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Introduction to tubes...


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Re-introduction actually. Once upon a time I had some really nice old tubed McIntosh equipment. Alas divorce has a way of forcing you to give up the things you love in order to do things like eat...

Is anyone using Dynaco tube amps with their Klipsch speakers? I see quite a few of them for sale in various states of restoration. I'm especially interested in the brand because you can still get pretty much all of the parts fairly easily.

Got a Dynaco? Hooked up to Klipsch speakers? OK... Which amp and what speakers? Most importantly how does it sound?

F.Y.I. I've got a pair of poor-mans Cornscalas, a pair of La Scalas undergoing restoration & upgrade, and a pair of Heresys. I haven't decided on a preamp so I'll probably use my Marantz 2240 as a preamp until I become inspired.


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i've heard them with Klipschorns, La Scalas, Cornwalls and Heresys and they sounded great with each. If not experienced with buying used Dynaco equipment I would contact someone like Craig from NOSValves.com a frequenter on the forum here so you know what questions to ask if you decide to buy. He will steer you in the right direction and a super man.

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I've used MKIII's for LaScala, Klipschorn, and Heresy. Juicy Music preamps and the sound was very good.

My MKIII's were rebuilt works of art by Will Vincent. You might catch some of his stuff on Audiogon. His work is amazing and a bang for the buck champ.

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At the moment, my basement rec room setup is powered by a Dynaco St-70, McIntosh C-26 preamp, a Sansui T-4065 Tuner, and a '58 Weathers turntable with the wooden tonearm. These are feeding a pair of '76 Heresy I HDRBs (still in raw birch....)

I have a sub hooked up down there too, for rock, and jazz, and the occasional classical.

Last week the amps there were my pair of Heathkit A-9cs, but the left one caught a buzz that I haven't cleared. I also had a SS SAE in there over the weekend, and I would almost swear that it sounded better than the tubes.....but then , my hearing isn't what it used to be, and the Timpanaplasty didn't really take all that well.....

I do have some new Sonicap caps on order, so I expect that they'll sound even better by this time next week. I figure after 33 years they could use some refreshing......

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Is anyone using Dynaco tube amps with their Klipsch speakers? . . .

Got a Dynaco? Hooked up to Klipsch speakers? OK... Which amp and what speakers? Most importantly how does it sound?

ST-70 + PAS-3 + Forte IIs = Sonic Bliss!

The Dynaco stuff is original. Forte IIs have Crites titanium diaphrams.

Source components: Rega Planet, Thorens TD 160 (AR-XA awaiting possible mods) & a Marantz 2100 tuner. Oh yeah, I run ALAC files through an old Powerbook (iTunes) & a KECES DA-151 DAC, too.

I've used my Marantz 1152DC as a preamp with good results as well.


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Classic Dynaco ST70 EL34 integrated tube amplifier

I am quite surprised that Art Dudley’s lists of list in the
September 2004 issue of venerable Stereophile magazine did NOT include the
classic Dynaco ST70 integrated EL34 tube amplifier. Over 300,000 units of this
hefty 35 IHF-watts per channel stereo amplifier sold from 1958 to 1977. Today,
the ST70 is remains a popular model among tube enthusiasts and a benchmark of
quality performance. Its EL34 define the pentode sound. This summer, the original
and modified versions of this perennial classic are selling on eBay between
$275 and $375.

Posted: 8/23/2004

Old tube equipment, with large transformers and new parts,
such as the best selling tube amp ever made, the popular Dynaco ST70 (with EL34
tubes), can rival the sound of more expensive solid state amps, especially when
couple to the dynamics of horns. Tubes exhibit a soft clipping characteristic
and different types of distortion, which makes them easier on the ears.

The ST70 was originally designed as a low-cost stereo
amplifier. It had been sold over 300,000 times during its life from 1958 to
1977 (due to its low price ?). Until today, the ST70 is very popular under the
group of tube enthusiasts.

Anyway, as a teenager I had a sweet system Ralph Karsten, of
Atmosphere OTL Music amplifiers provided for
me. NAD pre-amp (1020?) and two rusty old Dynaco ST70s with a pair of Robert
Fulton 100s (yes, Fulton) speakers
(the ones that had the midrange tweeters arranged in a diamond pattern –
anybody know them?).

Michael Jackson’s “Thriller” changed
me away from the dual Dynaco ST70s with my Fulton FM100 loudspeakers.
bought a 48-pound solid-state (SS) monster, the Class A Pioneer M-22 reference
amp, for $250 over a dozen years ago. I could not stand the scratchy sound of
my rusty Dynaco ST70s with their compliment of 4-EL34 tubes any longer.

Pentode/tetrode tube amps tend to broadcast dynamics in
three dimensions -- the way instruments themselves do -- so that the
instrumental image seems to change in size, shape, and volume as intensities
wax and wane. Solid-state amps tend to focus dynamics, as they focus images,
more tightly. In terms of musical realism, hearing a trumpet playing fortissimo
through a solid-state amp is a bit like watching a film run in reverse; it’s as
if the trumpet’s image were getting denser, more focused as it gets louder,
rather than growing larger and bloomier and more "freed up," as it
would in life. If the Krells’ "control" has one drawback, it is in
the slightly over-focused way it images (not in tone color or dynamics).


Power Output

35 watts continues, 80
watts peak each channel

Frequency response

+/- .5 dB from 30 Hz to

Power Response

20 Hz to 20kHz within 1 dB
of 35 watts at less than 1 % distortion

Intermodulation Distortion

less than 1 % at 35 watts
(normally about .5 %), Less than .05 % at 1 watt

Hum and Noise

inaudible; better than 90
dB below rated power


1.3 volts RMS input for 35
watts out

Output impedance

4, 8, 16 ohms each channel

Damping Factor


Minimum channel separation

55 dB

Power Consumption

190 watts 50/60 Hz

Tube Complement

4 x EL34, 2 x 7190,
GZ34/5AR4, selenium rectifier


13" by 9-1/2" by
6-1/2" high


32 pounds

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