Amperex (diy audio member) triggered my fantasy when said that 6085 could be stellar in the driver position in the machine. Since I have E80CC I thought I could try this in that position. What are your thoughts? Amperex?
Transfer function tweaking
There is an article in a recent Audio Xpress where the author explains how to change tube transfer function. An example is given showing a 6V6 with the transfer function of a 300b. You might want to have a look. Regards Moray James.
There is an article in a recent Audio Xpress where the author explains how to change tube transfer function. An example is given showing a 6V6 with the transfer function of a 300b. You might want to have a look. Regards Moray James.
Poindexter's 6V6.
Having bought a matched quad of Electro Harmonix 6v6s for no other reason than they were cheap, I searched around for something to build with them. Poindexter's amp seemed an ideal project so I now have a new pair of 8K outputs and a few other bits in the box ready. Poinz reckons the 5965 is the way to go and I'm not experienced enough to argue so I bought three matched pairs. They are genuine GE 5965s (JAN NOS) and I thought they were cheap at £3.50 per pair. I bought three sets because the preamp I use at the moment uses four ECC81s and the 5965s are very similar. So I slipped two pairs in and was pleasantly surprised. A month later and they're still in and sound great. So I'll stick with these for my 6V6 amp. Can't say how long it's going to take to get it finished as I don't have much spare time at the moment. Si.
Having bought a matched quad of Electro Harmonix 6v6s for no other reason than they were cheap, I searched around for something to build with them. Poindexter's amp seemed an ideal project so I now have a new pair of 8K outputs and a few other bits in the box ready. Poinz reckons the 5965 is the way to go and I'm not experienced enough to argue so I bought three matched pairs. They are genuine GE 5965s (JAN NOS) and I thought they were cheap at £3.50 per pair. I bought three sets because the preamp I use at the moment uses four ECC81s and the 5965s are very similar. So I slipped two pairs in and was pleasantly surprised. A month later and they're still in and sound great. So I'll stick with these for my 6V6 amp. Can't say how long it's going to take to get it finished as I don't have much spare time at the moment. Si.
In my countless flea market searches I bought an old Zenith colsole radio. It had ten original Zenith tubes in it, including 2 6V6G's. I figured that the radio could live with some wafer base Sylvanias, so the 6V6G's were available for science.
I triode wired them into a Tublab SE that was set up for 45's (5K load). External power supply for filament. What did they sound like? A lot like 45's. I tried some of the wafer based Sylvanias. They sound ok but the 6V6G's blow them away.
I triode wired them into a Tublab SE that was set up for 45's (5K load). External power supply for filament. What did they sound like? A lot like 45's. I tried some of the wafer based Sylvanias. They sound ok but the 6V6G's blow them away.
I've communicated with Poinz on choice of input tubes, and sent him a pair of E180CC Mullard to use - that was one of the best in my 5965 shootout, where I went through several types. He liked that. Even better is Amperex shouldered waist 7062.
But the E80CC is in my view a better valve than all the above types - I've compared them all and the Mullard/Tungsram E80CC is an exceptionally fine sounding valve, and yes you could certainly use that. Since you have some, start with that. Even better than that is the ECC40 if you can find a pair, but you will need rimlock sockets - it's not 9 pin so few people use it. If you're a bit short of gain you may need a preamp stage, but try it and see.
I've used two pairs of 6V6 in fixed bias into 6K6 PP OPT for the outputs, and I used the loctal versions which are a lot cheaper. That went quite loud. I used an all loctal input - 7A4 into 7AF7. Again, cheap. All the loctal valves with their silver tops looked great! 12 altogether on the stereo chassis. Very pretty. Sounded really excellent.
But the E80CC is in my view a better valve than all the above types - I've compared them all and the Mullard/Tungsram E80CC is an exceptionally fine sounding valve, and yes you could certainly use that. Since you have some, start with that. Even better than that is the ECC40 if you can find a pair, but you will need rimlock sockets - it's not 9 pin so few people use it. If you're a bit short of gain you may need a preamp stage, but try it and see.
I've used two pairs of 6V6 in fixed bias into 6K6 PP OPT for the outputs, and I used the loctal versions which are a lot cheaper. That went quite loud. I used an all loctal input - 7A4 into 7AF7. Again, cheap. All the loctal valves with their silver tops looked great! 12 altogether on the stereo chassis. Very pretty. Sounded really excellent.
Thanks. You think that I can use the E80CCs in poindexter's circuit without changing something? I have both Amperex made and Tungsram. Former sounds warm in (both as preamp and phase splitter), latter sounds resolute.
Hello
I'm also very interrested in your project since I am also building a Poindexter's "Musical Machine". This one seems like a very popular project. I have all bits and pieces in house since a few days, and I will begin construction very soon.
Anybody can comment on the sound?
I'm very happy to see many people interrested in this circuit and trying modifications also.
F
I'm also very interrested in your project since I am also building a Poindexter's "Musical Machine". This one seems like a very popular project. I have all bits and pieces in house since a few days, and I will begin construction very soon.
Anybody can comment on the sound?
I'm very happy to see many people interrested in this circuit and trying modifications also.
F
Hi all,
This dicussion has got me excited about 6V6 and 6L6 tubes. I have a pair of both tubes but I only have a 6.6K output transformer. Are there any good sounding circuits around that use a 6.6k transformer with either of those tubes? Or should I go get another transformer, i'm trying to avaoid that since I am broke, unless someone wants to trade with me.
Thanks
Lawrence
This dicussion has got me excited about 6V6 and 6L6 tubes. I have a pair of both tubes but I only have a 6.6K output transformer. Are there any good sounding circuits around that use a 6.6k transformer with either of those tubes? Or should I go get another transformer, i'm trying to avaoid that since I am broke, unless someone wants to trade with me.
Thanks
Lawrence
Actually, it's the 6AQ5 which is very much like a 6V6. The 6AQ5 is a 7 pin min. version of the 6V6 with a downrated Vpk. The 315Vdc operating point isn't recommended, nor does the spec sheet give the 285Vdc operation. That's unfortunate since this one has the lowest distortion estimate.
salas said:
It's a matter of gain. The mu of the E80CC is 27, while the mu of the 5965 is 44. If you want to work without a line stage, you definitely need the 5965. OTOH, if you have a line stage with gain, the E80CC may be fine.
Miles Prower said:
Miles,
Peruse the "El Cheapo" thread. Jim McShane makes the point about the 'AQ5 data sheet giving CONSERVATIVE design center ratings. He also gives an example, from experience, running the tube harder. While I would not push the 'AQ5 as hard as some 6V6 designs do, the tube is not particularly fragile.
The "12" W. multi-grid tube that has a FRAGILE screen grid is the SV83/6p15p-ev/EL84N. It's definitely not a candidate for ultralinear topology, when combined with "typical" O/P trafos.
I have a nice line stage. I will try with both tubes and and both approaches. Less stages is always a good thing though. On the other hand my Benchmark has a very healthy variable output option and an output pot. Hmmm E80CC's gain may suffice.
lawbadman said:
For the 6L6:
Vpp= 360Vdc
Vsgsg= 270Vdc
Vgk= -22.5Vdc (Fixed bias)
Ip= 88.0 -- 132mA
Isg= 5.0 -- 15.0mA
R(L)= 6.6K (P-to-P)
Po= 26.5W
THD= 2.0%
Class AB(1)
That operating point (lowest THD as well 🙂 ) will work quite well with the 6.6K xfmr if it's rated for that output power.
6V6 UL operating points?
i read this thread with much interest. Lately i have been thinking of building an amp with a little more power than my PP 6B4G amp.
So therefore i am thinking of parallel SE UL 6V6 amps.
But, I do not see any UL operating points or curves.... and i think i may have some 6v6's.... lemme see:
5x GE 6005 / 6AQ5
4x Sylvania 7408
2x RCA 6V6
2x GE 6F6
i also have some wierd looking Western Electric 311B's....
anyways any help is greatly appreciated.
i read this thread with much interest. Lately i have been thinking of building an amp with a little more power than my PP 6B4G amp.
So therefore i am thinking of parallel SE UL 6V6 amps.
But, I do not see any UL operating points or curves.... and i think i may have some 6v6's.... lemme see:
5x GE 6005 / 6AQ5
4x Sylvania 7408
2x RCA 6V6
2x GE 6F6
i also have some wierd looking Western Electric 311B's....
anyways any help is greatly appreciated.
My 6V6G Amp
I'm building an 6V6G Amp for an "arty" niece because I thought it would look good.
Take Poindexter push pulll triode mode 6V6 circuit. Substitute semiconductor current source in the tail of the front end diff amp (see Baby Huey schematic for an example) instead of a resistor returned to a largish negative rail. I used 6SL7 for the front end diff amp. Then started modifying and listening.
ALL stuff below DONE with ZERO global feedback
1) Mod 1 - changed 6V6 from triode mode to Ultralinear - more power but not as well defined apart from improved top end (reduced miller capacitance at 6V6G grid 1).
2) Mod 2 - added cathode feedback to the 6V6 Ultralinear connected from 4 Ohm secondary taps on the output transformer. This got back a lot of what I lost going from triode mode to Ultralinear mode (reduced output impedance, improved bass).
NOTE: I'm using "cheap" Hammond 1608 Output Trannies. The wiring diagrams for the output trannies say that the 2 off 4 Ohm secondary sections should be wired in parallel BUT I found no noticable degedation by separating them to implement the cathode feedback and wiring the speaker across just one of them. One 4 Ohm secondary section has slightly lower DC resistance than the other, I wired the speaker across this one.
3) Mod 3 - Added MOSFET Source followers after the diffamp to better drive the 100K Rg1 and the Miller capacitance of the output tubes - a noticable top end and definition improvement (reduced loading of the front end and better driving of the 6V6 Miller capacitance).
Its now sounding pretty good BUT still not in the same league as the Baby Huey - it sounds "covered" in comparison, a sure indidcation of too much 2nd harmonic distortion.
Sounds great for "Rock and Roll" BUT a little too raw for some classical stuff. It doesn't have the bass authority of the Baby Huey Amp either, the Hammond 1608s just don't have a big enough core for real bass power (saturating a too high a frequency).
Still to do:
1) Zobel Networks between anode and screen connections of the output trannies.
2) Apply some (6dB or less) global feedback.
Hope there is some usefull info here.
Cheers,
Ian
I'm building an 6V6G Amp for an "arty" niece because I thought it would look good.
Take Poindexter push pulll triode mode 6V6 circuit. Substitute semiconductor current source in the tail of the front end diff amp (see Baby Huey schematic for an example) instead of a resistor returned to a largish negative rail. I used 6SL7 for the front end diff amp. Then started modifying and listening.
ALL stuff below DONE with ZERO global feedback
1) Mod 1 - changed 6V6 from triode mode to Ultralinear - more power but not as well defined apart from improved top end (reduced miller capacitance at 6V6G grid 1).
2) Mod 2 - added cathode feedback to the 6V6 Ultralinear connected from 4 Ohm secondary taps on the output transformer. This got back a lot of what I lost going from triode mode to Ultralinear mode (reduced output impedance, improved bass).
NOTE: I'm using "cheap" Hammond 1608 Output Trannies. The wiring diagrams for the output trannies say that the 2 off 4 Ohm secondary sections should be wired in parallel BUT I found no noticable degedation by separating them to implement the cathode feedback and wiring the speaker across just one of them. One 4 Ohm secondary section has slightly lower DC resistance than the other, I wired the speaker across this one.
3) Mod 3 - Added MOSFET Source followers after the diffamp to better drive the 100K Rg1 and the Miller capacitance of the output tubes - a noticable top end and definition improvement (reduced loading of the front end and better driving of the 6V6 Miller capacitance).
Its now sounding pretty good BUT still not in the same league as the Baby Huey - it sounds "covered" in comparison, a sure indidcation of too much 2nd harmonic distortion.
Sounds great for "Rock and Roll" BUT a little too raw for some classical stuff. It doesn't have the bass authority of the Baby Huey Amp either, the Hammond 1608s just don't have a big enough core for real bass power (saturating a too high a frequency).
Still to do:
1) Zobel Networks between anode and screen connections of the output trannies.
2) Apply some (6dB or less) global feedback.
Hope there is some usefull info here.
Cheers,
Ian
- Status
- Not open for further replies.