Hand-Wiring Reissue Amplifiers
This month we are going to talk about hand-wiring current production “Reissue” model tube amplifiers. I remove the printed circuit (PC) boards from these models and install hand-wired fiber or turret boards depending on the amplifier brand I am working on. The most common models people have me do this to are the Fender ‘65 & ‘68 Princeton Reverb and the ‘65 & ‘68 Deluxe Reverb. Next most common amplifiers are the Fender ‘59 tweed Bassman with 4×10 speakers, ‘63 Fender Vibroverb and lastly the ‘65 Twin Reverb. I also get some Marshall amps through my shop for this procedure. I would use a turret board for the Marshall amps which is similar to the originals.
Some of you may ask why bother to gut a perfectly good amp and what are the benefits? I can tell you from about a decade of doing this that the benefits are many! Every amplifier that I have gutted & hand-wired sounded much better and had a more dynamic feel. Not to mention the dramatic increase in reliability. Each of my customers 100% agree that doing this was completely worth it. The stock PC board limits tweaking/modding ability and the choice of component quality (because of space limitations), plus the mass produced PC boards are just not as reliable and a good hand-wired circuit. Now, I am not anti-PC board at all. I have seen some manufacturers build a really nice PC board. The trouble with the mass produced PC boards is that they are thin, flex from the heat of a tube amp (especially the boards with tube sockets mounted to them) and the traces are typically very thin. Many of the Fender reissue amps use multi-conductor ribbon cables that can be flimsy and break which makes repair work more difficult. Another thing to point out is that most of the reissue circuits are not 100% true to the original circuit. The power supply of the reissue tweed Bassman and the lack of a rectifier tube in the Vibroverb comes to mind.
The hand-wiring procedure takes some hours and is not recommended for a novice or DIY type person. This is where experience comes in. Lead dress is very important in a hand-wired amp as well as good grounding which is a black art in itself…lol. I have had to troubleshoot and repair some home brew builds and amplifier kits built by people lacking experience. To absolutely no fault of their own there is no substitute for experience. Some of the wiring in the DIY builds and kits actually looked pretty good but mistakes were made and grounding was not correct. Thank goodness I never had to repair anything that was wired to be deadly or dangerous!
Anyway, here is a photo of a Fender Princeton Reverb reissue with stock PC boards. Notice the small ribbon cables at the top of the main PC board that connect to the PC board with the potentiometers mounted to it as well as the small PC board with the jacks mounted to it. These can sometimes be problematic and not that easy to repair. More often it’s easier to just replace the bad cable in the ribbon with a single wire. The stock IC power supply capacitors (also known as filter caps) are not the best quality available and are known to leak from day one…or maybe day two. Kidding aside I’ve seen more IC caps leak than I should have.
Here is a photo of the same chassis after removing the PC boards and hand-wiring with the vintage style fiberboard material.
I relocated the bias potentiometer between the two output tube sockets for easier access so the owner does not have to remove the chassis for bias adjustments.
This wiring layout is pretty much like a stock vintage amplifier. Lead dress is neat, grounding is correct and any tech can easily service this amplifier should it ever need anything. For this rebuild I used the stock transformer set. Some customers want to take their amp up to another level and choose to have the transformers upgraded to another brand like Mercury magnetics, Hammond or Heyboer. Upgrading the transformers really puts the amp over the top as far as tone and dynamic feel. Reliability also increases a bit with this upgrade. At this level the stock amplifier is transformed into a boutique version of a vintage classic!!
If you don’t own a reissue amp and are interested in a project like this do a search on CraigsList, Reverb, eBay and the Facebook marketplaces for a “non-working” or “project” amp. Most of the components are going to be removed and replaced anyway. You can sometimes find project amps like this for a good price and you get all the basic building-blocks for a really great amp.
Well, I guess that’s it for this month. I have some really great projects coming up that are more in depth like the Gretsch Anniversary featured last month. I will be getting into them soon and I’ll be taking lots of photos along the way. Thank you all for your kind words and positive comments on last month’s article and I’ll see you next month!!
Billy Penn is the owner of 300guitars Shop in Toms River, NJ. He has over 30 years of experience repairing, restoring and custom building guitars & tube amplifiers. Along with being an expert technician he draws upon his experience as a former I.B.E.W. electrician and musician. For contact please visit www.pennalizer.com. 848-218-0362