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Topic: Question about mod chips |
Tommy Boswell
From:
Virginia, USA
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Posted 25 May 2017 5:10 pm |
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Are mod chip kits available for a Reno 400?
And, how can I tell if it already has one installed?
My Reno 400 has been re-purposed for steel...in a Rick Johnson cabinet, with a new Sica speaker, and no horn. |
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Lane Gray
From:
Topeka, KS
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Posted 25 May 2017 6:50 pm
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Any mods would certainly have replaced the IC chips.
Pull the chassis, read the markings on the chips.
Replacement chips would likely include OPA2134
_________________
2 pedal steels, a lapStrat, and an 8-string Dobro (and 3 ukes)
More amps than guitars, and not many effects |
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Steven Paris
From:
Los Angeles
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Posted 25 May 2017 10:25 pm
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I believe a Reno 400 is nearly identical to a Nashville 400.
You'll have to pull the chassis out and look at the chips on the board. Stock chips were RC4558s (awful!); Peavey mod chips were OPA2604s (better); Ken Fox mods would be OPA2134s (very good); latest state-of-the-art TI IC is an OPA1642 (best). If the Reno is like the NV400, the ICs are socketed and it's pretty straightforward to swap 'em out. I don't know if the NV400 voicing mods would be appropriate or not. Certainly the Metzger reverb mod would be in order.
_________________
Emmons & Peavey |
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Jack Stoner
From:
Kansas City, MO
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Posted 26 May 2017 2:20 am
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| I replaced the op-amp chips in my NV400, that had the Peavey factory tone mod installed but NO op-amp updates. Made no difference at all. On the other hand replacing them in a 1000 or 112 made a significant (plus) difference. |
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Ken Fox
From:
Nashville GA USA
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Posted 26 May 2017 4:45 am
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| Steve, I would like to the OPA1642, but it does not appear to come in DIP packaging. |
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Ken Fox
From:
Nashville GA USA
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Posted 26 May 2017 4:48 am
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Tommy, I can put a kit together with directions if you need.
Lane, I never replace the reverb drive/return chip with Butt Brown chips anymore. The chip can cause the reverb section to go into oscillation at around 10KHz at full output on the chip. Has not been an issue on N112 amps. |
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Tommy Boswell
From:
Virginia, USA
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Posted 26 May 2017 5:11 am chips
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I found a bunch of RC4558P chips (7 to be exact), and one RCA 632.
Ken, yes please, and let me know how to pay. PM or email works for me.
Thanks to all! |
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Ken Fox
From:
Nashville GA USA
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Posted 26 May 2017 5:23 am
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| PM sent |
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ajm
From:
Los Angeles
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Posted 26 May 2017 6:48 am
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| Ken Fox: "Butt Brown"? |
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Ken Fox
From:
Nashville GA USA
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Posted 26 May 2017 7:46 am
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| Not sure if that was spell check or a fat finger😆😀 |
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Lane Gray
From:
Topeka, KS
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Posted 26 May 2017 12:01 pm
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| Ken Fox wrote: |
| Not sure if that was spell check or a fat finger😆😀 |
But in no way an editorial comment?
_________________
2 pedal steels, a lapStrat, and an 8-string Dobro (and 3 ukes)
More amps than guitars, and not many effects |
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Steven Paris
From:
Los Angeles
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Posted 26 May 2017 9:30 pm
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| Ken Fox wrote: |
| ..., I never replace the reverb drive/return chip with Butt Brown chips anymore. The chip can cause the reverb section to go into oscillation at around 10KHz at full output on the chip. Has not been an issue on N112 amps. |
That's curious to me. I wonder if the oscillation is due to the fact that the opamp reverb driver IC (U5) has its positive rail bypass capacitor (C73) located so far away from the IC + power pin 8. All the other IC's power bypass caps are right next to the IC. Perhaps a bypass cap right across the IC power pins would cure the oscillation.
_________________
Emmons & Peavey |
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Steve Sycamore
From:
Sweden
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Posted 27 May 2017 1:34 am
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| I had some low noise/high slew rate op amps on hand when I installed the Le May kit in my NV400. Even with the stock speaker I noticed a subtle improvement right away. I tend to use a bright, aggressive setting so the amp sounded and felt like it was smoother, more refined and more agile. It gave a higher resolution sound but maybe the feeling was the more important and obvious difference rather than the sound because most of the difference due to the higher slew rate occurs in the first few ms of picking a string. |
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Ken Fox
From:
Nashville GA USA
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Posted 27 May 2017 6:17 am
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Some people prefer the higher slew rate sound. I do not, as I prefer a tube amp and it slow slew rate. When I used tantalum caps in my "Intense Mod" in the signal path they (according to my friend Derrel Stevens) it slowede the slew rate down, giving it a more compressed feel. The combination of that and the better frequency response of the Burr Brown chips seemed to please a lot of folks for sure. I did around 300 of those mods over a period of several years.
I never really went after a cure for the oscillation problem. It was a thing that rarely happened, too. I discussed it with Jim Evans and others. The wide frequency response of the Burr Brown chips was probably the root cause.
The Metzger reverb mod was a large improvement in the reverb. However I had to modify it a bit as it could tend to lend to the oscillation as well! |
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Jim Cohen
From:
Philadelphia, PA
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Posted 27 May 2017 10:31 am
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Ken,
I believe that late last year you mentioned that you were thinking to record a video of yourself doing a mod and replacing the chips on a 112 or similar amp. Is that something we can look forward to in the future?
Thanks.
_________________
www.JimCohen.com
www.RonstadtRevue.com
www.BeatsWalkin.com |
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Steven Paris
From:
Los Angeles
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Posted 28 May 2017 12:09 am
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| Ken Fox wrote: |
| Some people prefer the higher slew rate sound. I do not, as I prefer a tube amp and it slow slew rate. When I used tantalum caps in my "Intense Mod" in the signal path they (according to my friend Derrel Stevens) it slowede the slew rate down, giving it a more compressed feel. The combination of that and the better frequency response of the Burr Brown chips seemed to please a lot of folks for sure. I did around 300 of those mods over a period of several years. |
For the 22uF caps, I prefer the polyester dielectrics over the tantalums (actually, I would rather a polypropylene, but they're just too damn big at that capacitance) due to much lower ESR. These caps are rated at a max of 2.5 volts/uSec rise time (can't find this spec for tantalums), which would also tame the 20v/uSec slewing of the OPA2134s down quite a bit.
_________________
Emmons & Peavey |
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Tommy Boswell
From:
Virginia, USA
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Posted 30 May 2017 10:30 am Fox mods
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| Thanks to Ken Fox for the mod chips. The Reno 400 sounds very fine after the upgrade, much better than the stock chips! |
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Ken Fox
From:
Nashville GA USA
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Posted 30 May 2017 1:13 pm
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You are most welcome, Tommy! Thanks again
I have a Nashville 400 chassis that I recently put in a Special 130 cabinet. I installed a 1203 BW. I check and somehow had put 4 of the OPA2134PA chips in it. I missed #5 chip ion the signal path!
I added that chip and did the full "Intense Nashville 400 mod" that I did for others for several years. The signal caps all replaced with tantalum caps, Metzger reverb mod and more.
Night and day difference in the amp. Clarity and string separation and such a pleasing tone now in the mids and highs!! |
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Steven Paris
From:
Los Angeles
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Posted 31 May 2017 1:19 am
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| Ken Fox wrote: |
I have a Nashville 400 chassis that I recently put in a Special 130 cabinet. The signal caps all replaced with tantalum caps, Metzger reverb mod and more.
Night and day difference in the amp. Clarity and string separation and such a pleasing tone now in the mids and highs!! |
Hmmmm....according to Cyril Bateman ("Capacitor Sounds", Electronics World magazine), "Some audio designs have used small Tantalum bead capacitors, with apparent success……... Tantalum capacitor stocks produced at least ten times more distortion than found with low cost polar Aluminium electrolytics."
I am left wondering if, in the case of steel guitar amplification, additional distortion from the tantalums sounds BETTER????
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Emmons & Peavey |
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Ken Fox
From:
Nashville GA USA
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Posted 31 May 2017 1:26 pm
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| After modding over 300 or more of these amps with tantalum caps I disagree. The amps still out out a clean 200 watts RMS |
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Steven Paris
From:
Los Angeles
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Posted 31 May 2017 7:13 pm
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| Ken Fox wrote: |
| After modding over 300 or more of these amps with tantalum caps I disagree. The amps still out out a clean 200 watts RMS |
Your experience and knowledge speak loudly. I believe you. What brand and series of tantalum capacitors did you use? I looked back and noted that Bateman's paper was written in 2003; there have been discussions that some tantalums have improved greatly since then.
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Emmons & Peavey |
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Ken Fox
From:
Nashville GA USA
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Steven Paris
From:
Los Angeles
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Posted 5 Jun 2017 11:26 pm
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| Ken Fox wrote: |
http://www.mouser.com/catalog/specsheets/m39006.pdf
These are the type I used |
Thanks---yes, those appear to be the more modern tantalums that actually have a lower ESR than polar electrolytics. You also used "orange drop" capacitors for the tone and reverb modifications---did you use the polypropylene (715/716) types or the polyester (225) ones?
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Emmons & Peavey |
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Ken Fox
From:
Nashville GA USA
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Posted 6 Jun 2017 6:43 am
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Ken Fox
From:
Nashville GA USA
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Posted 6 Jun 2017 6:45 am
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| I never used the tantalums listed from Mouser. My own kits were comprised of caps from Mouser and another supplier of caps from the internet (that is where the tantalums and electrolytics were purchased). |
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