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 Post subject: Ampex output transformers for DIY amp build
PostPosted: Jun Sun 02, 2019 6:55 pm 
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Joined: Aug Thu 20, 2015 3:09 pm
Posts: 1227
Location: Albion, CA, USA, 95410
Hi All,

I am starting to gather up parts and pieces to build a stereo amp. I have a couple of Ampex 2010 suitcase amplifiers and I am looking at pirating the output transformers. Are these of decent quality? They are marked 58-0005-D. They are good to use with 6V6's and I have a few of those kicking around. They appear to only be rated for 10 watts, a little less than I might want but truly 20 watts of sound is more than I actually need.

Thanks!


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 Post subject: Re: Ampex output transformers for DIY amp build
PostPosted: Jun Sun 02, 2019 8:42 pm 
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Joined: Sep Tue 15, 2015 1:16 am
Posts: 640
Location: 18424 PA
Those ampex are worth about $200 each. You would be better off buying the transformer you need and selling those.


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 Post subject: Re: Ampex output transformers for DIY amp build
PostPosted: Jun Sun 02, 2019 8:57 pm 
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Joined: Aug Thu 20, 2015 3:09 pm
Posts: 1227
Location: Albion, CA, USA, 95410
Hmm. Mine are a little beat up, or rather one is decent and the other not so much. I live in the middle of nowhere so selling them would be something for that auction site we all love. I'm not sure I want to deal with that but I might.


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 Post subject: Re: Ampex output transformers for DIY amp build
PostPosted: Jun Tue 04, 2019 12:06 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Beaver Falls, PA. USA
If you want 20 watts, you might be better off using 6L6 tubes.

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Tim KA3JRT


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 Post subject: Re: Ampex output transformers for DIY amp build
PostPosted: Jun Tue 04, 2019 1:35 am 
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Joined: Aug Thu 20, 2015 3:09 pm
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Location: Albion, CA, USA, 95410
Maybe I am not up on amplifier terminology. 10 watts per side would be a total of 20 watts, no?

Still curious as to the quality of these output transformers.


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 Post subject: Re: Ampex output transformers for DIY amp build
PostPosted: Jun Tue 04, 2019 1:33 pm 
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Joined: Jul Mon 08, 2013 2:48 pm
Posts: 360
Quality is average and you only have a single secondary, very likely for a 16 ohms speaker impedance. This transformer would be best suited for a guitar amp, there are many better OPT's available for Hi-Fi use. The 2010 circuit used a special global feedback network to compensate for speaker/enclosure/amplifier deficiencies and tailoring the sound.The transformers used on the little Ampex 6973 console amps are much better but it would be a pity to part out these amps.


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 Post subject: Re: Ampex output transformers for DIY amp build
PostPosted: Jun Tue 04, 2019 3:15 pm 
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Joined: Aug Thu 20, 2015 3:09 pm
Posts: 1227
Location: Albion, CA, USA, 95410
Thanks for the information. I may have to reconsider my plan. However, I really don't know how I would get these back into the hands of someone who would use them. For sure "local pick up" isn't going to happen, I live 2-3 hours away from anywhere it might.

If I was to try to sell them, should I re-cap and get them going or sell as is? I am very unfamiliar with the audio market.


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 Post subject: Re: Ampex output transformers for DIY amp build
PostPosted: Jun Wed 26, 2019 11:51 pm 
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Joined: Aug Thu 20, 2015 3:09 pm
Posts: 1227
Location: Albion, CA, USA, 95410
OK, I couldn't bring myself to gut them. I re-capped one of them and it sounds pretty good. I bought the caps for the other but haven't dug into that one yet. Turns out these need line level input so not much good for a guitar unless you used a pre-amp. I think I'll use this one for parties out in the garden.


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 Post subject: Re: Ampex output transformers for DIY amp build
PostPosted: Jul Tue 23, 2019 2:53 pm 
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Joined: Dec Sun 25, 2016 5:53 am
Posts: 216
Do your suitcase amps still have the OEM JBL 8" speakers? They were quite good. It's hard to beat these amps for what
they are. May not look impressive on paper but very musical sounding when operating correctly. Replace at least the phase inverter outputs to 6V6 control grid caps to avoid red-plating the output tubes. This is a common occurrence in these amps.
BTW looking beat up doesn't necessarily detract from the sound of these industrial units. They were built to survive lots of
out-in-the-field abuse.

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1970's Avionics Tech, USN Attack Squadron 147, "ARGONAUTS" A-7E A/C


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 Post subject: Re: Ampex output transformers for DIY amp build
PostPosted: Jul Tue 23, 2019 3:18 pm 
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Joined: Aug Thu 20, 2015 3:09 pm
Posts: 1227
Location: Albion, CA, USA, 95410
As far as I know they do. The speaker box is sealed and there is even a thing saying not to open them. Now that I have played it for a while I would say it is a little bassy, I leave the tone control 3/4+ of the way to treble. Might have to figure out a cap value to change in the tone circuit.

However, it does sound pretty good and is easily loud enough for garden party music.


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