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Post subject: Deluxe Reverb Reissue '65 + Orange PPC212
Posted: Sat Apr 04, 2015 12:01 pm
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Hi guys,

I just got an Orange PPC212 cabinet for an Orange Tiny Terror amp. The PPC212 comes with 2X12" Celestion Vintage 30 watts speakers, and it has an impedance of 16 Ω.

1. I was wondering, does it make any difference (headroom, power) if I use the DRRI amp through the PPC212? I am completely ignorant on this, but I understand I could get cleaner headroom.

2. The DRRI external speaker output impedance says 8 Ω. Will I damage the amp if I plug it to the PPC 212 cabinet? If not, how should I do it? Plug both, the internal and external outputs to the cabinet? Only the external?

Thanks!!


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Post subject: Re: Deluxe Reverb Reissue '65 + Orange PPC212
Posted: Sun Apr 05, 2015 3:57 am
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Other impedance ( ohms ) is not recommended ; but work

From Weber Speakers ;
http://www.webervst.com/sptalk.html

Question from Chuck ;
I have heard various views on impedance mismatches between the amp and the speakers. One is that you should always match the impedance (4 ohm amp = 4 ohm speaker or two 8 ohm speakers in parallel), or you can blow your transformer. The other is that it is fine to mismatch, but you may lose power. Should the impedence match? If yes, then how quickly could you damage your amp when you have a mismatched impedence?

Chuck, technically, you should always provide a load that is recommended by the manufacturer of the amp. The designer of the amp chose a particular output device (tube) and specified all of the operating voltages for the output stage so the tube would work at its optimum efficiency while delivering maximum power to the load with minimum distortion. Ok, so let's discuss the problems associated with mismatches. When you use a load that is lower than the intended load, the output has to drive the load (speaker) with more current because it is a lower impedance than is expected. Two inherent problems associated with transformers are flux leakage and regulation. Flux leakage is also referred to as leakage inductance. It is related to the current in the secondary, and these problems increase as the current increases. As the current draw in the secondary increases, the primary has a more difficult time transferring the signal to the secondary, so the secondary signal to the load gets squashed, or 'soft-clipped'. This soft clipping is called regulation. While regulation is desireable in a power supply, it is undesireable in a transformer. In other words, in a power supply, if the input voltage or the output load current changes, we don't want the output voltage to change. In a transformer, we want the output voltage to follow the input voltage
and not regulate at all.


When you put a heavier load on the output than was intended, ( 16 ohms speaker on 8 ohms load ) it will pull the output voltage down, hence regulation. The leakage inductance problem arises because the current from the heavier load causing the regulation to occur reduces the efficiency of the transformer by not allowing the output to follow the input. Transformer designers simulate or view this problem as having extra inductance in series with the primary. The extension of this idea then, is that with the heavier load, you could affect the efficiency of the transformer, alter the frequency response (due to the extra leakage inductance in series with the primary), and cause other distortions to occur. OK, on to mismatching the other way. A speaker is a current operated device in that it responds to the current through it to generate a magnetic field that works against the magnetic field of the speaker magnet to make the cone move in and out. Thinking in very short amounts of time, when the output charges up the voice coil with current, then the signal goes away or gets reduced, the cone system moves the voice coil back to its home or resting position. As it is moving back, it generates a voltage that is fed back up the line into the transformer and appears in the output circuit of the amp. This generated voltage is often referred to as flyback voltage, because we are charging up an inductor, then when we disconnect or stop charging the inductor, the magnetic field in the inductor collapses and induces this big voltage into itself. This big voltage then 'flies back' to the source of the charging current. There is a mathematical formula to determine how big the voltage is and it is related to the inductance of the voice coil, the amount of time it was fed current, and how much current it was charged with. The bottom line is that the voltage fed back to the output circuit is oftentimes much higher than the voltage that was used to drive or charge up the voice coil initially. This voltage gets transformed up by the turns ratio of the output transformer, and in many cases can be over 1,000 volts. What happens then is that arcing can occur between the pins on the output tube socket. Once this has occured, a carbon path forms on the tube socket between the pins. The carbon path allows a steady current to flow between the pins and eventually burns up the socket due to the heat that is generated. For example, it wouldn't be too uncommon to see a transformer turns ratio of 30:1. If we had a voltage fed back from the voice coil that was around 50 volts, 30 times 50 would be a 1,500 volt spike at the plate of the output tube. This is why you often see designers connect diodes in a string between the output tube plates and ground. They are trying to suppress these spikes and dissipate the energy in the diodes rather than allowing an arc to occur at the tube socket. So, when you use a higher impedance load on a lower impedance tap, the turns ratio is higher and resulting fed-back (flyback) voltage gets multiplied up higher than what it would have been with the correct impedance load.
It's just about impossible for me to answer how long an amp would last under these conditions. It all depends on how the designer took these potential problems into account in his or her design with regards to the quality of the tube sockets, the use of stringed diodes, the output circuit operating voltages, etc.

Red color is from stratele52 also (16 ohms speaker on 8 ohms load )


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Post subject: Re: Deluxe Reverb Reissue '65 + Orange PPC212
Posted: Sun Apr 05, 2015 7:59 am
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It the time it took to read all of that hoodoo, you could have been trying the speaker for yourself and see if you like the sound, with no worry of damaging anything.

The DRRI can safely and easily drive a speaker load of anywhere between 4 and 16 ohms. In fact, it has an external speaker jack, which was designed to be used simultaneously with the internal speaker (8 ohms), and the combination of internal 8 ohms with an external cab of 8 ohms will produce an expected total speaker load of 4 ohms.

If you use an external 16 ohm cabinet in conjunction with the internal 8 ohm speaker, the total speaker load will be 5.33 ohms, and obviously this is between the 8 ohm and 4 ohm load that the amp was designed to handle to begin with.

Using the external cab of 16 ohms in place of the internal speaker (plugged into the main speaker jack) is also perfectly acceptable, and as noted, the amp might not produce the full rated power.

For nearly any tube amp, keep the impedance mismatch to within a 2 to 1 ratio, high or low and it will be fine, and sometimes that impedance mismatch can produce a more pleasing tone than when "matched".

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Post subject: Re: Deluxe Reverb Reissue '65 + Orange PPC212
Posted: Sun Apr 05, 2015 2:37 pm
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I wouldn't call it hoodoo. Weber doesn't make money by selling information. Max, you can go with a slight mismatch. Personally I don't like the way it sounds. But I wouldn't dismiss the caution from Weber. On my amps builds I use Classic Tone transformers. I contacted them with the same questions, and they recommend running at the proper load that was designed for the amps transformer. On a 8 ohm load, either a 16 or 8 will work and you'll be fine. I would feel bette using a 16 ohm load. Personally, I use a Weber Z-Matcher because I always want my amp to run the proper load regardless of the cabinet I use. I don't care who says it's fine. This is a hot topic on this forum and I get tired of arguing the topic. It boils down to let you conscience be your guide, but keep the warnings in mind. Like I said, I don't like the way an impedance mismatch sounds, you might like it. YMMV

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Post subject: Re: Deluxe Reverb Reissue '65 + Orange PPC212
Posted: Sun Apr 05, 2015 3:49 pm
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By hoodoo I mean that it is confusing, even if you understand the technical terms, so it isn't very helpful.

The fact of the matter is, Fender put an external speaker jack on the DRRI and many of their other amps, and they certainly knew that it just might be used for plugging in an additional speaker cabinet (ya think?). Fender speakers are usually 8 ohms, and it doesn't take a brainiac to realize that plugging in another 8 ohms speaker in conjunction with the internal speaker will reduce the total speaker load to 4 ohms, so it is perfectly clear that Fender designed the amp to handle a speaker load other than 8 ohms total. :wink:

I think that where the confusion lies is that with a "mismatched" speaker load, the amp might not develop its full output power, and many people take that "warning" to mean some other kind of "danger" when none really exists.

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Post subject: Re: Deluxe Reverb Reissue '65 + Orange PPC212
Posted: Sun Apr 05, 2015 3:54 pm
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Putting aside hot button topics for the moment, I'm curious about the Weber Z Matcher Supro mentioned. I haven't heard of it before. I'm faced with an impedance choice at the moment. I'll have to investigate that. Thank you!!

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Post subject: Re: Deluxe Reverb Reissue '65 + Orange PPC212
Posted: Sun Apr 05, 2015 4:51 pm
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Thank you all for your kind and wise advise.

Just to be clear. First, I am completely ignorant on using cabinets and head amps, and I have only owned Fender combos. Secondly, I haven't receive yet the Orange gear. I didn't mention that besides the amp and the infamous 16 ohms cabinet, I also bought an Orange PPC 108 (for practising/on-the-go valve amp), which is a 1x8" 20-Watt Speaker Cabinet, 8-ohms. As you know, this is a much smaller speaker than the Jensen that came with my DRRI, in terms of size and power.

I am thinking about plugging the DRRI through "External Speaker" output jack to the PPC108. I am aware I shouldn't power the amp if nothing is plugged out of the "Internal Speaker" jack, so I will leave the combo's speaker plugged there.

Bottom line: knowing that both are 8 ohms, and leaving the "Internal speaker" output plugged into the combo's speaker, will my small Orange speaker suffer any damages because of wattage issues? Being sillier, will the 22-watt power be split evenly between the 2 speakers? How does these things work?

Thank you all!

PS: Some people asked me why would I want to plug my DRRI to these cabinets since the DRRI has such a heavenly sound. The answer is simple. The "External Speaker" output is there and I will have 2 extra cabinets around to play with. Who wouldn't think about doing it?! I mean, I love musical experiments, but I would rather be extremely conservative than blowing away any of my gear, specially my beloved DRRI!


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Post subject: Re: Deluxe Reverb Reissue '65 + Orange PPC212
Posted: Sun Apr 05, 2015 5:54 pm
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When using two or more speakers/cabs of equal impedance simultaneously on one amp, the output power of the amp will divide equally between the speakers/cabs. When using two or more speakers/cabs of unequal impedance on one amp, the output power from the amp will divide proportionally with the lower impedance speaker/cab getting the majority of the divided output power.

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Post subject: Re: Deluxe Reverb Reissue '65 + Orange PPC212
Posted: Sun Apr 05, 2015 6:37 pm
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shimmilou wrote:
When using two or more speakers/cabs of equal impedance simultaneously on one amp, the output power of the amp will divide equally between the speakers/cabs. When using two or more speakers/cabs of unequal impedance on one amp, the output power from the amp will divide proportionally with the lower impedance speaker/cab getting the majority of the divided output power.


Thank you!

Now, what does it mean lower impedance? Is 8 ohms higher or lower than 16 ohms?

Many thanks


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Post subject: Re: Deluxe Reverb Reissue '65 + Orange PPC212
Posted: Sun Apr 05, 2015 7:27 pm
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Smaller number is less impedance. Impedance, another term for resistance, is expressed in ohm value, and the lower ohm value means less resistance. Using the term "Impedance" signifys AC, meaning that the impedance changes with changes in frequency.

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Post subject: Re: Deluxe Reverb Reissue '65 + Orange PPC212
Posted: Mon Apr 06, 2015 5:07 am
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BMW-KTM wrote:
Putting aside hot button topics for the moment, I'm curious about the Weber Z Matcher Supro mentioned. I haven't heard of it before. I'm faced with an impedance choice at the moment. I'll have to investigate that. Thank you!!


Beemer, here's a link.
https://taweber.powweb.com/store/zmatch.htm
This was one of the best purchases I ever made. What's cool is I took the phono jack out of my 74 Champ and replaced it with a 1/4" phone jack and use the Z-Matcher to match the impedance to any cabinet I want to use. Turns that little amp into a beast. It's great for heads if it has no impedance switch too. It will match anything from 2-16 ohms. It also has a line out with a volume control.

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Post subject: Re: Deluxe Reverb Reissue '65 + Orange PPC212
Posted: Mon Apr 06, 2015 5:28 am
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Cool!!
Thanks

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Post subject: Re: Deluxe Reverb Reissue '65 + Orange PPC212
Posted: Mon Apr 06, 2015 6:42 am
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63supro wrote:
I wouldn't call it hoodoo. Weber doesn't make money by selling information. Max, you can go with a slight mismatch. Personally I don't like the way it sounds. But I wouldn't dismiss the caution from Weber. On my amps builds I use Classic Tone transformers. I contacted them with the same questions, and they recommend running at the proper load that was designed for the amps transformer. On a 8 ohm load, either a 16 or 8 will work and you'll be fine. I would feel bette using a 16 ohm load. Personally, I use a Weber Z-Matcher because I always want my amp to run the proper load regardless of the cabinet I use. I don't care who says it's fine. This is a hot topic on this forum and I get tired of arguing the topic. It boils down to let you conscience be your guide, but keep the warnings in mind. Like I said, I don't like the way an impedance mismatch sounds, you might like it. YMMV


For my Fender DRRI, am I OK with the 50 watts ZWeber impedance matcher, or I should get the 110 watts? It is a 22-watt amp, but the electric power says it uses 100 watts. This is all soooo confusing!!! :oops: :cry: :cry:


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Post subject: Re: Deluxe Reverb Reissue '65 + Orange PPC212
Posted: Mon Apr 06, 2015 7:35 am
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Just got this info from Weber:

Hi Max.

yes, you can get the 50w z-matcher.

now there are two ways you can connect it.

(A)
Amp speaker output -> internal speaker
Amp external output -> z-matcher input set at 8 ohm
z-matcher output set at 16 ohm -> Orange cabinet


(B)
Amp speaker output -> z-matcher set at 8 ohm
z-matcher set at 5.3, front output -> internal speaker
z-matcher rear output -> orange cabinet


you can try both ways and see if you happen to like one way better than the other.


So, finally, I have found a solution to use my DRRI with the Orange cabinet without damaging any of them.

Thanks everybody, and I'm sorry it took me this long to nail it!


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Post subject: Re: Deluxe Reverb Reissue '65 + Orange PPC212
Posted: Mon Apr 06, 2015 7:38 am
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63supro wrote:
I wouldn't call it hoodoo. Weber doesn't make money by selling information. Max, you can go with a slight mismatch. Personally I don't like the way it sounds. But I wouldn't dismiss the caution from Weber. On my amps builds I use Classic Tone transformers. I contacted them with the same questions, and they recommend running at the proper load that was designed for the amps transformer. On a 8 ohm load, either a 16 or 8 will work and you'll be fine. I would feel bette using a 16 ohm load. Personally, I use a Weber Z-Matcher because I always want my amp to run the proper load regardless of the cabinet I use. I don't care who says it's fine. This is a hot topic on this forum and I get tired of arguing the topic. It boils down to let you conscience be your guide, but keep the warnings in mind. Like I said, I don't like the way an impedance mismatch sounds, you might like it. YMMV



Sorry I didn't get the Z-Weber Impedance Matcher part here. That was actually the solution I was looking for after getting all the advise on not mismatching impedances. Thanks!


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