appears to be the schematic for the Mark VI, produced in the late days of Dynaco. Very VERY few were built and IIRC those few were sold in Japan only.

Atlplasma

  • Full Member
  • Posts: 963
  • Just off the boat
Re: Hafler'a "Dyna 120"
« Reply #2 on: 22 Jun 2017, 12:47 pm »
You might be able to order a transformer from Heyboer. Vintage equipment owners do it all the time.

avahifi

  • Industry Contributor
  • Posts: 4682
    • http://www.avahifi.com
Re: Hafler'a "Dyna 120"
« Reply #3 on: 22 Jun 2017, 02:30 pm »
We built a pair of these many years ago when they first were produced by Dyna and we were Dyna dealers.

We were underwhelmed by their audio performance.  Sound kinda like big flabby guitar amplifiers.

Close examination told us not enough bandwidth in output transformers, unobtainium output tubes which needed to be replaced in matched quad sets, amp used series/parallel sets of 4 x 400V power supply caps to get 600V working power supply voltage as 600V rated ones not available.

We built the pair, measured and listened to them, sold them, and never built or recommended them again.  A real mistake for Dynaco in our opinion.

Frank


Bobzilla

Re: Hafler'a "Dyna 120"
« Reply #4 on: 22 Jun 2017, 06:00 pm »
 Great information all around, thanks much.
 There was also a design in ADI (long gone, of course) that used the MKIII output transformer with a quad set of EL34's and their version of a MKIII driver board along with a much higher current power transformer. ( 800 ma. as I recall) The prototype was 100 watts output. The impedance mismatch of the EL34's / MKIII output transformer was said to be insignificant. This was torward the end of ADI's publications.