looking for ideas (TO-3 amp design)

[kyleaudio]

recently i got an old hafler DH-200, it is missing all of the output transistors, i was going to replace them, but after searching i found that they are about $40 each! that is too much for this old amplifier, but it does have a nicely upgraded power supply (toroid transformer with dual outputs, two 10,000uF 75v caps per output, i dont know the voltages yet as i have not gotten to test it yet), from the origional specs the transformer is probably arround 40-60v out on each output and i'd say at least 300va due to the size (not certain tho), the heatsinks have been upgraded to have 6 TO-4 package chips mounted on them each (2 large heatsinks, six TO-4 spots each).

i have decided that $480 is VERY steep to get this old amp working in original form. so i'm looking for ideas on a less expensive amp design that i could use with this power supply and set of heatsinks.

what would be a high quality sound with good power rating (maybe arround 100-300watts per channel) amplifier design using TO-4 package chips?

i'm not exactly sure where i want to go with this amp, it could turn into a normal full range amp, a subwoofer amp, or a bass guitar amp, so ideas for all any thing are good! i'll attach a few pics of what i have to work with, thanks!

kyle

[kyleaudio]

transformer size.

[kyleaudio]

both heatsinks

[kyleaudio]

TO-3 transistor setup

[AndrewT]

Hi Kyle,
look at LME49810 - a new cousin for LM4702
for ideas on chipamp front end and discrete power transistors on the output.

By the way, modern To3 replacements for the Halfler transistors can be got for about $10 each (are they lateral FETs?). BJTs are much cheaper. Don't try converting to vertical FETs.

[kyleaudio]

i will read through that thread, thank you! where can i find those replacements for the hafler? i did some semiconductor crossreferance and all i could find was replacememt parts that were in the $40ea range and a few "originals" from ebay for about the same, i still dont think that i will go that way since there are a few broken parts on the boards too, but just outta curiosity.

[AndrewT]

Hi,
are they lateral FETs?
Give us the numbers.

[sandstorm33]

Some time ago I was interested in putting together a Borbely designed 60 watt amp that originally appeared in the Audio Amateur Mag. I had built one in the 80's back when the Hitachi Mosfets were readily available. Borbely designed the D200 for Hafler and essentially it was the same circuit that appeared in The Audio Amateur.

A year or two ago I needed a medium powered amp and looked to TAA now AUDIOXPRESS and to my surprise found they still offered the PCB's . I contacted Mr.Borbely and was told that the readily available 2SK1058/2SJ162 are drop in's for the original Hitachi's . I bought the boards (copy of the original article comes with them) and the mosfets but never built the amp deciding on class A instead. I checked the AUDIOXPRESS website and and see they still offer the PCB's.

[AndrewT]

The Renesas 162/1058 are To247.

[kyleaudio]

well the original chips were 4 hitachi 2sk134 and 4 hitachi 2sj49 (2 of each per side) and the 2SK1058 2SJ162 arent TO-3 chips so they wouldnt work well as a direct replacement, i'd rather make an amp using the mounting holes that are already there, but if i cant find what i'm looking for maybe i'll drill some holes in them and make a couple LM3886 boards, that power supply would be nice for that.

are there any good kits that include all TO-3 chips?