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Eddycycles
02-01-2015, 09:16 AM
https://www.youtube.com/watch?v=JDuO-L38Xro&list=UUJ5EOEiQ3LuXWYAIPXSSyjg&index=1

BMWCCA
02-01-2015, 09:40 AM
I can't believe the Rube Golberg record-playing contraption atop a lowly Mac C20. I should be so proud of the little pre-amp I've owned since i was a teenager over 40-years ago, but perhaps I under-appreciate it?

Is this your system, or a video of something extreme from the Interwebs? :thmbsup:

Mr. Widget
02-01-2015, 10:17 AM
Another example of how many paths we can take.

I wonder if the owner has read about DOT-3?


Widget

Eddycycles
02-02-2015, 01:47 AM
Another example of how many paths we can take.

I wonder if the owner has read about DOT-3?


Widget

Sorry , what is DOT-3?

Eddycycles
02-02-2015, 04:52 AM
I can't believe the Rube Golberg record-playing contraption atop a lowly Mac C20. I should be so proud of the little pre-amp I've owned since i was a teenager over 40-years ago, but perhaps I under-appreciate it?

Is this your system, or a video of something extreme from the Interwebs? :thmbsup:


little pre-amp :banghead:

Mr. Widget
02-02-2015, 09:56 AM
Sorry , what is DOT-3?I'll guess then that this is your system. While far from conventional by our standards, it is a magnificent product of much work and love I can tell.

In answer to your question, DOT-3 is a specific type of brake fluid frequently used here in the US. The reason I mentioned it is that your LE15A woofers have their original Lans-a-loy foam surrounds which harden and stiffen over the years. I'll get back to the DOT-3 in a minute. These surrounds were much more compliant when new allowing these woofers to have a measured free air resonance of 20Hz. With these old surrounds I am sure you are not getting the bass response that these speakers are capable of.

You can replace the surrounds with new gray foam or you can treat the originals with the DOT-3. This fluid will soften the surround and allow the woofers to operate correctly. It is better to replace the surrounds, but if you want to keep the vintage look, you should remove the woofers and carefully apply a bit of fluid to the front and rear of the surrounds. I recommend that you take frequent free air resonance measurements to dial in the correct compliance... however most people are not technically able to due this. Even a single treatment will help. (Take great care not to get any fluid on the paper cone, it will be permanently stained... and it must be DOT-3 fluid.)


Widget

BMWCCA
02-02-2015, 05:41 PM
little pre-amp :banghead:

If it's your system, tell me why you chose the C20 when it's obvious you had other choices?

I'm serious about owning mine for over 45-years! Still love it. And it is little! :D

Eddycycles
02-02-2015, 06:11 PM
I'll guess then that this is your system. While far from conventional by our standards, it is a magnificent product of much work and love I can tell.

In answer to your question, DOT-3 is a specific type of brake fluid frequently used here in the US. The reason I mentioned it is that your LE15A woofers have their original Lans-a-loy foam surrounds which harden and stiffen over the years. I'll get back to the DOT-3 in a minute. These surrounds were much more compliant when new allowing these woofers to have a measured free air resonance of 20Hz. With these old surrounds I am sure you are not getting the bass response that these speakers are capable of.

You can replace the surrounds with new gray foam or you can treat the originals with the DOT-3. This fluid will soften the surround and allow the woofers to operate correctly. It is better to replace the surrounds, but if you want to keep the vintage look, you should remove the woofers and carefully apply a bit of fluid to the front and rear of the surrounds. I recommend that you take frequent free air resonance measurements to dial in the correct compliance... however most people are not technically able to due this. Even a single treatment will help. (Take great care not to get any fluid on the paper cone, it will be permanently stained... and it must be DOT-3 fluid.)


Widget


All understand, i have plan to replace the surrounds but not now. I love at the original look first. It's hard to find such a good condition this time. Thanks for your advice very helpful.

Eddycycles
02-02-2015, 06:26 PM
If it's your system, tell me why you chose the C20 when it's obvious you had other choices?

I'm serious about owning mine for over 45-years! Still love it. And it is little! :D


I'm the vinyl lover. C20 is make very good sound. McIntosh lover too.

BMWCCA
02-02-2015, 10:08 PM
I'm the vinyl lover. C20 is make very good sound. McIntosh lover too.

What I love about the C20 is the quaintness of the compensation controls and the range of the variable loudness. It has always had a lovely sound to it. After owning mine since around 1968 it pleases me to see one being used in such a bespoke system.

Yours looks to be the same series as mine. My serial number is 6L061, what's yours?

:thmbsup: