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Topic: Nashville 400 Mod |
Bob Moss
From:
Redford, Michigan
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Posted 10 Dec 2010 11:08 am |
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| Just modded a Nasville 400 Using tandelam Caps and OPA2134AP chips and I must say the tone is very nice just love the mellow bottom end and volume is flat right across the spectrum and highs to die for. |
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Dick Sexton
From:
Greenville, Ohio
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Posted 10 Dec 2010 11:41 am 400 Mod?
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Bob, how many 2134s does the 400 take and did you try the chips first or the caps first. Or did you do both at the same time?
Curious... |
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Bob Moss
From:
Redford, Michigan
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Posted 10 Dec 2010 5:32 pm
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5 chips or 6 if you include the reverb chip will do it. I did the caps first and tried it while I was waiting for the chips to be delivered.The Caps really open up the bandwidth and quiet down all the floor noise, can't tell when it's on or off now.
The chips made a big change in the tone,Mellow lows like the 112 and nice sharp highs.
Well worth the time and trouble. |
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Ken Fox
From:
Nashville GA USA
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Posted 11 Dec 2010 4:57 am
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The tantalum caps also exhibit even order harmonic distortion as well (like a tube). The Burr Brown chips use the JFET transistor technology that again acts like a tube, as opposed to the bi-polar transistors that are used in the stock 4558 chips.
These are two critical parts of the "Intense mod" we came up with several years ago. We also do the reverb mod as well.
With the increased bandwidth of the Burr Brown chips you can occasionally get issues with the reverb circuit going into oscillation at a very high frequency. This has happened on a few of the nearly 300 amps we have modded. Could not really find a cure, I think it had something to do with the reverb tanks themselves. On those few we kept the stock chip for the reverb circuit.
Be careful when replacing the audio coupling caps so that polarity is observed. |
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Earnest Bovine
From:
Los Angeles CA USA
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Posted 11 Dec 2010 9:12 am
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| Ken Fox wrote: |
| The tantalum caps also exhibit even order harmonic distortion as well (like a tube). |
How can two capacitors (of same capacitance) be different, unless one of them is not a capacitor? |
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Ken Fox
From:
Nashville GA USA
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Posted 11 Dec 2010 9:31 am
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Because the frequency response and other things differ from one type of cap construction to another. There is a world of difference between Orange drop, Mallory 150, Astron and other caps. Might be the same capacitance but they do sound different. Just like two different brads of tubes or opamps can sound different.
This is from an article I read on the net (concerning the famous Neve preampsm that used tantalum caps)
"Yes, you can argue that different capacitor materials have a sound. Dave Hill of Crane Song once told me a story about replacing the tantalum caps in an old Neve module. Apparently, the non-tantalum replacements changed the sound of the module. Dave's research determined that tantalum caps contributed more even-order harmonic distortion, not as clean—but pleasing." |
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