View Full Version : Dynaco ST-150, PAT-5

01-04-2005, 11:33 AM
Picked up a freebie ST-150 solid state stereo Dynaco amp and a Dynaco PAT-5 preamp for free.

Both power up and seem to work, though the preamp's balance control is kind of screwed up. Got the manuals with them, too.

Are these worth their salt, or more of a novelty-collectible item?

01-04-2005, 11:45 AM
Since they were free, they're awesome! Here's some Orion info(always on the low side though) Check the bay completed auctions for current value.

Manufacture Years: 1974 - 1979
Additional Information:
Power: 75wpc
MSRP: $400.00
USED: $120.00

Manufacture Years: 1974 - 1979
Additional Information:
MSRP: $400.00
USED: $60.00

01-04-2005, 01:08 PM
Anything for free is good. As for sound, the Dyna SS preamps are right up there with the Crown IC150/150A as my picks for the worst sounding preamps ever made. The last PAT5 bi-fet that was a Frank Van Alstine mod appropriated by Dyna (per Frank) is decent sounding but still nothing great. Frank does have some updates for it that are really a strip and make a new preamp. I've used his SuperPAS3X for a number of years and respect what he can do. As for the amp, these were pretty decent then and far more reliable than the tempermental ST120. With a little updating as to the passive components, etc. it should still do well.

01-04-2005, 01:32 PM
Anything for free is good. As for sound, the Dyna SS preamps are right up there with the Crown IC150/150A as my picks for the worst sounding preamps ever made.

Brian, I appreciate your comments wholeheartedly, but I wonder in relation to what, other separate pre-amps, or just plain old anything?

I have a Technics SA-5370 receiver from the late 70's that I'm thinking of replacing with the Dynaco matchup and an as-yet-to-be-found tuner (this Technics series of receivers has LOUSY tuners, but I'm sentimentally attached to it, so it will go elsewhere).

Would I be better off using the receiver for it's tuner and basic pre-amp switching functions and just feeding the Dynaco power amp from a signal from my equalizer's output, or taking the receiver out of the picture?

01-04-2005, 02:36 PM
My undying love for the SS Dyna and Crown IC150 is related to any other preamp I've heard and even preamp sections of most receivers where the preamp can be isolated and I've listened to the preamp section. These are IC based preamps and sadly the ICs used in the designs are just terrible. Both coompanies should have waited a year or so. The preamps were designed to a price point and sadly had a limited selection of ICs to work from. This is so sad, especially related to the Crown since I really like the matching D60/D75 and OC150 components. If the Technics is the top piece you've had, then the Dyna pair may well be better sounding. These were entry level back then and compared to the receiver may be better while I'm comparing it to other units at the same level and slightly above. I would take them against an Panasonic (maker of Technics) I've heard and most of the low end Technics I've heard.

I tend to compare apples to apples and therefore preamps to preamps. That said sometimes there is a gem out there that things can be compared to. For instance, The preamp of the Marantz 1060 IMHO is better than the PAT-5 and though the 1060 is an integrated amp, I'd but it and unstrap it and simply use the preamp first. Likewise the amp section of the H-K 630 is better than the amp of the 1060 but it has a weaker preamp so I'd not have a problem recommending taking the 630 and unstrapping it, taking the 1060 and unstrap it and then use the 1060 preamp with the 630 and what you have is a very good 45 watt/channel system. I think you are suggesting this with the Technics/Dyna. I'm not familiar with the Technics so can not tell you whether the PAT-5/ST150 is better than the preamp/amp section of the Technics or either Dyna is better than the corresponding section of the Technics.

Not sure if the Equalizer output is a preamp output of fixed output. If fixed then forget using it into the ST150. If variable then can try it with the 150. If the receiver has preamp outputs/main inputs, then unstrap them and try different combinations until you get what sounds best of the groupings and for now go with that. Thing about vintage is there is always something out there to buy and put into the system and listen to the effects and go from there.

Give it a try and provide us with feedback.

01-04-2005, 03:38 PM
Trust your ears. The Dyna 150 is probably the most uncolored and natural amp dynaco ever made. The preamp is fine also. These units have no sound of their own. They have no artificial warmth and the treble is extended not rolled off. This sound does not appeal to some. I think you will love them.

01-04-2005, 04:25 PM
The Pat 5 is a much more useful Pre amp than the four.
The ST 150 is super reliable as I have two of them and only had to replace the pilot bulb in one of them after twenty years.


01-06-2005, 09:41 PM
I used to test prodcution runs of the driver boards for the Dyna 150 and 400/410/416 for a vendor who resurrected the product after Dyan sold out. From a design standpoint, I like the 150 much better than the 4XX. The 150 is a modifiers' dream. Plenty of space in there. Sometime in the 80's, there was an extensive article in The Audio Ameteur about the 150. The pat 5 also was written onextensively in TAA. Electronic parts for the the the stuff is readily available from the standard supply houses. Watch EBAY for some Dyna hardware/switches/pots.

01-07-2005, 04:30 PM
"I used to test prodcution runs of the driver boards for the Dyna 150 and 400/410/416 for a vendor who resurrected the product after Dyan sold out."

Hi d3, I don't supose you have any extra 400 driver boards lying around? :)


01-07-2005, 05:42 PM

I checked, none around. Keep a watch on ebay. I wouldn't be surprised to see some show up.

10-30-2011, 02:04 PM
Always enjoy updating an old thread.
I picked up a 1986 Dynaco Pat-5 Frank Van Alstine Transcendence Two
preamp. Man, that was a mouthful.
The lighted power toggle switch is broken, so I can't power it up to see if it is in working order.
I contacted Frank, and he said he has NOS switches for $20 total, but I also saw this eprey ad.

Are these basically the same switch? Or is one better? Should I spring for the NOS one?
I hope Brian of 2005 is wrong on the sound quality as well as in regards to the phono stage. Presently using a diy grounded grid.
Thanks for any feedback,
Salt Lake City

Doc Zinger
10-30-2011, 09:07 PM
The Van Alstine PAT5 Transcendence pre amp has had all the original circuits/boards replaced with his own design. The reason Frank used the Dynaco chassis is because it is well built and large enough to easlly work on. Also had good stock transformer. It is really a different pre amp from the Dynaco PAT5.

10-30-2011, 09:43 PM
Yes, Doc, I knew that.
Just wondering since the original was gutted on the inside just for the chassis, if I should care to buy the original power switch or the other one. I got a message back from the ebay seller who said it fits exactly into the chassis. That both would be fine, just a question of aesthetics.
A white toggle switch with all the other black knobs would seem a bit strange.
Original toggle power switch (on the second photo)

And the power switch with the white toggle