45 AMP WITH STRAIGHT 8

najo49 · 3778

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Offline najo49

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on: May 19, 2013, 06:30:27 AM
I HAVE STRAIGHT EIGHT LOUDSPEAKERS AND I AM USING THEM WITH A 45 PARAFEED,DIRECT COUPLED,ACTIVE LOADED DRIVER STAGE 45 AMP. I HAVE NICKEL MAGNAQUEST 45 OUTPUTS. WHAT IF ANYTHING CAN BE DONE ABOUT MATCHING THESE OPTS WITH THE 15 OHM LOAD OF THE EIGHT SPKR. JAN OLSEN

Jann Olsen, [email protected].  Lowther medallion 2 with pm2a./ extended foreplay lll,/EROS phono /Grado ref/ SOTA star Vacuum SME V, /  45 amp direct coupled,c4s,mQ nickel  / paramour  2a3 w MQ iron /Original SEX monos /Jena Cables /heathkit wm6a/ proAc Tablette 50 sig , with push pull


Offline Paul Birkeland

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Reply #1 on: May 19, 2013, 06:59:40 AM
Which Magnequest transformers are you using?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Paul Joppa

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Reply #2 on: May 19, 2013, 12:01:16 PM
I presume it's an EXO-45, 5K-8 ohms. Ideally of course, in that case, you would sell those and get some EXO-46's which are 5K:16 ohms.

There are impedance-changing transformers and autoformers on the market that have taps for input and output of 4-8-16 ohms; those can be (for instance) installed at the speaker. But it does add another transformer into the signal path.

There is nothing technically wrong with driving the16 ohm speaker from an 8 ohm tap; you lose a couple dB of power but gain slightly better damping factor. Given the low impedance of the stock tweeter, a 16-ohm transformer would change the timbre of the speaker a bit, making it less bright. Still,  it's not a big difference.

Paul Joppa


Offline 2wo

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Reply #3 on: May 19, 2013, 06:41:18 PM
I typically feed my Straight 8's from 8 ohm amps. As a mater of fact I have a set of nickel EXO-45, in my SR-45, works fine...John 

John S.


Offline najo49

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Reply #4 on: May 20, 2013, 05:46:57 AM
Thanks to all for your replys. Yes I am using exo 45 in the amp. ideally I would use the exo 46 but considering all the feedback and pauls comments I think I will stick with the 45. I will get my Lowthers soon ,but they are 15 ohm too, but way more efficient . Thanks again for all your help! Jan O

Jann Olsen, [email protected].  Lowther medallion 2 with pm2a./ extended foreplay lll,/EROS phono /Grado ref/ SOTA star Vacuum SME V, /  45 amp direct coupled,c4s,mQ nickel  / paramour  2a3 w MQ iron /Original SEX monos /Jena Cables /heathkit wm6a/ proAc Tablette 50 sig , with push pull