I have just picked up a box of Telam/Polam NOS PCL86 tubes (I got 40 for $60 total)
These are essentially an ECL86 with a 13/14volt heater.
The data sheet for the PCL86 goes to great lengths to disguise the fact that this tube is an ECL86 and can be used for audio. All the measurement points are adjusted slightly and all the detail about audio use is omitted.
But of course all the inter-electrode capacitance readings are identical as are the power ratings.
Is there any reason why this won't make a good audio tube compared to its expensive and rare twin the ECL86?
I have designed a circuit that can use four of these tubes in Parallel push pull, using the triodes as phase splitters, preamp and differential error amplifier in a regulated tube PSU supplying the HT thereby putting all four triodes to good use in the 4 pentode parallel push pull output stage...
If anyone knows why I should now swap these for four ECL86 tubes per channel let me know, because to me I can see (nor hear) no reason to do so except that nagging doubt in the back of my mind.
The Telam tubes are of top quality....
Any advice is of course greatly appreciated...
These are essentially an ECL86 with a 13/14volt heater.
The data sheet for the PCL86 goes to great lengths to disguise the fact that this tube is an ECL86 and can be used for audio. All the measurement points are adjusted slightly and all the detail about audio use is omitted.
But of course all the inter-electrode capacitance readings are identical as are the power ratings.
Is there any reason why this won't make a good audio tube compared to its expensive and rare twin the ECL86?
I have designed a circuit that can use four of these tubes in Parallel push pull, using the triodes as phase splitters, preamp and differential error amplifier in a regulated tube PSU supplying the HT thereby putting all four triodes to good use in the 4 pentode parallel push pull output stage...
If anyone knows why I should now swap these for four ECL86 tubes per channel let me know, because to me I can see (nor hear) no reason to do so except that nagging doubt in the back of my mind.
The Telam tubes are of top quality....
Any advice is of course greatly appreciated...
Peter,
PCL86 will do very nicely. The 6GW8/ECL86/PCL86 was a stunning tube, I really don't know why modern tube manufacturers seemed to decide to remake the inferior 6BM8/ECL82 instead.
For a gorgous ECL86 Amp, look up Yves ECL86 Amp at Dissident Audio
http://www.dissident-audio.com/PP_ECL86/Schema.gif
There is also a 6GW8/ECL86 Baby Huey version based entirely on Yves design but incorporating Ultralinear connection in lieu any of global feeedback. The schematic for that can be found in the Baby Huey thread.
Cheers,
Ian
PCL86 will do very nicely. The 6GW8/ECL86/PCL86 was a stunning tube, I really don't know why modern tube manufacturers seemed to decide to remake the inferior 6BM8/ECL82 instead.
For a gorgous ECL86 Amp, look up Yves ECL86 Amp at Dissident Audio
http://www.dissident-audio.com/PP_ECL86/Schema.gif
There is also a 6GW8/ECL86 Baby Huey version based entirely on Yves design but incorporating Ultralinear connection in lieu any of global feeedback. The schematic for that can be found in the Baby Huey thread.
Cheers,
Ian
My first amp that I made some 20 years ago, used a pair of ECL82's in push pull ultralinear (43%) with 6as7G tube regulated HT, it sounds great, I love the sound, it gives about 6W rms per channel using some very substantial Sowter output transformers, it gives full power down to below 10Hz. I am hoping that the 5K 20W sowter transformers I have will do the same for a two pairs of parallel push pull PCL86 tubes,...
That would be great thankyou!
Pics of the Polam tubes are here, for $2 each you can't go wrong!
Vacuum Tube Audio - Home | Facebook
Hi Ian,
I looked at that schematic and it has some elements to it that I have included in my design, namely the current source to balance the long tailed pair. I am using an EF86 CCS to do this rather than a transistor. Also that amp is using a constant screen drive (Pentode mode) for maximum power, but I am using 43% ultralinear taps for lower distortion slightly, and a bit less power.
That would be great thankyou!
Pics of the Polam tubes are here, for $2 each you can't go wrong!
Vacuum Tube Audio - Home | Facebook
Hi Ian,
I looked at that schematic and it has some elements to it that I have included in my design, namely the current source to balance the long tailed pair. I am using an EF86 CCS to do this rather than a transistor. Also that amp is using a constant screen drive (Pentode mode) for maximum power, but I am using 43% ultralinear taps for lower distortion slightly, and a bit less power.
Peter,
I did a search for the BH version:
http://www.diyaudio.com/forums/attachment.php?postid=619363&stamp=1113448831
I believe Fran converted a Rogers Cadet3 to this schematic (without the UL Taps).
Cheers,
Ian
I did a search for the BH version:
http://www.diyaudio.com/forums/attachment.php?postid=619363&stamp=1113448831
I believe Fran converted a Rogers Cadet3 to this schematic (without the UL Taps).
Cheers,
Ian
That "Odd" bit is the heart of the Baby Huey scheme. It provides balanced shunt feedback which:
- trades some output tube gm for reduced rp. This results in lower output impedance and reduced distortion which largely obviates the need for any global feedback.
- The cross coupling forces perfect balance.
Cheers,
Ian
- trades some output tube gm for reduced rp. This results in lower output impedance and reduced distortion which largely obviates the need for any global feedback.
- The cross coupling forces perfect balance.
Cheers,
Ian
Looks like I might have some pcl86/ecl86 comparison work, picked up a stash of ECL86 Raytheon tubes, they weren't cheap, but they didn't break the bank either! This was a pleasant find.. - Vacuum Tube Audio | Facebook
A simple, but high quality ECL86 amplifier circuit can be found on page 86 of the January 1963 Electronics Illustrated issue. You can find this entire magazine here: https://www.americanradiohistory.co...lustrated/Electronics-Illustrated-1963-01.pdf
Sorry for the delayed reply, Ian, but I just saw this rather old thread.
I think the reason is that the tube manufacturers in the former Soviet Union didn't know the ECL86 tube. So they would have to create a completely new design now.
Best regards!
Yes, maybe. But in European TV sets the PCL86 became very successful in the 1960ies and managed to completely displace the PCL82 in the AF section (as did the PCL85 as frame deflection tube). Same for the ECL86 which became a quasi standard in radios from about 1965 on. Perhaps in the tube heydays the manufacturers more easily managed to cope with the (possible) drawbacks?
Best regards!
Best regards!
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PCL82 replaced by the Stronger PCL85.
Both of them are frame tubes with very good linearity. They can be used as AF amplifiers with good results.
PCL 86 is an audio amplifier tube with its triode section the same characteristics as a half of an ECC83.
PCL 82/85 have better triode sections with driving capabilities. u=17.
Both of them are frame tubes with very good linearity. They can be used as AF amplifiers with good results.
PCL 86 is an audio amplifier tube with its triode section the same characteristics as a half of an ECC83.
PCL 82/85 have better triode sections with driving capabilities. u=17.
For modern production tubes:
Use either the:
6BM8/ECL82
6DX8/ECL84
Of these I prefer the 6DX8/ECL84, the modern Russian versions are good.
A friend runs a little HiFi Amp using PP Russian 6DX8. I was impressed with it.
There was also a ECL80 but it is Rocking Horse Poo availability these days. It was used in a lot of early portable record palyers in Single End.
For Aussie guys like me there are an absolute ton of NOS 6GV8/ECL85 floating around from tube TV days. Not sure if they were popular elsewhere. These alo make reasonable audio amps.
If you can get NOS then
PCL86/ECL86/6GW8 is great for both HiFi and Guitar Amps.
My Bedroom Clock Radio which wakes me up each morning is a programmable timer switching an old Sony Tuner into a Rogers Cadet III Amp driving Vintage Warfdales which double as the bedside tables. The Cadet III runs ECL86 in push pull.
I built myself an Orange Tiny Terror Clone Guitar Amp using 2 off ECL86 in lieu of the 12AX7 phase splitter and EL84 PP Outputs. It does Clean to Mean well.
Cheers,
Ian
Use either the:
6BM8/ECL82
6DX8/ECL84
Of these I prefer the 6DX8/ECL84, the modern Russian versions are good.
A friend runs a little HiFi Amp using PP Russian 6DX8. I was impressed with it.
There was also a ECL80 but it is Rocking Horse Poo availability these days. It was used in a lot of early portable record palyers in Single End.
For Aussie guys like me there are an absolute ton of NOS 6GV8/ECL85 floating around from tube TV days. Not sure if they were popular elsewhere. These alo make reasonable audio amps.
If you can get NOS then
PCL86/ECL86/6GW8 is great for both HiFi and Guitar Amps.
My Bedroom Clock Radio which wakes me up each morning is a programmable timer switching an old Sony Tuner into a Rogers Cadet III Amp driving Vintage Warfdales which double as the bedside tables. The Cadet III runs ECL86 in push pull.
I built myself an Orange Tiny Terror Clone Guitar Amp using 2 off ECL86 in lieu of the 12AX7 phase splitter and EL84 PP Outputs. It does Clean to Mean well.
Cheers,
Ian
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