Speakers for a Dynaco ST-70?

[Tavi]

Hello all. I'm new to the forum having surfed in during my searches for a set of speakers. I am just finishing up a complete re-build of my dad's old ST-70. I used to crank it when I was a teen into his home-built corner horn type speakers but haven't heard it since. I have kept the signal path as close to original as possible (for better or worse) as I want to hear the sound that made this amp such a classic. With that in mind, I'm looking for a set of speakers that I can use to experience the "tube sound". Now, like most people, my budget isn't up to my taste! I may eventually acquire one of those fancy Fostex single driver kits that seem to be popular with tube folks. I am also aware of the huge and efficient Klipsch designs. With that in mind, what would be a suggestion for a large bookshelf or small floor type speaker that has the desirable characteristics to allow me to HEAR and appreciate the "tube sound". I'm not looking for the cheapest but perhaps the hidden gem of great value and acceptable sound. I've looked at the cheap Dayton Bookshelves but sure think an 8" woofer or better would be more what I need. Don't roll your eyes too much but something like the Klipsch RB-81s seem to be a good compromise of size and efficiency but are fairly expensive for me. With patience, I would have a good chance of picking up a used pair off eBay. Thank you in advance for any thoughts or suggestions for my quest!

 

[slipperybidness]

Welcome to the forum! Nice to see another Dyncao builder hanging around!

First thing's first: It would be good to know how large of a listening room you are in and how loud you typically listen to music. That can help to make recommendations.

I have built a Dynaco ST-70 from the Bob Latino (Tubes 4 HiFi) kit. Running EL34 output tubes.

To date, I have run my ST-70 on the Infinity P363 towers, the Philharmonitors, and the Def Tech SM350s. All in a relatively small room.

Here are my opinions:
*Philharmonitors: Don't bother. At low levels it was fine. But at slightly higher listening levels, I could hear the ST-70 struggling. This may be in part to lesser sensitivity from the Phils, but probably as much due to the un-forgiving transparency of the Phils.

*P363: I ended up going back into the ST-70 to install the 4-ohm taps. This greatly improved the sound and power delivered of the P363 as compared to the 8-ohm taps. No surprise, as the P363 was determined to be 4-ohm as measured here on AH.

*Def Tech SM350: Dang, the ST-70 really shines on these speakers! When properly placed, these speakers have more bass than you would expect for a smaller bookshelf. I'm sure these speakers are more forgiving than many, so that helps on the ST-70. I bought a pair from NewEgg for $200 a while back, and I say these are dang tough to beat if you can get that price!

So, from my own personal experience, I would suggest a pair of DT SM350, or even better spring for the SM450. The 350 can be found for $200 a pair if you are patient, and I have seen the 450 as low as the $300 a pair range. At those prices, they are good speakers, at full retail there are better options.

No personal experience, but a few of the AH members have suggested that a pair of vintage Klipsch Heresy speakers would also be a good match for the ST-70.

Now, to be clear, to get the BEST performance out of your ST70: I recommend getting a pre-amp or receiver with bass management and adding a subwoofer to the system. That will get you around one of the biggest limitations of the ST70 and / or Bookshelf speakers.

I had been running my ST-70 permanently on my P363s, being fed a source from drum machines and synths, but 1 of my channels on my ST-70 recently quit. I just haven't had a chance to really deal with troubleshooting that.

 

[slipperybidness]

On a side note, peruse the Tubes 4 Hi-fi site. You can see that he has made some updates (most noteably on the driver board) to the original design.

And, here is a link to a dedicated Dynaco forum that is run by Bob Latino. He is probably the leading expert for all things Dynaco and very pleasant to deal with.
http://dynacotubeaudio.forumotion.com/f2-basket

 

[crossedover]

Take a look these. http://www.decware.com/newsite/TPMINI.html

 

[Tavi]

Thank you for your reply! I hope for your sake you haven't lost an output tranny ($$$)! There have been so many modifications and improvements to the original design over the years, I determined that it would be better to just rebuild the stock design and experience the ST-70 of 1960. Especially since the original power transformer is fairly anemic and barely up to the task anyway. Once I've had my fill of the original, I intend to build up the tubes4hifi kit which includes all of the upgrades including a beefier power transformer.

I'm getting the impression that "back in the day", if you wanted bass, your only option was to use large and clever horn designs or do without. I want to experience that, at least for a while. It will help me appreciate the simple act of adding in a sub-woofer! It's funny how as time passes, and I am up to my ears with bells and whistles, I am starting to desire the simplicity of an "old fashioned" 2.0 system. I may even end up regretting giving away all of my LP's 20 years ago!

To finally address your question, it will be in a smallish room in a townhouse so thunderous volume is not a concern. I want to get home from work, flop into a recliner, NOT turn on the TV, and enjoy really hearing a remastered copy of "Dark Side of the Moon" on my dad's old tube amp!

 

[slipperybidness]

Thank you for your reply! I hope for your sake you haven't lost an output tranny ($$$)! There have been so many modifications and improvements to the original design over the years, I determined that it would be better to just rebuild the stock design and experience the ST-70 of 1960. Especially since the original power transformer is fairly anemic and barely up to the task anyway. Once I've had my fill of the original, I intend to build up the tubes4hifi kit which includes all of the upgrades including a beefier power transformer.

I'm getting the impression that "back in the day", if you wanted bass, your only option was to use large and clever horn designs or do without. I want to experience that, at least for a while. It will help me appreciate the simple act of adding in a sub-woofer! It's funny how as time passes, and I am up to my ears with bells and whistles, I am starting to desire the simplicity of an "old fashioned" 2.0 system. I may even end up regretting giving away all of my LP's 20 years ago!

To finally address your question, it will be in a smallish room in a townhouse so thunderous volume is not a concern. I want to get home from work, flop into a recliner, NOT turn on the TV, and enjoy really hearing a remastered copy of "Dark Side of the Moon" on my dad's old tube amp!

It's pretty unlikely that my problem is OT.

I did the 4-ohm and 8-ohm tap upgrades several months ago. So, that is the first place to start looking for the problem.

Yeah, "back in the day", power was expensive. So, the speakers were built to be more sensitive to account for the lesser power available. Today, power is cheap, so we can run less efficient / less sensitive speakers and simply feed them more power.

For a smaller room, I really like the DT SMs that I mentioned.

A couple other options:

Check out the Tekton Lores. I have absolutely no experience with these. But, they are efficient. And, another member on AH has the Lores on a tube amp and says it makes a great bedroom system. IMCloud is the member, perhaps he will chime in.

The Goldenear Triton 1, 2, or 3 towers would probably work well with a tube amp. If you read up on the GE site, Sandy (owner of GE) says he uses his on a SET tube amp! the T1, 2, or 3 have built-in "subwoofers" with built in amps. IIRC, I think they also have a Zoebel network. What this means is that the GEs are a very easy load to drive.

I do have a pair of the T2s, but I have not hooked my ST-70 up to them, mostly because my ST-70 is in my upstairs system and my T2s are in the downstairs living room. I know, I've been slacking.

 

[ski2xblack]

I may eventually acquire one of those fancy Fostex single driver kits that seem to be popular with tube folks. I am also aware of the huge and efficient Klipsch designs... Don't roll your eyes too much but something like the Klipsch RB-81s seem to be a good compromise of size and efficiency but are fairly expensive for me.

Regarding single driver speakers, I would suggest a pair of these or these (preferably the latter, well executed mltl vs. reflex for the bookshelf). The kits may be in striking distance budget wise. I've played around with enough full rangers and like the TB-W8 the best so far, much more than the fostex I've tried. Those in the mltl towers reach to ~40 hz in clean fashion, sensitivity ~94 even with bsc.

Regarding classic Klipsch, check the used market for forte II, typically in the $400 range. They're a legit 95db/w, and a great compromise w/ Hoffman's Iron Law with robust response into the low 30 hz area. These would be a great match for your dad's amp, but may be too expensive and/or too big, and that's assuming you can find a pair. The Quartet is similar but a bit smaller, another option to keep an eye out for. Corns, Heresys, etc. are probably over budget unless you get really lucky.

The RB-81's are a good choice for bookshelf types, no eye rolling from my direction. They're far less sensitive than Klipsch claims, but higher than average.

I'll second the Sandy Gross designed speakers w/ lower power amps, in my case older Def Techs BP7006 Super Towers. Worked very well.

 

[Tavi]

Welcome to the forum! Nice to see another Dyncao builder hanging around!

First thing's first: It would be good to know how large of a listening room you are in and how loud you typically listen to music. That can help to make recommendations.

I have built a Dynaco ST-70 from the Bob Latino (Tubes 4 HiFi) kit. Running EL34 output tubes.

To date, I have run my ST-70 on the Infinity P363 towers, the Philharmonitors, and the Def Tech SM350s. All in a relatively small room.

Here are my opinions:
*Philharmonitors: Don't bother. At low levels it was fine. But at slightly higher listening levels, I could hear the ST-70 struggling. This may be in part to lesser sensitivity from the Phils, but probably as much due to the un-forgiving transparency of the Phils.

*P363: I ended up going back into the ST-70 to install the 4-ohm taps. This greatly improved the sound and power delivered of the P363 as compared to the 8-ohm taps. No surprise, as the P363 was determined to be 4-ohm as measured here on AH.

*Def Tech SM350: Dang, the ST-70 really shines on these speakers! When properly placed, these speakers have more bass than you would expect for a smaller bookshelf. I'm sure these speakers are more forgiving than many, so that helps on the ST-70. I bought a pair from NewEgg for $200 a while back, and I say these are dang tough to beat if you can get that price!

So, from my own personal experience, I would suggest a pair of DT SM350, or even better spring for the SM450. The 350 can be found for $200 a pair if you are patient, and I have seen the 450 as low as the $300 a pair range. At those prices, they are good speakers, at full retail there are better options.

No personal experience, but a few of the AH members have suggested that a pair of vintage Klipsch Heresy speakers would also be a good match for the ST-70.

Now, to be clear, to get the BEST performance out of your ST70: I recommend getting a pre-amp or receiver with bass management and adding a subwoofer to the system. That will get you around one of the biggest limitations of the ST70 and / or Bookshelf speakers.

I had been running my ST-70 permanently on my P363s, being fed a source from drum machines and synths, but 1 of my channels on my ST-70 recently quit. I just haven't had a chance to really deal with troubleshooting that.

I bought a pair of Def Tech St450's. VERY pleased, especially after placing them on spiked, heavy steel stands. Thanks for taking the time to chime in with some good suggestions!

 

[slipperybidness]

Hey, I'm glad you like them and I'm glad that what worked well on my Dynaco also works out well for you!

Those older DT SMs don't seem to get a lot of love on here. But for some situations they work out great, sound good, and can't be beat for the price when you catch them on a good sale!

 

[Tavi]

Once the price dropped to $225, my complete disdain for their deceptive low end numbers went away enough to try a pair. Whatever low end they actually go to, I find myself listening to them with no equalization at all. Well maybe goosing the lowest two freqs. in iTunes a bit helps me avoid adding a sub. Putting them on the steel stands with the passive radiators facing inward was a real eye opener for me. I'm a believer now!

 

[slipperybidness]

Once the price dropped to $225, my complete disdain for their deceptive low end numbers went away enough to try a pair. Whatever low end they actually go to, I find myself listening to them with no equalization at all. Well maybe goosing the lowest two freqs. in iTunes a bit helps me avoid adding a sub. Putting them on the steel stands with the passive radiators facing inward was a real eye opener for me. I'm a believer now!

Haha, yup. I just about snatched up a pair myself when they hit that $225. I absolutely don't need them but that price was still tempting. I guess even worse is that I wouldn't even have a place for them if I bought them!

I think a L/C/R of SM450, surrounds SM350, and add a decent sub and you could have a pretty good 5.1 set on the cheap.

And yeah, when the passive radiators are done well, I think the results are very good!