I got a big mono amplifier.
Now sadly I dont like mono.
Its got a good dozen tubes in it.
Its has El34 X 2
12au7 X 2
5u4-gb X 2
12ax7 X 4
and 1 or 2 6l4gb I think ... 2 I believe.
It also has a 750V ct 300 ma transformer ...
And a output transformer too, but I am hoping to build a tube pre amp that may not use a output tranny, cos them is $$$$$ ....
Thanks in advance.
Cool.
srinath.
Now sadly I dont like mono.
Its got a good dozen tubes in it.
Its has El34 X 2
12au7 X 2
5u4-gb X 2
12ax7 X 4
and 1 or 2 6l4gb I think ... 2 I believe.
It also has a 750V ct 300 ma transformer ...
And a output transformer too, but I am hoping to build a tube pre amp that may not use a output tranny, cos them is $$$$$ ....
Thanks in advance.
Cool.
srinath.
Please give us your goal again, sounds like you would like to build a stereo preamp with the parts on hand from your mono amp. Is this right?
You can't build a stereo transformer-less amp from this parts.
The better option is to find one more such an amp and get stereo.
The better option is to find one more such an amp and get stereo.
Yes
Yes a good sounding tube preamp ... and these raytheon tubes in this amp are new. Never been burnt in. Man I have to get it made out of these.
Cool.
Srinath.
Yes a good sounding tube preamp ... and these raytheon tubes in this amp are new. Never been burnt in. Man I have to get it made out of these.
Cool.
Srinath.
Oops...
I did not realize that you want a preamp
There are many options available.
The better way to start is to answer the question first:
What do you want from the preamp?
I did not realize that you want a preamp
There are many options available.
The better way to start is to answer the question first:
What do you want from the preamp?
http://www.audiofanatic.it/Schemi/Tipo/Valvole/finali/pic_finali_SE/EL34SE_12AX7.jpg
you could make something like this (or better) with a bit of wheel'ing 'n' deal'ing on ebay
you could make something like this (or better) with a bit of wheel'ing 'n' deal'ing on ebay
Wow that is an amp ? cos that 373 transformer, I got that in this thing.
I also have the el34's ... The rest I will buy of course.
That is so cool, 1 12ax7 and 1 el34 per channel ... I'll check it out. Thanks so much.
Cool.
Srinath.
I also have the el34's ... The rest I will buy of course.
That is so cool, 1 12ax7 and 1 el34 per channel ... I'll check it out. Thanks so much.
Cool.
Srinath.
1st of all, that schematic you like so much from pointy is a power amp, not a preamp.
2nd, I really doubt you have a mono power amp with the tube complement you describe. I think it is almost certainly a stereo amp.
My recommendation is that you back up a bit, tell us what you have in more detail or with a picture, and what you are trying to achieve.
2nd, I really doubt you have a mono power amp with the tube complement you describe. I think it is almost certainly a stereo amp.
My recommendation is that you back up a bit, tell us what you have in more detail or with a picture, and what you are trying to achieve.
Stereo
The grommes people are pretty certain its a mono amp.
I suspect it is a bridged mono though. But it does have only 1 output transformer.
Here is the schematic, I have a photofact @ home with a better pic and I would scan it in first chance I get.
Please let me know if it can be turned into stereo, cos its a very well made amp. Hate to just cannibalise tubes from it.
Cool.
Srinath.
The grommes people are pretty certain its a mono amp.
I suspect it is a bridged mono though. But it does have only 1 output transformer.
Here is the schematic, I have a photofact @ home with a better pic and I would scan it in first chance I get.
Please let me know if it can be turned into stereo, cos its a very well made amp. Hate to just cannibalise tubes from it.
Cool.
Srinath.
Attachments
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I am unable to get the schematic any smaller so it will load.
I probably would scan and check my photofact and upload that.
Cool.
Srinath.
I probably would scan and check my photofact and upload that.
Cool.
Srinath.
What are all the controls for? Is it a P.A. or musical amp? With all those preamp type tubes and controls it looks like it's integrated anway. It's maybe PP to have 2 EL34 output tubes or they could be SE parallel. If it is HIFI and you want stereo just look for another or copy most of what what you have. You might use an improved circuit if needed. What model # etc is it? It looks too nice to scrap!
Story of Grommes
"As an engineering student in the late fifties, I was introduced to a young nurse who wanted to buy a 'Hi-Fi' with her Christmas bonus check and wanted the best system she could get for her money. I helped her assemble a component set with the first LJ-5 at its heart.
About a year later she contacted me with the question 'Could the set be modified to play stereo records?' That led to the purchase of the second LJ-5 and with a new phono cartridge and additional speaker we created her 'Stereo.'
Well, one thing led to another and she eventually married me and got a lifetime guarantee on her stereo!"
"As an engineering student in the late fifties, I was introduced to a young nurse who wanted to buy a 'Hi-Fi' with her Christmas bonus check and wanted the best system she could get for her money. I helped her assemble a component set with the first LJ-5 at its heart.
About a year later she contacted me with the question 'Could the set be modified to play stereo records?' That led to the purchase of the second LJ-5 and with a new phono cartridge and additional speaker we created her 'Stereo.'
Well, one thing led to another and she eventually married me and got a lifetime guarantee on her stereo!"
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Grommes - yea all that romantic stuff ... yea ...
Sadly I only have 1 that I got from someone who pulled it out of an old church.
Cool.
Srinath.
Sadly I only have 1 that I got from someone who pulled it out of an old church.
Cool.
Srinath.
It is almost for sure a PA amp. Some of the bits are likely mic inputs.
Takes 2 12AX7 for a stereo RIAA (say the RCA circuit). I hesitate to suggest the 12AU7 for the job (maybe get a ECC88 or 6N1P) as a gain stage, and the EL34 as cathode followers for the output stage (remember to CCS the bottoms). If it is fixed bias there will be a useful B- and you can just clean up the existing PS.
You can send me the schema, i can make it fit.
dave
Takes 2 12AX7 for a stereo RIAA (say the RCA circuit). I hesitate to suggest the 12AU7 for the job (maybe get a ECC88 or 6N1P) as a gain stage, and the EL34 as cathode followers for the output stage (remember to CCS the bottoms). If it is fixed bias there will be a useful B- and you can just clean up the existing PS.
You can send me the schema, i can make it fit.
dave
Oh gee...
That's a a PA/mixer.
The cans in the back are input transformers.
Check to see if they are line in to line out or HIGH Z in to line out...
Some of these are "worth the price of admission".
do not cannibalize this.
sell it on ebay, and take the money and buy the things you need or want.
the parts in it are worth FAR LESS than the whole unit as you now have it.
It is clearly NOT "bridged" anything, since that would require 4 output tubes,
and you have two. And they don't make SE Public Address power amps! 😀
Again, it is probably a very BAD idea to strip this down.
It has some collectors and brand name value beyond the functionality.
Preamps are easy and cheap to make, and you do not need those big power amp parts - if that is what you are after?? Preamp tubes are cheap, and PS parts for preamps are cheap too, easy to find.
Ok then?
_-_-bear
That's a a PA/mixer.
The cans in the back are input transformers.
Check to see if they are line in to line out or HIGH Z in to line out...
Some of these are "worth the price of admission".
do not cannibalize this.
sell it on ebay, and take the money and buy the things you need or want.
the parts in it are worth FAR LESS than the whole unit as you now have it.
It is clearly NOT "bridged" anything, since that would require 4 output tubes,
and you have two. And they don't make SE Public Address power amps! 😀
Again, it is probably a very BAD idea to strip this down.
It has some collectors and brand name value beyond the functionality.
Preamps are easy and cheap to make, and you do not need those big power amp parts - if that is what you are after?? Preamp tubes are cheap, and PS parts for preamps are cheap too, easy to find.
Ok then?
_-_-bear
OK guys yea I agree
I guess I better hold on to it huh ...
OK so now I guess I go back to dinking with my dynaco st70.
Cool.
Srinath.
I guess I better hold on to it huh ...
OK so now I guess I go back to dinking with my dynaco st70.
Cool.
Srinath.
Holy moly - that's a lovely amp. Looks like a 4 input one with input transformers as noted above - wow, probably rather valuable now too.
On no account pillage that - it's a great piece of engineering!
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