Search found 365 matches

by reVintage
Sun Dec 10, 2023 9:45 pm
Forum: Your name here.
Topic: Free lunch PP with DHT
Replies: 0
Views: 3086

Free lunch PP with DHT

3A52A3chokePPtest.asc
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pp.png
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by reVintage
Mon Jul 23, 2012 9:05 pm
Forum: Lurkers Lounge
Topic: D3A
Replies: 10
Views: 12670

Note that an EQ network can be done without series resistance as shown in the other thread Maturin participated in the other day. Daves is with a D3a.
by reVintage
Sat Jul 21, 2012 10:08 am
Forum: Lurkers Lounge
Topic: D3A
Replies: 10
Views: 12670

Try www.ebay.de , D3a are easy to find there.
by reVintage
Fri Jul 20, 2012 7:31 am
Forum: Phono
Topic: C3G pentode for phono use ?
Replies: 16
Views: 29754

Gurevise,

Note Rp of C3g is not infinite!

These are the 20-100k plots of the corrections I advised you. Note scale!

About my preference for the other correction, the answer is in the link I added in my previous post.
by reVintage
Wed Jul 18, 2012 7:59 am
Forum: Phono
Topic: C3G pentode for phono use ?
Replies: 16
Views: 29754

Using the original working points these are two alternatives that possibly will be closer to corrrect. I would personally go for the second as I have found the absence of series resistor in the network sound better. There is also a thread by Dave with a similar solution here: http://www.intactaudio....
by reVintage
Tue Jul 17, 2012 9:37 am
Forum: Phono
Topic: C3G pentode for phono use ?
Replies: 16
Views: 29754

Hey gurevise,

Did you measure RIAA response IRL? My sim check indicates errors.

Are you also aware that Zout is in the ballpark of 4kohm due to the unbypassed cathode resistor?
by reVintage
Mon Sep 26, 2011 5:59 am
Forum: Transformers
Topic: Looking for some good iron
Replies: 4
Views: 5736

There has been posts in other foras that verifies what I mentioned. The people at JJ may do good tubes, but they used RCAs 2A3 curves in the datasheet for their 2,5V 300B. Insane! But maybe they have changed by now. Instead of seriesconnecting the heaters for 5V as in 300B they parallell them for 2,...
by reVintage
Sat Sep 17, 2011 2:31 pm
Forum: Transformers
Topic: Looking for some good iron
Replies: 4
Views: 5736

JJ 2A3=300B but with different heater voltage. Has nothing whatsoever to do with the real 2A3.
by reVintage
Wed Sep 07, 2011 6:42 pm
Forum: Sim City
Topic: anyone have an LT spice model for an MJE340
Replies: 4
Views: 9929

.MODEL MJE350 pnp( IS=6.01619e-15 BF=157.387 NF=0.910131 VAF=23.273 IKF=0.0564808 ISE=4.48479e-12 NE=1.58557 BR=0.1 NR=1.03823 VAR=4.14543 IKR=0.0999978 ISC=1.00199e-13 NC=1.98851 RB=0.1 IRB=0.202965 RBM=0.1 RE=0.0710678 RC=0.355339 XTB=1.03638 XTI=3.8424 EG=1.206 CJE=1e-11 VJE=0.75 MJE=0.33 TF=1e-0...
by reVintage
Sat May 21, 2011 8:05 am
Forum: Inductors
Topic: Voltage DAC and grid choke
Replies: 24
Views: 26384

Rk=Ug/Ia
Rk=2V/0,010A=200ohm
by reVintage
Fri May 20, 2011 7:43 pm
Forum: Inductors
Topic: Voltage DAC and grid choke
Replies: 24
Views: 26384

Hey Oko, You can have as high B+ as you like using a CCS. If you want low Zout take the signal at the source instead of at the anode. Cathode resstor sets Ua and CCS sets current. Decide Ia and then adjust cathode resistor to get the right Ua. If using a high B+ and low Ua just take care not to over...
by reVintage
Thu May 19, 2011 8:14 pm
Forum: Inductors
Topic: Voltage DAC and grid choke
Replies: 24
Views: 26384

Hey Oko,
How could you use something like SRPP? In my point view this is awful compared to a well designed SE. IF you want to have low Zout the only thing you can do this to use a HighGm device on top of the triode in SRPP-style. It´s easy done with a depletion MOSFET like DN2540. This sounds OK!
by reVintage
Mon May 16, 2011 10:15 am
Forum: Inductors
Topic: Voltage DAC and grid choke
Replies: 24
Views: 26384

Why use 6N6P in a fairly unlinear region? 10-12mA is Ok but move Ua lower to better linearity. Shouldn´t have to be a problem at all to drive your EL34PSE. But if you have listened and found it best ignore this. About your 12B4 remove both the 1k and 27k and instead bit by bit add a gridstopper tha...
by reVintage
Mon May 16, 2011 9:41 am
Forum: Inductors
Topic: Voltage DAC and grid choke
Replies: 24
Views: 26384

Probably selfoscillation. Were is the gridstopper? Must be soldered directly at the input pin of the tubesocket. No other explanion for me. Down to 100ohm should usually work. Keep seriesresistor as low as possible as it usually causes loss of dynamics. Your workingpoint of the 6N6P seems somewhat w...
by reVintage
Mon May 16, 2011 8:17 am
Forum: Inductors
Topic: Voltage DAC and grid choke
Replies: 24
Views: 26384

Hi Artur,
The grid is best stabilized with low DCR so no problem.

About inductance/reactance in the low band, you don´t need to worry as the Wolfson with it´s low Zout will not be sensitive to load at all. Anyway when load is of 12k magnitude.
by reVintage
Mon Apr 18, 2011 10:56 am
Forum: Sim City
Topic: 6AH4
Replies: 2
Views: 5762

Try this one: .SUBCKT 6AH4 A G K BGG GG 0 V=V(G,K)+1.2375 BEP EP 0 V=URAMP(V(A,K))+1e-10 BSTM STM 0 V=URAMP(V(GG)+V(EP)/7.262)+1e-10 BM1 M1 0 V=(0.040277471770862*(URAMP(V(EP)-1e-10)+1e-10))^-0.620126359531028 BM2 M2 0 V=(0.707505*V(STM))^2.12012635953103 BM M 0 V=V(M1)*V(M2) BSTP STP 0 V=URAMP(V(GG...
by reVintage
Sat Mar 19, 2011 9:41 am
Forum: Sim City
Topic: Models for 6AM4 and EC8010
Replies: 7
Views: 9783

Should it be more difficult than this? .subckt 6am4 P G K Bp P K I=(0.01033900924m)*uramp(V(P,K)*ln(1.0+(-0.007076797646)+exp((1.906422463)+(1.906422463)*((116.802414)+(-1169.550306m)*V(G,K))*V(G,K)/sqrt((17.88295266)**2+(V(P,K)-(-11.80479238))**2)))/(1.906422463))**(1.420116524) Cgk G K x.xP Cgp G ...
by reVintage
Fri Mar 18, 2011 9:33 pm
Forum: Sim City
Topic: Models for 6AM4 and EC8010
Replies: 7
Views: 9783

Hi Stephen,
Could one have a look at one of the modesl you did?
by reVintage
Fri Mar 18, 2011 7:02 pm
Forum: Sim City
Topic: Models for 6AM4 and EC8010
Replies: 7
Views: 9783

Hey Stephen,
Suppose you add them manually by taking the figures from the datasheets.
by reVintage
Tue Feb 15, 2011 6:52 am
Forum: Sim City
Topic: primer on creating ltspice models
Replies: 8
Views: 18744

DN2540 came directly from Supertex site. If you don´t make the models yourself, "Google is your friend".

But beware some models aren´t good enough. To check this, one can easily plot the Ua/Ia-characteristics in LTSpice and compare to the original curves. Measure current through R6.
by reVintage
Wed Dec 08, 2010 8:00 am
Forum: Resistors
Topic: I/V resistor for TDA1541 Vishay Bulk Foil
Replies: 1
Views: 9234

Hey Martin,
In fact the 100ohm you used is the upper limit. Try from 25 to 100ohm. AFAIK Dave has an application in where lots of parallelled 1543 where used together with an input transformer.
by reVintage
Fri Dec 03, 2010 8:17 am
Forum: Circuits
Topic: new jc circuits
Replies: 51
Views: 53179

An "El Cheapo" example I made in Dave´s "Pentode phono"-thread a while ago. This single stage RIAA might be bettered with the Gm-tecnique added. A CCS might also substitute the "gyrator"(fixed voltage AC-CCS) to simplify. http://www.intactaudio.com/forum/files/d3ahyb_9...
by reVintage
Thu Dec 02, 2010 10:33 pm
Forum: Circuits
Topic: new jc circuits
Replies: 51
Views: 53179

The ".step param" was to compare gain with only 610k load against 47k. Off course there should be a load on a pentode, as this could/should be looked upon as current source. And as I said my previous post, there is no big difference in gain, only 4dB, between the two when loaded with 47k. ...
by reVintage
Thu Dec 02, 2010 6:32 pm
Forum: Circuits
Topic: new jc circuits
Replies: 51
Views: 53179

These are the files. Doublechecked FET against BJT and no big differences when simmed.
by reVintage
Thu Dec 02, 2010 4:19 pm
Forum: Circuits
Topic: new jc circuits
Replies: 51
Views: 53179

Interesting circuit, tried simming it during my lunch-hour. Compared it with a "gyrator"-fed conventional D3a. Used a depletion-FET instead of the BJT as this seems to give the same result. Without the 47k(last resistor to the left in pentofax schematic) loading, gain as expected was highe...
by reVintage
Fri Nov 26, 2010 9:09 am
Forum: Circuits
Topic: new jc circuits
Replies: 51
Views: 53179

the shunt resistor. N, hahahahah, you really crack me up. Didn´t you check my last .asc/post where I say shunt is the solution. So if you run the input device at extremely low current the 100k will work. As I have no knowledge in sand, please explain what the diodes do. So when C4 is actaully in t...
by reVintage
Thu Nov 25, 2010 2:55 pm
Forum: Circuits
Topic: new jc circuits
Replies: 51
Views: 53179

Hey Dave, Haven´t seen you around for a while. Of course it will make noise. Maybe you listened to something with other component values than here. Still A CCS on top of pentode is an absolute nono, load has to be substantialy low and it is still not DC-coupled.Think you showed the loading thing in...
by reVintage
Thu Nov 25, 2010 10:42 am
Forum: Circuits
Topic: new jc circuits
Replies: 51
Views: 53179

Hej! Your circuit will not in any way work in its present form. A pentode must have a defined voltage on top. Either a resistor or a gyrator. With a current source Ua will be all over the place. Also a pentode needs loading to work with low distortion. In my example I have used tubes suitable for th...
by reVintage
Tue Sep 14, 2010 10:29 pm
Forum: Transformers
Topic: Zen I/V with transformers.
Replies: 5
Views: 13726

Looks interesting. Those three-leg buggers behaves like pentodes. PP-transformer too, if I understand it right. Not sure the circuit is useful though. As far as I know the mainpart of DACs are with DC offset. Some are also balanced out together with DC offset. Haven´t bothered to read the thread whe...
by reVintage
Sat Aug 28, 2010 7:59 am
Forum: Current Cancellation
Topic: 6B4G with a twist
Replies: 4
Views: 10838

Hi Stephie, We actually began with the concept you described but with a tetrode instead of the MOSFET. Built it and showed the results at diyaudio a few years ago. Great success at the yearly Swedish DIY-fest.It is close to the schematic below, the only one I could find. We discussed another one her...