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Cogito
PostPosted: October 3rd, 2026, 1:42 pm 
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David McGown wrote:

Fair enough. I am always concerned about keeping circuits simple and to a minimum, since any additional active stage is going to have an influence on the overall sound.

David


I used to an analog purist also, but lately my opinion is changing.

In my current system, I am using four 3-way Sublime Acoustic K231 active analog crossover. Two crossovers daisy chained on each channel for the 5-way system. They are based on Burr-Brown opamps. They are transparent and extremely versatile. This leads me to believe that active components could be equal or better than analogy components if implemented properly.
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SoundMods
PostPosted: October 3rd, 2026, 2:01 pm 
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HAL wrote:
I do not like transformer limitations. No low or high frequency limitations with DC coupled systems. I hear it every time listening to systems with them.

Enough is already done in studios that use TX coupling to further limit the response for recordings.

There are proaudio versions of this available, but all I found use carbon film resistors, electrolytic coupling caps and single ended DC power supplies in this price range.

My findings EXACTLY! :thumbup:

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tomp
PostPosted: October 4th, 2026, 7:18 pm 
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Back in 2009 I did an article on balanced to unbalanced and vice versa conversions where I described two devices from THAT corporation. They were designed by Bill Whitlock, the former president of Jensen Transformer who makes some of the best transformers.
Attachment:
That balanced line receiver.pdf [38.32 KiB]
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Attachment:
That balanced line receiver.pdf [38.32 KiB]
Downloaded 21 times
He realize their limitations and came up with a novel solution to get the best results. When it comes to balanced signals, the ability to maintain Common More Rejection Ratio (CMRR) to reduce noise is dependent of each line having the same impedance, not voltage. As little as 1% difference in impedance can result in 60 dB drop in CMRR. Here is some measured data for that device along with measurements I took. In each measurement, the input signal from the generator is on top and the output of the device in on the bottom. In each case the output is a direct copy of the input. Especially note the 5 HZ square wave which would be impossible with a transformer. What goes in the chip comes out of the chip. There is no degradation. You won't top that with any adapter or transformer.


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HAL
PostPosted: October 4th, 2026, 8:41 pm 
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The THAT120x series are now end of life devices according to their latest post. The lead time is 22 weeks! :o

At least this is a version that is simple to implement and people can experiment with opamps.
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SoundMods
PostPosted: October 4th, 2026, 11:45 pm 
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tomp wrote:
What goes in the chip comes out of the chip. There is no degradation.

I am sure my late friend Walt Jung would disagree with that assessment -- I know I do. :handgestures-thumbdown:

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tomp
PostPosted: October 5th, 2026, 7:01 am 
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The proof is always in the listening and listening to those chips confirms the transparency on a very high resolution system.
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SoundMods
PostPosted: October 5th, 2026, 11:29 am 
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tomp wrote:
The proof is always in the listening and listening to those chips confirms the transparency on a very high resolution system.

If your device has DIP sockets and the IC op-amps can be easily replaced with something else. Why don't you try J-Fet based discrete op-amps?

I expect that the Burson V7 Vivid discrete op-amps are seriously superior to any IC op-amp currently manufactured. Why?

They run class A biased (hot) -- they're not limited by the real-estate available in a tiny silicon die -- and they have substantial current availability not unlike a unity-gain video buffer.

When I "hot-rodded" my optical-cartridge equalizer I installed high-performance IC op-amps replacing the stock JRC072B J-Fet op-amps (which were pretty good).

I got a major improvement in playback quality with the Bur-Brown mil-spec ceramic package OPA2604-Q1 chips.

On paper they checked all of the boxes. Gain/bandwidth -- slew rate -- DC offset -- phase margin -- power bandwidth -- settling time -- very low distortion -- low noise -- unity gain stable.

They were designed for professional audio equipment including PCM DACs. The playback quality was much improved -- I was happy -- until I took a chance on the Burson product.

Temptation overwhelmed me -- what can I say? I am an audio addict. WOW! The comparison wasn't even a contest!

The playback quality was much improved over the Bur-Browns in terms of overall transparency -- more open mid-range -- more open sound stage -- musicality -- all that together with a more refined treble.

I don't dispute the fact that IC op-amps have come a long way; however discrete J-Fet op-amps -or- tube-based op-amps can out-perform IC op-amps in every category that counts for quality audio playback.

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HAL
PostPosted: October 5th, 2026, 1:32 pm 
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The unit I have built has 8 pin IC sockets for that reason.

I have multiple discrete opamps to try along with the NS LME49710 TO99 can devices.

I have Sparkos Labs SS3601 bipolar and Staccato OSH-S JFET discrete versions for listening.

It would have been nice to compare to the THAT1200P, but not waiting 22 weeks for devices from Newark and they are the only outlet I could find. I need 4.

The BUD chassis arrives today to install the system.
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GaryB
PostPosted: October 5th, 2026, 2:31 pm 
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HAL wrote:
. . . It would have been nice to compare to the THAT1200P, but not waiting 22 weeks for devices from Newark and they are the only outlet I could find. I need 4.

Mouser has 461 of the That 1200P08-U in stock as of 10/5/26.
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SoundMods
PostPosted: October 5th, 2026, 2:38 pm 
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HAL wrote:
It would have been nice to compare to the THAT1200P, but not waiting 22 weeks for devices from Newark and they are the only outlet I could find. I need 4.

Maybe don't waste your money. I downloaded the THAT data sheet and it's nothing more than another IC op-amp that doesn't even look to me on paper.

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