Hi all,
I have built this circuit. It is the driver for a spring rev. transducer. In my reading 'being a novice' i have discovered that a there are specific diodes for the signal path. currently D1 and 2 are 1n4001's should i use something different?
Anyway; heres the schematic.
Cheers!
I have built this circuit. It is the driver for a spring rev. transducer. In my reading 'being a novice' i have discovered that a there are specific diodes for the signal path. currently D1 and 2 are 1n4001's should i use something different?
Anyway; heres the schematic.
Cheers!
Attachments
1N4148's seem to be commonly used in that type of circuit. It may not make much of a difference,4001's should be okay.
Hi DigitalJunkie,
Thank-you for your reply, I have a few 1n4148's at my disposal i also have some OA91 germanium type NOS I should try them as well.
Cheers
Thank-you for your reply, I have a few 1n4148's at my disposal i also have some OA91 germanium type NOS I should try them as well.
Cheers
oa91s are germanium types they would probably work but bear in mind the forward voltage is only approx 0.2V . this means in your circuit, as it stands, reduced output transistors' bias current.
in fact (too early in the morning here) your output transistors would be biassed practically off this would be running class b with significant crossover distortion. maybe not such a good idea?
I'm not saying you can't use them - just you'd need 6 or so in the same place as the two silicon ones you're replacing
I got one of those reverb lines somewhere - are they any good for hi-fi use?
I was going to rig it up with a SE 2W valve driver and pick up the other end with a valve signal amplifier. What sort of signal in/out do these things need typically? I have absolutely no data and plenty potential to fuse the windings!
I was going to rig it up with a SE 2W valve driver and pick up the other end with a valve signal amplifier. What sort of signal in/out do these things need typically? I have absolutely no data and plenty potential to fuse the windings!
I would like to use a single component where possible in my mind if i can keep it as simple as possible the is less room for mistakes.
With regards to the reverb all the information I know is from the following websites: ::::::::: Accu Bell Sound Inc ::::::::: Spring Reverb
the first site has the translation for the code that should be printed on the unit somewhere.
Cheers
oh yeah, and as far as valves are concerned check this guy out, The Valve Wizard
typically most valve drivers use a transformer to match the impedance for the reverb input but I quite like the 12au7 srpp mentioned at the end of the page, super simple!
cheers
typically most valve drivers use a transformer to match the impedance for the reverb input but I quite like the 12au7 srpp mentioned at the end of the page, super simple!
cheers
Thankls for that. Looks like my suspicion a ECL82 SE driver stage (-or for that maater, the SRPP circuit you mentioned) are suitable!
What it didn't say is what sort of level do I expect at the other end? All the Valve Wizard says is to use a couple of gain stages, so I assume its quite small, ~50mV say?
Oh yes and I remember where that reverb unit came from - it was salvaged from a 80s Sanyo Integrated amplifier with early "Karaoke" feature!!
What it didn't say is what sort of level do I expect at the other end? All the Valve Wizard says is to use a couple of gain stages, so I assume its quite small, ~50mV say?
Oh yes and I remember where that reverb unit came from - it was salvaged from a 80s Sanyo Integrated amplifier with early "Karaoke" feature!!
the output depend on the impedance of the transducer it goes something like this:
Coil Impedance DC Resistance Output Voltage (Typ)
500 42 3.0mV
2,250 200 6.5mV
12,000 800 15mV
this was on the esp site. Spring Reverb
Very minimal output clearly. the other problem with these units it they are very boomy below about 200hz a roll off filter is required strait of the output of the pan. I like the idea of a sweep-able filter but have not researched it properly as yet.
Coil Impedance DC Resistance Output Voltage (Typ)
500 42 3.0mV
2,250 200 6.5mV
12,000 800 15mV
this was on the esp site. Spring Reverb
Very minimal output clearly. the other problem with these units it they are very boomy below about 200hz a roll off filter is required strait of the output of the pan. I like the idea of a sweep-able filter but have not researched it properly as yet.
Thank you I'd just been reading that same part! Like the idea more and more now.
filters no problem was never convinced audible frequency extremes needed "reverb" anyway!
filters no problem was never convinced audible frequency extremes needed "reverb" anyway!
I assume spring reverbs sound better with added crossover distortion? That is what the circuit will provide. The designer also seems unable to decide whether to use current or voltage drive, so he designs a crude voltage amp then uses negative feedback to raise its output resistance but then changes his mind and adds a resistor in parallel with the drive coil to lower it again.
The ancient Sony TA 313 amp had a delay line built in. Simple discrete driver, single rail,
Sony TA-313 | Owners Manual, Service Manual, Schematics, Free Download | HiFi Engine
Don't know how similar the characteristics are between these things. Looks like it need little driving though.
Sony TA-313 | Owners Manual, Service Manual, Schematics, Free Download | HiFi Engine
Don't know how similar the characteristics are between these things. Looks like it need little driving though.
interesting comment DF96, as a novice i didn't see that, its crude nature is ok for my purposes. However I would like to to have the circuit as clean as possible. The whole project is off the esp Spring Reverb site.
I am interested in any solutions you might have
Cheers
I am interested in any solutions you might have
Cheers
I'm surprised. ESP circuits are usually better than that. However, it seems he uses current drive, with R7 damping the HF resonance. I would use small signal diodes for output bias, not rectifiers.
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