Jul 202013
 

Yesterday I posted in Today’s Fresh Catch about the spade terminal adapters for vintage McIntosh amplifiers with terminal strips that I found and purchased on eBay. While the price was right at slightly less than $10 USD, the performance and design of the adapters was not really up to what I wanted for use with the ultra-performing Sablon Audio Panatela speaker cables and interior wiring for the Westminster Royal SEs. It’s pretty silly to compromise the über Panatelas with $10 adapters, so I knew I needed to rethink my approach.

Adapters in place with Panatela

Somewhat embarrassingly,  I had attributed the degradation of the sound quality caused by the adapters to another component in the system that was not at fault, so I’m glad I figured out what was going on in time to remedy the situation.

I decided to try a variation on the binding post bypass approach that I used for the Duelund-WRSE Project crossovers (see the archive links), and I’m happy to report it turned out to be a remarkably good sounding solution, so I wanted to share the details with you in case you might benefit from the approach on a pair of your vintage amps.

In the photo below you can see the inexpensive Dayton Audio BPA-38G HD binding posts that I used for the binding post bypass in the Duelund-WRSE Project crossovers.

Duelund silver-carbon resistor 0

The Dayton binding posts are unnecessarily long for this application so I snipped the mounting bolt off to shorten things up with my handy Shimano cable tool that I use for cycling applications.

Modded Dayton binding posts

In the photo above you can also see the few inches of Neotech 14 gauge copper UP-OCC mono-crystal design hook-up wire I had left over from wiring the low-frequency section of the Duelund-WRSE crossovers that I used in making the binding post bypass adapters for the MC240. I was astonished at how much better sounding the Neotech was than the generic hookup wire that I had tried earlier.

Modded Dayton binding posts with Neotech wire

After cutting my leftover Neotech into four equal lengths, I stripped of the ends and inserted it into the modified Dayton binding post. (above)

Then I wrapped the Neotech wire and Dayton binding post with Peavey microphone tape to secure the Neotech wire in place. (below)

Modded Dayton binding posts with Neotech wire and Peavey tape

To finish the binding post bypass adapters I covered the Peavey tape and wire with color-code shrink-wrap tubing. (below)

Shrink wrapped adapter

If you look closely below, you’ll see the details of the completed binding post bypass adapter on the McIntosh MC240. The Neotech wire end is inserted into the MC240’s terminal strip with the set-screw securing it in place. The silver spade connectors of the Panatela speaker cables are clamped directly to the Neotech wire that is connected to the terminal strip for the purest connection possible.

completed binding post bypass adapter on MC240

I repeated the process for the other binding post bypass adapters …

Binding post adapter

Here’s the right channel all connected … notice the ground connection from the Tannoy Dual Concentric driver (banana connector) inserted into the end of the binding post bypass adapter.

Binding post adapters on R channel

Below is the completed set of binding post bypass adapters with five-wire Panatela speaker cables in place.

Binding post adapters on R & L channels

Admittedly, it looks a little busy with the five-wire Panatela component speaker cables mounted on the binding post bypass adapters, but the sound quality is astonishingly good, so a little busyness can be forgiven.

If you’re wanting an ultra-quality sounding adapter for your vintage amps’ terminal strip, you’ll be hard pressed to find something better than the binding post bypass adapters with the Neotech wire, I’d wager. Highly recommended!

Thanks for stopping by!

 Posted by at 3:20 pm

  14 Responses to “DIY: Binding Post Bypass Adapters for the McIntosh MC240”

  1. Hey you still out there? I want to fabricate the adapters like you did for Vinatage Mac amp that I have. It looks like you run the neotech wire all the way through the banana receptacle correct? How does the banana plug fit through the hole with the wire in the way (the one you used for ground)? Could banana plugs be used on this set up instead of spades? Thanks

    • Hi Brian,

      There’s not much room to attach speaker wires at a vintage Mac’s screw terminals, so I use the binding posts as a convenient way to clamp together the speaker wires and the Neotech wire that inserts into the Mac’s screw terminals, giving a more flexible interface at the screw terminals for attaching multiple or heavier gauge speaker wires.

      I use bare wire ends, but if one uses spade connectors on the speaker cables, the adapter would also allow for them to be used with the vintage Mac screw terminals to clamp them directly to the Neotech.

      The idea was to clamp the wires directly together at the binding post so there is a direct wire-on-wire connection of the speaker wires to the amp, but I suppose you could insert a banana into the end of the binding as well.

      Binding post adapter

      To make them, a length of Neotech wire is inserted through the hole in the binding post per the photo, and runs down the side of the binding post, with the end stripped to insert into the screw terminal. I taped the Neotech wire down against the length of the binding post with microphone tape, then secured it in place with a length of heat shrink tubing. That’s all there is to it.

      I hope that helps!

      Best, Jeff

  2. That does help. I still don’t see how the banana plug would work? Seems like the banana plug would be too long and bottom out into the neotech wire that goes through the hole of the adapter? I am looking to demo some cables so would like to be able to use spades or plugs. I not really that familiar with how long plugs are. Have you run across the Tuneful adapter? Saw it on ebay and it’s $240 which is a bit pricy. Tech from McIntosh says the cheapo adapters like you used first work fine (100% of power and fidelity according to him??). Obviously that was not your experience correct? Thank so much for your help.

    http://www.ebay.com/itm/Tuneful-Cables-Speaker-Cable-Adapters-for-McIntosh-Amps-Vintage-Amps-Speakers-/331818621042

    • The cheapo adapters degrade the sonics just like I said in the blog post, which is why I went to the trouble to build my clamp-style adapters.

      My clamp-style adapters work much better, and the only thing that’s better is unterminated speaker cables so you can attach the bare wire directly to the Mac screw terminals (the less metal & number of solder connections the signal goes through the better the connection is going to sound).

      Banana’s plug right into my adapters just like they do any binding post as you can see in the photo below. That’s not really how I intended them to be used, but you could do it.

      I haven’t seen the Tuneful adapter before, but they look like they’d work fine, but are kind of expensive for what they are.

  3. I am a little confused on your explanation about using bare wire ends. The picture you posted shows the adapters connected to the amp with the only contact direct to the amp being the neotech wire from the adapter. The speaker cable connects to the adapter via spade in your example. Am I missing something? Sorry to be slow on this.

    • Correct, the bare Neotech wire is inserted into the screw terminal. The binding post just serves as a clamp to press the spade connectors to the Neotech wire on the clamp end.

  4. Much appreciated. Thanks

  5. $240 for the ebay one is too much, so, going to fab my own like you did. Dumb question, but, is Dayton adapter as good as I can get regarding sound quality? What about the neotech silver wire vs copper. The silver seems very popular these days? Also, is Mic tape just elec tape with colors? Thanks for your input / opinions. I can’t help over thinking stuff…

    • In my example, the Dayton is used to clamp the wires together rather than to serve as a signal conduit, so it works fine for that. If you want to run signal through the binding post you probably would be better off with Oyaide or Cardas.

      These days I much prefer the Duelund DCA tinned copper wire to the Neotech. If you search for ‘Duelund DCA’ here you’ll find lots of good information on it.

      The microphone tape is colored electrical tape that is useful for identifying different microphones in the studio, and I’ve also found it to be very useful in marking signal paths. It’s cheap and useful. If you search for Peavey tape on Amazon you should be able to find it.

      Have fun!

      Best,

      Jeff

  6. Any suggestions on speaker cable to try? Bi-wire vs using jumpers of same cable? The choices are mind boggling. I have a solid state 150watt Mac amp and B&W 805D3 speakers. Looking to stay around $500 MSRP, and hope to find used.

    • Hi Brian,

      I recommend that you make a pair of speaker cables out of the Duelund DCA16GA tinned-copper tone wire, it’s right up there with the best available today, and it’s inexpensive as well.

      Kind regards,

      Jeff

  7. Hello Jeff,

    I have found Furutech makes spade connectors that are perfect fit for strip barrier speaker terminals. The model number is FP-209 G or R. The outer diameter of the fork is 8mm and inside is 4mm. I have confirmed the fitment with Chris Johnson of partsconnexion.com. They cost less than $4.00 each. Using this connector can eliminate the need for bulky adapters that degrade the sound.

    Now a question for you Jeff, since both Gold-plated and Rhodium-plated available, which do you think is better for the Duelund 16AG speaker cable tonally? Thanks.

    Griffin

    • Hi Griffin,

      Thanks for mentioning the spade connectors, that could be a nice solution for some applications.

      For my MC30’s screw terminals I prefer bare wire connections, which is what I’m using with the Duelund DCA wire.

      The adapters I made don’t really degrade the sound significantly, as they just clamp the speaker wires to a short length of wire that connects to the screw terminals.

      I haven’t tried the spade connectors you mention, but the others that I have tried degraded the sound more than my adapters, mostly due to the additional solder joint of the spade, I suspect.

      It’s hard to beat bare wire though, as it eliminates a solder connection and a spade that the signal has to go through.

      In my opinion, for the DCA16GA, bare wire is better than any connector regardless of the plating.

      I hope that helps!

      Best,

      Jeff

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