I've been gone from here for a long time because of school but I figured it's time to get back to my favourite thing... amp building.
So I've got a hold of various tubes, and also transformers for them that will come to me soon, but the problem is they are not really tubes like your standard EL84, EL34, 6L6 etc, but what they are, they are a lot of ECF80, EABC41, EF184, EF80, EF89, EF85, 6X8A, 6C5, ECC85, PCC85, 6101 (6J6WA) and the list of "preamp" ones goes on and on, and the power ones: PL36, PCL86, PCL85, PCL84, and a whole bunch of ECL80s...
I really want to get down to business with every one and last of 'em if it can be done, so if you would be kind to give me ideas I would be very grateful.
So I've got a hold of various tubes, and also transformers for them that will come to me soon, but the problem is they are not really tubes like your standard EL84, EL34, 6L6 etc, but what they are, they are a lot of ECF80, EABC41, EF184, EF80, EF89, EF85, 6X8A, 6C5, ECC85, PCC85, 6101 (6J6WA) and the list of "preamp" ones goes on and on, and the power ones: PL36, PCL86, PCL85, PCL84, and a whole bunch of ECL80s...
I really want to get down to business with every one and last of 'em if it can be done, so if you would be kind to give me ideas I would be very grateful.
You can, but will have to design (ouch!!) specific gain and power stages around each tube you have, so start by downloading the datasheets and studying them.
"A tube is a tube" and Audio amplification is a relatively simple task, so most (all?) can be used, but you won´t find ready made examples, you´ll have to cook your own.
Not such a big deal and you can tweak to taste.
A Brazilian friend of mine makes tasty Guitar Tube amplifiers using **only** "TV Tubes" , here´s one using 2 x UCL82 Miniwatt as power ones and a Toshiba 6BQ7 as preamp.
The beauty is that TV/Radio tubes are cheap (usually around 1$) and plentiful, and of course all are NOS and made by the great factories of yesteryear, and the beast is that you have to experiment and cook your own circuits.
FWIW I bought a mixed lot of 1000 ECC/PCC189 at 50 cents each, and am using them for a very tubey (all the second harmonic you can eat
) "Valvulizer" stage to be inserted between SS preamp and power stage in Guitar amps, go figure.
Wave assymetry is very visible (you can also hear it ) with even moderate drive levels
Oh, almost forgot
YouTube
In principle, wire each tube as a triode, connect screen to plate if available, some radio tubes have many useless (for us) extra elements inside, such as signal diodes, RF mixer screens, etc. , connect plate to some reasonable+V, say +150V (many radio tubes don´t stand much more than that) and try different cathode resistors, say between 1k and 10k , until plate sits about bhalfway from +V.
Presto!!! , you have just biased it as a clean audio stage
Bypass cathodeb resistor with, say, a 10uF capacitopr and measure your new triode stage gain; then use as you like it.
You can "pick" tone controls and general layout and structure from known amplifiers, although in general gain will be less than, say, 12AX7 .
But very usable anyway.
As of power stages, it´s more complex, and in any case you´ll need proper output transformers, and that will be a problem.
"A tube is a tube" and Audio amplification is a relatively simple task, so most (all?) can be used, but you won´t find ready made examples, you´ll have to cook your own.
Not such a big deal and you can tweak to taste.
A Brazilian friend of mine makes tasty Guitar Tube amplifiers using **only** "TV Tubes" , here´s one using 2 x UCL82 Miniwatt as power ones and a Toshiba 6BQ7 as preamp.
The beauty is that TV/Radio tubes are cheap (usually around 1$) and plentiful, and of course all are NOS and made by the great factories of yesteryear, and the beast is that you have to experiment and cook your own circuits.
FWIW I bought a mixed lot of 1000 ECC/PCC189 at 50 cents each, and am using them for a very tubey (all the second harmonic you can eat
) "Valvulizer" stage to be inserted between SS preamp and power stage in Guitar amps, go figure.Wave assymetry is very visible (you can also hear it
) with even moderate drive levels Oh, almost forgot
YouTube
In principle, wire each tube as a triode, connect screen to plate if available, some radio tubes have many useless (for us) extra elements inside, such as signal diodes, RF mixer screens, etc. , connect plate to some reasonable+V, say +150V (many radio tubes don´t stand much more than that) and try different cathode resistors, say between 1k and 10k , until plate sits about bhalfway from +V.
Presto!!! , you have just biased it as a clean audio stage
Bypass cathodeb resistor with, say, a 10uF capacitopr and measure your new triode stage gain; then use as you like it.
You can "pick" tone controls and general layout and structure from known amplifiers, although in general gain will be less than, say, 12AX7 .
But very usable anyway.
As of power stages, it´s more complex, and in any case you´ll need proper output transformers, and that will be a problem.
ECC85's and PCC85's make pretty good preamp tubes. I actually used the UCC85/26AQ8 in a series string guitar amp with UL84/45B5 output tubes. Pick your favorite "Marshall 18 watt" schematic and tweak to taste. The gain is obviously lower than a 12AX7, so add another gain stage or use a mosfet buffer between stages.
The 6J6 types make decent PI's since there is only one cathode and the triodes are relatively well matched. I haven't tried any of the other tubes on your list.
The 6J6 types make decent PI's since there is only one cathode and the triodes are relatively well matched. I haven't tried any of the other tubes on your list.
The EL/PL36 is great for powerful PP stages. Anode supply at 300V, G2 at 150V, 3,5k output transformer. Power output around 40W. I haven't used them for guitar amps (yet), so I don't know their overload handling. Keep the screen low and it should be ok. The 12W anode rating is conservative 'tv' power. It can handle more for audio.
Yeah, if a ECC83 is heated on approx. 9~12 volts (pins 4 and 5), you can pop a PCC85 in there, and it sounds awesome, few months ago I built a simple modded ValveCaster pedal that runs off a 12V DC supply, and today i popped a PCC85 in there, well sounds 10 times better than 12AX7 and especially 12AY7, it has huge presence and a punch, and adds ton of bass that no ECC83 managed to do in that pedal, when running a stack amp that has no master, and you don't want to terrorize your neighbours, my pedal is an awesome solution!
Have tried it today, what an awesome tube.
I modified a 100V schematic from a topic called 2W+2W PL36 for dummies to a guitar one, the results were, eh... not what I expected. It sounds really boxy, but that's probably because i messed up the values when redesigning it, oh and also used a mains transformer 220V 24V as an OT.
On another note, the bigger tubes that i got showed great and non oscillating due to my poor layout skills, but ECL/PCL 84, 80, 86, 85 just everything audio-related I try with them, they just oscillate and make funny noises, and those triodes in there, well all i can say is that they sound awful when speaking guitar related because of low gain, what I would like to do with them is not use the triode and maybe try using 6J6 tubes since I have many of them, and one of the later projects will be a rack studio tube preamp for guitar with as many PCC85s i can put in there
It's plain SE, it's a toroidal that has 24V outputs with center tap, when using center tap it becomes 12V
There are a lot of projects on wattkins . com that use cheap interesting pre-amp tubes. The Tone Per Buck club has produced several designs based on ECF82/6U8 and 5725/6AS6 input, resulting in the price of 6U8 rising from $1 to $5 and 5725 from $1 to $3. There are still alternatives to these tubes in the Dollar Days list, which I am reluctant to mention in case prices go up again. 6X5 have gone from $3 to $20 recently - prices only stay low for neglected types as long as they appear to be neglected. Supply and demand, yknow.
I find some of this surprising. Here are some points from what I know -
ECL86 are a ridiculous price, but you should be able to get them to co-operate. Almost anything using EL84 and 12AX7 can be a basis. They are in fact a combination of EL86/6CW5 and half an ECC83, and should be quite tractable as long as you observe the HT max of 300V and keep the screen below 275V.
PCL86 are a different animal, but should be similarly tractable. The pentode differs from ECL86, it is the UL84/45B5 pentode, but again it is amenable to common designs as long as you don't try to run it at high volts.
ECL85 - I hear recent favourable reports from Australia of a small amp which uses two in push pull, and uses the triodes.
ECL84 - a lot of people have used the pentodes and ignored the triodes, as you are proposing. Some people have used one of the triodes as a PI and ignored the other one.
I know what the problem is - that triode is designed to function as part of an automatic gain control, so it does not behave like a general purpose voltage gain triode.
ECL82 - I have seen several designs using triode and pentode with good reports. OTOH I am not generally interested in tubes which will not wake a baby, even in push-pull . . .
Please don't ask me to provide an answer to the ECL84 triode problem. I'm just replying in passing, trying to be helpful. This is my first post in four years! If you PM me I will try to help by pointing you towards a few schematics and projects.
I'm not saying more because I'm trying to keep prices down on something I'm working on which might be commercially viable. Nothing worse than finding prices have rocketed because you "helped" someone, and the rest of the world at the same time. I can remember when I could afford to use ECL86.
I find some of this surprising. Here are some points from what I know -
ECL86 are a ridiculous price, but you should be able to get them to co-operate. Almost anything using EL84 and 12AX7 can be a basis. They are in fact a combination of EL86/6CW5 and half an ECC83, and should be quite tractable as long as you observe the HT max of 300V and keep the screen below 275V.
PCL86 are a different animal, but should be similarly tractable. The pentode differs from ECL86, it is the UL84/45B5 pentode, but again it is amenable to common designs as long as you don't try to run it at high volts.
ECL85 - I hear recent favourable reports from Australia of a small amp which uses two in push pull, and uses the triodes.
ECL84 - a lot of people have used the pentodes and ignored the triodes, as you are proposing. Some people have used one of the triodes as a PI and ignored the other one.
I know what the problem is - that triode is designed to function as part of an automatic gain control, so it does not behave like a general purpose voltage gain triode.
ECL82 - I have seen several designs using triode and pentode with good reports. OTOH I am not generally interested in tubes which will not wake a baby, even in push-pull . . .
Please don't ask me to provide an answer to the ECL84 triode problem. I'm just replying in passing, trying to be helpful. This is my first post in four years! If you PM me I will try to help by pointing you towards a few schematics and projects.
I'm not saying more because I'm trying to keep prices down on something I'm working on which might be commercially viable. Nothing worse than finding prices have rocketed because you "helped" someone, and the rest of the world at the same time. I can remember when I could afford to use ECL86.
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Miking up? You reminded me of an occasion I heard about when Steve Marriott was sitting in at a Grateful Dead concert - remember that Wall of Sound? Steve was playing through a 15W Ampeg combo and was asked to turn it down because it was too loud!
Effects pedals
Well, now when I know what I got in my tube lot, I think that studio effects is the REAL way to go, so the plans are as the list goes:
Rack module using 6x PCC85 for a tasty tube sweetener for mic/guitar
Bass pedal with PCC189
Mic preamp EF80
Studio compressor or limiter with ECF tubes
A bunch of variable μ tubes for a rack module flanger/chorus if it could be done as well as 6X8A and ECH tubes to use all of them
And a little of 6J6 tubes for a small active EQ spectre booster before the signal enters my 8 channel reel to reel
Could all this be done, or is it just my fantasy? Haven't started experimenting with schematics yet because I'm pretty new to tube effects that are not only reverb and vibrato.
Well, now when I know what I got in my tube lot, I think that studio effects is the REAL way to go, so the plans are as the list goes:
Rack module using 6x PCC85 for a tasty tube sweetener for mic/guitar
Bass pedal with PCC189
Mic preamp EF80
Studio compressor or limiter with ECF tubes
A bunch of variable μ tubes for a rack module flanger/chorus if it could be done as well as 6X8A and ECH tubes to use all of them
And a little of 6J6 tubes for a small active EQ spectre booster before the signal enters my 8 channel reel to reel
Could all this be done, or is it just my fantasy? Haven't started experimenting with schematics yet because I'm pretty new to tube effects that are not only reverb and vibrato.
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I have not experimented with the ECL86 or PCL86, so I can't say what they will do.
I have however done some extensive testing on the EL86/6CW5, the PL84/15CW5 and the UL84/45B5. Other than the heater voltages and currents, these are all identical. They are all specified for a maximum screen voltage of 200 volts, which MUST be respected. Simply plugging these into an EL84 circuit will result in a short unhappy life unless the screen voltage is reduced.
A quick look inside the glass reveals a plate identical to that in an EL84, so why is the 6CW5 rated for a mediocre 250 plate volts. The rating probably has more to do with the intended application than reality since I have had them to 430 volts without issue!
I built this little screamer, mentioned in post #3 based loosely on a "Marshall 18 watt" schematic. It runs UCC85/26AQ8 tubes in the preamp, and UL84/45B5 tubes in the power amp. Power output is just under 20 watts clean (3%THD) and nearly 30 watts cranked. The UL84's get 170 volts on their screens and 340 volts on the plates. The little isolation transformer on top of the chassis is the power transformer. The Antek toroid under the deck is the OPT. It puts about 3500 ohms load on the tubes.
The "in cabinet" pictures were taken before the amp was completely finished.
The schematic shows what was laid out on the PC board, which was intended as an experiment. The amp turned out to have way too much gain, so one gain stage was bypassed and the Mosfet buffers were eliminated except for the one feeding the tone stack. All the mosfet stuff in the cathodes for variable gain sucked, and was likewise eliminated.
This amp was done during the Hundred Buck Amp Challenge, and more details are scattered throughout that thread. The HBAC thread (the sticky at the top of this forum) is an interesting read to see what several builders did to make an amp with low budget parts. The budget was set to exclude the use of common guitar amp tubes.
It was my attempt to squeeze the most possible power and sound out of exactly $100 (8 years ago). I included a picture of the bottom side. The flying resistor and cap in series bypasses a stage and sheds some gain as well. Even with TV sweep tubes capable of 60+ watts, FIVE gain stages was far to many, but three weren't enough with the UCC85's.
It has a bigger brother that also squeaked in at under $100 using TV sweep tubes. It needed a bigger OPT to really scream, which broke the $100 budget. Since the $100 budget was busted, I hacked the board to fit some "real guitar tubes." The EL34's through a real guitar OPT just flat rocked!
I also made an "ultimate cheapness" amp to see just how cheap I could build a good sounding amp for. It came in at under $50 and a slightly modified version of that amp is the one that still gets daily playing time today.
The pictures of the bare board sitting on top of a speaker were taken during design and test. Various combinations of tubes and transformers were tried with 4 or 5 different guitars and speakers.
The big brother and its EL34 variant are also pictured.
So is the little cheap one in its case. It has since been rebuilt although the original is still around here somewhere.
Attachments
[] I am using ECC/PCC189 for a very tubey (all the second harmonic you can eat
Wave assymetry is very visible (you can also hear it
.
I just made such a "harmonizer" with the PCC189, very excellent results. I am wary of the digital sound, want to have some 2ndH to get a good soundstage (like Nelson Pass argues, but his harmonizer is very tricky to set up with finding the right spot on the knee of a FET).
I used to have something like this with EC90CC and 6J6, excellent sound and predominant 2ndH but the 6J6 gave severe ringing as they aged.
Depending on the power supply the harmonics vary between 0,28% 2ndH and 7-15% 2ndH. [results are almost lineair in relation to output rms. So I will make a knob that changes the Vb so I can find the sweet spot in my room and for a specific source. I will also incorporate the concept in a 'distortion box' for the guitar.
Just two pictures. Base concept: Broskie non-inverting stage - CF in, CCS about 3 mA, Grid follower out, CF buffer. Some 4.5-6 dB feedback. I used 7,2, 7,6 and 6.3, the latter has the lowest distortion.
The pictures say it all, first low distortion at 200Vb/6.3Vheater; then 125Vb & 7.2V Vh
Ouch! Facts are:
ECL86 and PCL86 are the same tubes, besides the heaters.
EL86, PL84 and UL84 also are the same tubes, beside their heaters.
The ECL86/PCL86 pentodes have nothing to do with EL86/PL84/UL84. They resemble the EL41 power pentode.
Best regards!
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