Newbie looking for guidance...tube amp

[lifeinstereo]

First off, I would like to express my gratitude to ak. The information contained in the forum has been an invaluable go to tool for me. Next, this being my first time posting, I will try not to look like a complete idiot. Now to the point...I have never owned a tube amp and really don't know a lot about them. I like to learn the hands on way and have never been afraid to jump into a new task. I am going to try and build a tube amp. I have a console to use for parts. It's an RCA Victor PVCRH106. My question is where to go for guidance. Obviously there is an almost infinite amount of info here to help. I wish I had time to go through all of it but I don't. If some of you could point me in the direction of some of your favorite or if some of you could point me in the direction of some good information I would greatly appreciate it. Tube amp building for dummies isn't available anywhere, but something close to that would be ideal. Thank you in advance!

 

[SiliconTi]

Just out of curiosity, why not learn a bit of the basics by rebuilding the amp you have?

One word or warning - voltages in tube amps are very high and will kill you given the chance.

 

[lifeinstereo]

Just out of curiosity, why not learn a bit of the basics by rebuilding the amp you have?

One word or warning - voltages in tube amp are very high and will kill you given the chance.

Thank you for your response. Actually that's the kind of advice I'm looking for. Can I take the amp out of this unit and use it as a standalone? I do have some experience with electricity and do know of the dangers especially when dealing with capacitors and so forth, but appreciate your warning.

 

[Poinzy]

My father built and serviced his own tube amps until I was about 15, when he switched to solid state amps. He never got shocked working on tube amps, but he would probably say that you shouldn't use fixing or building a tube amp as your introduction to electricity.

 

[SiliconTi]

If the amp is stereo, and if it can be used stand-alone, sure!

Most console amps have an umbilical cord to the pre-amp which can make the process a bit trickier. Now, if the pre-amp is a good one, you can pull them both, make a nice enclosure and voila - your own tube integrated amp.

 

[lifeinstereo]

SiliconTi, you make it sound so simple! I should get the console home tomorrow where I can get a good look at what I'm dealing with. My plan was to plug in the console and see if it actually works. Or is that not a good idea?

 

[lifeinstereo]

One more quick question, the back of the console has specifications written on it and says that it is 285 Watts. How accurate are those ratings? I would assume that is all channels driven? Or how did they rate those?

 

[BillWojo]

That's input watts for the entire unit and has nothing to do with the rated output of the tube amps. If those tubes are 6BQ5 that your probably looking at about 12 watts a channel or so. On efficient speakers they will play plenty loud.
You may be better off posting this thread on the tube forum, that's where the tube guru's hang out.
On Edit, looks to be 3 channels, all three channels are 6BQ5 PP amps, so yes approximately 12 watts per channel. The B or third channel powers a bass speaker.

BillWojo

 

[elnaldo]

I don't think it's a good idea just plugging it to mains without at least some minor testing, like a visual inspection for burned components or checking the transformer for continuity or shorts.

If you plug it, keep one hand on the plug to disconnect it innediately if you see some smoke or a tube getting Red. I usually try this amps without the tubes first and a DBT or a step down transformer to give the capacitors a bit of charge at lower voltages.
There is a web site about old radios with detailed instructions to power on an old unit. Of course don't touch anything , specially the metal chassis. It could have hundred of volts if some caps are bad. Wen I work with tube amps I keep my hands out of a powered unit. I never touch anything "to check if it's warm" "to check for a broken solder" or such things. Hands far from the chassis and you'll be quite safe.
And make an habit of double checking the unit is unplugged from the wall before touching it. Repeat it in your mind (unit unplugged ) before touching it.

Then, what to me is the 1st thing to check: power supply voltages at each stage of the power supply, after each filter capacitor, and voltage at the plate at each tube. That usually points to the problem if there is some. All this following a schematic.

 

[gadget73]

That one should be a fairly easy rebuild project. Blow the dust off the amp chassis and see if you can get a number off it. Looks like a 3 channel amp, so it will be best used either in the cabinet or with a speaker system that is more or less similar. The way these 3 channel rigs worked, the left and right do mids and highs only. The center is your bass channel. Think of it as an early 2.1 system. It works fine but it does want that single big speaker to have any kind of bottom end.

All advice about visual inspection and bringing it up slow should be applied here.

 

[lifeinstereo]

Thanks for the great advice! It is still in the cabinet with the 2 mids on each end and the 12" bass speaker in the center.

 

[slimecity]

Build a dim bulb tester and use that to power it up for the first time. Instructions are on this site to build one, piece of cake.

Never power up a valve amp without speakers connected to it.

Obviously also as other have said - Valves have higher voltages floating around in the circuit, so be cautious when working on them.

What may need replacing first in this unit are old caps, some old caps in valve circuits can explode or rupture if they havent been used for a while.

Are you put off yet?????

 

[soundmotor]

View attachment 1094619

Your amp looks no better or no worse than the console amps that show up here. It would be an excellent starting point. I'd go in this order -

(1) Find schematic for your amp

(2) Find local that can test your tubes and OK them (good chance they are or good enough to start with)

(3) Watch youtube video(s) on DBT (dim bulb tester) then make one-

(4) Get basic tool set (soldering iron & solder, DVM, electronic needlenose pliers & diagonal cutters, spudger stick)

(5) Watch soldering, meter use, and basic tube amp rebuilding videos until eyes cross

(6) Start asking questions here about the teardown & rebuild then ask more questions, repeat

(7) Make parts list and order from AEC, Digikey, Ebay, Mouser, Parts-Express, et al x1000s

(8) High Voltage can kill you or at least spoil your day

(9) Hold cold end of soldering iron and begin

 

[Bob]

follow the advice of the above.

yes there are books for tube newbies. search (bing/google/msn/amazon/ebay) for
Morgan jones' book - he also has the designing valve amps book. try the US navy
books on electronics. search for online copy. push comes to shove, try the beginning
chapters of any RCA tube manual (there are dozens of versions available). then
go online look for valve/tube lords/wizards with their tutorials.

based on the dust, the caps need to be reformed, best is a variac, DBT is OK if
you have multiple bulbs to lower the initial voltages then to raise them gradually.

before you start, clean it. bing/google how to really clean an amp. no mind control
use cloths, rags, sprays, brushes of all kinds ranging from fine tips to wide coarse
hairs. use water, windex, alcohol (pads, sprays, liquids), air (compressed), Dawn, etc

and before you power anything other than a battery-powered flashlight (torch if you're british),
download the schematic and the SAMs (former for schematic experts, the latter for
completeness).

buy tools. ( I can send you a set of soldering iron, solder sucker, solder, meter) for
postage or free if you post your progress with pictures). buy completely covered
clip probes for the meter that reduces the tendency to short several hundred volts
across your chest (instant fibrillation), across the unit, etc.

do non-powered testing (using resistance mode of meter) check for shorts on the
caps, transformers, etc. look up on web or here on AK.

I would not assume any of the caps are anywhere near working condition. especially
if they're older than you. find heavy plastic shield to cover unit if you do power it up
and mandatory if you do not reform caps or don't use a voltage limiter.

anticipate explosions by always wearing safety glasses.

hope you're not a lefty,

but good luck. post here and continue using pictures. they help as you learn more
about tube amps and explain in severe detail.

 

[rmunson]

This fellow posted a really good series of videos on restoring a tube hifi - worth checking out:

https://youtu.be/iHgKbGp67_s
My story is similar to yours - I got started working with tube amps from hifis and organs -- with help from very generous people on AK I learned a lot and had a lot of fun --

retrofitting hifis and organs is a good way to get experience and learn -- another good way is though kit building - I always wanted to build one of the S5 tube amp kits

definitely check out Hackaweek's videos!

 

[triode17]

Morgan Jones also wrote a book about building tube amps. Another good book is Principles Of Power. I forget the author. BTW, I wouldn't try a console amp. for parts because they are so old now, most of the parts may no longer be in spec. Get catalogs from Mouser Electronics. Go to Antique Electronic Supply, Triode Electronics, there are many online. They can provide fresh parts. Start with rebuilding something simple - a small powered amp or preamp and most of all, BE CAREFUL!!!! We say there are only two types of electronic technicians, old ones (who are always careful) and careless (dead) ones.

 

[lifeinstereo]

Put off?? Oh no, I love audio equipment. Love to spend any of my free time just listening...I was away for a little while for some work stuff, but am back and on the task.

 

[lifeinstereo]

follow the advice of the above.

yes there are books for tube newbies. search (bing/google/msn/amazon/ebay) for
Morgan jones' book - he also has the designing valve amps book. try the US navy
books on electronics. search for online copy. push comes to shove, try the beginning
chapters of any RCA tube manual (there are dozens of versions available). then
go online look for valve/tube lords/wizards with their tutorials.

based on the dust, the caps need to be reformed, best is a variac, DBT is OK if
you have multiple bulbs to lower the initial voltages then to raise them gradually.

before you start, clean it. bing/google how to really clean an amp. no mind control
use cloths, rags, sprays, brushes of all kinds ranging from fine tips to wide coarse
hairs. use water, windex, alcohol (pads, sprays, liquids), air (compressed), Dawn, etc

and before you power anything other than a battery-powered flashlight (torch if you're british),
download the schematic and the SAMs (former for schematic experts, the latter for
completeness).

buy tools. ( I can send you a set of soldering iron, solder sucker, solder, meter) for
postage or free if you post your progress with pictures). buy completely covered
clip probes for the meter that reduces the tendency to short several hundred volts
across your chest (instant fibrillation), across the unit, etc.

do non-powered testing (using resistance mode of meter) check for shorts on the
caps, transformers, etc. look up on web or here on AK.

I would not assume any of the caps are anywhere near working condition. especially
if they're older than you. find heavy plastic shield to cover unit if you do power it up
and mandatory if you do not reform caps or don't use a voltage limiter.

anticipate explosions by always wearing safety glasses.

hope you're not a lefty,

but good luck. post here and continue using pictures. they help as you learn more
about tube amps and explain in severe detail.

I really appreciate the offer of the tools, but I've been playing with things I probably have no business playing with for many years...I do have the basics, just no real test equipment aside from a fluke meter. I will be happy to post pics as I go. I have harvested the organs from the cabinet and a quick visual has revealed some issues already before even cleaning...

 

[lifeinstereo]

SiliconTi, you make it sound so simple! I should get the console home tomorrow where I can get a good look at what I'm dealing with. My plan was to plug in the console and see if it actually works. Or is that not a good idea?

That's input watts for the entire unit and has nothing to do with the rated output of the tube amps. If those tubes are 6BQ5 that your probably looking at about 12 watts a channel or so. On efficient speakers they will play plenty loud.
You may be better off posting this thread on the tube forum, that's where the tube guru's hang out.
On Edit, looks to be 3 channels, all three channels are 6BQ5 PP amps, so yes approximately 12 watts per channel. The B or third channel powers a bass speaker.

BillWojo

The only speakers I have at the present time are an all original pair of Klipsch Forte. Really wanting to get the caps replaced in them sooner than later

 

[lifeinstereo]

I apologize for that post showing up out of the blue...thought I had posted that a week ago