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26th Feb 2011, 11:51 pm | #1 |
Heptode
Join Date: Feb 2011
Location: Washington DC, USA
Posts: 619
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Valve tremolo circuit
Does any one remember a circuit for a valve tremolo, that may have been published in Practical Wireless, or some of the other magazines.
I remember building one when I was in secondary school, and the design may have come out of one of the Practical Mags, it would have been in the mid to late 1950's. I have various designs using both triodes and pentodes but I cannot remember much about the one I built, it was a long time ago, and I would like to try to build it again. Thanks for any insight. |
27th Feb 2011, 10:56 am | #2 |
Dekatron
Join Date: Nov 2003
Location: Near Leeds, West Yorkshire, UK
Posts: 4,609
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Re: Valve tremolo circuit
If no luck with finding the circuit referred to, most of these used in electronic organs used a Wien Bridge as an LF oscillator, typically using a double triode.
Hammond used a set of LC sections scanned using a motor. Note that tremolo is not the same thing as vibrato. Tremolo is an amplitude variation, vibrato is a frequency variation.
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27th Feb 2011, 10:57 am | #3 |
Octode
Join Date: Jan 2011
Location: Southwell, Nottinghamshire, UK.
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Re: Valve tremolo circuit
I have a copy of Babani Press No12 (HiFi, PA & Discotheque Amp Designs) which has designs for a 2 valve tremelo unit 1 x ECC82 & 1 x ECL86 and also a combined tremelo and vibrato unit using just 1 ECC83. Any use?
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28th Feb 2011, 12:14 am | #4 |
Heptode
Join Date: Feb 2011
Location: Washington DC, USA
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Re: Valve tremolo circuit
Thanks for the feedback.
The unit I had built those many year ago was only a tremolo, not a vibrato. As I recall there were two valves one of which was a pentode, and I think it may have been an EF80, I know this is an RF valve, but EF80's were everywhere, and thus cheap. Anyway, I am going to go with one I have found that uses an ECC83 as a phase shift oscillator, and an ECC82 as a cathode follower, and see out it works out. It helps that I have a number of ECC8_'s and the 12A_7 equivalents to play with. |
28th Feb 2011, 1:21 am | #5 |
Heptode
Join Date: Jul 2009
Location: Stoke-on-Trent, Staffordshire, UK.
Posts: 719
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Re: Valve tremolo circuit
I wonder if this was part of the circuit used in the "PW Guitar Amplifier"? That certainly used an EF80 oscillator valve, as a phase shift oscillator I think.. The main amplifier used two 807's, and I think it dated from about 1965, plus or minus a bit.
If so, I have a very tatty PW "blueprint" somewhere. I will try and find it if that's the one, and happily scan it... it's a big sheet and in many shreds but the circuit should be recoverble at least. Pete |
28th Feb 2011, 11:05 am | #6 |
Dekatron
Join Date: Jul 2009
Location: Sleaford, Lincs. UK.
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Re: Valve tremolo circuit
The Wem dominator had a tremolo effect on it using an ECC83 I think.Quite a simple circuits as I recall,Andy
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1st Mar 2011, 12:14 am | #7 |
Heptode
Join Date: Feb 2011
Location: Washington DC, USA
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Re: Valve tremolo circuit
Hi DangerMan,
I would like to the see the cct. Might bring back some memories. |
1st Mar 2011, 9:25 am | #8 |
Heptode
Join Date: Jul 2009
Location: Stoke-on-Trent, Staffordshire, UK.
Posts: 719
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Re: Valve tremolo circuit
Hi MrElectronicman,
I've scanned the circuit diagram of the preamplifier and also, for what it's worth, the main amp. Now I just hope I've attached them successfully! Pete |
1st Mar 2011, 9:12 pm | #9 |
Heptode
Join Date: Feb 2011
Location: Washington DC, USA
Posts: 619
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Re: Valve tremolo circuit
Hi DangerMan,
Thanks for the diagrams, they came through just fine. I now have to find a good EF80, I had one in my box but when I looked at it closely the tip must have broken and the vacuum has gone. The pre-amp looks very much like I one I am looking for, but in the mean time I have made a lash-up, and I mean a lash-up, using the ECC83. When I left the UK many years ago now, I threw out most of my Practical Wireless and Practical Television magazines, and only kept a few. Unfortunately years later we had a flood in the basement and that put paid to the rest. |
3rd Mar 2011, 11:30 pm | #10 |
Heptode
Join Date: Jul 2003
Location: North Walsham, Norfolk, UK.
Posts: 516
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Re: Valve tremolo circuit
Wow this looks interesting iI would like to see Tterry Bbull,'s diagrams and am interested in getting a copy of his book. Danny.
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4th Mar 2011, 11:18 am | #11 |
Octode
Join Date: Aug 2003
Location: Welwyn Garden City, Herts. UK.
Posts: 1,906
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Re: Valve tremolo circuit
I am sure any small signal pentode would do or even triode.
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4th Mar 2011, 11:31 am | #12 | |
Nonode
Join Date: Jan 2010
Location: Edinburgh, UK.
Posts: 2,008
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Re: Valve tremolo circuit
Quote:
Al
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4th Mar 2011, 11:46 am | #13 |
Heptode
Join Date: Apr 2003
Location: Ayr, Ayrshire, UK.
Posts: 630
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Re: Valve tremolo circuit
You may be interested in also having a look at the tremelo circuit of the Heathkit PA-1 amplifier.
I posted the manual for it here : https://www.vintage-radio.net/forum/...2&postcount=13 It uses half an ECC83 as a phase-shift oscillator to modulate the screen grid of an EF86. Andy
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4th Mar 2011, 7:48 pm | #14 |
Octode
Join Date: Jan 2011
Location: Southwell, Nottinghamshire, UK.
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Re: Valve tremolo circuit
Here is a pdf of the tremolo circuits I previously referred to. A couple expressed interest. I apologise for the poor quality but my scanner is not here at present so they were done quickly on a phone camera. You can just about make out the detail. If anyone wants a better scan send me a PM and I'll sort it out.
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4th Mar 2011, 9:25 pm | #15 |
Heptode
Join Date: Feb 2011
Location: Washington DC, USA
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Re: Valve tremolo circuit
Looks as if I have started something here. I now have a circuit working using an ECC83 and ECC82, and I am now going to try using an EF80.
I found these diagrams at following website, they look much like the ones in terrybull's pdf. http://www.triodeel.com/studio.htm There are some interesting circuits that use a phase shift oscillator to directly modulate the drive current of a couple of EL84's in push-pull. A bit of overkill if you ask me. I like the idea of using a ring modulator for the vibrato, so I might try to incorporate this option as well. |
4th Mar 2011, 9:36 pm | #16 |
Octode
Join Date: Jan 2011
Location: Southwell, Nottinghamshire, UK.
Posts: 1,779
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Re: Valve tremolo circuit
You are right MrElectronicman. The link you posted look precisely like scans from the Babani book and my pdf
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9th Mar 2011, 10:31 pm | #17 |
Octode
Join Date: Aug 2008
Location: Rayleigh near Southend-On-Sea, Essex, UK.
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Re: Valve tremolo circuit
Hi There,
I’ve attached a picture of a Tremolo project in the Feb 1961 copy of Practical wireless; it may be the one you’re after? If it’s the one I can do a better scan/copy for you. I also remember Practical Wireless doing a complete valve guitar amplifier project in 1964. This used 807’s and the Radiospares De-Luxe output transformer. Regards Terry. |
9th Mar 2011, 10:53 pm | #18 |
Nonode
Join Date: Jan 2010
Location: Edinburgh, UK.
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Re: Valve tremolo circuit
Hi Valvepower.
A very elegant implementation there, using the variable slope characteristics of the EF80. To my mind it should sound very good. Al
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10th Mar 2011, 4:15 am | #19 |
Retired Dormant Member
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Location: North London
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Re: Valve tremolo circuit
Hi .. mm very interesting - F J Camm's usual ingenuity, but its got to be mentioned the EF80 ISN'T strictly a Vari-Mu type - so by all means build the circuit, but then perhaps try popping in an EF85 or EF183 for smoother operation ?
BTW, Tremolo Pedantry:- SOME people used the term to mean pitch bend (eg a 'Tremolo arm') though it IS actually 'Vibrato' (says Wikipedia and the dictionary) The only serious attempts at THIS (using, phase-rotation) are the aforementioned Hammond scanner - (wonderful ol' thing with a spinning 'distributor arm') and Magnatone guitar amps http://www.vibroworld.com/magnatone/ (DO read the diagrams - great stuff!) - who I suspect had shares in a Valve company, due to the mega preamp arrangement - Vox and fender used something far simpler, and concentrated on raw power ! Just my .02 worth - F J Camm Lives ! Pete G |
10th Mar 2011, 11:05 pm | #20 |
Heptode
Join Date: Feb 2011
Location: Washington DC, USA
Posts: 619
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Re: Valve tremolo circuit
Hi Valvepower,
That's the circuit I was looking for, I see It was in PW in 1961, so it's about the right date give or take a couple of years. Can you do a better scan? or shall I PM you? |