I agree with JC on the pots. The ALPs from Radio Shack measured extreamly well but they add a veil over the sound. hard to know which ALPs are good when they made so many types... I have 3 different ALPS models - all are same body color.
The Spectrol MOD 534 10 turn W.W. is superior ... . if the L does not cause any issues.
THx-RNMarsh
The Spectrol MOD 534 10 turn W.W. is superior ... . if the L does not cause any issues.
THx-RNMarsh
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Scott,
I am undecided as to use a 709 or 741 either in the DC servo or pilot light driver.
How stable would the DC offset be after trimming?
I am undecided as to use a 709 or 741 either in the DC servo or pilot light driver.
How stable would the DC offset be after trimming?
Totally off subject, I had a customer order a dozen pieces of one item. The independent manufacturer's representative quoted me $6,400.00 each. As that was the unit price I inquired about a better price of $5,800.00. So I called a buddy who has a better rep. With a bit of discussion and order combinings he will sell them to me for $4,800.00. That means he is getting them for $4,400.00 each. He also gets his regular discount increased by about 10%.
The issue is that pricing is really quite fluid.
The issue is that pricing is really quite fluid.
Because a noisy or distorted pilot light can ruin your day...let me tell you..I suggest you use WWII surplus #47 dial lamps, preferentially ones made by Western Electric, they have the warmest...um, errr...IR output. You'll have to buffer the 709/741 output since the #47 pulls 150 mA. Also be careful of the turn-on ramp, this can compromise the life of the filament.
In all seriousness some of the coolest pilot lights I have seen have been faceted glass with #47s behind them...like Fender amps from the 60's and 70's. or the variable shuttered ones on military equipment. Round or rectangular LEDs are so blah by comparison.
To address the subject du jour: I have found the TKD pot/stepped attenuators to be pretty reliable as well, and have built them into several line-level pieces. Although, I still like the rotary P&Gs with the basically noise-free plastic element. Also their sealed silicone damped shaft assys give a really nice feel:
Cheers,
Howie
I have had LED's seriously degrade the performance of a product (do not use uP controlled PWM modulated LED's anywhere near a sensitive circuit) and that #47 bulb will be lower noise than any LED. . .
If Ed is interested we may be able to negotiate the Tech Labs/Holco pots for his uberpreamp.
I would not hog out a case from a block of aluminium, any mechanical resonances would be higher Q. Use a stack of laminated metals of different properties, perhaps brass and aluminium.
I did build an UBER preamp many years ago that used 1" Delrin for the case and was airtight with a separate chamber for the cable connections. The customer loved it. I really got tired to the calls from him however. . .
If Ed is interested we may be able to negotiate the Tech Labs/Holco pots for his uberpreamp.
I would not hog out a case from a block of aluminium, any mechanical resonances would be higher Q. Use a stack of laminated metals of different properties, perhaps brass and aluminium.
I did build an UBER preamp many years ago that used 1" Delrin for the case and was airtight with a separate chamber for the cable connections. The customer loved it. I really got tired to the calls from him however. . .
Ever try an Alps RK50? Expensive but has a great reputation.
https://i.ebayimg.com/images/i/260966536400-0-1/s-l1000.jpg
No Alps is as good as P&G or TKD. Sorry. uA709's are quieter than 741's, but still very noisy by today's products.
Maybe someone has already posted regarding the Khozmo attenuators:
High Quality Audio & Industrial Attenuators
Has anyone had experience with them? They look very good for the price.
Howie
High Quality Audio & Industrial Attenuators
Has anyone had experience with them? They look very good for the price.
Howie
Manly men who survived James Roberge's comprehensive opamp textbook, would prefer the LM101 / LM301 because it is externally compensated. Choose the gain-bandwidth tradeoff that YOU like, rather than mindlessly accepting the greatest-good-for-the-greatest-number compromise dreamed up by Fairchild.
And oh by the way, externally compensated opamps permit two-pole compensation for an additional performance boost, as explained in Linear Brief LB-4 (April 1969!)
I chose the externally compensated AD744 (JFET inputs) for the Norwood buffers, precisely because I wanted to (externally) set the phase margin to the number I wanted. Not to the number that the factory wanted.
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And oh by the way, externally compensated opamps permit two-pole compensation for an additional performance boost, as explained in Linear Brief LB-4 (April 1969!)
I chose the externally compensated AD744 (JFET inputs) for the Norwood buffers, precisely because I wanted to (externally) set the phase margin to the number I wanted. Not to the number that the factory wanted.
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I have a better one. Who knows what power amp it is?
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Why do the manufacturers try to save every penny? Why do they use a non-latching XLR connectors in this amp, why not a Neutrik?? Why, at the same moment, they speak about careful part selection?? Your answer, R.S.?
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Why do the manufacturers try to save every penny? Why do they use a non-latching XLR connectors in this amp, why not a Neutrik?? Why, at the same moment, they speak about careful part selection?? Your answer, R.S.?
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