DCC Archive Look at this amp...

How much do you think something like this is worth? The seller has another in almost the same shape.

With such a low power output, what kind of speakers can you match up with them?
http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=1301473696

 

I not sure the two units are compatible for monoblock applications. The one at the top is completely rebuilt. Look at the pics of its underside. Unreal. I also know of a couple of rebuilt units going for $400.

I'm wondering how practical it would be for someone with little technical knowledge (me) to own and maintain such a beast?

re: 35W What about reserve power for handling transients? I always thought that was important for driving speakers to their full dynamic potential. I was told long ago that, when matching speakers, you can't directly compare tubes to SS, the implication being you can drive a speaker with less power with tubes. Is it true?

Decisions: I was actually getting ready to order a micro ZOTL tube headphone amp. I haven't done my homework for the main system upgrade yet. (sigh)

 

Monoblocking an ST70 is not a wholesome idea. There's nothing really to be accomplished when you try to monoblock them, for power or for sound. I learned that, imperically it just isn't a good idea.

Medium-sensitivity speakers are just fine. Now, remember, an ST70 is a STRONG 35/w per channeler. If you think 35w/per is weak for 8ohm middle efficiancy speakers, you'll be quite suprised. They won't power electrostatics (although they try) and the sound from the ST70 is enough to make most audiophiles plesantly comfortable for a long, long time. Tubes and cap upgrades turn the sound from amazing to godlike for mere wallet residue.

I don't have Dynaco's as main 2 channel on my main system anymore, as I've switched happilly to electrostatics and a Hafler 225w amp. Take a look into Haflers if you're looking for high-powered SS amps. You'll find the Dynaco and Hafler carry a distinct connection in the designer.

The Dynaco will instead go into a new room with the Foreplay, some equipment I repaired for nickles, and my older DIY speakers. It'll sound wonderful, and powerful too.

 

The last iteration of my JBl L100 system (pre-diasphora) consisted of an early 80's 100w Hafler. Are you talking vintage units or are they still in production?

Can you clarify "med. efficiency speakers"? Is that related to sensitivity? Is there a specification I should be looking for, and what range would that fall under?

Caps are capacitors, right?

I think I'm finally getting over this neurotic attachment to the long gone L100 sound and am ready to setup something different.

thanks

 

I would strongly suggest you check out the David Hafler site at www.hafler.com David and his respected team are alive and well. They're still producing some of the best amplifiers ever built. Mine is the H-225, bought from eBay at $200. It's 175w per at 4oHms. I unscrewed the rack mount face off of it, and it looks new. The side cage has scratches and dents in it, but it runs like new. I can call it "vintage" if it's older than 20 years?

Listen to what this guy had to say about the 220: "It even survived a lightning strike that trashed all of my other equipment. I constructed the 1984 model for my fraternity house's sound system. Last year, they bought a new system and gave me the old Hafler. It only needed a fuseholder to work perfectly. Any amplifier that can survive 15 years of wide open party operation has to be good. I think it is near impossible to find amps built as sturdy today without spending a lot of money."

Yes, Caps are capacitors. "Med Efficiency speaks" refer to most any speaker, usually cone types, and unless they're specifically speakers that require a lot of power (like electostatics or such) then they should be just fine. Check the ratings, but for the most part, the Dynacos will drive most anything with ease.

As far as owning Dynacos, or DIY tube amplifiers (or any tube amp) I'd say that if you don't want to become somewhat electoronic savvy, then avoid tubes. When you get a hold of a ST70, weather you like it or not, or weather if you realize it or not, you will become a little more familiar with how it works. It may be years or just days from the date you purchase one, but you'll soon come to understand how they work. You WILL assimilate.

Tube amps are not for everyone. If you can respect the amp, pay attention to detail, and do some reading on tweeks, tubes (and promise to check the bias setting with a volt meter every once in a while) then it will love you back. It's a lot like keeping a pet, investing love, understanding, time and care. Be very careful, as there's deadly voltages inside, while turned on. There are parts that are usually very rare on the amp, but upgrades of "modern" type can be had. They can also get hot on a regular basis, so if you have children under 6, be very careful. You can almost toast bread on the tube cage, while it's running happilly.

Oh, and still, I hail most newly made Russian tubes with confidence. Favorites are Sovtek and Electro-Harmonix. I have one ST70 running a Sovtek rectie and 4 EH EL34s. Steve will tell you NOS tubes are the best, and they are. They will eat your pocket alive sometimes too. The other Dynaco runs Mullards, original tubes still going strong after 30+ years of sparatic use in the amp's life. Virtually no mechanical noise ever!!

[ November 25, 2001: Message edited by: Sckott ]

 

Sckott, thanks for the help and information. I need to do more homework as there is much to take into consideration.

 

Pig,

I got my Dynaco ST-70 in the first week of September. It is a fantastic amp. There are tons of helpful info on the net (Audioasylum is very, very helpful) to get you familiar with the unit and what "tweaks" or repairs may need to be done. I got mine by posting a WTB ad on a few newsgroups and I was getting very fair prices. I decided to buy from a local guy (I was worried about any shipping mishaps). He had a ST-70 for $325 in excellent condition with Russian tubes. We were going to meet the following week. Two days before our date he left me a message that his partner (unaware of our deal) sold the unti to someone else but he had another one in near mint condition (some of the lettering was rubbed off but everything else was top-notch/A-470 transformers/cloth leads/pre-zip code markings/etc.) with Mullard tubes (tested strong). It was worth a lot more than our agreed price and he decided to honor our deal... I've done some work on it. I upgraded the power supply with the SDS board (from Triode Electronics). I have replacement ceramic tube sockets and some new caps for the stock board but that's another weekend. I've polished up the chassis with Fliz and cleaned all the inputs/etc. with Blue Shower and some other products. It sounds superb. The mid-range is very exciting to listen to. Instruments sound very full and realistic. Vocals have a great preseance. I have Paradigm Studio 20 speakers (89db sensitivity) and the 35 watts have no trouble driving them (no strain when cranked up). Tubes have a very seductive sound. Last night we had my mother over for her birthday and we we listening to a lot of Capitol-era Sinatra (in pure High Fidelity), Duke Ellington, Ella Fitzgerald, Miles Davis, etc. My step-father (he's in his late 70's) really enjoyed the tube sound. They both reconized the Dynaco when they saw it (oh, remember that...) He could hear the different levels and details of the singer/instruments/etc. very clearly. He was drawn into the music. Anyway, I think the Dynaco St-70 is a great machine.

Todd

 

That's really encouraging Todd. As I find myself reaching for my classical discs more and more, I also find myself wondering what I can do to enhance that experience. What you describe sounds so sweet. I guess you are doing your own mods.

 

Pig,

I'm doing my own simple mods but with very heavy research before each step (I hate fires). It seems complicated but the basic stuff is not too much trouble (it's like waiting to jump in a pool and dreading the initial temp change but then it's ok after you do it).

Classical music sounds great with the Dynaco (I was listening to an old Boston Pops album a few days ago). Lots of warmth and texture. Acoustic guitars are also really nice. It's difficult to describe the sound. Warm? It doesn't sound harsh or thin. It's very round and full. A good recording of a vocal sounds like a good recording. It's musical...

I would suggest doing a lot of reseach (get an idea of what you may getting into) and maybe go to some shops and listen to some tube gear. I tried for a month to get one on Ebay (in my budget) and kept losing the auctions. It was driving me nuts. I decided to post the WTB ads and had better luck that way.

Todd