So...What will I Fry by Running my ST70 into (4) 8 Ohm Bozaks? It really Sounds Marvelous. Much Nicer Bass now that I have (4) 8" B800BC's doing the work..
5 posters
4 Speakers on a St70
Sled108- Posts : 40
Join date : 2010-02-03
erlingt- Posts : 16
Join date : 2010-06-23
Location : Denmark
4*8 Ohms speakers, is 2*8 Ohms in each channel. So you just connect them to the 4 Ohm connectors, and everything is OK.
Sled108- Posts : 40
Join date : 2010-02-03
No, I mean running 4 Speakers out of the 8 Ohm Outputs..
Sal- Posts : 221
Join date : 2009-02-05
Location : Central New Jersey Dynaco-ST70.com
Why not connect them to the 4 ohm tap on the speaker terminals? Then it will be a non issue.
Sal
Sal
GP49- Posts : 792
Join date : 2009-04-30
Location : East of the sun and west of the moon
You won't blow up anything but two 8Ω speakers in parallel on each channel makes a 4Ω load, so why do you want to connect them to the 8Ω tap? All that will do is make for a non-ideal load to the output tubes, and lower output power.
Sled108- Posts : 40
Join date : 2010-02-03
I do not have 4 Ohm Taps on my 'ST70'... Only 8 Ohms...
Bob Latino- Admin
- Posts : 3274
Join date : 2008-11-26
Location : Massachusetts
Sled108 wrote:I do not have 4 Ohm Taps on my 'ST70'... Only 8 Ohms...
You probably DO have an 4 ohm tap for your output binding posts and it is probably INSIDE the amp. Open the amp up. If it is a stock A-470 output transformer or even a clone A-470 output transformer they have the same wire color coding as the original Dynaco A-470 output transformer as below.
16 ohm > YELLOW wire
8 ohm > ORANGE wire
4 ohm > BROWN wire
To set up your amp for a 4 ohm tap you just unsolder the ORANGE wire from the binding post on each channel and solder on the BROWN wire. Be sure to insulate the end of ORANGE wire that you just removed.
Bob
Sled108- Posts : 40
Join date : 2010-02-03
Hi Bob, thanks for the reply...You've already seen my Not-So 'ST70' with the 6u10s...I've been trying to figure where to go with this since one of the A-470s has started running Hot...I now have a Pair of Edcor 60W 4.2K 8 Ohm OPTs ready to be Installed...But, I also have 8 JJ KT77s with Small Pins, and it could use a new set of Tube Sockets...That, and a very Hot running PT has me thinking...I can get an Edcor XPWR029 700V Ct, 50V, 6.3v Ct for $83...So, if I'm doing all this, maybe I can also upgrade to KT88s?
Sled108- Posts : 40
Join date : 2010-02-03
Thanks Bob...I just went for the Easy Fix as you Said....Swapped the 8 Ohms with the 4 Ohms in all of 5 minutes...It's Sounding Great now...After 25 years, this is the first time that I've Heard the 4 Ohm Taps, and it pretty much Sounds the Same on 4 Speakers...Thanks Again...
I guess I'll put in the Edcors come Cooler Weather and maybe Re-think the KT88's..I've read they need -70V to Bias...
I guess I'll put in the Edcors come Cooler Weather and maybe Re-think the KT88's..I've read they need -70V to Bias...