McIntosh MC-2105 and SDA-2 Speakers

cjmustang69

I intend to hook my pair of SDA-2 speakers to my McIntosh MC-2105 amp - would like to verify the amp is common ground design. I believe it is as I see several posts of members using this amp with their SDA speakers. Just like to verify prior to connecting the umbilical cord. Thank you in advance for replies.

mhardy6647

So -- the short answer is: I dunno Sorry!

This being said, 1) the MC-2105 is an autoformer coupled amp and 2) I do have an MC-2100 in a box in the basement (it's not my idea of a good sounding amplifier); I believe (?!?!?) the MC-2105 is virtually identical other than its packaging and the big ol' blue Mac meters. I can get out a DMM & check the grounds of the two channels of the MC-2100 for continuity if it might add any value.

I know that the MC-2100 and its kin were bridgeable, which makes me suspect the grounds are all tied together -- but I do not know that as fact.

Schematics for most of the legacy Mac products are available on the internet, and I have the MC-2100 docs someplace -- but it's not particularly likely that this info would be explicitly contained in the docs or the schematic. This is a testable hypothesis, though

EDIT: MC-2105 manual, in case you don't have it:
http://www.berners.ch/McIntosh/Downloads/MC2105_own.pdf

SM @ http://www.vintagevacuumaudio.com/schematics-manuals/mcintosh/mcintosh-2105-service-manual.pdf

see also: https://www.hifiengine.com/manual_library/mcintosh/mc2105.shtml

cjmustang69

Thanks for reply and information. I've read some of your posts regarding your MC-2100 amp know you were less than impressed with its performance. I've had my MC-2105 amp for almost 3 years now - having it looked over by AudioClassics to ensure it was performing to spec, when I purchased it. Primarily use a C-22 tube preamp. I've paired it with Quad ESL-2905, Klipsch Cornwall (with ALK crossovers), and Usher 718Be speakers. For me, never been less than thrilled with its performance with each of these speakers. This is reason I'd like to hear how it pairs with my SDA-2 speakers. Thanks again.

[Deleted User]

The amp's schematic shows the amplifier to have both channel's negative speaker terminals tied to ground. You should be fine with an SDA connection.
Interestingly, if you look at the amp's input circuit there are two 0.22uF mylar coupling caps that can be bypassed with the "direct" switch these are labelled C1 and C2. Then there are two 0.47uF mylar caps (C3 and C4) and the last stage uses two 10.0uF non-polarized electrolytic caps (C9 and C10) in the signal path. With today's relatively small film type caps these two could be easily replaced with better results.

cjmustang69

Thanks for reply - hooked them up without issue. Initial impression is combination sounds quite good. The speakers have the RDO -194 tweeters and Larry's rings installed on passive radiator - but not the mid drivers. I intend to install them tomorrow.

Unknown

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leftwinger57

My friend who was a protetge of Phil Lesh .Complete w/ a 6 string Alembic bass, a Mc 2100 the industrial looking one, Furman pre/amp and double hard trucker cabinets w/ 2 15" JBLs in each. Personally I liked the Mc 2105 w/ the meters and the walnut cabinet w/ the slanted legs for home use and not road worthy at all.. I have only fantasies.

motorstereo

Just to change things up occasionally I'll use my pair of strapped Mc2100's in place of my bridged Mc2500's on my 1.2tl's. Initial impressions of the 2100's was "damn these things sound great"! After those initial impressions had faded and spending some time with them I noticed there's a bass and treble boost that does get annoying on the polks that don't need the extra "help". But with period correct speakers (ML1C's) that do benefit from that slight boost at the bottom and top end they sound fine.

cjmustang69

I have a MC-7300 amp, which is at AudioClassics being repaired. I'll be interested in hearing how it sounds with the Polks in place of the MC-2105. Currently have the MC-2105 with MX-117 and Polks. Listened to the system for a few hours last night, I enjoyed the combination a lot. I had forgotten how nice the SDA speakers perform. My first decent pair of speakers, bought new in 1986 or 1987, was a pair of SDA-2A speakers bought new in Amherst, NY. Sold them in 1994 or 1995.

mhardy6647

Yep2 wrote: »

mhardy6647 wrote: »

So -- the short answer is: I dunno Sorry!

This being said, 1) the MC-2105 is an autoformer coupled amp and 2) I do have an MC-2100 in a box in the basement (it's not my idea of a good sounding amplifier); I believe (?!?!?) the MC-2105 is virtually identical other than its packaging and the big ol' blue Mac meters. I can get out a DMM & check the grounds of the two channels of the MC-2100 for continuity if it might add any value.

I know that the MC-2100 and its kin were bridgeable, which makes me suspect the grounds are all tied together -- but I do not know that as fact.

Schematics for most of the legacy Mac products are available on the internet, and I have the MC-2100 docs someplace -- but it's not particularly likely that this info would be explicitly contained in the docs or the schematic. This is a testable hypothesis, though

EDIT: MC-2105 manual, in case you don't have it:
http://www.berners.ch/McIntosh/Downloads/MC2105_own.pdf

SM @ http://www.vintagevacuumaudio.com/schematics-manuals/mcintosh/mcintosh-2105-service-manual.pdf

see also: https://www.hifiengine.com/manual_library/mcintosh/mc2105.shtml

I would like to see a list of vintage kit you deem worthy listed in order, best to worst.
Vintage gear.
Almost worth paying for!

I would put the Marantz 8B and McIntosh MC-225 very near the top of the list for storebought stuff.

Things like Western Electric & Langevin amplifiers don't quite count as consumer/storebought, unfortunately.

My experience with the sound of various MC-250s and MC-2100s (and one MC-2105) , most of them rehab'ed, is uniformly not impressive. They have all been harsh and/or grainy sounding to me.

Msabot1

Yep2 wrote: »

mhardy6647 wrote: »

So -- the short answer is: I dunno Sorry!

This being said, 1) the MC-2105 is an autoformer coupled amp and 2) I do have an MC-2100 in a box in the basement (it's not my idea of a good sounding amplifier); I believe (?!?!?) the MC-2105 is virtually identical other than its packaging and the big ol' blue Mac meters. I can get out a DMM & check the grounds of the two channels of the MC-2100 for continuity if it might add any value.

I know that the MC-2100 and its kin were bridgeable, which makes me suspect the grounds are all tied together -- but I do not know that as fact.

Schematics for most of the legacy Mac products are available on the internet, and I have the MC-2100 docs someplace -- but it's not particularly likely that this info would be explicitly contained in the docs or the schematic. This is a testable hypothesis, though

EDIT: MC-2105 manual, in case you don't have it:
http://www.berners.ch/McIntosh/Downloads/MC2105_own.pdf

SM @ http://www.vintagevacuumaudio.com/schematics-manuals/mcintosh/mcintosh-2105-service-manual.pdf

see also: https://www.hifiengine.com/manual_library/mcintosh/mc2105.shtml

I would like to see a list of vintage kit you deem worthy listed in order, best to worst.
Vintage gear.
Almost worth paying for!

My vintage kit that gets the most use around here is as follows...Dual 1229 table..MX110Z pre...MC240 amp and into a pair of JBL120ti or Polk 10B's...plus a slew of vintage first release vinyl....this little combo gets more work than a lot of my 'newer' equipment....vintage sound rules the roost here!..

cjmustang69

cjmustang69 wrote: »

I have a MC-7300 amp, which is at AudioClassics being repaired. I'll be interested in hearing how it sounds with the Polks in place of the MC-2105. Currently have the MC-2105 with MX-117 and Polks. Listened to the system for a few hours last night, I enjoyed the combination a lot. I had forgotten how nice the SDA speakers perform. My first decent pair of speakers, bought new in 1986 or 1987, was a pair of SDA-2A speakers bought new in Amherst, NY. Sold them in 1994 or 1995.

I finished installing Larrys Rings yesterday and have been enjoying the SDA-2A performance a lot. Enough so, I have pending purchase of a nice pair of SRS2 speakers - which I hope to get to my house next week. Looking forward to how they compare to the smaller SDA speakers.

warren

The amp's schematic shows the amplifier to have both channel's negative speaker terminals tied to ground. You should be fine with an SDA connection.
Interestingly, if you look at the amp's input circuit there are two 0.22uF mylar coupling caps that can be bypassed with the "direct" switch these are labelled C1 and C2. Then there are two 0.47uF mylar caps (C3 and C4) and the last stage uses two 10.0uF non-polarized electrolytic caps (C9 and C10) in the signal path. With today's relatively small film type caps these two could be easily replaced with better results. HUH!!

F1nut

You must get a lot of headaches.