Reverb Tank

wdcw · 23rd July 2010, 08:48 AM

I have two (OC Electronics Type 56 Foldline Reverberation Devices)
They have the Z type spring arrangement, both the Input & Output DC resistance of the coils is around 172 Ohms.

One Coil is Yellow & the other is Red, I am trying to determine which is the Input & the Output?

Does anyone know the Input Impedance Specs or have the Datasheet info they could share or a link etc?.

Cheers

dumptruck · 23rd July 2010, 03:25 PM

I believe the input jack on all the OC tanks is on your right if you are facing the jacks from the outside, but accutronics still has all the info on most of these so you could try asking them for the specs.

wdcw · 23rd July 2010, 11:08 PM

Quote:

Originally Posted by dumptruck

I believe the input jack on all the OC tanks is on your right if you are facing the jacks from the outside, but accutronics still has all the info on most of these so you could try asking them for the specs.

Thanks dumptruck,

Yes, I have read that somewhere else as well, I will check things out with accutronics as you mentioned.

Cheers

Enzo · 24th July 2010, 12:10 AM

I am looking at one now. facing the jacks, INPUT is the jack on the right. I know this because the words INPUT and OUTPUT are stamped into the metal next to each jack.

wdcw · 24th July 2010, 06:11 AM

Ah ha, thanks ENZO, it is stamped into the metal.
The outside of the metal covers are all surface rust on the two I have & after cleaning them up a little I can see the stampings clearly.

Does anyone know how much power is required to drive these at 1kHz?

Cheers

Enzo · 24th July 2010, 10:52 AM

Not much.

Keeping in mind that DC resistance is not impedance, and looking at the chart of Accutronics specs, I'd have to think that 172 ohms DC means these are on the high impedance end of the reverb scale. For Accutronics that would mean about 1500 ohms.

Since reverb pans all work the same way, I feel reasonably comfortable comparing the two brands

The pan needs a drive of like 3-5ma.

Look up just about ANY Peavey amplifier with reverb and you will find a single 4558 dual op amp driving and recovering the reverb pan. Pretty simple, and it works. I have seen some that add a couple little push pull transistors to assist the op amp, but they are typically nothing more than 2N3904/3906.

Also, go to the Accutronics web site, and they have some suggested circuits to drive their reverb pans. You should be able to adapt those with little or no modification.

And if you are going to roll your own reverb, you generally cut out the low end of the audio fed to it. Low freq notes don;t reverb well, and mostly just make the sound muddy.

wdcw · 25th July 2010, 11:40 PM

Thanks Enzo,

Yes, I have noticed the 4558 dual op amps in my Amp, it's a Peavey Classic Chorus 130 stereo series.

I am building a small Tube-Valve drive & recovery for these reverb pans, for a small amp I am building, it's an interesting project so I will see how I go.

I think your correct in that you can compare different brands, there's not much difference in the way they operate.

I see what your saying with cutting the low end, it makes perfect sense.

Thanks for the advice & the tips, much appreciated.

Cheers

indianajo · 26th July 2010, 12:41 AM

My H100 organ drives the Hammond reverb tank with a 7247 tube with a 500 ohm choke on the plate to 275V B+, and a 1000 ohm resistor from the cathode to ground. The input is a EF86 tube with about 7000 mhos sensitivity. The schematic is in the Hammond H100 service manual on archive.org. Figure 41, upper right. (upper left since it is turned sideways). I was reading about 8v PP out, and about 25 mv back in with my 20 mhz scope.

wdcw · 26th July 2010, 05:24 AM

Thanks indianajo,

I had a look at the schematic you mentioned, lots of interesting ideas on it as well.

I will do a few tests & post some results.

Thanks again

Cheers

Enzo · 26th July 2010, 08:56 AM

They make the various impedance pans for a reason. the op amp circuit like in the Peavey amps expects the high impedance input to drive. The other end of the scale is the transformer driven reverbs like Fender has used for decades. These are typically tube driven by a small single ended stage driving the pan through a transformer. Those usually drive the low impedance input pans. COnsidering the high impedance of your imput stage, I wouldn't think it was expecting a transformer drive.

Look at some old Ampeg circuits, they used a high impedance pan and drive it off the plate of a drive tube through a cap.

23rd July 2010, 08:48 AM	#1
wdcw diyAudio Member Join Date: Jul 2010	Reverb Tank I have two (OC Electronics Type 56 Foldline Reverberation Devices) They have the Z type spring arrangement, both the Input & Output DC resistance of the coils is around 172 Ohms. One Coil is Yellow & the other is Red, I am trying to determine which is the Input & the Output? Does anyone know the Input Impedance Specs or have the Datasheet info they could share or a link etc?. Cheers

26th July 2010, 12:41 AM	#8
indianajo diyAudio Member Join Date: Jan 2010 Location: Jeffersonville, Indiana USA	tube reverb My H100 organ drives the Hammond reverb tank with a 7247 tube with a 500 ohm choke on the plate to 275V B+, and a 1000 ohm resistor from the cathode to ground. The input is a EF86 tube with about 7000 mhos sensitivity. The schematic is in the Hammond H100 service manual on archive.org. Figure 41, upper right. (upper left since it is turned sideways). I was reading about 8v PP out, and about 25 mv back in with my 20 mhz scope. __________________ Dynakit ST70, ST120, PAS2,Hammond H182(2 ea),H112,A100,10-82TC,Peavey CS800S,SP2-XT's, T-300 HF Projs, Steinway console, Herald RA88a mixer, Wurlitzer 4500

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23rd July 2010, 03:25 PM	#2
dumptruck diyAudio Member Join Date: May 2010 Location: MN	I believe the input jack on all the OC tanks is on your right if you are facing the jacks from the outside, but accutronics still has all the info on most of these so you could try asking them for the specs.

24th July 2010, 12:10 AM	#4
Enzo diyAudio Member Join Date: Sep 2004 Location: Lansing, Michigan	I am looking at one now. facing the jacks, INPUT is the jack on the right. I know this because the words INPUT and OUTPUT are stamped into the metal next to each jack.

24th July 2010, 06:11 AM	#5
wdcw diyAudio Member Join Date: Jul 2010	Ah ha, thanks ENZO, it is stamped into the metal. The outside of the metal covers are all surface rust on the two I have & after cleaning them up a little I can see the stampings clearly. Does anyone know how much power is required to drive these at 1kHz? Cheers

24th July 2010, 10:52 AM	#6
Enzo diyAudio Member Join Date: Sep 2004 Location: Lansing, Michigan	Not much. Keeping in mind that DC resistance is not impedance, and looking at the chart of Accutronics specs, I'd have to think that 172 ohms DC means these are on the high impedance end of the reverb scale. For Accutronics that would mean about 1500 ohms. Since reverb pans all work the same way, I feel reasonably comfortable comparing the two brands The pan needs a drive of like 3-5ma. Look up just about ANY Peavey amplifier with reverb and you will find a single 4558 dual op amp driving and recovering the reverb pan. Pretty simple, and it works. I have seen some that add a couple little push pull transistors to assist the op amp, but they are typically nothing more than 2N3904/3906. Also, go to the Accutronics web site, and they have some suggested circuits to drive their reverb pans. You should be able to adapt those with little or no modification. And if you are going to roll your own reverb, you generally cut out the low end of the audio fed to it. Low freq notes don;t reverb well, and mostly just make the sound muddy.

25th July 2010, 11:40 PM	#7
wdcw diyAudio Member Join Date: Jul 2010	Thanks Enzo, Yes, I have noticed the 4558 dual op amps in my Amp, it's a Peavey Classic Chorus 130 stereo series. I am building a small Tube-Valve drive & recovery for these reverb pans, for a small amp I am building, it's an interesting project so I will see how I go. I think your correct in that you can compare different brands, there's not much difference in the way they operate. I see what your saying with cutting the low end, it makes perfect sense. Thanks for the advice & the tips, much appreciated. Cheers

26th July 2010, 05:24 AM	#9
wdcw diyAudio Member Join Date: Jul 2010	Thanks indianajo, I had a look at the schematic you mentioned, lots of interesting ideas on it as well. I will do a few tests & post some results. Thanks again Cheers

26th July 2010, 08:56 AM	#10
Enzo diyAudio Member Join Date: Sep 2004 Location: Lansing, Michigan	They make the various impedance pans for a reason. the op amp circuit like in the Peavey amps expects the high impedance input to drive. The other end of the scale is the transformer driven reverbs like Fender has used for decades. These are typically tube driven by a small single ended stage driving the pan through a transformer. Those usually drive the low impedance input pans. COnsidering the high impedance of your imput stage, I wouldn't think it was expecting a transformer drive. Look at some old Ampeg circuits, they used a high impedance pan and drive it off the plate of a drive tube through a cap.

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