use pa tube amp for home?

[doodz66]

I just got a rack with three cool pa tube amps in it. the tubes are rca brand. it came from an old church that I being torn down. these amps look awesome. I know that the one on the bottom has what looks like eight tubes and four transformers on top. I would love to use these for my home speakers and am wondering about any problems. will try to put pix on later when I get home feom work.

[markus]

they sound cool whatever they are :yes:

anything rackmounted is killer in my book . ..

when you get a chance, take a peek for any manufacturer plate / label so we can get a make / model # . . . also, rattle off the tube compliment, and lets see some pix !

[Endspec]

See if you can get some of the speakers too, at least two of them will be pritty big and probly sound good too.

[dshoaf]

It sounds like they may well have been there for many decades. If this is that case, be aware that just plugging them in again can cause some real problems. I'd suggest that you have them looked at by someone competent to deal with old tube amps.

There are many posts here of folks doing just what you're contemplating only to find that they rushed them into service without understanding how to do it right.

I'd strongly recommend that you take your time, get more details about them and read up here on how to deal with old tube gear safely.

Congrats on a nice score, too, BTW.

Cheers,

David

[markus]

It sounds like they may well have been there for many decades. If this is that case, be aware that just plugging them in again can cause some real problems. I'd suggest that you have them looked at by someone competent to deal with old tube amps.

There are many posts here of folks doing just what you're contemplating only to find that they rushed them into service without understanding how to do it right.

I'd strongly recommend that you take your time, get more details about them and read up here on how to deal with old tube gear safely.

Congrats on a nice score, too, BTW.

Cheers,

David

YES . . . by all means take your time . . . these old tube amps are like an old 'barn find' classic car . . . you just can't fire them up - bad things can happen. Also, the bastards can bite !

By all means, find a local tech (pro or amateur, as long as he knows his shit), or be prepared for a long (and fun) journey with DIY . . . I have no formal training, but I mess with tube stuff. It's taken about 6 years of learning by self-teaching, absorbing knowledge from mentors, f*ck-ups of my own doing, and most importantly, working with one hand in my pocket to avoid DEATH :D

but it sure is fun (can't wait to see pix !)

[doodz66]

I will take ome pictures after work tonight. I know that the pa amps were used up to a few years ago. I actually got another pa amp that I did hook up today. it has two el34 tubes in it. I hooked up an old grundig speaker to it and the sound was great. I wish that this smaller amp had two channels for stereo.

[markus]

I will take ome pictures after work tonight. I know that the pa amps were used up to a few years ago. I actually got another pa amp that I did hook up today. it has two el34 tubes in it. I hooked up an old grundig speaker to it and the sound was great. I wish that this smaller amp had two channels for stereo.

naaaaaaaaaaaah ! fogetaboutit ! get some mono action going :thmbsp:

http://audiokarma.org/forums/showthread.php?t=137301&highlight=mono

[motorstereo]

I have a pair of pa tube amps and they sound wonderful. I had the same questions as you and took them to someone in the know. Sometimes pa amps are made to handle mainly vocals and aren't made for hi-fi use. I had mine checked before I had them restored and found they do indeed amplify the entire audio spectrum. This may be something you may want to check into before you have them restored. Sounds like you may have a diamond in the rough there.

[markus]

:worthless

[doodz66]

I can't get the stupid pictures of these amps to attch. It keeps saying that it failed and I am trying to copy and paste to no avail!

[doodz66]

I've been trying to get pix up. will someone tell me if they see these?????


C:\Users\Byron&Wendy\Pictures\2008-10-08\013.JPG

[coman61]

:no:

[Tinkerbelle]

Still no pics.

One question - why do you need to copy and paste as it seems that you are uploading from your "C" drive?

Maybe you're already doing the following procedure and it isn't working for you but just in case, the following should work:

- Hit the "Post Reply" button to send a response.
- Click the "Manage Attachments" button below the AK message box that you are typing in.
- A new "Manage Attachments" window should open.
- Hit one of the "Browse" buttons in the "Upload File from your Computer"
section of the new manage Attachments window.
- Browse to the locatation of one of the files that you want to upload (i.e. C:\Users\Byron&Wendy\Pictures\2008-10-08\013.JPG).
- Check that the file size is within the file size limitations specified in the manage Attachments window (e.g. 195.3 KB if a .jpg file). BTW, it should still upload if it is oversize as the AK file handler should reduce it although it could be significantly reduced - at least that has worked for me with oversize .jpg files.
- Hit the "Upload" button
- Now hit the "Preview Post" button and you should see your email message with the attachment in it.

If so, hit "Submit Reply"

Good luck.

[similost]

as far as the first question, yes, you can use PA tube amps at home. I've got one, and am trying to score a second right now. THe one I have sounds fantastic on my Altec speakers.

I agree with others though. BE SURE to have them checked out before putting them into daily service.

[soundmotor]

I've been trying to get pix up. will someone tell me if they see these?????


C:\Users\Byron&Wendy\Pictures\2008-10-08\013.JPG

Good Lord, it's even linked as an email addy!

http://wilk4.com/humor/img/doh-1.jpg

[dividebytube]

in theory the maker of the PA amp may not have cared as much about distortion levels and frequency range versus a hi-fi amp. Of course results may vary, so go ahead and give it a try! I've heard some PA amps that sound just fine.

[salb203]

Can you email me the pictures at salb203@optonline.net, I will post them for you..

Sal

[doodz66]

here are the amps I picked up. Iam wondering how many channels they are capable of. Also, I would like some info on them.

[Tinkerbelle]

Wow, that is some serious iron with Thordarson transformers. Looks like it may be a 3-section power supply on the bottom, a 4-channel power amp in the middle and the preamp at the top? I only see 2 wires connecting from the top amp to the middle power amp. How were the speakers connected? Presumably that top amp had controls/pots going through to the front side.

Hopefully someone familiar with these units will chime in with good info.

Great find :thmbsp: and thanks for sharing.

[doodz66]

yes, the top amp sat upright in the rack and had four control switches for the mics, phono, and bass/treble. This sounds like a crazy idea, but I would ideally like to get the four channel amp going and then run two channels to the highs and two to the lows and 'biamp' to my magnaplaners. sound too crazy to be?

[doodz66]

here are some more pictures to make sense of.

[dshoaf]

Have you got a shot of the front? This looks a lot like the systems I would pull out of deparment stores when I was installing replacement Muzak systems in the 70s. I'd date that thing from the late 50s to early 60s, for sure. The things that aren't clear are:

- Who the integrator/vendor was

- Why you have what looks like 4 power amps but may well not be. Something like that would have been used for multiple floors in a Macy's or similar. They could also be strapped together for higher power and/or further distribution of speakers as in a large manufacturing facility where you had to overcome lots of other noise with the broadcast.

- Whether the output transformers are built for 4/8/16 ohm drivers. I'd suspect there are provisions for 70.7 volt distribution given my assumptions above.

Lots of unkowns but a really cool setup for sure.

Cheers,

David

Edit: We just cross-posted with the second set of pics. Here's what I see so far:

- Clearly just used in a church - you said that early on, right?
- The power amp set of 4 output transformers and tube groupings are likely strapped in some way.
- The driver tubes are, however, found on the control unit.
- You have a distributed power supply. That is, some of the voltage dividers, filter caps and distribution for the preamp is contained in the preamp. This means that you'll not be able to not run the whole thing together without some serious re-engineering of the power supply and the power amps. In other words, this rig isn't really set up for 4 channel operation in the way we see it with contemporary tube gear.

Hope that helps a bit more.

[Tinkerbelle]

yes, the top amp sat upright in the rack and had four control switches for the mics, phono, and bass/treble. This sounds like a crazy idea, but I would ideally like to get the four channel amp going and then run two channels to the highs and two to the lows and 'biamp' to my magnaplaners. sound too crazy to be?

I guess that will depend on how that power amp is currently wired, which is why I was asking about the speaker configuration and referenced the single pair of wires from the preamp. It looks to be mono input (3 inputs - 2 mic, one RCA) so presumably mono signal to the power amp section. So may be 4 channels in parallel, or two sets of parallel or may have 4 separate. Tough to tell without detail on how wired. So, to do what you want to do would take quite some mods anyway.
Do you have a close up pic of that front panel with the two controls below the 4 selector switches?

[doodz66]

here are the 'guts' of the two bottom components. the two internal pictures are of the 8 tube component and the one that is black inside is of the one that was in the middle of the rack. thanx

[doodz66]

there were no speakers that i know of with this. the church had changed hands and this was by itself in storage. I have a friend who used to run the sound there years ago so that I can get some details.

[dshoaf]

So this PA system appears to have driven the horns in the steeple, I suspect, and was then switched to be used for the sanctuary services. My father was a minister and had to deal with all sorts of strange things that happened to wayward electronics during sermons.....

My overall take on this system is that it will take a lot of rework to get it to work for audio work. Part of the evaluation would be to get the specs for the output transformers to see if they are suitable for wide-band audio. Given the costs involved in replacing all those electrolytic caps (I see 7 cans @ ~$35 ea, for instance) plus all the other coupling caps, would start to rule against restoration. In other words, the costs to restore will quickly overvalue the potential benefits of the project.

Cheers,

David

[Tinkerbelle]

I would agree with dshoaf that there could be a lot of work to get this into something for home audio use, assuming that the transformers cover a sufficient part of the audio frequency range and provide a usable output impedance for home speakers. So there's some research and assessing to do. However, for the seven electrolytic cans, the ones in the power supply seem to be single section (2 wires on each, with black wire going to chassis maybe), so a less expensive way to replace those could be with single axial or radial electrolytic caps underneath and there seems to be plenty of room under there. If the one can in the preamp is a multi-section, that too could perhaps be replaced with less expensive individual caps underneath.

Otherwise, if the transformers are not that good for wide spectrum audio, being as you were hoping on maybe using for bi-amping, you might be able to modify for use in part of the frequency range, supplemented with another amp. Alternatively, you could look at using the parts to make instrument amps.

Good luck with this and hopefully your friend who used to run the sound there can provide you with needed information to help you make your decisions.