Speakers for use with a Dynakit ST-70

Spawndn72

Looks like I am going to be getting a vintage ST-70. This is going to be my first tube amp and was just wondering what kind of speakers I can power with this thing? Will it be enough to power a set of SDA 2's? Or am I going to be using it for a second system?

Thanks,
Todd

organ

Check out the Klipsch Reference line. I power a pair of RF-35 with mine and the combo is pure magic. With the right speakers, that amp will blow away your Adcom. That's what it did to my NAD C270. Just becareful. If you fall in love with tubes, say bye bye to your ss equipments;).

Is this a restored/rebuilt unit or is everything stock? Don't power up the amp as soon as you get it. Vintage tube amps need a few checks ups before powering up.

Zen Dragon

The answer to your question depends on some of your tastes. The tube amp will give you the rich mids, and the softer unfatigueing highs. You will lose a little punch in the low end.
If you are a volume/power junkie the ST-70 may not provide enough volume for you. I for one like my music very loud at times, to the point where you are enveloped in the music vs just listening.
If you listen at moderate volume you may find the sound enticingly sweet, and you can use a sub to round out the bottom end if it doesn't have enough punch.
Let us know what you think.

faster100

Boy long time no see, you ever move to TN ? I had this very amp and its more powerful then you might think.

I think it can power any typical speaker or smaller sda with no problem. I beg to differ on the loudness, this amp can get pretty loud.

Bear in mind though, it gets really hot.. make sure you have A/C in said room and a fan.. those power tubes can heat up a small room quick. one reason i got rid of mine,(florida room with no a/c) besides needing money to buy my sda's i had.

Id get it though if i had the chance

Spawndn72

I am back in Nashville, now. I guess I need to update my profile.

The amp is being checked over right now, so it will be functional before I get it. As far as I know it is stock.

organ

Zen Dragon wrote:

The answer to your question depends on some of your tastes. The tube amp will give you the rich mids, and the softer unfatigueing highs. You will lose a little punch in the low end.
If you are a volume/power junkie the ST-70 may not provide enough volume for you. I for one like my music very loud at times, to the point where you are enveloped in the music vs just listening.
If you listen at moderate volume you may find the sound enticingly sweet, and you can use a sub to round out the bottom end if it doesn't have enough punch.
Let us know what you think.

You're right and wrong here. What you've described is the typical sound of lower effeciency speakers being powered by tube amps. That's what you normally get, soft highs less bass punch.
That's why I recommended the Klipsch to him. Being close to 100db/w/m is super efficient, and his ears will give up (and bleed;)) way before the amp. On my RF-35, the ST-70 sounds a lot more powerful than my NAD ss amp. Even the bass have way more punch.
So with the right speakers, the ST-70 will satisfy any volume/power junkie.



Todd,
Keep us posted and get some pics taken. I love Dyna stuff and I'm curious to see what kind of condition your unit is in and what type of transformers, tubes, etc you got with yours. The original tubes are worth a lot of money. Remember not to power up the amp without speakers connected.

BlueMDPicker

Polk RTA-12C

Synergy out the wazoo.

ohskigod

dont rule Bozaks out, My Bozaks with 8 watts from the Radii sounds great from top to bottom. Laid back in the highs butpleasant. strong mids (I have heard from more than one person that the 5 1/2" midrange driver in the Bozaks were some of the best made, hell I cant argue) Remarkably big sounding, and loud, from such little power.

obviously not made anymore, and you would have to cruise Ebay or audiogon.

organ

Oops, forgot to mention, the RT series also sound fantastic on tubes. I've tried the RT5, 800i and 15i on my ST-70. Try both the 4 and 8 ohm taps. I prefer the 4. More bass and smoother treble.

Zen Dragon

organ wrote:

You're right and wrong here. What you've described is the typical sound of lower effeciency speakers being powered by tube amps. That's what you normally get, soft highs less bass punch.
That's why I recommended the Klipsch to him. Being close to 100db/w/m is super efficient, and his ears will give up (and bleed;)) way before the amp. On my RF-35, the ST-70 sounds a lot more powerful than my NAD ss amp. Even the bass have way more punch.
So with the right speakers, the ST-70 will satisfy any volume/power junkie.

I concur with the Klipsch recommendation based on efficiency. That however is one of the great shortcomings of many tube amps IMO. Many subscribe to the school of thought that you find the speakers you love, and build the system around them. It follows that many many great speaker systems reside in the 87-91db efficiency spectrum.
This means someone looking to run 105DB plus out of their speakers needs to use high amplification.
There are advantages and disadvantages to high efficiency speakers. I think many 90dbish efficient speakers are much warmner with better imaging than high efficiency speakers. Also while I have never heard horn tweeters on tubes, they are just too much for me on SS.
As to the slightly diminished bass punch, contrary to popular belief, that is not solely a function of tubes, but also a charachteristic of the impedance curve of most transformers. Since output tubes mostly are transformer coupled, it can be a difficult reality to circumvent. Not the absolute, just the norm.
Tubes are wonderful, but like many situations in audio, there are tradeoffs.

ND13

Believe it or not, my Monitor 7As sound EXTREMELY good on my Wave 20s, which are only 20 watts each. Ask HTRookie, his jaw dropped to the floor when he came over. He was more impressed with them than my SRS2s.

organ

Zen Dragon wrote:

I concur with the Klipsch recommendation based on efficiency. That however is one of the great shortcomings of many tube amps IMO. Many subscribe to the school of thought that you find the speakers you love, and build the system around them. It follows that many many great speaker systems reside in the 87-91db efficiency spectrum.
This means someone looking to run 105DB plus out of their speakers needs to use high amplification.
There are advantages and disadvantages to high efficiency speakers. I think many 90dbish efficient speakers are much warmner with better imaging than high efficiency speakers. Also while I have never heard horn tweeters on tubes, they are just too much for me on SS.
As to the slightly diminished bass punch, contrary to popular belief, that is not solely a function of tubes, but also a charachteristic of the impedance curve of most transformers. Since output tubes mostly are transformer coupled, it can be a difficult reality to circumvent. Not the absolute, just the norm.
Tubes are wonderful, but like many situations in audio, there are tradeoffs.

You're right High eff have their pros and cons. They are brigter and more forward. The tube amps give them warmth and brings the sound back a bit. The thing that attracted me to the Klipsch is their ability to sound great on tubes and still keep their dynamics due to the high eff design.
But even with tubes, the horns are still more forward than other speaers. I like my Klipsch and Polk RT15i on tubes and I like to power my LSi9 with SS.
Yeah, it's not just the tube that give bass, the output tranny and how well it transfers power to a speaker's impedance curve is very important. The OT on the ST-70 (A470 on earlier versions) is considered one of the best. Many people scrap Dynacos and build their own amp around the output transformers.