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Old 18th July 2008, 04:57 PM   #1
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Default counterpoint 3.1

Hello there!
I've got me a Counterpoint 3.1 preamplifier and want to modify it. Is there someone on the forum that can help me with it. First question is: what are the values of the tranny. I want to put an amplimo toroidal instead! Thanks for the answer allready. Grtz Teake
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Old 18th July 2008, 05:29 PM   #2
SY is offline SY  United States
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Why do you want to use a toroid?

And what are the specific shortcomings that you want the modification to overcome?
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Old 18th July 2008, 05:51 PM   #3
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Hello Sy! I wanna modify it, because its more than 20 years old. I know that Micheal Elliot does the same, but that will cost me to much and I like upgrading vintage audio. Caps are drying out and the circuits can be improved by putting newer/better material in it. Michael Elliot himself says the toriodals will be better. Thanks for the answer, Teake.
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Old 18th July 2008, 06:16 PM   #4
SY is offline SY  United States
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Well, he DOES want to sell you mods, whether you need them or not.

Toroids are very efficient at coupling line noise into the circuit. So a good modder will also add common-mode filtering to end up with an expensive replacement for a cheap E-I transformer at a higher parts count with only a small performance degradation. Seriously: don't do it. You'll do better by merely adding a separate transformer (E-I or R-core) for the heaters; it will take some load off the main transformer and keep the HV diodes' switching spikes from coupling noise back through the heaters. And it's a cheap and easy mod.

Replacing the electrolytics is pretty straightforward. I'd avoid the exotic types and stick to major manufacturers available through places like Allied, Mouser, or Digikey.
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Old 18th July 2008, 06:49 PM   #5
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Hello Sy! I wanna modify it, because its more than 20 years old. I know that Micheal Elliot does the same, but that will cost me to much and I like upgrading vintage audio. Caps are drying out and the circuits can be improved by putting newer/better material in it. Michael Elliot himself says the toriodals will be better. Thanks for the answer, Teake.
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Old 18th July 2008, 06:51 PM   #6
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Thanks Sy, I will see what I can do, grzt Teake
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Old 18th July 2008, 08:40 PM   #7
SY is offline SY  United States
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One other thing: if these mods are for improved reliability, anatech will know about it (he probably knows about these, too). Let me ping him and see what he has to say.
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Old 19th July 2008, 12:20 AM   #8
anatech is offline anatech  Canada
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Smile Ouch! I've been pinged!!!

Hi Teake,
Wow. You do not have a good reason to do what you are planning to do. Just because it's there, it needs changing???

No.
Quote:
I wanna modify it, because its more than 20 years old. I know that Micheal Elliot does the same, but that will cost me to much and I like upgrading vintage audio.
Huh? Many old designs are very solid. There is no upgrade or change that will make things better (believe it or not!). All you can do is replace the tired parts with good quality ones of the same. SY made this very clear. I know, it lacks the romance of changing things. Newer designs are more likely to be faulty. Having said that, the 3.1 is done "more right" than most of M.E.'s later productions. His newer preamps are said to be a return to this basic design. I have not investigated that. I honestly do not see the need until I get one in front of me.
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Well, he DOES want to sell you mods, whether you need them or not.
I have to agree more than 100 % with SY on this. Sad but true.

I am extremely familiar with these (and other) Counterpoint products as I did warranty service on them. I have spent the years since Counterpoint went out of business by correcting the design errors to make these more reliable. More often than not, they sound better as a side benefit.
Quote:
what are the values of the tranny. I want to put an amplimo toroidal instead!
Bad idea - for all the correct reasons SY stated. He's right you know, Toroid transformers are only a good choice if your mounting height is limited. Yours is not. Also, the mods M.E. is doing to that transformer are not right. They run too hot as the part is under sized. If I were to redesign that power supply, I would probably install an EI core that was a bit larger to reduce the operating temperature. I'd go with a Hammond product. Something stock and close if possible. There is zero reason to do this unless yours burns out.
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Michael Elliot himself says the toriodals will be better.
Well, he is wrong. What makes his mod better is that he can make more money off the same product for years to come. Now the part I don't like about this. You are taking the information he is giving and doing it yourself without knowing enough. Do you know how M.E. mounts that new transformer? It rolls around loose inside. I've seen a couple.

Teake, it sounds like you are reading too much without a good understanding of the reality of circuit design. No fault of yours and I am not putting you down for this. It does make you an easy mark for the people who do unnecessary work, and worse - the hackers. Electronics and the sub class of audio are simply a small part of the study of physics. All those laws apply. There are some unknowns and some people exploit that in ways I can't agree with. Others learn the subtleties to create better sounding equipment. To do this, you must understand both the subject matter and parts.

In closing, my advice to you is simple. As long as you can solder neatly, without damaging anything, replace some of the capacitors. Do not install larger values! Buy new tubes. I recommend Electroharmonix. Big bang for the buck and their 6922EH does solve some Counterpoint issues.

Then,as you listen to some music, learn about electronics. Avoid "white papers" like the plague. Most are about 10% truth and the rest is marketing hype. Since you like to restore older equipment, buy and read books of the era. Another excellent source of information is "Valve Amplifiers" by Morgan Jones. This is a new look at audio electronics. Tubes in particular. Get it. Read it. Available from Amazon (and yes, I have both Morgan's excellent books). Another would be RDH4. That should keep you busy for a bit. After reading those, your knowledge will exceed that of most "modders". Knowledge will also save you a ton of money. Far more than the books will cost.

-Chris
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Old 19th July 2008, 07:51 AM   #9
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Hi Chris! Thanks for replying. And you're right about learning. I'm new to tubes, and have to do some reading and asking to understand something about it. All my equipment is PassDIY, so I do know something of building ClassA, but tubes are another world. Thanks again. Teake
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Old 19th July 2008, 05:46 PM   #10
anatech is offline anatech  Canada
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Hi Teake,
We are all learning, every day as we go through life. I do admire those who are willing to actually sit down and do something.

Take my words as helpful advice. I do want you to enjoy the hobby, but I also want to keep you from doing something you will regret later once you know more. You should ask for opinions and help when you think it would be helpful. I figure it's up to experienced people to help out the less experienced.

I do have an idea for you. Something that will really help you get used to electronics and audio in general. It doesn't matter whether you work with tubes, solid state or both. I am in that latter camp. Get some equipment together and set up a workbench where you can experiment, and also do some projects. Then, take some basic circuits. These can be low powered audio units (tube or transistor), or a circuit you build up from scratch. Kits are fine. I think that the SymAsym would be a pretty good place to start. The important thing is sound quality rather than power output. You could run the SymAsym from 30 volt rails and experiment with different concepts. You will need a sine wave signal source and harmonic distortion analyzer (HP product is not expensive and works very well for these). You will need a dual trace 'scope, 20 MHz is fine. A half decent sound card / computer with some programs to run it with is a good addition. Notice that you need other instruments, not just a sound card. You will understand why once you start to use the equipment.

The only problem with this is that is can be frustrating and addictive at the same time. A very satisfying hobby where you can learn your entire life.

-Chris
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