Best Preamp for use with a Dynaco ST-70

nunhgrader · « **on:** 26 Mar 2010, 08:18 pm »

Hi!

I am purchasing (eventually - within the next two months) a rebuilt Dynaco ST-70 (by Will Vincent) - love tube amps - would love some helpful suggestions for preamps (tubed/ solid sate/ hybrid). I would love to have a subwoofer output and a decent headphone output would also be nice but, I can live without.

Remote nice as well but, again all recommendations welcomed!

Thanks for looking/ responding

baldrick · « **Reply #1 on:** 28 Mar 2010, 02:25 pm »

The obvious answer is to use a restored Dynaco PAS preamp, but I've found that the ST-70 responds very well to a variety of solid state preamps as well. The Hafler DH110 is a nice preamp to use with the 70 as is a variety of others. The input impedance of the ST70 is high enough that most preamps will work very well with it.

joeriz · « **Reply #2 on:** 28 Mar 2010, 04:26 pm »

Quote from: nunhgrader on 26 Mar 2010, 08:18 pm

Hi!

I am purchasing (eventually - within the next two months) a rebuilt Dynaco ST-70 (by Will Vincent) - love tube amps - would love some helpful suggestions for preamps (tubed/ solid sate/ hybrid). I would love to have a subwoofer output and a decent headphone output would also be nice but, I can live without.

Remote nice as well but, again all recommendations welcomed!

Thanks for looking/ responding

What is your budget/price range? Also, are you looking to buy new or vintage/used?

nunhgrader · « **Reply #3 on:** 29 Mar 2010, 03:43 am »

Thanks for the answer thus far.

I am in budget mode - from $400 - $1200.

I am swaying away from vintage for the preamp. Interested in people's suggestions - thinking of passive vs. active and tube vs. ss preamps.

WGH · « **Reply #4 on:** 29 Mar 2010, 05:15 am »

The second obvious choice is a new Audio by Van Alstine Insight+ SL prepamp with remote control ($1200). There is a used OmegaStar EC full function preamplifier with tone controls on AVA's site for $595 but when a buddy and I compared the Insight+ to an OmegaStar the Insight+ was clearly the superior pre-amp.

Give Frank at AVA a call, he knows Dynaco amps very, very well.

Wayne

baldrick · « **Reply #5 on:** 29 Mar 2010, 11:40 am »

If you're shopping for a new preamp and are not concerned with frills like source switching or tone controls, then this might do the trick for you, plus it's a very good DAC:
http://www.economik.com/benchmark/dac1-usb/
http://www.audiojunkies.com/blog/1223/benchmark-dac1-pre-preamp-dac-headphone-amp

2gumby2 · « **Reply #6 on:** 29 Mar 2010, 12:13 pm »

I used a Carver CT-3 preamp/tuner with my ST-70 and I thought it was a great match. Highly recommended if you can find one.

nunhgrader · « **Reply #7 on:** 30 Mar 2010, 02:01 pm »

Well, I've narrowed down the playing field and I have made an offer on one unit thus far (might be buying two):

Canary CA-200 Passive Preamp

Totally passive design with zero distortion.
Swiss made ELMA rotary switch is used as input selector for multiple signal sources.
High quality Alps potentiometer is used for precise volume adjustment.
Point to point hand wiring with Teflon coated silver wires.
Five stereo line level RCA inputs (five pairs of L and R inputs).
Two stereo RCA output to power amplifier (two pairs of L and R outputs)
Thick steel chassis with beautiful black powder coating finish.
Heavy duty CNC milled aluminum faceplate and knobs.
Dimensions: 9.5" W x 9" D x 3.75" H
Weight: 12 lbs.

I'm also considering two addtional preamps - one being the AES/ Cary AR-3 - I also like the Bottlehead and the Decware preamps.

Any comments or additional advice welcomed - and thanks for the advice thus far!

avahifi · « **Reply #8 on:** 30 Mar 2010, 02:58 pm »

A passive preamp is not a good choice for use with a Dyna St-70 amplifier because it (the passive preamp) has no gain.

The Dyna St-70 has lower than "normal" gain in the first place, about a voltage gain of 15 as compared with most amplifiers that typically have a voltage gain of 20 to 25.

This means with a passive preamp, it is very likely that you will not be able to turn the volume up on your system loud enough, unless you are using very efficient speakers (90dB or higher).

Best regards,

Frank Van Alstine

joeriz · « **Reply #9 on:** 30 Mar 2010, 05:20 pm »

Quote from: nunhgrader on 29 Mar 2010, 03:43 am

Thanks for the answer thus far.

I am in budget mode - from $400 - $1200.

I am swaying away from vintage for the preamp. Interested in people's suggestions - thinking of passive vs. active and tube vs. ss preamps.

In that price range (or any price range for that matter) - and given the fact that you are shying away from vintage - I would recommend anything (tube or solid state) by Van Alstine. You could get a really nice new or used AVA unit with remote and these would meet your requirements of having a headphone output and second line out for a sub. A brand new Insight SL with remote is almost exactly $1,200. Or there is something like this:

http://cgi.ebay.com/Van-Alstine-FET-Valve-Preamp_W0QQitemZ190383972218QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item2c53c4df7a

which looks to use the larger 'old style' chassis which means it could be updated to include a remote if it doesn't have one already.

I've used an AVA Super PAS-3i that I built from a kit with a few different ST-70s for the last 15 years and I still love it.

Best of luck.

Joe

nunhgrader · « **Reply #10 on:** 30 Mar 2010, 08:34 pm »

Thanks again for all the replies!

I think I threw up a little when I read Mr. Frank Van Alstine's comment (fanboy here) - I am saving for one of your preamps as well! I guess I made a mistake with the passive

- no worries - I will start looking into the active options now

turkey · « **Reply #11 on:** 30 Mar 2010, 09:02 pm »

Quote from: nunhgrader on 30 Mar 2010, 08:34 pm

Thanks again for all the replies!

I think I threw up a little when I read Mr. Frank Van Alstine's comment (fanboy here) - I am saving for one of your preamps as well! I guess I made a mistake with the passive - no worries - I will start looking into the active options now

I suspect that an Insight+ preamp would work very well with an ST-70, but one of Frank's tube preamps should too. Maybe you can keep your eyes open for a used preamp like one of the Super PAS series or even a T8?

I'd recommend you don't get anything earlier than a Super PAS 3 though. I don't remember exactly when the replacement for the original 4-section filter cap came out, but any preamp with one of those old clunkers is probably living on borrowed time - like the Super PAS I have. The electrolytic caps and the tubes are pretty much the only things that wear out on an AVA product. The older Super PAS models are also probably less likely to have been fitted with the replacement gold-plated jack set, and the original Dyna jacks are horrible.

avahifi · « **Reply #12 on:** 30 Mar 2010, 09:07 pm »

Don't overlook the obvious.

Take a look at the current project of Bill Thomas in the Vintage Circle very near your postings.

Regard,

Frank Van Alstine

nunhgrader · « **Reply #13 on:** 30 Mar 2010, 10:08 pm »

Quote from: avahifi on 30 Mar 2010, 09:07 pm

Don't overlook the obvious.

Take a look at the current project of Bill Thomas in the Vintage Circle very near your postings.

Regard,

Frank Van Alstine

I have been reading his work - wonderful. I have never tried a diy project yet. I was thinking I should take babysteps in that arena - learning how to solder and electronics 101.

I think it's really great to be apart of this community and see a pioneer like yourself participate with all of us - including us newbies like myself

baldrick · « **Reply #14 on:** 31 Mar 2010, 12:09 am »

Hey Nunhgrader,

The DIY experience is the most rewarding of all.A great place to start is with a simple Velleman kit, a good 25W soldering iron and a web tutorial on how to solder parts to a pcb:
Velleman:http://www.vellemanusa.com/us/enu/product/list/?id=523008
Soldering Training:http://video.google.com/videoplay?docid=-1438613870956797134#docid=6895625482306263240

nunhgrader · « **Reply #15 on:** 31 Mar 2010, 01:08 am »

Thanks baldrick - now you have my interest peaked - thanks for the links - no doubt I will be buying something besides the wrong preamp this week

TONEPUB · « **Reply #16 on:** 31 Mar 2010, 01:55 am »

Id buy a clean Krell PAM-5. It was the most "Un-Krell" sounding preamp they made and had an awesome
MC phono preamp section. Two outputs, so you can run the subwoofer but no headphone stage. Used to
use one with my ST-70, MK III's and a variety of CJ and ARC tubed power amps.

You can usually find a clean one for about $600 bucks, built like a tank.

nunhgrader · « **Reply #17 on:** 31 Mar 2010, 03:28 am »

Hey thanks Mr. Dorgay!

Really love your magazine! Your mag sure is pretty - love the fact that you do pieces on high end pens, watches (timepieces) etc - love the variety. Also, love that fact that you take time to respond to so many letters including several of mine (of praise and thanks).

AudioCircle has all the famous people!

I'll shut up now.

TONEPUB · « **Reply #18 on:** 31 Mar 2010, 06:40 am »

Thanks for the kind words.... Best of luck finding a preamp you like!

nunhgrader · « **Reply #19 on:** 1 Apr 2010, 12:55 am »

Last question (yes I am a pain in the arse - sry) - what type of gain should I be looking for regarding the preamp selection?

Well - I lucked out on the passive purchase attempt - owner did not respond in the 48 hour audiogon window so I am free to purchase an active now!