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Modern Preamps for Dynaco ST-70 and MK III

What's the signal source? Do you need RIAA phono? I used a Stereo 70 and MkIII amps for many years with simple solid state DIY preamps. Eventually I just used a passive pot level control and that worked really well for moderate volumes. I have a problem with commercial preamps. Being a DIY person, I know what the parts cost is for any reasonable version of a preamp, and I'm not willing to pay the markup. There are all manner of very good solid state preamps you can build for very little money that will outdo the front end of almost all receivers.
 
Lavane said:
So did Holger sell the PAS part of his business?
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Not privy to any details, but earlier in the year I was after his regulated power supply to build out a preamp. I wanted to make use of the tone control line stage and PH10 I had sitting around after replacing them with the Aikido and PH20 in my current pre. The old site wasn't taking orders and there was a note to contact the new owner / operator via email. I did and he was gracious enough to sell me the power supply even though he wasn't technically up and running. Looking at the new site, they are just about ready to go live. Beyond that, I can only speculate he has sold off the PAS upgrade operation.
 
SS904 said:
Not privy to any details, but earlier in the year I was after his regulated power supply to build out a preamp. I wanted to make use of the tone control line stage and PH10 I had sitting around after replacing them with the Aikido and PH20 in my current pre. The old site wasn't taking orders and there was a note to contact the new owner / operator via email. I did and he was gracious enough to sell me the power supply even though he wasn't technically up and running. Looking at the new site, they are just about ready to go live. Beyond that, I can only speculate he has sold off the PAS upgrade operation.
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It sounds like it. Thanks for the info.
 
Quadaptor! said:
I've been dabbling in the Dynaco ST-70 and MK III amps for nearly 40-years and have come to the conclusion that the PAS series preamps, though likely good for their time, may not be the best components for letting these amps shine today.
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I agree, my restored PAS, although bench tested and very quiet, sounds kind of dull when running the phono preamp

Quadaptor! said:
I'm just curious here, but I'd be interested in hearing the results of those who have tried different preamps (tube or solid state) with the ST-70 a
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I've tried a number of solid state preamps with my ST-70 but the best sounding phono section was a 1970's Kenwood integrated using the "pre-out" jacks to the amp.
 
All of this thread reminds me of Steve Deckert's story about spending almost two years building his famous single ended triode circuit. He did a great video interview about the story. He and fellow audiophiles did "amp wars" where he blind tested every single component change in the circuit, step by step. He'd compare the original "good" amp with the modified, otherwise identical amp. Once a change was deemed an improvement, this new "good" amp would be changed with a new value for a component until that amp became the "good" amp.

At nearly two years, he then tested it scientifically and the amp was a piece of crap on paper. So he tried to fix it so that it would conform to scientific standards of good audio quality. Everyone hated it. Sterile and boring. So he decided to sell the original circuit anyway because he and his crew thought it sounded fantastic. If you order one of his SET amps today you'll be on a 3-4 year waiting list. Sound quality is whatever you enjoy.
 
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Last year I restored a pair of Dynaco MKIVs- same circuit as the ST70 but the dual power supply monoblock versions that get a few extra watts. Stock circuits and transformers but used premium parts. I've used them extensively with a fancy version of the Tubes4HiFi SP14 preamp and a CJ PV5 I rebuilt last year. My current Dahlquist speakers are less than ideal for the MKIVs as they are rather power hungry and I end up pushing them pretty hard, although it sounds quite good.

I like tube preamps and these two are at the opposite ends of the spectrum. The SP14 sounds closer to solid state to me. The PV5 is tubey but in the best way possible- I find it magically intoxicating. It really depends what you are going for. The SP14 I often wonder if it would just be easier to get a good solid state preamp, as the Dynacos impart their own tube magic. The PV5 is a lot of tube sound on top of the Dynacos sound. It's also very noisy compared to the SP14 which runs dead quiet. I like the sound of the PV5 better but if I had sensitive speakers I may not like the noise it adds. Honestly Id like to find something in between- the quietness of the SP14 and just as important the remote with a sound about half way to the PV5 on the tubey-meter. If I ever see a DeHavilland Ultraverve with remote I may try that and sell off the loser or suck it up and attempt to build my own.

I hate to admit it as I love tube amps, but the PV5 with a hot rodded B&K SS amp stops me in my tracks over and over and over and over.
 
albusark said:
All of this thread reminds me of Steve Deckert's story about spending almost two years building his famous single ended triode circuit. He did a great video interview about the story. He and fellow audiophiles did "amp wars" where he blind tested every single component change in the circuit, step by step. He'd compare the original "good" amp with the modified, otherwise identical amp. Once a change was deemed an improvement, this new "good" amp would be changed with a new value for a component until that amp became the "good" amp.

At nearly two years, he then tested it scientifically and the amp was a piece of crap on paper. So he tried to fix it so that it would conform to scientific standards of good audio quality. Everyone hated it. Sterile and boring. So he decided to sell the original circuit anyway because he and his crew thought it sounded fantastic. If you order one of his SET amps today you'll be on a 3-4 year waiting list. Sound quality is whatever you enjoy.
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IMO, this is a really important point. There's no law that says flat response/low THD equals good sound. I spent a long time designing a speaker system for flattest response and other good things. It sounded terrible! The problem with electronics is you need a target. If that target isn't flat response and low THD (plus phase and other things), then how do you ever design it? We often regard a change or difference as an improvement, but different isn't always better. In fact, if I have several amps and one of them sounds "better" than the others, I assume there's something wrong with it and go looking for the cause. IMO again, audio is a never-ending struggle because the biases of the human brain ensure we're always reaching for the greener grass on the other side of the fence.
 
ConradH said:
IMO, this is a really important point. There's no law that says flat response/low THD equals good sound. I spent a long time designing a speaker system for flattest response and other good things. It sounded terrible! The problem with electronics is you need a target. If that target isn't flat response and low THD (plus phase and other things), then how do you ever design it? We often regard a change or difference as an improvement, but different isn't always better. In fact, if I have several amps and one of them sounds "better" than the others, I assume there's something wrong with it and go looking for the cause. IMO again, audio is a never-ending struggle because the biases of the human brain ensure we're always reaching for the greener grass on the other side of the fence.
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I'll soon be 66 and have pretty much reached my end game with amps and a lot of hifi gear. As I said before, Dynaco got me into tube electronics back in the 80s. At that time, the tube amps I listened to just sounded more dynamic and larger (wide sound stage) than the solid state units that were on the market. Today I have settled into a Fisher 800B that I picked up in a dusty old shop north of San Francisco in the late 80s. The Fisher was rebuilt about three years ago and, if we can take stuff with us when we go, that 800B is on my list. Having said that, I'm still drawn to Dynaco and have a couple ST 70s and a set of Mk IIIs waiting for attention. The Fisher drives a pair of modified Heresys (see the Super Heresy discussions on this forum) and a stereo pair of SVS 100 Pro subs. When the MK IIIs come back on line, I have a set of Cornwalls that will go with them. As for signal sources, I have a KLH turntabe, and an Audiolab 6000 CD transport. I also have a Pioneer Elite N-30 Network Player that gets less and less use these days. My CDs (largely mid 50s to early 70s jazz) are burned onto two hard drives (with one serving as a back up) and I use a laptop with a SMSL PO100PRO (as a reclocker) for playback. And in between it all are a stack of Schiit units that consist of a Modi 3+ DAC, a Loki EQ, a Mani phono preamp and a SYS that is used as a switch-box for the phono preamp. That's my stuff, however for the MK IIIs I'm still Jonsing over the Erhard Europa preamp that was mentioned earlier in this thread.
 
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Quadaptor! said:
I'll soon be 66 and have pretty much reached my end game with amps and a lot of hifi gear. As I said before, Dynaco got me into tube electronics back in the 80s. At that time, the tube amps I listened to just sounded more dynamic and larger (wide sound stage) than the solid state units that were on the market. Today I have settled into a Fisher 800B that I picked up in a dusty old shop north of San Francisco in the late 80s. The Fisher was rebuilt about three years ago and, if we can take stuff with us when we go, that 800B is on my list. Having said that, I'm still drawn to Dynaco and have a couple ST 70s and a set of Mk IIIs waiting for attention. The Fisher drives a pair of modified Heresys (see the Super Heresy discussions on this forum) and a stereo pair of SVS 100 Pro subs. When the MK IIIs come back on line, I have a set of Cornwalls that will go with them. As for signal sources, I have a KLH turntabe, and an Audiolab 6000 CD transport. I also have a Pioneer Elite N-30 Network Player that gets less and less use these days. My CDs (largely mid 50s to early 70s jazz) are burned onto two hard drives (with one serving as a back up) and I use a laptop with a SMSL PO100PRO (as a reclocker) for playback. And in between it all are a stack of Schiit units that consist of a Modi 3+ DAC, a Loki EQ, a Mani phono preamp and a SYS that is used as a switch-box for the phono preamp. That's my stuff, however for the MK IIIs I'm still Jonsing over the Erhard Europa preamp that was mentioned earlier in this thread.
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I also use a Modi dac and find it to be an "invisible" component between my pc as an audio source, I am very happy with it. Would love to explore a Fisher 800B, looks like a fantastic piece of gear.
 
zackthedog said:
GE's are cheaper than most of the new ones, and by far my favorite vintage 6SN7.
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I'll look into them. I like the GE driver tubes I put in my Dynakit ST-35.
The JJ's weren't bad, but the GE's were noticeably better sounding to my ears.
 
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albusark said:
I also use a Modi dac and find it to be an "invisible" component between my pc as an audio source, I am very happy with it. Would love to explore a Fisher 800B, looks like a fantastic piece of gear.
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That Fisher is a solid piece of gear. When I was in my late 20s and early 30s I worked for NPS and the Forest Service in a number of parks and national forests and went to grad school at New Mexico State University in Las Cruces. And that Fisher went everywhere I could take it. It is my audio/hifi right arm. There are still plenty Fisher 800 Bs and Cs out there plus a quantity of their integrated amps. If I was to do it again today, I would get an integrated amp and not a receiver. The receivers look really nice, but FM is pretty obsolete these days. But I encourage you to get a piece of Fisher tube gear. I don't think you'll regret it.

As for the Modi, I am not convinced that any DAC really does much more than what the Modi does. Regardless of cost. I look at the basic function of a DAC as the conversion of the digital signal to analog. I also consider all the differences in sound that various DACs make to be, dare I say it, coloring of the sound. I think when it comes to DACs we are messing with ourselves a little too much. It was a conversation about DACs that got me onto the Super Heresy project. A forum member wisely advised me that a better change in sound quality in my system would come from changing a component like the speakers and not the DAC. And that made good sense. But now I digress.........
 
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Quadaptor! said:
That Fisher is a solid piece of gear. When I was in my late 20s and early 30s I worked for NPS and the Forest Service in a number of parks and national forests and went to grad school at New Mexico State University in Las Cruces. And that Fisher went everywhere I could take it. It is my audio/hifi right arm. There are still plenty Fisher 800 Bs and Cs out there plus a quantity of their integrated amps. If I was to do it again today, I would get an integrated amp and not a receiver. The receivers look really nice, but FM is pretty obsolete these days. But I encourage you to get a piece of Fisher tube gear. I don't think you'll regret it.

As for the Modi, I am not convinced that any DAC really does much more than what the Modi does. Regardless of cost. I look at the basic function of a DAC as the conversion of the digital signal to analog. I also consider all the differences in sound that various DACs make to be, dare I say it, coloring of the sound. I think when it comes to DACs we are messing with ourselves a little too much. It was a conversation about DACs that got me onto the Super Heresy project. A forum member wisely advised me that a better change in sound quality in my system would come from changing a component like the speakers and not the DAC. And that made good sense. But now I digress.........
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I also came to the same conclusion about DAC's, as long as they're well engineered for low noise, etc., no need to invest in more than a Modi or equivalent. It has great driver support on various operating systems and goes up to 32-bit 192khz I think, which might be useful for recording/mixing applications / playback. A solid well built dac solution for sure. Once I have room on the bench I'll try a Fisher 800, I love the design.
 
Just for reference I have never owned a Dynaco, surprising considering how many other brands I own. I was always turned off by the exposed old circuit board on top. Regardless, I would think any good performing preamp should match well with one, there really isn't any reason why it wouldn't. As long as the sensitivity of the Dynaco matches the output level of the preamp I would focus on what features your looking for, such as balance and tone controls, the number of inputs and outputs, and does it look like something that you think goes well in your mind with your system.

I think your going to find in these threads your going to end up with hundreds of models based on other members likes, so in the end you just have to jump off and test the water. Focus on items that are easy to sell, in good condition as it is not like a marraige for life, if you don't like it move on go thru a few if needed till you settle on something that fits your needs and you love how it sounds.

So far, my favorites are Cary SPL98's for their great sound and ease in tube rolling, and a VAC Statement, VAC in my mind makes really good products.
 
Here's an interesting YouTube program that was just put up and is relevant to this thread:


Although it may be reversing the direction of my original thesis, it does beg a need for asking a basic question. Is the PAS, after all, good enough for the ST 70 and Mk III? My original thesis was that a more modern preamp would allow the Dynaco amps to perform and sound better . But, is this fundamentally correct? Would a more modern preamp be overkill for the older Dynaco amps? Is the PAS the weak link in bringing out the potential of the ST 70 and Mk III? I still think it is, but I also think this is a topic worthy of discussion and highly related to this thread. Thanks much to those who have contributed to my thread and I look forward to reading your thoughts on these questions.
 
I don't. My Dynakit ST-35 isn't stock. My ST-70 is one of Bob Latino's, and its been modded even more.
<edit> I'm not sure about adding a SS buffer stage to the PAS3 though.
Then it's a hybrid.
 
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