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Post subject: 1970 Deluxe Reberb breaking up
Posted: Tue Jun 07, 2016 8:05 pm
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I'm not sure what the problem is. I generally use a 72 Pro Reverb in my gigs. I just purchased a 70 Deluxe Reverb. It's in excellent shape and sounds great, however, I carried it to a gig and every time I kicked in an overdrive pedal for a ride the volume just melted away. The sound man said he had to really kick it up every time I took a ride. Of course with this happening I was raddled most of the night.

The previous owner put a Celestion G12 Vintage 30. It originally had a Utah speaker which I have. Could it be that the speaker is breaking up at higher volumes. It almost seemed as if the life was being sucked out of it everytime. However, once I kicked out it was okay.

Any help, I would appreciate it.

I'm posting here because I could not find a place to post.


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Post subject: Re: 1970 Deluxe Reberb breaking up
Posted: Tue Jun 07, 2016 8:53 pm
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Celestion's V30 is rated for 60 watts so I doubt that your problem is a speaker breakup issue. There are better driver choices that would be more efficient and sound more Fenderesque (Kendrick's Blackframe or a JBL D120F springs to mind).

As well, bear in mind that the 6V6GTA does not possess the clean headroom of a 6L6GC and if you're expecting Pro Reverb performance from a Deluxe Reverb it just ain't gonna happen. I own both (each of them a '68 drip-edge silverface) and while I love them in their own right, an objective comparison reveals stark differences in their individual performance.

It's possible that your Deluxe Reverb is ready for servicing -- electrolytic caps, screen-grid resistors, tubes, etc. When's the last time the chassis saw a tech's bench?

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: 1970 Deluxe Reberb breaking up
Posted: Wed Jun 08, 2016 6:45 am
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Hi Scheek, welcome to Forum! Are you saying only when you use a certain OD pedal, the amp loses steam? If so, could be an impedance mis-match. Are you using a 9-volt battery or AC/DC adapter? Could be a weak battery?


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Post subject: Re: 1970 Deluxe Reberb breaking up
Posted: Wed Jun 08, 2016 4:40 pm
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scheek wrote:
I'm not sure what the problem is. I generally use a 72 Pro Reverb in my gigs. I just purchased a 70 Deluxe Reverb. It's in excellent shape and sounds great, however, I carried it to a gig and every time I kicked in an overdrive pedal for a ride the volume just melted away. The sound man said he had to really kick it up every time I took a ride. Of course with this happening I was raddled most of the night.

The previous owner put a Celestion G12 Vintage 30. It originally had a Utah speaker which I have. Could it be that the speaker is breaking up at higher volumes. It almost seemed as if the life was being sucked out of it everytime. However, once I kicked out it was okay.


If the problem only happens when you turn the pedal on, then it has something to do with the pedal. Try it with another tube amp (preferably one with a 12AX7 input).

As far as the Celestion goes, those are my least favorite speaker in an open back combo. Go with something more suited to that amp. A JBL would be sweet in that amp. There are a few Eminence models which would be a great match.

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Post subject: Re: 1970 Deluxe Reberb breaking up
Posted: Wed Jun 08, 2016 4:53 pm
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thompal wrote:
A JBL would be sweet in that amp.


+1

I have a gray-basket D120F in mine......

Image

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: 1970 Deluxe Reberb breaking up
Posted: Mon Jun 13, 2016 9:10 am
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The OD pedal could have a leaky output electrolytic capacitor.
It's common when a pedal gets a reverse polarity hit.
The DC leakage from the pedal will cause the input stage to fade out.
The DC voltage on the grid slowly builds and the DC balance of the tube is thrown off. It quits amplifying at that point.
A momentary unplug/plug at the amp's input jack should restore volume if that is the culprit.


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Post subject: Re: 1970 Deluxe Reberb breaking up
Posted: Mon Jun 13, 2016 7:14 pm
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Tim, good point. Ever replace the output coupling cap in a pedal? Nichicon film cap be a good choice?

Thanks!


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Post subject: Re: 1970 Deluxe Reberb breaking up
Posted: Tue Jun 14, 2016 8:51 am
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Any film cap will sound better than an electrolytic. They're not sensitive to polarity either.
If your pedal uses 2.2uF caps on the output, a film cap could fit. But many use 10uF for better bass response. It would be hard to fit anything that size in a pedal..
When you get on the Mouser site, the capacitor search has a filter for audio grade electrolytics which I find very handy for selecting replacements. Enter your search as 10uf, not 10 uf.
The audio grade caps seem to all have low ripple current capacity.
That is the opposite of what I use for power supply applications, where high ripple current is needed.
I'm assuming this is for greater sensitivity to audio signals.


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Post subject: Re: 1970 Deluxe Reberb breaking up
Posted: Tue Jun 14, 2016 7:33 pm
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How good are metalized-polypropylene film caps, for coupling in these pedals?

Thanks!

http://www.ebay.com/itm/10uF-250V-Axial ... 1081182374


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Post subject: Re: 1970 Deluxe Reberb breaking up
Posted: Tue Jun 14, 2016 7:55 pm
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The one you listed there is way too big to get inside a pedal. The 250 volt rating needs to come down to 50 volts or so to get it down to a reasonable size.
The extra voltage rating means a thicker insulator and more distance between the plates, theoretically reducing sensitivity.
Sonically, I can hear the improvement poly caps make over ceramic or electrolytic caps, But between poly caps, I can't say I ever compared types. Someone with better ears should do that test.

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