Greetings all.
Does anyone know or have access to; the specified values of the Secondary voltages of the original Dynaco 416 power transformer.
I will need to get 2 units made for 240v supply down here in Tasmania. I'm building two from scratch.
I've had no luck finding specifications (anywhere) and guessing the values may end up being expensive.
A point in the right direction would be very helpful.
Thanks in advance.
Does anyone know or have access to; the specified values of the Secondary voltages of the original Dynaco 416 power transformer.
I will need to get 2 units made for 240v supply down here in Tasmania. I'm building two from scratch.
I've had no luck finding specifications (anywhere) and guessing the values may end up being expensive.
A point in the right direction would be very helpful.
Thanks in advance.
See this thread: https://www.diyaudio.com/community/threads/dynaco-st416-amplifier-schematic.53380/
if you do not want to pay manualslib , audiokarma, or servicemanuals.net. I don't
The opinion in that thread is that ST416 is similar to ST400.
The schematics that are available show one pair of output transistors for each channel. I have an advertisement that shows ST400 for sale in 1975. The state of the art in output transistors in 1972 IMHO was npn 2n5630,32,33,34 and pnp 2n6229,30,31. Vcesus 140 v were the max values, but they leaked 200 ma at those values.
8 ohms*200w^2 is 1600 so output voltage would have been 40 Vac. Thus by the 2* rule indicates rail voltages were 80. I find single output transistor pair pressed at 200 w/ch, Peavey used 2 pairs in the PV-4C. Peavey used 2 pairs 2n5630 at 75 w/ch in the M-2600, at +-42v. The rail caps in the dynaco were ???? my computer refused to download parts values from djp.com as unsecure. If dynaco was actually using +-80 rails they were really living dangerously with those parts and heatsinks. I'd use those cap values but expect lower rail voltages.
PV-4C had 80 v rail caps, so we may postulate transformer voltages of +-63 to 67.
As PV-4c has 2 power transformers for some stupid reason, I would go looking for a Crown xls-402 or DC300 to salvage the transformers out of. The xls-402 voltage is not listed but the DC-300 is +-60v.
You need double the voltamps of the transformer for a class AB amp, so you want at least 800 voltamps.
As much as I respect the ST-70 and PAS3 kits, dynaco's tendency to violate heatsink rules and soa rules (which were not invented in 1975) caused a certain disdain among users. of the transistor amps. Blown output transistors. You did not see ST-400 on stage at 1975 rock concerts. You did macintosh, and crown. The styling of the PV-4c is **** but it is a workhorse. IMHO I'd rebuild one of those or a crown xls-402 or xls-602 if I intended to use my system for any length of time at anything near 200 watts/channel. Besides the PA amps have DC protection built in. A ST-400 front panel is lovely, as is a crown DC300. Absolutely do not rebuild the DC on speaker capable DC300, however many rock bands used them in the day.
if you do not want to pay manualslib , audiokarma, or servicemanuals.net. I don't
The opinion in that thread is that ST416 is similar to ST400.
The schematics that are available show one pair of output transistors for each channel. I have an advertisement that shows ST400 for sale in 1975. The state of the art in output transistors in 1972 IMHO was npn 2n5630,32,33,34 and pnp 2n6229,30,31. Vcesus 140 v were the max values, but they leaked 200 ma at those values.
8 ohms*200w^2 is 1600 so output voltage would have been 40 Vac. Thus by the 2* rule indicates rail voltages were 80. I find single output transistor pair pressed at 200 w/ch, Peavey used 2 pairs in the PV-4C. Peavey used 2 pairs 2n5630 at 75 w/ch in the M-2600, at +-42v. The rail caps in the dynaco were ???? my computer refused to download parts values from djp.com as unsecure. If dynaco was actually using +-80 rails they were really living dangerously with those parts and heatsinks. I'd use those cap values but expect lower rail voltages.
PV-4C had 80 v rail caps, so we may postulate transformer voltages of +-63 to 67.
As PV-4c has 2 power transformers for some stupid reason, I would go looking for a Crown xls-402 or DC300 to salvage the transformers out of. The xls-402 voltage is not listed but the DC-300 is +-60v.
You need double the voltamps of the transformer for a class AB amp, so you want at least 800 voltamps.
As much as I respect the ST-70 and PAS3 kits, dynaco's tendency to violate heatsink rules and soa rules (which were not invented in 1975) caused a certain disdain among users. of the transistor amps. Blown output transistors. You did not see ST-400 on stage at 1975 rock concerts. You did macintosh, and crown. The styling of the PV-4c is **** but it is a workhorse. IMHO I'd rebuild one of those or a crown xls-402 or xls-602 if I intended to use my system for any length of time at anything near 200 watts/channel. Besides the PA amps have DC protection built in. A ST-400 front panel is lovely, as is a crown DC300. Absolutely do not rebuild the DC on speaker capable DC300, however many rock bands used them in the day.
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The Stereo 410 was a better sounding, less expensive, less complex, more reliable amplifier.
https://www.hifiengine.com/manual_library/dynaco/stereo-410.shtml
https://www.hifiengine.com/manual_library/dynaco/stereo-410.shtml
Rails are +/-75V, trafo is 53-0-53V, 750 VA. Common to the 400, 410, 416.
120-140V transistors we’re used, but they were series connected. Being only an EF2, with TIP drivers, it was far too easy to get the voltages between them unbalanced under load - and those drivers wouldn’t take much more than 100V. Using MJE1503x drivers instead helped these amps in almost every way.
120-140V transistors we’re used, but they were series connected. Being only an EF2, with TIP drivers, it was far too easy to get the voltages between them unbalanced under load - and those drivers wouldn’t take much more than 100V. Using MJE1503x drivers instead helped these amps in almost every way.
It’s a nice transformer, heat sink and chassis to build upgraded amplifiers into. Caps were underrated at 75V so mine were toast when I got it. It’s the same transformer as the PL400 or Ampzilla, and a decent size heat sink, which can be drilled for more TO-3 transistors.
Buy a 750/1kw isolation tx and wire it in bucking mode that will get you 120 volts. NOTE: You need to check the orignal tx for its 50Hz operation.
IF YOU BUY A NEW TX IT NEEDS 20% MORE STACK (BIGGER WIDTH).
DUKE
IF YOU BUY A NEW TX IT NEEDS 20% MORE STACK (BIGGER WIDTH).
DUKE
I had a 400, there are better sounding amplifiers of that power rating using more available and less fragile semiconductors if you’re going to build something. Bob Cordell’s Hafler upgrade ( on the dH 500) is a much better amplifier as is his bipolar amp.
See #6. Twice as many power transistors, and all MJ15024/5. It’s got more heat sink than both my PL400’s put together.
There’s an Audio Amatuer redesign of the Dynaco 400 addressing some design issues, if you can find someone to send you the article. I’ll check with a friend who may have it. Yes 416 is better
The Audio Amateur 3/83 by Bill Rollins update of the stereo 400.
Transformer with least 2 x 50 VAC secondaries (55VAC will get you +/- 74VDC after the bridge rectifier )
So a 110 VAC transformer - with dual secondaries you could use a separate bridge rectifier for each polarity.
Transformer with least 2 x 50 VAC secondaries (55VAC will get you +/- 74VDC after the bridge rectifier )
So a 110 VAC transformer - with dual secondaries you could use a separate bridge rectifier for each polarity.