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Dynaco ST-70's, some ?????

6/16/1999 6:37 PM
Wyatt	Dynaco ST-70's, some ????? Okay, I've a ST-70 on it's way to me. Of course, I haven't given it a look-over yet, but I'm fairly confident I'm buying from someone who has kept it up nicely. I know some of who have mentioned using a Dynaco power amp, so I pose some questions to you. My questions were what do you all use with it? It's eventually going to be part of a simple set-up for music in my bedroom. That means it will probably be paired up with a variable output CD player (Dynaco CDV-Pro?) and some speakers and that's it. But in the meantime, I was wondering about preamps and such. Do those of you who have one use a tube preamp...SS preamp, Dynaco PAS 2 or 3, etc.? And if I did pair it up with a nice but affordable SS preamp for now, will the tone suck? Also, any suggestions on tubes. Are the Sovtek 7199's any good or should a pay for NOS? And, what are your opinions of current model EL34's for HiFi use? Thanks for any answers, guys. -Y.

6/16/1999 6:37 PM

Wyatt

Dynaco ST-70's, some ?????

Okay, I've a ST-70 on it's way to me. Of course, I haven't given it a look-over yet, but I'm fairly confident I'm buying from someone who has kept it up nicely.

I know some of who have mentioned using a Dynaco power amp, so I pose some questions to you.

My questions were what do you all use with it? It's eventually going to be part of a simple set-up for music in my bedroom. That means it will probably be paired up with a variable output CD player (Dynaco CDV-Pro?) and some speakers and that's it. But in the meantime, I was wondering about preamps and such. Do those of you who have one use a tube preamp...SS preamp, Dynaco PAS 2 or 3, etc.? And if I did pair it up with a nice but affordable SS preamp for now, will the tone suck?

Also, any suggestions on tubes. Are the Sovtek 7199's any good or should a pay for NOS? And, what are your opinions of current model EL34's for HiFi use?

Thanks for any answers, guys.

-Y.

6/16/1999 11:06 PM
anonymous	Uncle Ned knows a lot about ST70s. www.triodeel.com Reid

6/16/1999 11:52 PM
Steve M.	Hi Y, > My questions were what do you all use with it? I found a matching PAS-2 preamp to go with it. The CD player is low-end Sony. > It's eventually going to be part of a simple set-up for > music in my bedroom. That means it will probably be > paired up with a variable output CD player (Dynaco > CDV-Pro?) and some speakers and that's it. It is supposed to be a 35w amp, but the tech who fixed it up a while back said it was closer to 25w, FWIW. IMHO, this amp sounds pretty good with a decent set of bookshelf speakers. > But in the meantime, I was wondering about preamps and > such. Do those of you who have one use a tube preamp...SS > preamp, Dynaco PAS 2 or 3, etc.? At first I had it paired with a $75 AGI 511 SS preamp. Now it is paired with the aforementioned PAS-2. > And if I did pair it up with a nice but affordable SS > preamp for now, will the tone suck? Yes. I don't claim to have golden ears, so if I can tell a difference, there probably is one The SS pre sounded a little flat for the want of a better word. The PAS 2 sounds much more lively and warm. Of course this would depend on the preamp, too. > Also, any suggestions on tubes. Are the Sovtek 7199's any > good or should a pay for NOS? The Sovtek 7199s are re-pinned 6BL8s according to Ned at Triode Electronics, a similar tube with slightly different ratings. The amp will work best with NOS 7199s, but they are getting pricey, upwards of $25 each the last time I checked. Mine has been modified with the Sound Valves/Sound Values replacement driver board. It isn't an modification of the circuit per se, it merely corrects some problems of the original board has 30+ years later. Mainly drifing carbon comp resistors, leaky coupling caps, and inferior material for the PCB substrate. It uses the 6GH8 tube which is similar to a 7199, but with a different pinout. I just bought a lifetime supply at a hamfest for $1 each. The 6GH8 has the same pinout as the 6BL8 and 6U8. Some people don't think that the 6GH8 sounds as good as the 7199, FWIW. If you can afford it, I would recommend a replacement driver board, or at the very least upgrading all the components on the original driver board. Ned at Triode Electronics sells a nice replacement board using EF-86s and a 12AU7, I believe. http://www.triodel.com Check it out. > And, what are your opinions of current model EL34's for > HiFi use? Mine has NOS Siemens EL-34s in it. I've also heard that the Sovtek EL-34WXT and the Svetlana EL-34 sound great in this amp. Maybe someone else can elaborate on the various differences in sound. > Thanks for any answers, guys. No problem, let us know how it turns out for you. Regards, Steve

6/16/1999 11:52 PM

Steve M.

Hi Y,

> My questions were what do you all use with it?

I found a matching PAS-2 preamp to go with it. The CD player is low-end Sony.

> It's eventually going to be part of a simple set-up for

> music in my bedroom. That means it will probably be

> paired up with a variable output CD player (Dynaco

> CDV-Pro?) and some speakers and that's it.

It is supposed to be a 35w amp, but the tech who fixed it up a while back said it was closer to 25w, FWIW. IMHO, this amp sounds pretty good with a decent set of bookshelf speakers.

> But in the meantime, I was wondering about preamps and

> such. Do those of you who have one use a tube preamp...SS

> preamp, Dynaco PAS 2 or 3, etc.?

At first I had it paired with a $75 AGI 511 SS preamp. Now it is paired with the aforementioned PAS-2.

> And if I did pair it up with a nice but affordable SS

> preamp for now, will the tone suck?

Yes. I don't claim to have golden ears, so if I can tell a difference, there probably is one

The SS pre sounded a little flat for the want of a better word. The PAS 2 sounds much more lively and warm. Of course this would depend on the preamp, too.

> Also, any suggestions on tubes. Are the Sovtek 7199's any

> good or should a pay for NOS?

The Sovtek 7199s are re-pinned 6BL8s according to Ned at Triode Electronics, a similar tube with slightly different ratings. The amp will work best with NOS 7199s, but they are getting pricey, upwards of $25 each the last time I checked. Mine has been modified with the Sound Valves/Sound Values replacement driver board. It isn't an modification of the circuit per se, it merely corrects some problems of the original board has 30+ years later. Mainly drifing carbon comp resistors, leaky coupling caps, and inferior material for the PCB substrate. It uses the 6GH8 tube which is similar to a 7199, but with a different pinout. I just bought a lifetime supply at a hamfest for $1 each. The 6GH8 has the same pinout as the 6BL8 and 6U8. Some people don't think that the 6GH8 sounds as good as the 7199, FWIW. If you can afford it, I would recommend a replacement driver board, or at the very least upgrading all the components on the original driver board. Ned at Triode Electronics sells a nice replacement board using EF-86s and a 12AU7, I believe.

http://www.triodel.com

Check it out.

> And, what are your opinions of current model EL34's for

> HiFi use?

Mine has NOS Siemens EL-34s in it. I've also heard that the Sovtek EL-34WXT and the Svetlana EL-34 sound great in this amp. Maybe someone else can elaborate on the various differences in sound.

> Thanks for any answers, guys.

No problem, let us know how it turns out for you.

Regards,

Steve

6/17/1999 3:52 AM
dan	Re: Dynaco ST-70's, old hardware I bought one of these things new in 1971.. finally retired it. but am keeping it purely for sentimental value. Firstly: don't believe the hype.. it just ain't a very good amp.. even with the Curcio mods it simply does not work as well as a cheap NAD.. sad but true. (try for yourself) As this thing is new to you, you haven't been disillusioned yet, try it without any preamp connecting it directly to your cheap Sony CD's headphone output.. should work on yours.. does on mine..surprisingly well. With a decent pair of speakers.. anything in the PSB line you should be happy. The telefunken el 34's tubes are the best sounding that you are likely to find... don't fix what ain't broke

6/17/1999 3:52 AM

dan

Re: Dynaco ST-70's, old hardware

I bought one of these things new in 1971.. finally retired it. but am keeping it purely for sentimental value.

Firstly: don't believe the hype.. it just ain't a very good amp.. even with the Curcio mods it simply does not work as well as a cheap NAD.. sad but true. (try for yourself)

As this thing is new to you, you haven't been disillusioned yet, try it without any preamp connecting it directly to your cheap Sony CD's headphone output.. should work on yours.. does on mine..surprisingly well.

With a decent pair of speakers.. anything in the PSB line

you should be happy.

The telefunken el 34's tubes are the best sounding that you are likely to find... don't fix what ain't broke :-)

6/17/1999 1:58 AM
BicBogartPeas	Re: Dynaco ST-70's, some ????? For a pre-amp, I use a PAS-3X. There really isn't much difference between it and the PAS-2. I also recommend recaping both your ST-70 and PAS2 with good quality polypropylene or polystyrene caps. I did it to mine and it made a world of difference. Use NOS 7199's, preferably RCA. I have a few laying around if you want to make some kind of deal. I personally don't like Sovtek tubes and prefer the sound of NOS instead..

6/17/1999 1:58 AM

BicBogartPeas

Re: Dynaco ST-70's, some ?????

For a pre-amp, I use a PAS-3X. There really isn't much difference between it and the PAS-2. I also recommend recaping both your ST-70 and PAS2 with good quality polypropylene or polystyrene caps. I did it to mine and it made a world of difference.

Use NOS 7199's, preferably RCA. I have a few laying around if you want to make some kind of deal. I personally don't like Sovtek tubes and prefer the sound of NOS instead..

6/17/1999 3:22 AM
SpeedRacer	I have the soundvalves board in my ST70 and the amp never sounded better IMO. There are a bunch of ST70 mod boards, and I'd bet they're all pretty neat, and _worthwhile_. I use it as the monitor amp in my home studio set up and have used it as the power amp for our regular "home stereo" at times. It has plenty of power if you use a reasonably efficient speaker. I use a SoundValves pre-amp I bought used (and which I highly reccomend!) and Tannoy PBM 6.5's (nearfield monitors) for speakers. I used my old PAS-3x until I got the SV, and there's no comparison. I sometimes long for more low end, but that's a speaker issue (6.5" woofers and physics being what they are). The detail and "air" are great and BURY my Nak receiver which is the current normal duty hifi around here. Listening to Dire Strait's "Tunnel of love" is practically a religious experience... Yeah there are better amps and bigger amps, but in the bang for the buck (not to mention that elusive vintage mojo..) the ST 70 rules IMHO. Yours Truly, S. R.

6/17/1999 3:22 AM

SpeedRacer

I have the soundvalves board in my ST70 and the amp never sounded better IMO. There are a bunch of ST70 mod boards, and I'd bet they're all pretty neat, and _worthwhile_. I use it as the monitor amp in my home studio set up and have used it as the power amp for our regular "home stereo" at times. It has plenty of power if you use a reasonably efficient speaker. I use a SoundValves pre-amp I bought used (and which I highly reccomend!) and Tannoy PBM 6.5's (nearfield monitors) for speakers. I used my old PAS-3x until I got the SV, and there's no comparison. I sometimes long for more low end, but that's a speaker issue (6.5" woofers and physics being what they are). The detail and "air" are great and BURY my Nak receiver which is the current normal duty hifi around here. Listening to Dire Strait's "Tunnel of love" is practically a religious experience... Yeah there are better amps and bigger amps, but in the bang for the buck (not to mention that elusive vintage mojo..) the ST 70 rules IMHO.

Yours Truly,

S. R.

6/17/1999 12:08 PM
MKB	Hi, Wyatt. Another $0.02 worth from a ST70 owner. I now have three of these amps (not by design, through trades and stuff). Two are stock, one has the Glass AudioCurcio mod in it, with the regulated PS. I really like these amps and they sound great, all of them. However, later I got a pair of Macintosh MC30's which stomped the ST70's. I then built a pair of 211A based triode monoblocks, and these stomped the MC30's. All, including the ST70's, stomped any SS amp I have owned. I now use an ST70 in my studio and it works fine. Several suggestions; first, use fairly efficient speakers if you want any volume. These amps are good for 25W at the most. Second, remove the cover and ventilate the unit, as the power transformers seem to be underdesigned and run hot. Third, a question; what exactly are you wanting to hear in an amp? The stock ST70 is very warm and "old" sounding, it can make a harsh CD player more listenable. The Glass AudioCurcio mod ST70 is COMPLETELY different, highly detailed with an unforgiving top end. If you mod your ST70, it will basically be a different amp. It is almost the perfect modding amp, however; lots of room and good transformers. It may help to get an idea what you are looking for before modding. Finally, be sure your 5AR4 is not the small one the size of a 6V6, I have heard these are amp eaters. I had one short out on me the other day and nearly fry the PT on my tweed Princeton clone; the 5AR4 came with one of my ST70's.

6/17/1999 12:08 PM

MKB

Hi, Wyatt. Another $0.02 worth from a ST70 owner. I now have three of these amps (not by design, through trades and stuff). Two are stock, one has the Glass AudioCurcio mod in it, with the regulated PS. I really like these amps and they sound great, all of them. However, later I got a pair of Macintosh MC30's which stomped the ST70's. I then built a pair of 211A based triode monoblocks, and these stomped the MC30's. All, including the ST70's, stomped any SS amp I have owned. I now use an ST70 in my studio and it works fine.

Several suggestions; first, use fairly efficient speakers if you want any volume. These amps are good for 25W at the most.

Second, remove the cover and ventilate the unit, as the power transformers seem to be underdesigned and run hot.

Third, a question; what exactly are you wanting to hear in an amp? The stock ST70 is very warm and "old" sounding, it can make a harsh CD player more listenable. The Glass AudioCurcio mod ST70 is COMPLETELY different, highly detailed with an unforgiving top end. If you mod your ST70, it will basically be a different amp. It is almost the perfect modding amp, however; lots of room and good transformers. It may help to get an idea what you are looking for before modding.

Finally, be sure your 5AR4 is not the small one the size of a 6V6, I have heard these are amp eaters. I had one short out on me the other day and nearly fry the PT on my tweed Princeton clone; the 5AR4 came with one of my ST70's.

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