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Old 7th September 2011, 05:59 PM   #1031
TheGimp is offline TheGimp  United States
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Lots of devices can be used as drivers and receivers. Springs are the problem that I find, or rather can't find.

too many projects, not enough time...
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Old 7th September 2011, 06:11 PM   #1032
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Springs Mcmaster Carr!

McMaster-Carr

But you already have the sender!
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Old 7th September 2011, 06:45 PM   #1033
ChrisA is offline ChrisA  United States
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Originally Posted by simon7000 View Post
So has anyone else figured out for a reverb you can use the speaker frame as the sender?
Sort of, maybe yes it will almost work but you will not like the result.

I'm slowly building what I call a modernized clone of a Fender 6G15. The reverb pan came in the mail long before I had electronics built to drive it. So I was messing around with an audio signal generator and a scope. And I was pretty much able to verify that everything on the Acutronics web site about how to use a reverb pan is correct.

Now to your question: Yes the pan is microphonic. If you shake the pan you get signal out of the pan even with input disconnected, however the fidelity is horrible. In other words the frequency response and noise of the mechanical coupling is such that the method is useless for audio. You really do need a reverb driver amplifier. And just as stated in the Acutronics web site the driver needs to be powerful enough to totally swap any input from the mechanical coupling. It also turns out it is very easy to mechanically "over drive" the pan and then the only sound you hear is "spring crash" which sounds even worse than microphone handing and wind noise.

Leo Fender was smart. He must have figured that he could improve the sound not only by going over the top with a big driver but also at the same type removing the pan from the combo amp and flying the pan on a spring suspension inside it's own cabinet. The signal to noise as very much improved when you do what he did with the Fender 6G15. This means (1) isolate the pan from the speaker as best you can and (2) drive the pan as hard as you can, to just below saturation. Using a speaker to drive the pan violates both of the above in a big way.
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Old 7th September 2011, 11:47 PM   #1034
taj is offline taj
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Originally Posted by tubelab.com View Post

My $40 three tube circuit ... fulfils my "so simple that even a drummer can build it" criteria....
Hah ha. Then you have to go one giant step further and make one so simple a lead singer can build it.

..Todd
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Old 10th September 2011, 03:29 PM   #1035
PB2 is offline PB2  United States
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Quote:
Originally Posted by jazbo8 View Post
Sorry if this topic is OT wrt the amp challenge, I am just curious to learn from you experienced builders on how one would start to guess at what may or may not work before buying the transformer

The math on how to calculate the impedance is pretty straight forward, since we can derive the turns ratio from the transformer's spec, but how do you figure out the inductances, thus frequency response if the manufacturers do not provide the data in their spec sheets?

Anyway, did you check out the Piltron 4002-1? It goes for $12 and its spec looks pretty good, but may be under-powered for your needs...

Jaz
I thought I saw a link to the $12 price for this a while back, did that turn out to be fake? Seems too good to be true ... and I can't find the link now.
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Old 10th September 2011, 05:28 PM   #1036
ChrisA is offline ChrisA  United States
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Originally Posted by PB2 View Post
I thought I saw a link to the $12 price for this a while back, did that turn out to be fake? Seems too good to be true ... and I can't find the link now.
A couple more low cost transformers at Triode Electronics

1) Single ended 7.5K load matched to 8 ones. up to 28ma $16.40
Output Transformer for 6G15 Add-On Reverb Unit OT47605 MADE IN USA

2) Single ended, 25K to 8 ohms The claim "3.5 watts". $15.96
Fender Vintage Style Reverb Driver ClassicTone 40-18034

Both are made in the US by Magnetic Components Inc. under they "Classic Tone" brand name. They are intended to drive an 8 ohm spring reverb pan and so are only good for a 1 or 2 watts. Yes they are spec'd for more but you never but bass through a reverb so these would only be flat to about a few hundred Hz at full power, but for a flea powered bedroom amp these two transformed are ideal. They were designed for guitar amps. Classic Tone claims to use "vintage" production techniques, correct interleaving and paper between the layers and so on. You can read their sales pitch here:
ClassicTone Transformers By Magnetic Components, Inc.

I have the first one listed above. Build quality is good. I's going to be powered by a 6K6 tube. The 6K6 is a lower powered version of the 6V6 and 6L6 tubes and sounds like it. THese are easy to buy for about $3.50 each

If you can live with about 1W power a Classic tone 7.5K:8 transforer and a 6K6 and one 12AX7 tube lets you build and authentic but with limited power Fender Champ. The smaller tube lets you get into power tube distortion more quickly although it's still to loud for bedroom volume.

The second transformers is good if you want use something like an 12AU7 section as a single ended power tube.
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Old 11th September 2011, 09:56 PM   #1037
PB2 is offline PB2  United States
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Thanks I'll look into those but I was specifically asking about jazbo8's statement:
"out the Piltron 4002-1? It goes for $12 "
There was a link associated with this offering it for $12 that seems to be gone, was the link a fake?
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Old 11th September 2011, 11:38 PM   #1038
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Originally Posted by PB2 View Post
Thanks I'll look into those but I was specifically asking about jazbo8's statement:
"out the Piltron 4002-1? It goes for $12 "
There was a link associated with this offering it for $12 that seems to be gone, was the link a fake?
Maybe they sold out.
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Old 12th September 2011, 10:27 AM   #1039
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Originally Posted by Printer2 View Post
Maybe they sold out.
No, it was a scam, the moderator deleted most of the posts relating to the topic, I also informed Plitron about it, perhaps the phony site will get shut down soon...

Jaz

Last edited by jazbo8; 12th September 2011 at 10:31 AM.
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Old 12th September 2011, 11:46 PM   #1040
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Originally Posted by jazbo8 View Post
No, it was a scam, the moderator deleted most of the posts relating to the topic, I also informed Plitron about it, perhaps the phony site will get shut down soon...

Jaz
Meant tongue in cheek.
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