*Happy New Year! Hope all the best for my audio friends in 2023. Let your year be filled with happiness, love and music !* *website to use for buying vintage* www.canuckaudiomart.com/ www.usaudiomart.com/ www.hifishark.com/ *Binding post adaptors for Vintage amplifiers:* Lil' piggies: amzn.to/3VwOkEB Vintage adaptor seen in video: amzn.to/3GsWfP9 *Speakers seen in this video that works well with Dynaco ST70:* Tekton Lore: tektondesign.com/product/full-range-speakers/mid-towers/lore-reference/#color Tri-art Horn System: (not yet available) inquire @ www.triartaudio.com/?page_id=408 Arendal 1723 THX: arendalsound.com/store/product/1723-tower-thx/?refer=iyagi (use code 65GHTY78 to get $100 off ) Klipsch 8000F II (walnut): howl.me/ch8K5hdPDcP Support on Patreon: www.patreon.com/jayiyagi follow on Instagram: instagram.com/jays_iyagi/ follow on Facebook: facebook.com/jayiyagiofficial Follow soundstage take 2 reviews: ru-vid.com/group/PLPOzvlhtSqn5xdc__ftuSt4Rxy_wm5Af0 Speaker stands: amzn.to/3ssRhI3 Better speaker stands: solidsteel.it/my-product/ss-7-vintage-hi-fi-speaker-stands/ acoustic panels I use: ua-acoustics.com/ acoustic curtain: amzn.to/31d1zAM BDI Cabinet I use: bit.ly/2OJRwQQ amzn.to/3chBuFZ other BDI Cabinets: bit.ly/3ctxXV1 amzn.to/30bsUCH my fav hifi tweaks: (Isoacoustics devices) amzn.to/3j5FGvM 0:00 Dynaco ST70 Amplifier information 3:37 Does Dynaco ST70 need refurb/repair/re-cap? 5:07 My first Tube Amp was Dynaco ST70 9:32 Is the Dynaco ST70 any good in 2022/2023? 13:55 Best Pre-amplifier for Dynaco ST70 16:55 Common problems with Dynaco ST70 18:58 Dynaco ST70 Upgrades/Modificatitons 20:06 Best Tubes For Dynaco ST70
Bout time. Far too many times people who review tubes these days treat them like they are something exotic and primarily for those with deep pockets of money and finiky taste. Dynaco, as well as Heathkit, got a lot of people into hifi and did it with reltively afordable and acquirable gear, much like what Schitt does today with their lower priced DACS, amps and equilizers. And kudos to Dynaco for doing that in the past and kudos to Schiit for doing it today. When I got into tube stereo in the 80s it was for a couple reasons. One was because the amps could be had at a reasonable if not cheap price as they were "yesterday's news" (I bought my first ST 70 for 80-bucks, or about 235-bucks with inflation), but primarily I found the amps had much better dynamics and psychoacoustics (imaging) than solid state could come close too in the 1970s and early 80s. If you want to explore this topic further then I would reccomend finding some other equipment from the period of your ST 70 such as Heathkit, Scott, Harmon Kardon and Eico. Maybe even Dynaco's Mk III and IV monoblocks or their EL 84 powered ST 35. There is a world of gear from that time that deserve more and better attention. Just a thought. Thanks for this program and keep up the good work!
The ST-35 is supposed to be extraordinary, and is highly collectable, but its limited power output makes it useful only in certain applications, such as bi-amping an efficient horn midrange or when used for quiet listening in a small room.
Happy New Year all. I own a Bob Latino ST-120 with KT-88Ss and a pair of Altec VOTT A7 loudspeakers with DIY passive crossovers. For me, audiophile heaven!
Props for recognizing the potential in vintage gear. Don't forget that the real magic of these vintage tube amplifiers is due to their output transformers (and hopefully you will think of other brands of vintage amps with even better OPT's). Upgrading the preamp tubes and the rectifier tube can have a significant influence on the sound as well. Also, you have further potential upgrades (since you have DIY experience) in terms of upgrading the components - better coupling caps (e.g.. Myflex, V-Cap) and resistors (e.g., An, z-foil), wiring, and connectors, You would be pleasantly surprised.
I've got a Will Vincent ST-70 version from 2011, coupled with a MCcormack LD-2 pre-amp, driving Spatial Audio M3 Sapphire speakers. Getting fantastic sound from this combo. What I like about Will's ST-70's (at least mine) is that all connections are on the back, with the power switch in front. I've pretty much gotta have that now. Also, I can use either EL34, KT77, or KT66 output tubes. --Tons of fun.
No mention of the AC line voltage these old amps are designed to run on. The ST-70 was originally designed for 115 VAC and even at that voltage the power supply was run to its limits to approach that 35 wpc rating. On today’s typical AC line voltage of 122-125 VAC, the power supply as designed will push both the can filter capacitor and output tubes beyond their safe voltage limits. Do not replace the filter cap with one with a higher capacitance hoping for tighter bass and/or a better signal/noise ratio because the output tubes will likely spark and short or go into runaway. Also never, never, replace the 5AR4 rectifier tube with a solid state one as that will considerably raise the high voltage and sparking will ensue 🎉. The only safe solutions for longevity (aside from replacing the power transformer with one with a lower secondary voltage) are to use a step-down transformer at the AC input, or best yet, and highly economical, is to build a bucking transformer in series with the AC input of the amp (a VARIAC could be used, too, but those are very heavy, expensive, and often noisy). Plans for a bucking transformer are available online or on RU-vid. Try Blueglow Electronics on RU-vid for a great explanation of how the bucking transformer works and easy to build plans. Anyone using vintage tube amps designed before 1975 or so should be using one..
That amp got me into tube amps, I remember watching my dad build this tube amp when I was a child back in the 60s I learned my first curse word when he dropped a tube I also burned my finger when he turned his back and I thought it was ok to touch after he had turned it off. I did not know why he had a pair of them until I learned about Hifi at a later date.
Granted that it had half the output, but some claim that the Dynaco ST35 is superior to the ST70, since the ST35 used EL84 tubes, the same tubes used today in prized amps such as the Decware Zen Triode amps.
I've used a Dynaco ST-70 as my primary power amplifier for decades, and it's still amazing. A long time ago I purchased two matched pairs of those Svetlana EL34s, and they're still going strong. I also upgraded various capacitors in the power supply, but especially the old black capacitors that were in the audio path on the circuit board. I have one question, though. In your video, you mentioned re-capping the ST-70, but then didn't say much more. Can you talk about which capacitors you upgraded/replaced, and where in the circuit they were? It also looks like you might have replaced the 7199s with different tubes. Thanks.
Hi Jay- Love your channel- mad respect- I have a totally refurbished DynaKit- w/ "cryo"- El 34 tubes- diving it w/ new Quicksilver Tubed Pre- killer combo- cheers
You are completely correct about Dyna preamps, they sound quite terrible even after a complete rebuild and after bypassing the unnecessary tone controls and replacing the awful volume pot. Bloated, fuzzy, overly warm, dark, the stereotypical old tube sound that is little better than an old AM radio. Some people like that sort of thing, I certainly don't. That being said the FM3 is one of my favourite tuners of all time and can be found for cheap.
Hi Jay, your observations are spot on with mine on the stereo 70. In regards the PAS, whether recapped or leaky old caps, both sound extremely compressed. The compression coming from the extremely low capacitance of the power supply (combined with the high resistance of the pi filters). On a side note, that compression made watching movies with tons of gunshots and loud special effects much more watchable as I did not get shell-shocked when I just wanted to watch a movie quietly. (With a dynamic preamp when you turn down volume for quiet at special effects, you hear the dialogue no more...) So, compression of the PAS can have its use.... LOL. For PAS owners, if you increase the capacitance of the power supply, then it really opens up the dynamics. Taking out the tone controls, balance etc... that is, hot rodding it, turns it into an amazing preamp. Taking out its feedback loops, and converting second stage to cathode follower turns it into an astonishing preamp that holds its ground against many modern preamps. Cheers, Janos
Really good video i especially give kudos on your review/conclusion of el34 tubes by manufacturer. Svetlana (real ones from St Petersburg) & JJ'S perform the best of affordable tube. Currently I have 3 ST-70's all modded all different. I recommend modding to correct the issues you mention about base not being tight & to make the high-end sweet. The 7199's tubes sux & all the mods get rid of those. I have driver boards using (3) 12AT7's, (2) 12AU7's & (4) 6DJ8's. I installed the Curcio power & driver full mod which is incredible. I'll put it up against my friends MC-240 Any Day. I did this mod 3 times putting in 100's of hours. Turned out there were 2 errors on the power board schematic. I started the mod 1993 & finished it in 2006. Keep up the good work
It’s been a while since I checked in with you, and I must say I feel the quality of your content has improved tremendously. You give me a reason to watch in the first few minutes, instead of making me want to switch you off. (I realize this may seem like faint praise, it is a significant hurdle to get over.) I got a lot out of the video, too. Thank you.
Jay , you should have put those Tannoys Berkeleys in a Arden sized 6 ft3 cabinet. They become a different speaker all together. I'm talking from experience. Happy New Year.
I'm looking to sell the amp with the companion preamp they are original condition I don't know if they work at this moment. There's also a moron's mono tuner and I have paperwork. They are astonishing pieces of audio history and also just astonishing pieces of audio. Thanks Jay n
Built the Latino/Tubes4HiFi ST-70 clone back in early 2014; run it with Winged C EL-34s and a 5U3C (5U4 equivalent) rectifier - love it, great amplifier! It's currently driving an old pair of Polk S8 speakers that were purchased some time in the early 90s.
🎉excellent channel friend and great reviews, greetings from Mexico 🇲🇽 a question, can this dynaco 70....can it be used as monoblocks??? created yes since I am thinking of purchasing it, since I have sensitive speakers
I hope you review the Tekton Lore's with the beryllium tweeters that were shown. They are fabulous. I've enjoyed them for 3 years now. Great video Jay.
St-70 was built over 18 years. There were like 350,000 of them made, not including kits and repros. There was also a version of it sold in the 90’s for a while.
I’ve looked at these a dozen times along with Bob Latino tube amps… never pulled the trigger along with jolida and mick. Currently own a Cayin but looking at upgrades perhaps of the 300b or 845q variety. This viva monos keep winking at me.
The Dynaco A 25 is the most successful bookshelf loudspeaker sold as well...Is there a trend here? What we need is a modern David Hafler and not these esoteric HiFi champions who charge obscene money for their products. Hafler offered more innovations than most of the contemporary designers combined. He also did in the same in the form of introducing people to HiFi and supporting the audio industry. It should be about the inclusion of listeners and not the contemporary exclusive products being marketed. Is there any wonder why the younger music enthusiasts are not engaged and HiFi is declining?
Had to grab my charger to let you know this review was absolutely beautiful. You put me in the presence of a tube amplifier with your verbiage.. have always considered one , seen dozens of reviews from many reviewers and reading. This convinced me to explore in my own journey. Thank you !!
Have You ever Listen to a Heathkit W-5 m with Pre-amplifier . Its also a All Tube.KT66, I Believe it was a kit you would build, came out 59 -60 if you get a chance have a Listen.
You're quit right about the Heathkit W_5M. I had a pair of them I let go of about ten years ago. It was a big mistake! The W-4 sounds good also, with a good quality speaker it can produce incredible bass. Ah, the sound of a Williamson amp........................
Its OK Jay, you can say it....the bass isn't great on the Dynaco ST-70. Only suitable for guys who listen to jazz, classical, or female singer-songwriters.
Hi Jay I thought I would make your day LOL I'm 78 years old so I've been around awhile. Back in the mid to late 1960's I used to go to Chicago to Allied Radio we could but genuine Mullard matched pairs of EL 34's for $6.86 and the real Gold Lion KT88's were $11.85 for a matched pair. I sure wish those days still existed
Jay when you kiss your fingers like that, that is how I feel about my Beveridge Model 3 electrostatic acoustic transducers. Put them eye to eye half way or so down the long wall of a rectangular room like most living room furniture would be and the sound field will flow between them and through you so holographic you feel you can put out your hand and touch. They were absolute heaven with a Kronzilla Solid State driver Integrated double 807 in one envelope about 10 inch high pair of power tubes with an 800 KVA brute force massive transformer power supply integrated amp. Fed by an EERA $10,000 Tentacion CD player. But folks I have a problem.
I’ve owned, used, and repaired/restored all of the Dynaco tube amp models since the early 1970’s. The ST70 is my favorite and I still have one today. In the 1970’s the ST70 (in kit form) sold for just a bit over $100. The PC board came out of the box fully assembled so constructing the kit required only about 4 hours on the workbench. The ST70 is still an incredible value today.
jay, chinese 'shu guang' EL34M surprisingly good. i've been building valve amps for fifty years, almost a thousand stereo/monoblock/instrument, all use EL34, 6L6, KT66/77 etc, output transformers mainly american 'hammond', more recently english 'OEP', almost always amazing result, (triode connected, no nf, polypropylene signal caps but most importantly 680uf 450v electrolytics in each chan 400v dc supply), if u ever in new zealand look up 'garamp' amplifiers.
Hello Jay, long time fan of your audio journey. Is it just me or does there seem to be a fair amount of resonance in your listening room? While listening to you speak I'm hearing some slight but noticeable room modes and reflections. I checked to see if it was just this particular video but it's consistent with past videos as well. I see various room treatments in play, which has me scratching my head and wondering how this might effect one's ability for critical listening. Is this just some kind of RU-vid compression thing, a glitch in the matrix, or are you actually hearing what we are? It's especially prevalent on this video: Anti-Audiophile MUSIC FIRST DAC - Audio Note 0.1x Tube/R2R DAC
I got my first Stereo 70 in 1965. I also had the MK III's. Sorry I sold them. I used to drive my AR 3a"s without any problems. Please what does the overused word ICONIC mean?
Thanks for reviewing the Dyna 70 Jay. Ken Stevens ran one in his early days too! I've been running Dyna 70s for nearly 30 years with a Lazarus Cascade Basic preamp, then in 2020 upgraded with the VTA circuit board and mods and refreshed the preamp. Currently running them as single channel mono blocks with KT66 output tubes in triode on the midbass and tweeters, and a solid state integrated amp and active crossover to the woofers below 80hz. Absolutely loving what I'm getting from these amps and system. What an incredible value they are.
I rescued two of these crusty abused, abandoned and forlorn ST70 amps from a 10 year stint in a back yard shed. After rebuild, they both came up and played music, one from 1959 the other from 1965. Great EL34 amp
Hi Jay, have you come across TEKTRON Tk One 211i? It is a Single Ended (Class A) Vacuum Tube Integrated amplifier with 211 Tubes. Would like to know how it compares with a modern tube amplifier like Willsenton R8 or R800?
Try a fully resto-modded Audio Research SP3 preamp w/ a fully resto-modded Dyna ST70 + VTA board, and you’ll have something very hard to beat for the price..
I always wondered about the RCAs in the front myself. Turns out Dynaco did that to minimize the distance between the jacks and the location if the RCA outputs in the amp's cicuitry. Sees like Dynaco didn't want an excess of wires running around inside of the chassis and the problems that situation could impose on the sound quality of the amp. PS - it really isn''t recommended bridging the ST-70 into a monoblock. If you want to do that then its best to go with a set of MK IIIs or MK IVs.
That sure looks like what my father had in the late fifties. Garrard turntable, tube amp with a metal cover like a screen, and a speaker. Not sure what he used for a preamp, it was a long time ago.
Happy new year to you, hope to see more great products reviews. Thanks for sharing this vintage Dynaco. Always thinking what so great about it, had people talking, bragging and people complaining. Always wonder why??? Now that you did review the flaws and it's pros. I totally agree that these vintage can come back to life with re-cap, maybe even with better cable, inductor etc to help reduce the noise, the elevation of listening. But it can only reached to a threshold of it's limits. Another thing you did mentioned is that improvement of your room, matching with modern DAC or pre-amps. Looks like a lot of work too other than the Dynaco itself. Thanks and appreciate you make so many great points for this vintage. Thumbs up!
I put the JJ EL34II in my Chi-Fi EL34 amp. It really is a fantastic tube for the price. Also the Rectifier tube did the most to improve the sound for that amp. I put a NOS Mullard GZ30 in. Major upgrade. I dont think all Tube amps will benefit the most from a rectifier tube, but considering it usually is just 1 tube, thats where I will always start my Tube Rolling. Got 2x Decware SE84UFO 2.1’s on order for Bi-Amping or Running both Mono for a bit of extra power(6watts/ch as Monos). Doubt they will need any rolling, but looking forward to that next year.
Best wishes for 2023 to you Jay and all your subscribers. I enjoy your conviction, all round integrity and quality presentation. Keep up the good work.
I remember going with Dad as a 6 year old in the Plymouth ’57 wagon (wagon version of Christine ) he BUYING the kit and making it- bought from Allied Radio in Chicago in about '59 when you could only find stereo "demonstration records" and Sound Effects Lps that exploited this new left-right technology. The modern Danish walnut Knight cabinets loaded with 4 ohm EV woofers and a horn tweeter came from elsewhere. From 6 yrs old thru the Twist and then Beatles and then Hendrix NO ONE I knew still at that time had a stereo like this thing. One day I'm a snot nosed squirt on my Dad's lap in the '57 Plymouth buying this kit - next day I'm sweating going to the 'Nam blasting Hendrix and Cream, and finally leaving the East to come to CA at age 23. - the same stereo. woof. 🕰
@@Jayiyagi I agree with 'parts' from Compasitors to Volume Control - I mean the Volume control on the $8k U.S. Sony headphone amp its Shocking Jay ! 'Sony is a sleeping Giant' But their also a Powerhouse if need to be 😆
I have only built guitar amps but I’d imagine you need to bias those El34’s when changing them. Looking at the schematic it’s definitely fixed bias not cathode.
There is an individual bias pot for each channel, but not for each tube, which is why you need matched pairs. There's a labeled test point on the front in the sockets that look like tube sockets but aren't, visible in the video, where you measure the voltage relative to ground. It's set up so that the bias setting exactly matches the voltage of a new, non-alkaline D-cell battery, so you can calibrate your voltmeter to two decimal. places.
The multi-pin jacks, BTW, are just octal, or 8-pin tube sockets, identical to the tube sockets holding the tubes immediately above. They have voltages available to power a matching monaural preamp, most likely the Dynaco PAS-1. Unless those connections are lost due to subsequent modifications, these sockets have one more important purpose: See the label that says “Bias set 1.56V”? You would stick a probe from a voltmeter in the indicated (by the arrow) pin hole on the socket and the other (negative) probe you would touch to the chassis, which is ground. You would adjust the bias for the output tubes here with the potentiometers on the top until your voltmeter read 1.56 volts. Since really accurate voltmeters were really expensive in the ‘50’s and ‘60’s, Dynaco cleverly set the correct bias voltage here to be exactly 1.56 volts, identical to a brand new D sized battery. View your voltmeter on the new battery, note the reading, match that reading when adjusting your output tube bias.
