hello, im new to the forum.

dmagazz wrote:i have questions, and have also a barn of sorts st-70 that appears to be ALL original to me(dynaco tubes and all). it WORKS, is quiet and clean sounding  
cant post pics yet i guess.
OK....SO
my first question is, how loud is an ST-70's 35 watts?

Please read my much longer previous post on volume, headroom and such-like.

here is a comparison, my laptop is my music preamp, and being at 60 percent vol into a harman kardon 730 (SS 40 watts)-with both the bass and high on 60%, and the volume on 30%,with a pair of 4 way 4 ohm speakers. it results in about the same loudness as going straight into the st-70.(using the same speakers!) is that ceiling low?or is it me.i might add its still clean at that level.
but i was hoping and expecting much for more output,

so i also ask can that output increase with new caps,tubes,and diodes for the recto.
or do 4 ohm speakers somehow usually result in a lower output by nature?

another question is how can i figure out the date on this, the bios pots are stamped on the side, and i only saw 1 number,E09373(part number?)

Those part-numbers are not date-related. Dynaco used a number of pots from a number of suppliers. That stamp is the Dynaco P/N and remained the same.

the cornell dubilier part number UPN 10474 525v quad cap has a 4 digit at the bottom (6642)is that a date of 66?,

Yes - that is a 4-digit code, the first two are the year of manufacture, the last two are the week within that year. So, the 42nd week of 1966. That cap could be in the system for a long time before it got into that amp, however. So, as late as 1968 could be possible.

the power tranny has a white number stamp of PAO66.. is it safe to say the dates match? or is that not a date on the tranny.

That is the Dynaco part-number, not a date code. Are the leads cloth (early) or PVC (late)?  That amp was made from 1959 through 1989, sold as a  stock item through about July of 1990.

dmagazz wrote:

another question is how can i figure out the date on this, the bios pots are stamped on the side, and i only saw 1 number,E09373(part number?)
the cornell dubilier part number UPN 10474 525v quad cap has a 4 digit at the bottom (6642)is that a date of 66?,
the power tranny has a white number stamp of PAO66.. is it safe to say the dates match? or is that not a date on the tranny.

dmagazz wrote:thanks bob,and peter w the replies
bob, my pots resemble the post through indented cover style and are stamped on the side, i didnt see a number outside of the part number,come to think of it. i didnt see a value!. i will take a closer second look.

peter w, thats some serious technical insight right there, thanks.

my speakers are a custom desighn 4 way design, with   1-100 watt nominal 12 in sub,   1-60 nom  watt 6 in driver,   1-35 nom watt 3 in mid,    and 1-35 nom watt 3 inch cone tweeter, a variable vol control for the high drivers and a crossover network inside splitting up the frequencies, at the leads the measurable resistance is 3.8 ohms, so i guess its safe to say its about 3.8 ohms and can handle up to 200 watts

OK, stop there. 3.8 ohms nominal, meaning from about as low as 1.4 to as high as 10 ohms - the difference between impedance (frequency dependent) and resistance (fixed).

i ask about the reference you gave "the difference between 35 watts and 80 watts"  isnt a dynaco st-70, 70 watts by 2, as the HK730 is 80x2 making the reference for the hk730 40 watts not 80?

No. The 70 is 35 + 35 per channel, not 70 per channel.  The HK730 is rated at 40 per channel into 8 ohms, giving a theoretical 84.2 per channel into 3.8 ohms. Solid-state amps are a constant-voltage devices giving a theoretical doubling of output watts with each halving of impedance. Tube amps are constant-current devices, putting out a fixed wattage at each impedance as matching the OPT windings.

so aren't i comparing 35 watts to 40 watts(per channel) not 35 to 80. or was that a typo.

Not a typo. What you are actually comparing due to the different natures of the two beasts.

im starting to wonder(as i havent checked)if the previous owner bios'ed it on the light side for longevity, and is possibly why it seems to be only the power of a 15 watt amp.

a little more basic info,some irreverent.
the transformers have cloth leads

Older version, then

the selenium rectifier is still in use
all the original dynaco tubes are in use
as is the capacitors.
and thanks for helping me determine it is a 66.
the feet are a round bubble type, not the taller standoff type.
the cover is brown, however has the "dynaco" plate, not the "dynakit" plate.

Jefferson Street, then.

the wires are black and all mounts are screwed,not rivitet(making it a kit for sure)

Not necessarily. Until Dynaco moved to Jefferson Street they did not have a factory of any nature. "Factory Built" amps were assembled by Drexel Students on piecework. What they had for tooling would be a matter of individual preference. Some would have had rivet guns, some not. Some would have used color-coded wires, some not. That practice continued in a small way well into the Jefferson Street era. If the amp has a serial-number sticker, the odds of it being 'factory' (at whatever level) go to over 90%.

there is no pitting in the stainless.

dmagazz wrote:peter w, thats what i implied in saying!
"so aren't i comparing 35 watts to 40 watts(per channel) not 35 to 80
because you previously said
c) You have not given a speaker brand or efficiency, but suffice it that the difference between 35 watts and 80 watts is >3dB under any conditions.  

i initially thought you were referencing the dana at 35, and the hk730 at 80

OK - just to be sure as this is often confusing until it becomes well understood.

Your speakers are "seeing" 80 watt rms per channel from the HK730 as they are (nominally) half the impedance of its base rating (40 watts rms per channel). The HK does have a decent power-supply, and so is most likely able to make a 160 watt peak without clipping.

Your speakers are "seeing" 35 watts rms per channel from the 70, with an 80-watt peak.

Remember, *CONSTANT VOLTAGE (solid-state) vs. CONSTANT CURRENT (tube).

but you were referencing power and peak weren't you. i just realized that now.
sorry for the cofusion.