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Author Topic: Modding my Peavey Classic 50  (Read 2268 times)


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Modding my Peavey Classic 50
« on: July 08, 2009, 04:39:11 PM »
It looks like I'll be hanging on to my Classic 50 2x12 combo but would like to modify it to better deal with my current needs.

In order to address
1] cleaning up the clean channel, and
2] making it less heavy to carry
I was thinking of
1] replacing one of the 12AX7s with a 12AY7, as previously suggested by posters on the forum, and
2] taking out the existing two 12" blue marvel speakers and replacing with one 16 ohm Celestion Heritage 65 or Alnico gold 12"

the guitars I will be using are loaded with Lindy Fralin underwound humbuckers and Bare Knuckle Manhattan low output P90s

this is very much about playing clean at home level volume with possibly the use of an MXR Custom Audio overdrive and a Carbon Copy in the front end

what do you think?
all comments welcome
best regards
« Last Edit: July 08, 2009, 05:37:13 PM by DavidRees »


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Re: Modding my Peavey Classic 50
« Reply #1 on: July 08, 2009, 05:48:54 PM »
why does the amp need to be less heavy to carry if its for home use?  anyway, you could try a single Alnico Gold, or go with some 'neo' speakers like the Celestion Centurys which are very light due to the type of magnet they use.


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Re: Modding my Peavey Classic 50
« Reply #2 on: July 08, 2009, 08:18:04 PM »
I would try a 5751 rather than a 12AY7.

Firstly, very low gain valves like the 12AY7 can cause over dissipation in the plate load resistors which could compromise reliability. I know this as I've measured the actual dissipation in several amps. A 5751 draws about the same current as a 12AX7 so will be fine.

Secondly, 12AX7s etc contain two triodes. These are cascaded in V1 of the Classic 50 so any reductions in gain are multiplied, so you don't always need to use a much lower gain valve such as a 12AY7 to have a very significant effect on the gain structure of your amp.

Thirdly, the biasing of the pre-amp stages has been optimized for use with 12AX7s. Using a valve with radically different characteristics may mean that the valve is not optimally biased and my distort unpleasantly.

Using only one speaker will obviously reduce the weight, although if you are going to really crank the amp a Gold might be marginal for power handling.
« Last Edit: July 08, 2009, 08:28:18 PM by jpfamps »


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Re: Modding my Peavey Classic 50
« Reply #3 on: July 09, 2009, 04:51:16 PM »
Jumping in on this thread, but aside from the gain reduction, how would a 5751 sound different to a 12AX7?

I'm thinking about one for V1 of my amp.


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Re: Modding my Peavey Classic 50
« Reply #4 on: July 10, 2009, 11:39:18 PM »
I like the look of these peavey classics.

Not as much as those new blackstar series 1's though.