HELP: Unknown Vintage Canadian Tube Amp

[Drexl Jonez]

I have just gotten this PepCo/Regal Tube Amp which seems to be the model #500. After a few hours of vain research and unable to find much if anything at all on this little amp, I decided to give it a try and ask a dedicated forum. My purpose is to restore this amp or turn it into a project if it is worth te time and money, since I will have to do so via a local technician, but not willing to spend money on something "worthless", any clue would be welcome.

Based on the information that is available online on these low-cost Canadian amps from the 60's, it seems that they have a bad reputation when it comes to safety. Being completely uneducated in electronics, I assumed that this amp looked like others I have owned when it comes to components. Not sure what is a dreaded Series Heater amp or even if this is what I have taken home, I have a few questions someone here might be kind enough to answer before I take it to my local technician.

Here is what I know about the Amp:



- There are two transformer, a Main and a smaller Output [I assume it's the Output]
- The Tube Configuration is as followed: 6AR5 - 6X4 - 6AV6 - MALLORY FP - 6AV6 - 6AV6
- The Tremolo Pot is linked to one of the 6AV6
- The Fuse compartiment is missing
- Some component seem to indicate a 7-10W power output

There might have been a reverb but I only got the main chassis without the cab so who knows...

Some Pictures:

[MarkusBass]

I don't know anything about this amp but Pepco amps should be known in Canada. They are discussed here: The Canadian Guitar Forum - you may ask a question about the one you have.
They were also discussed on MEF: http://music-electronics-forum.com/t1299/ . Please note that this is on different model and the remark about the amp not being safe was most likely incorrect. Ask your technician about it - this can be easily verified.
If you don't know much about electronics and you don't have a cab for this amp, this may be very expensive project (taking into account that similar amps are available fo something like 50$).
I would also check whether the output tubes are 6AV6, or rather 6V6. "10W" symbol on a resistor inside the amp does not have anything in common with the output power of the amp.
Other places where the amps are mentioned:
Pepco tube amps
Pepco tube amps: History
Canadian Amps
Recordings From Studio Jonny: PEPCO Care and Maintenance

BTW, you forgot the most important photo of the amp - the front panel.

Mark

[Drexl Jonez]

Thanks Mark,

I've seen all the links you mentioned but I found very little info when it comes to specs.

[52 Bill]

I will preface my post with the fact that I know nothing about these amps. We do have a few Canadians that post here, so they may have some better input for you.

That being said, this amp does not have an AC line powered filament string, so it can be used or modded safely. Secondly, with a 6AR5 power output tube, you will probably only get about 5 watts of power from this circuit.

[g1]

Not meaning to discourage you, but don't want you to waste time & money either. If you are going to have a tech work on this, and hope to flip it for money, don't bother. I doubt you could recoup restoration costs.

[Drexl Jonez]

That being said, this amp does not have an AC line powered filament string, so it can be used or modded safely. Secondly, with a 6AR5 power output tube, you will probably only get about 5 watts of power from this circuit.

Thanks,

As long as the amp is safe to operate I'm fine with a 5 watter if the tone is decent. Just wouldn't want to get stiff-on-site

[Drexl Jonez]

Not meaning to discourage you, but don't want you to waste time & money either. If you are going to have a tech work on this, and hope to flip it for money, don't bother. I doubt you could recoup restoration costs.

No, no flip project here. I would have picked something a little less unknown, even though Silvertones, Sears and the likes were not worth a pack of smokes just 15 years ago and are now going for top hundreds.

I was just given this little amp by a friend who doesn't play guitar so I though it might get fixed on a small budget and if it didn't sound like canned sardines it might make a decent practice or even studio amp. The cheapest tiny all tube Orange amp goes for no less than 250€-300€ and they are cheaply made too [Though they don't sound bad at all, they are way over priced for MIC... Imo]

[g1]

Then I think it should make a nice player.

[Enzo]

Pine made SOME "hot chassis" amps, amps which had no power transformer. THOSE are inherently not safe. However that DOES NOT APPLY to amps with a power transformer, and your amp does have one of those. All your tubes are 6 volt heater types, which means a power transformer. SO do not paint all Pine amps with the same brush.

The Mallory thing is an aluminum can type capacitor, not a tube.

No reason this cannot be restored to useful function.

[Drexl Jonez]

Pine made SOME "hot chassis" amps, amps which had no power transformer. THOSE are inherently not safe. However that DOES NOT APPLY to amps with a power transformer, and your amp does have one of those. All your tubes are 6 volt heater types, which means a power transformer. SO do not paint all Pine amps with the same brush.

The Mallory thing is an aluminum can type capacitor, not a tube.

No reason this cannot be restored to useful function.

Thanks Enzo,

I know the mallorys are Caps but It might have helped to identify the Wattage of the amp. I've also read about the amsp without a tranny but never seen one. I'm not an expert, nor even a beginner in electronics beside a few stomp clones builds where all is required is to follow simple layouts.

Being in the "remote" area of southern Europe I do not have access to a proper Amp Tech. Ideally, I'd like to do everything myself but that isn't realistic. If extremely lucky I could find someone locally to draw a schematic of the amp and help me out to bring some mods, especially for tone control and perhaps to ad a reverb, but a simple refurbishing would do just fine. Seing that they sell for around 30-60 CA$ in the Montreal area, I wouldn't spend very much on it unless it could be modded to include slightly "higher-end" specs.

Cheers.

[Enzo]

The single 6AR5 power tube is good for a few watts, not many.

[Mick Bailey]

That's a nice little amp and it looks unmolested. The control panel and tube selection suggests to me it may be a Teisco, rebranded for the Canadian market. They were also branded Beltone - yours could be an AP-14 equivalent circuit. The control panel looks very similar anyhow from what I can see from your pic.


Edit: This schematic is probably pretty close;

[Drexl Jonez]

That's a nice little amp and it looks unmolested. The control panel and tube selection suggests to me it may be a Teisco, rebranded for the Canadian market. They were also branded Beltone - yours could be an AP-14 equivalent circuit. The control panel looks very similar anyhow from what I can see from your pic.


Edit: This schematic is probably pretty close; [ATTACH=CONFIG]37703[/ATTACH]

Hey Mick,

Thanks for that, it might come very usefull to this little project !

I found a little more on this amp, it might be an AGS Model 500. The tubes, reported by a user, are a pair of 6X4 dual diodes forming a full-wave rectifier on the high voltage circuit, and three 6AV6's. The one that was given to me only came with a one 6X4 (rectifier?) and a 6AR5 (power?).

Is it possible to just swap the 6AR5 for a second 6X4 to gain more "power"?

The user also states the presence of three 6AV6's is a bit puzzling. A single tube could be a class A amp, or a pair a class B in push-pull. It's barely possible that the three 6AV6's are haywired up in some kind of single-ended class C amp, but he's guessing that two form the power amplifier, and the third is the Tremolo driver.

It's a loud little puppy. He guessed at 25 watts RMS based on an old RCA tube manual and the data sheets for the 6AV6, but it could easily be more with a high plate voltage. The "Model 500" may signify something with respect to power (50 watts peak?) or nothing at all. He could only find one reference to AGS amplifiers on the 'net.

However, the CSA (Canadian Standards Association, equivalent of UL in the U.S. of A.) number matches up to that for AGS amplifiers, and the sequence of the approval number puts it somewhere mid-to-late 60's - most likely 1965-66. As mentioned, He'd guess the output at around 25 watts RMS, (120 volts at 1 amp, assuming a 50% rating on the fuse would be 120 watts input power. Assume a 40-50% efficiency, plus tube heater losses, and it comes out at easily 25 watts RMS).

It's allegedly considerably louder than a 10 watt practice amp with 8" speaker.

Thanks for all the inputs !

Let's hope this one lives to meet expectations...

[Gingertube]

DJ,
The Beltone schematic posted by Mick is almost certainly right.

Overview for an introduction:
Note that Points labelled "A" on the schematic connect together, ditto for points labelled "B", "C" and "D"

Point A, B, C are power supply feeds to the various stages.
Point D is the tremlo low frequecy signal usd to modulate the signal volume via control of the input stage 6AV6

Starting at the top left:

6AV6 input - 1st audio gain stage with the tremlo low frequency oscillator signal applied to its cathode to modulate the tube operating point (and hence the amplified guitar signal output from this stage) via the link lablled "D" which connects to the tremlo oscillator output point labelled "D".

That input gain stage drives Volume Control and the Bass/Treble Tone Control.

Output of the volume and tone controls drive the next 6AV6 (top center) which is the second audio gain stage.

The output of the second gain stage drives the audio output tube, the 6AR5. Note that a 6AQ5 can be used instead. This is your audio power output stage. It is good for about 4 Watts maximum.
TDSL Tube data [6AQ5]

The 3rd 6AV6 (bottom left) is the tremlo low frequency oscillator. It generates the control signal for the tremlo function.

The 6X4 is the power supply rectifier tube.

For your info:
The 6AV6 is a single triode which has identical specs to each of the 2 triodes in a 12AX7 dual triode.
The 6AQ5 (6AR5) is VERY similar to a 6V6 but in a smaller 7 pin tube.

You will need to check that the tubes are OK but apart from that, all that is likely to be required is to replace old electrolytic capacitors. That is, the 2 off 10uF / 350 Volt capacitors and the 2uF / 350 Volt shown at power supply points A, B and C.
Values are not critical, a 4.7uF or even a 10uF will do for the 2uF, 10uF or 22uF can be used for the 10uF, just make sure you use 350V or higher rated capacitors. The 6X4 rectifier is rated to handle up to 40 uF maximum as the 1st filter capacitor but I suggest you don't go above 22uF.

It might also be advisable to change the 10uF / 50V Volt electrolytic cap shown on the input stage (top left). Its value is a little more critical, stick to 10uF with a voltage rating of 50 Volts or more. Using too big a capacitor here could compromise the tremlo function.

I hope this is of some benefit to you.

Cheers,
Ian

[Mick Bailey]

The information you quote regarding the AGS-500 is incorrect. It may well be the same model, as the basic amp was re-branded for different markets, but the speculation that it's 25W RMS or 50W peak is incorrect. The source has determined that from the 120v input voltage and 1A fuse. 1A is just the fuse rating and is determined on the basis of how much current the amp draws on a cold switch-on, and how much current the amp can safely stand under a fault condition before the fuse blows to protect it. You can't speculate on the power of an amp in this way.

You also can't add another rectifier to increase power. It has a single dual rectifier (two rectifiers inside one glass envelope) which is what 99% of tube rectified amps use.