Grado Gold loading with the Gram amp2SE
Printed From: Graham Slee Hifi System Components
Category: DIY AUDIO
Forum Name: Owner's Hot-Mods
Forum Description: Tell us how and why you hot-modded your audio gear
URL: https://www.hifisystemcomponents.com/forum/forum_posts.asp?TID=1145
Printed Date: 27 Mar 2026 at 3:59am
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Topic: Grado Gold loading with the Gram amp2SE
Posted By: mrule
Subject: Grado Gold loading with the Gram amp2SE
Date Posted: 31 Jul 2011 at 6:46am
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Hi folks. I want to say thanks to all who contributed to the loading questions with the Gram amp2SE and cartridges such as my Grado Gold, having a loading of about 475ohms DC, 47Kohms Z and L45mh. In my installation, using a Dual CS5000/w adj. shell & 18" cables, it sounds best with additional resistive loading of about 50k across the output. Not only is the bass peak cleaned up, but the match is far better; less brassy (more adult supervision) than unloaded, and more punchy than with a lower value. The cartridge is now working into a resistive load of about 50% of design, at a barely noticeable 1/2 volume and sounds very nice indeed. The ability of the 2SE to sort out complex musical signatures is superb. Not less than "pretty darned good" in any respect, I haven't had this much fun since we started using Apt Holtman preamps in radio stations! Mine is powered by a 2A. unregulated power supply with a heavy #16ga. cord (minimizing instantaneous IR drop), run off of a constant voltage transformer. Other parts of the system are a Harmon Kardon AVR 125 amp, Revox, A-77, 2-300 CD decks and various other pieces. Speakers are all homemade, with mains being a wonderful set of modern day -don't fall off of your chair old-timers- 15" Karlson Enclosures. Whohoo... My background is radio engineering, from the day when setting up transcription turntables was critical, and cellular, where I've spent the last twenty years taking care of cellsites in rural coastal California. Alas, twice now, AT&T has bought my parent company and I am unemployed. Thanks to GS for a such great sounding, well-made preamp we can afford. Mine sits on a machined 15cm x 9.5cm x 2cm slab of aluminum billet from a friend's machine shop. The base was "vibropolished" to a matte finish, then 3/8" radii (matching those of the preamp) were cut around the top edge with a milling machine leaving a polished surface there. It sits on felt feet and the preamp is adhered to the base with adhesive foam squares, It looks elegant, is really heavy- cords don't move it- and it certainly doesn't allow any microphonics! |
Replies:
Posted By: mrarroyo
Date Posted: 31 Jul 2011 at 5:39pm
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How about posting some pictures of your setup? ------------- Miguel |
Posted By: mrule
Date Posted: 03 Aug 2011 at 9:25pm
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Greetings. Here is a picture of the machined aluminum base that my friend made for me for my nice new preamp. It started as a random slab that he machined on all sides, than ran for 24 hours on a vibrating table in a slurry of small plastic cones to give it a matte finish. The radii were then cut for a mirror finish. Felt feet were put on the base and the preamp was attached with adhesive squares. It is a nice touch for an elegant piece of audio gear that I am proud to own. I also have a 7 page writeup (in word) of my homemade Karlson speakers that some of your audiophile friends may find interesting if you have a corner of the forum for such things. I am completely new to forums. Let me know if you would like to post copy. 
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Posted By: mrule
Date Posted: 03 Aug 2011 at 10:28pm
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For those of you who may now be curious, here is one of my main speakers, an inverted, +6%, 15" Karlson Enclosure. It stands about 1m tall and features Morels, adjustable cabinet response and a remote, tunable crossover that uses ganged attenuators on the drivers for tone controls that introduce no phase shift.  |
Posted By: mrarroyo
Date Posted: 04 Aug 2011 at 12:24am
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Nice stuff! ------------- Miguel |
Posted By: tg [RIP]
Date Posted: 04 Aug 2011 at 12:49am
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Indeed, thanks for sharing. That looks like a most interesting and very nicely executed speaker. Perhaps you might like to copy and paste your word document in a new thread in the Speakers section ? BTW - thanks for posting the info on your loadings on the Grado, likely someone else will find this useful. regards, Tony G |
Posted By: Graham Slee
Date Posted: 04 Aug 2011 at 1:23am
Correct, it is inverted... How do I know? Well, to be honest I didn't take this book, pictured below and bought from Tandy (Radio Shack) 1974, for 60 pence (just over $1 US) very seriously until now.  Turning a few pages we find drawings that look uncannily like the Karlson enclosure in the photo.  For years I wanted some really great monitor loudspeakers but couldn't bring myself into believing any of the book's designs were worth the effort - just shows how the great hi-fi press filled me like others with the fear of the unknown as if hi-fi was a high tech art only the flavours of the month were capable of and nobody else. I was 19 in 1974. I have learned a lot since then, and quite a lot about hi-fi magazine BS...  ------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
mrule wrote:Posted By: mrule
Date Posted: 05 Aug 2011 at 7:57am
| Hi folks, Grahm, it's nice to hear from you. Good call on the Tandy book and the usefulness of building from it. I think I have that book- I was 19 in 72' and haunted the local Radio Shack & Lafayette stores. it is indeed a Karlson Enclosure. They were marketed by Dr. Karlson as kits in the 50's and were very popular, although their sound often left a lot to be desired. If you sold the kits through your tv repair shop, you were given a record of a thunderstorm to be played for prospective clients. If that didn't sell them, you blew out matches held in front of the ports. You are also right that it is not a viable design as originally depicted; it would be a pretty awful sounding speaker for a number of reasons. If I can figure out how to download the file I'll do so. It was a very successful project that I would encourage anyone to take on if they want a complex, rewarding project. They are the gold standard of all of my (discriminating!)audiophile friends. |