OTL Asylum

OTL, Output Transformerless Amplifier User Group.

Return to OTL Asylum

I am new here...

24.126.87.12
Posted on June 25, 2009 at 18:02:31
Penguin
Audiophile

Posts: 3973
Location: Maryland
Joined: August 5, 2001
Contributor
  Since: October 12, 2002
 Before I start taking things apart, is there enough room in the Atma Sphere MA-1 MK II to put a second set of binding posts on to make bi-wire easier? There is plenty of space on the back plate outside...but what about inside?

thanks

dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.

quote by Kurt Vonnegut
RE: I am new here..., posted on July 17, 2009 at 21:56:57
makarushka
Audiophile

Posts: 83
Location: Oakland, CA
Joined: April 29, 2003
 May not be what you're looking for but something to consider nonetheless: terminate one pair out of your bi-wire cable to a good banana plug of your choosing. This way you can use the binding post to connect two cables in the way the binding post was designed, and without crowding the thing too much. There is of course a spades-vs-bananas-vs-bare wire argument that may or may not be of relevance to you in this situation but like I said -- something to ponder.

Bi-Zeroing with Paul Speltz autoformers can yield some astonishing results…, posted on July 12, 2009 at 22:55:02
Wellfed
Audiophile

Posts: 11220
Joined: January 11, 2008
 Not what you asked about, I know. You can also use one pair of Zero's to bi-wire IIRC.

Re bi-Zeros, posted on July 20, 2009 at 10:21:14
Lew
Audiophile

Posts: 2686
Location: Bethesda, Maryland
Joined: December 11, 2000
 Dear Wellfed, I looked over on Paul Speltz's website. In general he advises against the need for bi-wiring with Zeros, and he says nothing that I can find re using two Zeros to drive the top and bottom of the same speaker, altho the concept does have some theoretical merit, where a speaker may present a radically different impedance in the treble vs the bass. Have you tried bi-Zero-ing?

Bi-Zeroing my former N.E.A.R. 50Me II's was unreal..., posted on July 20, 2009 at 19:03:15
Wellfed
Audiophile

Posts: 11220
Joined: January 11, 2008
 IIRC I used 4x leads on the bottom while definitely using the 'alternative' 2x leads on the top. Ooh, la la

RE: Bi-Zeroing my former N.E.A.R. 50Me II's was unreal..., posted on July 21, 2009 at 08:16:42
Lew
Audiophile

Posts: 2686
Location: Bethesda, Maryland
Joined: December 11, 2000
 But the amp sees the two Zeros in parallel, thus reducing the net impedance seen by the amp by half, assuming the impedances of the treble and bass components are equal. Whereas increasing the apparent impedance of the speaker is the main goal of using Zeros in the first place. I have to think about this, but I am guessing that the net impedance seen by the amp is not higher than what one achieves with one Zero. I would not argue with your real world results, however.

RE: Bi-Zeroing my former N.E.A.R. 50Me II's was unreal..., posted on July 24, 2009 at 02:10:08
Gnnett
Audiophile

Posts: 36
Location: N/L
Joined: September 7, 2002
 I think he is saying 1 zero and using 2 sets of taps. The question remains however if this puts the treble and bass in series or parallel?

Regards

Grantn

I was using 2 pairs…, posted on September 2, 2009 at 20:56:02
Wellfed
Audiophile

Posts: 11220
Joined: January 11, 2008
 Lew was wise to not doubt my real world results, bi-zeroing was definitely one of the most memorable audio epiphanies I've experienced, and I've had a few.

I don't use any Zeros with my current loudspeakers.
Parallel..., posted on July 24, 2009 at 06:34:34
Lew
Audiophile

Posts: 2686
Location: Bethesda, Maryland
Joined: December 11, 2000
 unless you deliberately create a series connection by reversing the leads for one driver vs the other. But if you can do that, you may not need a Zero at all.

Welcome..., posted on July 6, 2009 at 19:33:56
Rod M
Web Geek

Posts: 3656
Location: So. California
Joined: March 1, 1999
Contributor
  Since: March 1, 1999
 In my experience, a good set of jumpers at the speaker end worked better than bi-wiring, or I couldn't tell the difference, and cost a lot less.

Given the responses and my cheapness, you could just connect both cables to one terminal, they're big enough. Or you could re-terminate the bi-wire into one spade. Personally, I'd sell one set and buy a jumper for the speakers of the same wire type.

-Rod
RE: I am new here..., posted on July 2, 2009 at 19:15:35
Legendre
Manufacturer

Posts: 455
Location: Saint Paul
Joined: October 22, 2004
 You'll need to take a look at it, but you might be able to add a second set by using the existing (two) holes as provisions for two new pairs of posts.. i.e. you punch two holes, one each (respectively) left and right of the existing post hole pattern. In this way, the two original holes are split up to become one hole each for the new side-by-side setup.

I've never done it, but it sounds possible - at least before I look into an amp ;-)

-L

The notes about the wiring, posted on July 3, 2009 at 08:57:13
Penguin
Audiophile

Posts: 3973
Location: Maryland
Joined: August 5, 2001
Contributor
  Since: October 12, 2002
 by Ralph dampened my enthusiasm...But you guys may want experiment with your new designs and see if it is worth it. There are a lot of people who would welcome the extra set of binding post for bi-wiring or for hooking up subs. Just a passing thought. But the left right holes are a good idea....thanks

dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.

quote by Kurt Vonnegut
RE: The notes about the wiring, posted on July 3, 2009 at 22:05:48
Legendre
Manufacturer

Posts: 455
Location: Saint Paul
Joined: October 22, 2004
 If you are simply bi-wiring, the provided Cardas posts should have sufficient throw to easily accept two lugs per terminal. If you'd like to drive powered subs with the voltage signal from the output, then the female 'twin banana jack' design of the Cardas posts might well suffice.

Since Atma-Sphere OTLs (like most OTL amplifiers) tend to prefer moderately higher impedances, they do not anticipate the need to drive *paralleled* loads at any significant power.. as they tend to be of a lower impedance.

The other side of this, is that when we see units which have been modified in the field, far too often the work is of negligible quality. And while there are certainly individuals qualified to perform this type of work, we instinctively tend to discourage it - based upon what we have encountered over the years.

-L
I do appreciate your response..., posted on July 3, 2009 at 22:43:13
Penguin
Audiophile

Posts: 3973
Location: Maryland
Joined: August 5, 2001
Contributor
  Since: October 12, 2002
 The reason I even thought about the mod to start with has a lot to do with the configuration of the stuff here. I am using short 10 AWG flat silver wires, with my previous amps i was vertically bi-amping, so obviously the the low and top halves of the Soundlab'c crossovers were driven from different connectors. These wires do not have spades or connectors, i formed a U shaped cutout on the flat silver itself. So everything is on the stiff and bulky side that made connecting two wires to the same terminal quite challenging, But it is done and not going to be touched for a while. I could go back to single wire and a jumper on the speaker, or just take the backplate out and reconnect the two halves to the same terminal.

..... right now...it will stay as is.

dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.

quote by Kurt Vonnegut
Welcome to the fold, posted on June 26, 2009 at 16:24:24
Brian Walsh
Dealer

Posts: 7091
Location: Barrington, Illinois (Chicago area)
Joined: December 6, 1999
 Glad I could help you the other day when you called and that it turned out to be just a fuse. Ralph's amps are pretty bulletproof :-)

Just be prepared when you come here in September...

Brian Walsh
should i be afraid?, posted on June 26, 2009 at 18:57:57
Penguin
Audiophile

Posts: 3973
Location: Maryland
Joined: August 5, 2001
Contributor
  Since: October 12, 2002
 dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.

quote by Kurt Vonnegut
RE: I am new here..., posted on June 26, 2009 at 12:21:03
shermanr@prw.net
Audiophile

Posts: 498
Location: Sunny San Juan, PR
Joined: June 8, 2004
Contributor
  Since: June 24, 2009
 In my opinion depends on how one views such a modification.

The less invasive route would be to have your favorite cable manufacturer build a set of speaker cables 'bi-wire' ready.

Installing a second parallel set of binding posts on an MA-1 to some may be an invasive and value affecting modification.

Yet others don't even bat an eyelid on drilling a few holes and soldering a few extra parts in any piece of gear, regardless of cost, long term value, aesthetics or integrity.

Apart from achieving a desired result, whose improvements may be real or perceived, it's about choices made and the consequences of these choices.

I had to talk a friend out of punching a hole into a Cary SE300 chassis to install an XLR connector.

The thought of doing this to that besutiful shiny chassis made me cringe.

Producing the response to a quick e-mail to Dennid Had was all I needed for a cease and desist on that idea.

The word "ruin a perfectly good amplifier" was persuasive enough.

RE: I am new here..., posted on June 26, 2009 at 11:07:46
Ralph
Manufacturer

Posts: 1157
Location: Minnesota
Joined: April 24, 2002
Contributor
  Since: April 1, 2002
 Welcome!

All of the MA-1s ever built have an internal wiring scheme that is intended to minimize the effects of that wiring. Consequently it is a chore to disassemble the speaker connection, as the speaker signal is literally assembled on the speaker terminals themselves. This is the most critical connection in the amplifier- we had to make special tools to do the assembly correctly.

The MA-1 MkIIs do not have a lot of rear chassis space internally. The best location for for a second set of terminals would be directly beside the first pair, between them and the corner away from the fuses. Be very careful if you attempt this- most of the MkIIs are stainless steel (even the painted ones) -tricky to drill and punch through, so it will be very easy to make a mess, and that will be the easy part! Actually hooking up the second set of terminals so that they don't affect the sound will be the biggest challenge.

Ugh..., posted on June 26, 2009 at 15:45:31
Penguin
Audiophile

Posts: 3973
Location: Maryland
Joined: August 5, 2001
Contributor
  Since: October 12, 2002
 Thank you,

I guess "nothing is simple" applies here. Based on your comments Ralph, the risk is not worth the convenience gained by performing this mod. I did not realize the complexities of the internal wiring.

BTW thank you for making the asking of this question even possible ...I am simply lost for comments when it comes to the sound of these beasts.

dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.

quote by Kurt Vonnegut
RE: I am new here..., posted on June 26, 2009 at 06:44:03
Lew
Audiophile

Posts: 2686
Location: Bethesda, Maryland
Joined: December 11, 2000
 Welcome to the site, but I would advise you to ask Ralph Karsten about doing this, unless you have a very clear understanding of the circlotron topology. If you do, then why not just open up the amp and take a look?

Page processed in 0.182 seconds.

[ Top Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2009, Audio Asylum, all rights reserved ] [ Go Green ] [ Take5 ]
[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]