Dynaco ST70 - new to me

[bmwr75]

Bought this amp from an AKer.  Its had an upgraded driver board and cap board installed.  Have mated it up with a Dynaco PAS2 preamp and Dynaco A-35 speakers.  New production tubes are installed: four JJ KT77, two JJ EC802S (12AU7), and one Tung Sol 12AX7.  Sounds good.  

Am already wondering about rolling some NOS tubes in.  Any suggestions??

[OCCD]

Very nice pick up!

[NATOE]

6p3s-e look for quad of these. good new old stock tube. 

don't for get to check the bias on that.

[NATOE]

Just looking at that it looks like a solid state rectifier if it is I would be leery of a stock quad cap in there.

[bmwr75]

Natoe,

The quad cap is just for looks, a new cap board has been installed.  Checked and adjusted the bias first thing out of the box.  I actually have two quads of NOS 6P3SE tubes that were purchased from eBay Sergy in Russia.  Can't beat them for $35/quad delivered.

Thanks,
Scott

[Kingman]

Nice lookin set up.

[NATOE]

Scott, you have to watch that tube off of ebay I have not seen one quad on there say matched.I get them right here off a guy I know that specs them out for you. If you would like that info or any other stuff like the paper work on that cap board let me know.

Right out of a friend mouth- "What are the advantages and disadvantages of the SDS cap board?"

Advantage > It has more capacitance than the stock Dynaco quad cap > 505 uF
Disadvantage 1 > It is expensive > $75
Disadvantage 2 > It is only rated at 500 volts
Disadvantage 3 > Unless you just leave the old quad cap sticking up there and disconnected if you remove the old quad cap you have a big hole in your chassis and now your amp doesn't look original anymore.

heres what else-"In comparison with the Dynakitparts 80, 40, 30, 20 cap ..
1. The Dynakitparts cap is less costly than the SDS cap board at only > $52.95
2. The Dynakitparts cap board is rated at 550 volts with a 600 volt surge rating.
3. OK - The Dynakitparts quad cap has less capacitance (170 uF) but in the ST-70 anything over 150 uF or so is really more capacitance than you need to run that amp. Adding more capacitance does not really help the sound or let the amp play any louder."

Just some food for thought.These answers from my friend were to some questions I had on a brand new whole triode kit.Not one thing on it is original. brand new build that someone didn't know what they were doing with.

[tinpan]

Very very nice. That looks like it would be a lot of fun. Since i am new to tubes, I see you installed the KT 77s, what does that do for you? More power deeper sound?

The reason I ask is my dad turns 90 next month. Since I dug out his old Lowther driver and I just received the Bottlehead amps from Yracer, it appears dear old dad has taken renewed interest Hi Fi as he puts it.

All he talks about are KT 88 tubes, so i am thinking about maybe getting him an amp for his birthday. I showed him a Yaqin amp with KT 88s and a Jolida with KT 88s. It looks like the Dynaco ST 70 could also be configured this way.

Do you think this could be a good amp for him to consider?

Thanks

[bmwr75]

Tinpan,

This amp came with the KT77s installed.  So, I've not done any comparisons to EL34s, etc.

I'm also new to tubes, so am not qualified to give you any advice on KT88 amps.  NATOE might be a better information source.  Also, you could ask the question in the Tube Forum on AudioKarma.org.  You will have to register as a user.

http://www.audiokarma.org/forums/forumdisplay.php?f=14

Regards,
Scott

[bmwr75]

NATOE,

I received all the upgrade documentation with the amp.  Just need to read it.   

Thanks,
Scott

[NATOE]

The KT88's are more suited for a brand new build with the new transformer the old ones can do it but i would not advise it. to much current draw for that transformer. plus you have to change so resistor values on the board if i remember right.

[Falcon]

Very nice...

[schwarcw]

Scott, it looks fabulous!  A lot of ST-70 owners like the EL-34 tube.  I've never owned one of these so I can't give you any suggestions.  Let us know how it sounds!

I need to get over to your place someday soon and hear that nice system of yours.  BTW, nice wood case for the PAS

[bmwr75]

Carl,

You are welcome any time to come over for a listening session, as are any of the local Hi-Fi enthusiasts.  Just give me a call first at 724-835-1102.

Regards,
Scott

[BB3]

What A Beautiful Setup, Scott. You Must Be Very Proud, And Rightfully So Sir. I'm Sure The Sound Is Equally Impressive, As Well.

-----Sincerely, BILL(BB3)