Search found 281 matches
- Thu Oct 04, 2012 10:53 pm
- Forum: Sim City
- Topic: Drop Down Menus for selecting your tube
- Replies: 28
- Views: 62190
Hi Paul, The models certainly are a motley mixture from a lot of sources. As people notice limitations, I'll go thru them and update as needed. Let me look through it and see if I can provide a better model for the 'BH7. From your description it seems as though you are looking for A2 operation. As ...
- Sat Sep 22, 2012 5:37 pm
- Forum: Sim City
- Topic: 842 Triode Spice
- Replies: 7
- Views: 8157
I find that when I do some very complex simulations, the matrix math seems to get complex enough internally to cause those kind of problems. It gets particularly frustrating when you're using LT built in op amps and whatnot. Sometimes using GEAR analysis will relieve the problem. Also, try the .noo...
- Wed Sep 19, 2012 2:05 pm
- Forum: Sim City
- Topic: Drop Down Menus for selecting your tube
- Replies: 28
- Views: 62190
Added 842 to the list. In this version of triode_nh.txt the devices modeled are 01A, 01A_old, 205D, 2A3, 2A3_sofia, 2C51, 3A5, 3CX300, 6AM4, 6AN8T, 6AS7_6080, 4x6AS7_6080, 6AQ8_ECC85, 6BL8, 6BM8, 6BQ5_EL84, 6C33C_sofia, 6C4C, 6C45-PE, 6CG7, 6CW4, 6CG7, 6DJ8, 6H30, 6HV5, 6J4, 6J6, 6N1P, 6N6P, 6SL7GT,...
- Wed Sep 19, 2012 2:00 pm
- Forum: Sim City
- Topic: 842 Triode Spice
- Replies: 7
- Views: 8157
- Mon Sep 17, 2012 7:22 pm
- Forum: Sim City
- Topic: 842 Triode Spice
- Replies: 7
- Views: 8157
- Wed Jul 25, 2012 11:49 pm
- Forum: Circuits
- Topic: for the fun of it screen volume control
- Replies: 2
- Views: 4892
- Fri Jul 20, 2012 10:59 pm
- Forum: Lurkers Lounge
- Topic: D3A
- Replies: 10
- Views: 12679
- Fri Jul 20, 2012 3:17 pm
- Forum: Phono
- Topic: C3G pentode for phono use ?
- Replies: 16
- Views: 29762
gurevise: The sim I did was pretty much what was posted in the thread... steep rolloff at high frequencies, leading to amplitude and phase funnies. The AC vs DC loads. Since the 5687 was running unbypassed, the output resistance is higher than you might have planned for. The load on that circuit (n...
- Tue Jul 17, 2012 1:52 pm
- Forum: Phono
- Topic: C3G pentode for phono use ?
- Replies: 16
- Views: 29762
- Mon Mar 26, 2012 2:40 pm
- Forum: sbench 101
- Topic: RAT tube tester updates?
- Replies: 7
- Views: 9828
Goodness. That tester seems to keep coming around. I have recently answered a few questions on it on my private email channels as well. :shock: Actually, I think someone actually did a PCB for that. Try the geek zone forum at http://geek.scorpiorising.ca/GeeK_ZonE/index.php If I recall correctly the...
- Tue Feb 28, 2012 2:50 pm
- Forum: Circuits
- Topic: GM70 into A2
- Replies: 26
- Views: 28384
Stephie, How low in impedance does the grid drop do you think when in A2? It didn't seem to drop below 10K if I recall correctly when I was putting them on paper, meaning it shouldn't be to hard to drive if you have the voltage swing. There seems to be many tubes that could drive them, but your loo...
- Fri Feb 24, 2012 9:51 pm
- Forum: Circuits
- Topic: GM70 into A2
- Replies: 26
- Views: 28384
A quick model up shows the GM-70 operating PP Class AB1 (not driven into grid current) can provide about 150 watts. 8kCT to 8 ohm output transformer, 1500 volt anode, -170 volts bias for about 48 mA per tube quiescent current. The 170 volt bias suggests 340v p-p drive (120v RMS) are needed on each g...
- Fri Feb 24, 2012 3:29 pm
- Forum: Circuits
- Topic: GM70 into A2
- Replies: 26
- Views: 28384
P-P makes things easier in a number of ways, since even order products cancel. DC balances so the iron doesn't have to be as large for a given power level, and it is WAY more efficient. You get a lot more power, sometimes 3x as much as two paralleled SE tubes. Many people do not consider even the be...
- Wed Feb 22, 2012 10:44 pm
- Forum: Circuits
- Topic: GM70 into A2
- Replies: 26
- Views: 28384
G'day Drew, Some people are not bothered by paralleling tubes, others find the smearing you mention. I personally find that if you match the tubes AT SEVERAL OPERATING POINTS in the range you are expecting to operate, then they behave themselves and you get no smearing. The problem with matching onl...
- Wed Feb 22, 2012 2:44 pm
- Forum: Circuits
- Topic: GM70 into A2
- Replies: 26
- Views: 28384
I have made A2 amps from 841s and 809s. I find them quite good, but not quite as warm as A1. What I find in the 841 amp is a very detailed and accurate sound. Pleasant to listen to, but somehow darker and more sterile sounding than A1 amps. The real key in those amplifiers is to make the transition ...
- Tue Feb 21, 2012 10:07 pm
- Forum: Circuits
- Topic: GM70 into A2
- Replies: 26
- Views: 28384
- Tue Feb 21, 2012 8:56 pm
- Forum: Circuits
- Topic: GM70 into A2
- Replies: 26
- Views: 28384
For A1 operation, it looks like 30 to 35 watts into 10k is about the limit. The 50 watts I described above does include transformer losses etc, so from a practical viewpoint you are probably comparing a 30 watt A1 to a 50 watt A2 amplifier. For that added power, you end up with a 3 stage vs 2 stage ...
- Tue Feb 21, 2012 7:18 pm
- Forum: Circuits
- Topic: GM70 into A2
- Replies: 26
- Views: 28384
Awww, over 2kV of output? :wink: What Spice land shows is 6SN7 as a cathode follower: +300 volts on the plate, -127v on the cathode and a 30k resistor to -350 volts. The -127v couples to the GM-70. Adjust the bias by pot on the grid of the 6SN7. The gain stage is a cascode 6N1P/6N1P stage, with a 15...
- Tue Feb 21, 2012 3:55 pm
- Forum: Circuits
- Topic: GM70 into A2
- Replies: 26
- Views: 28384
Hi Drew and all, For the GM70, one operating point appropriate for A2 operation looks like it could be 1250 volts and 100mA, loaded into 12.5k load. This would require about -128 volts on the grid and about 300 volt peak to peak signal (Limits of -278 volts and +22 volts). Into 12500 ohms, that woul...
- Tue Jan 03, 2012 6:01 pm
- Forum: Sim City
- Topic: A tale of two simulators
- Replies: 3
- Views: 6558
- Fri Dec 16, 2011 3:12 pm
- Forum: Sim City
- Topic: InverseRIAA Generators
- Replies: 3
- Views: 6325
The 0.1 estimator is ever so slightly low, as you pointed out. (by .089 dB). If you want it EXACT, then the normalization should actually be 0.10105. You can set it up in LTSpice easily enough... just do a frequency response (AC) analysis from 999 to 1001 Hz, using 1000 or 10000 steps. The 0.1 facto...
- Mon Dec 12, 2011 5:38 pm
- Forum: Sim City
- Topic: InverseRIAA Generators
- Replies: 3
- Views: 6325
InverseRIAA Generators
I noticed we have several essentially identical Inverse RIAA generators being used, so I thought I'd do a sort of universal one. Place the attached INVRIAA.ASY file in the spice library symbol directory (under "special functions" is a good choice), and the attached INVRIAA.TXT file in the ...
- Mon Nov 28, 2011 4:32 pm
- Forum: Attenuators
- Topic: concerning slagle transformer VC
- Replies: 2
- Views: 3046
- Wed Nov 02, 2011 6:40 pm
- Forum: Sim City
- Topic: Drop down transformer models for LTSpice
- Replies: 13
- Views: 30630
For the capacitance, a LOT depends on how it's wound. For instance, bi-filar winding increases the coil to coil capacitance, but also provides better coupling than isolating the windings which decrease the capacitance but also the coupling. Ballpark values? Perhaps 100pF pri to pri, 50pF sec to sec,...
- Wed Nov 02, 2011 2:01 pm
- Forum: Sim City
- Topic: Drop down transformer models for LTSpice
- Replies: 13
- Views: 30630
- Wed Nov 02, 2011 1:56 pm
- Forum: Sim City
- Topic: Drop down transformer models for LTSpice
- Replies: 13
- Views: 30630
Hi Again. Essentially correct! Your two primary inductors in series would be 12Hy with 25 ohms each, giving a coupled inductance of 48Hy. The impedance ratio=the inductance ratio, so for a 1.5k impedance primary and an 8 ohm secondary, the total secondary inductance is .256Hy with .26 ohms. Since yo...
- Tue Nov 01, 2011 9:52 pm
- Forum: Sim City
- Topic: Drop down transformer models for LTSpice
- Replies: 13
- Views: 30630
Hi Christian, What's the resistance of the primary? To a very rough approximation the ballpark inductance can be approximated by the formula R/(2*pi*f). You *could* assume 1.5k/25 = 60Hy, but I would bet that it is lower than that. Sometimes the LF response assumes a low source resistance. If the pr...
- Fri Oct 21, 2011 8:13 pm
- Forum: sbench 101
- Topic: Subwoofer Single ended tube OTL amp?
- Replies: 6
- Views: 18858
- Mon Oct 03, 2011 10:03 pm
- Forum: sbench 101
- Topic: LR frequency anomolies.
- Replies: 2
- Views: 5748
- Mon Oct 03, 2011 2:57 pm
- Forum: sbench 101
- Topic: LR frequency anomolies.
- Replies: 2
- Views: 5748