GE Black-plate 6V6GT test - YouTube
Total sleeper man xD I want get to upgraded output tranny too I'm just not totally sure if the Heyboer 50w with 2 el34s would like the plate resistance of 4 6v6gt or the 4 JJ6v6 Might be worth a try though them Heyboers pop up on ebay for pretty good deals a Mercury Magnetics would no doubt be killer but I'm sure, they are pretty pricey though figures though they are meaty for sure more Iron and just built better than the cheapo Chinese trannys
Total sleeper man xD I want get to upgraded output tranny too I'm just not totally sure if the Heyboer 50w with 2 el34s would like the plate resistance of 4 6v6gt or the 4 JJ6v6 Might be worth a try though them Heyboers pop up on ebay for pretty good deals a Mercury Magnetics would no doubt be killer but I'm sure, they are pretty pricey though figures though they are meaty for sure more Iron and just built better than the cheapo Chinese trannys
Just catching up on your thread here. With the audio grade output transformer, compared to the Peavey stock, Keriwana is right in mentioning that the OT response has a big part to play on the amp's overall sound. Just a few suggestions in how to approach this: The Edcor will probably have very little roll-off up to 20kHz and you may find the amp sounds brighter. If you want to adjust for this, you may want to look at a zobel network, or perhaps adjusting cap and resistance values on the NFB ''presence'' circuit back through to the PI.
Based on the manufacturer code in the part number, they might have made the original Peavey transformer.
Depends on how many EL84's. Suppsedly the MM for the Classic 50 with 4 EL84's in PP is 4K. So is the Edcor I ordered.
I got the first bunch of parts from Peavey. I really don't like these teensie pots with teensie shafts, but they do leave room to add switches or pots to the panel. And the problems everyone had with the small split and fluted shafts getting bent and then the knobs falling off or they try to bend the shaft-halfs by inserting a knife into the slot and braking off a half-shaft tab...Peavey has definitely improved the new replacement knobs! These have an internal white plastic insert with its own springy split. So I'm going to do like the Blue Guitar dude did, and make some inserts from steel shim to glue into the pot shaft slots converting them from split to solid fluted so they have some strength, then I'll order more of the new-style Peavey knobs instead of jamming in teflon tape or paper. Now I need to order more of the new style replacement knobs.
I find if I'm careful I can work on both sides of most of the main preamp and control circuit board without disconnecting the ribbon cables. I've heard of so many people with cracked ribbon cables I'm considering just replacing them with suple new ones on principle as a preventive measure, though mine seem fine if a bit stiff.
Getting a larger full-size 3-spring reverb tank with longer decay and the same input and output impedances was looking difficult, so I even considered paralleling different tanks with impedances to end up about the same, or duplicating the drive circuit or changing the resistors at the recovery circuit. But the simple solution was to order one from Accutronics in Korea directly. They answered my email the next day, and it looks like I'm getting an electrically exact replacement with my physical preferences.
I got a LOT of tweed tolex that matches the Peavey covering, for a better price than thru Peavey. The replacement handle arrived without the chrome mount ends; I wish they'd have mentioned that when I made my phone order.
The circuit board mounts on the old broken volume pot came out very easily with de-soldering wick.
I find if I'm careful I can work on both sides of most of the main preamp and control circuit board without disconnecting the ribbon cables. I've heard of so many people with cracked ribbon cables I'm considering just replacing them with suple new ones on principle as a preventive measure, though mine seem fine if a bit stiff.
Getting a larger full-size 3-spring reverb tank with longer decay and the same input and output impedances was looking difficult, so I even considered paralleling different tanks with impedances to end up about the same, or duplicating the drive circuit or changing the resistors at the recovery circuit. But the simple solution was to order one from Accutronics in Korea directly. They answered my email the next day, and it looks like I'm getting an electrically exact replacement with my physical preferences.
I got a LOT of tweed tolex that matches the Peavey covering, for a better price than thru Peavey. The replacement handle arrived without the chrome mount ends; I wish they'd have mentioned that when I made my phone order.
The circuit board mounts on the old broken volume pot came out very easily with de-soldering wick.
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Yesterday I found a Peavey Classic 100 at Guitar Center, which is the more sensible way to upgrade my classic 50 for more clean headroom. But someone else bought it before I could. Another will come along when I have the cash to spend.. It's the same circuit, same boards, except it has 2 of the output boards, so it has 8 EL84's instead of 4 (and a bigger power transformer and output transformer). And I'll keep the 50 also. I wish I'd bought two of the upgrade reverb tanks; the shipping from Korea would have been about the same.
Cyclecamper - you might get a kick out of this.....http://www.diyaudio.com/forums/instruments-amps/200342-one-off-guitar-amp-2-a.html
Bob
Bob
I would advise getting rid of the classic 50 and buying a ceriatone kit head.
I've repaired / modded dozens of Classic 30's / 50's and they are basically a
fantastic value amp that is built to a price point. Every where you look there
are compromises.
- Tiny transformers / OP tubes need a fan / 3 way folded PCB is not
conducive to modding and a PITA to work on / components are cheap.
etc etc etc
With the ceriatone you will have the P2P board right there in front of you to
mod and play with to your hearts content. Lot's of space, no heat problems,
ultimately better sound.
cheers
T
I still want to know why one pair of EL84's has the screens connected directly to the screen + supply but the there are 100 ohm resistors between those and the screens on the other two EL84's. Why wouldn't you want the screens the same on both push/pull sets? At first I thought it was a mistake in the drawing, so I looked, and you can't miss those big 5-watters. So why would you supply 2 screens directly but feed the others with a 100 ohm resistor in series? Of course, 100 ohms is not much with tube voltages...
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I was looking at the schem for the Classic 50, and I think they have some jumpered-in resistor options if you look at the power supply feeding the plate and screen supply. The Classic 20, and 30 show similar setups. I am wondering if on a quad set of EL84s there is a reconfiguration done and those 100 ohm are to limit dissipation on the additional EL84 pair, because on the classic 20 the screen supply looks like it is developed simply in the power supply section without additional screen limiters.
Yeah it is a bit weird, the Classic 20 does not even have those separate screen resistors, it is only the voltage divider network on the power supply that is dropping the screen supply volts. That is why I suspected the added 100 ohms on second pair, keeping the total watts to a specified level.
Certainly not very straightforward
Certainly not very straightforward
OK now we're getting somewhere. I'm running a big 60-watt Edcor output transformer and the power transformer from a Peavey Classic 100 in my Peavey Classic 50. So maybe I don't need no stinking "power limiting"...
Still working on it. I have two seperate B+ supply regulators coming, one for the output power section and another for the preamp power. I
Still working on it. I have two seperate B+ supply regulators coming, one for the output power section and another for the preamp power. I
I also have some chokes and electrolytics. Still waiting for the arrival of a better used VTVM I picked up on eBay before I can do much, as there are a lot of things I want to measure before I start remaking the power supply. Sold all my bench equipment a few years back when "between contracts"...unemployed. I also have this 4-gang stacked variable pot and I might use it to simultaneously vary the anode resistors in the preamp. The full-size reverb arrived; I had to order it from Korea to get the correct impedances. I would have been better to use two tanks with different impedances in parallel, one fast decay and one long maybe, as the shipping killed me. Since i have the original small tank and the new full-size tank, I might put in both with a switch. I don't know whether it will do anything at all, but I glued a small heat-sink onto the op-amp that drives the reverb. And I installed a high-low switch for the new fan.
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