VC508_Line_Out_Without_Speaker_Kill

[hewo]

Thankyou Enzo, Steve andPrecision B and any others for your responses

ANY line out that derives its signal from the speaker output will have its level go up and down with the amp volume. If i turn my amp down I expect my signal level to go down. Setting levels with the PA or recording deck are what SOUND CHECKS are for. If you replace the resistor network with a transformer (far more expensive) you STILL have that problem. Can I turn up my pre gain and my master volunme down, yes, but what matter to the speaker driven line out is how loud the speaker is playing, it doesn;t matter how the volume level got there, it is none the less there.

If I play at some volume all week, then next week I play at lower volume, it is the sound mixer's job to adjust his levels. We don;t want a line out that always make the same level, you woould lose your dynamics. This is no different from using a microphone in front of the speaker, if you play quieter, you get lower signal levels. That is why mixers have level controls.

1. 5F1 Fired it up on the 300 htac and received 339.4DC first condesner node. That's perfect per legacy 5F1 schematic!
2. But I don't like the purity and I think it's that MV 1M log pot. It's gotta be lowered 4 fold maybe? you'd think it would get louder with the 1M log pot. Any disagreements? can this 1M log pot MV be impeding signal flow out from the preamp into the 6V6GT?
3. The tele plays clean just like yesteryears but appears to missing sparkle glisten shimmer. Could this be caused by the too tightly twisted ac wiring (Line_Utility's including snubber/fuse, PT's, OT's are spiraled coils both sides) ? the amp has absolutely zero motorboating, spectacular! But why no distortion dialed way up? even with 22K NFB disengaged still no distortion. could it be the cannibalized 4 ohm peavey 8" paper spkr still cabbed inside the transistorized peavey rage 108 ? or do i need a bypass silver mica, 220pico, on the preamp's 1M log pot? or do the legacy interstage coupling .022 caps 600wvdc need to be necked down to .01?
4. If proportional (PT primary to secondary ratios), can I engage the htac selectable to 330htac ? I did the math for 300htac into 330htac which yields by proportionality 372.96DC for the 1st condenser node, i.e., x=(333.4)*[339.4/303.4]
5. with 339.4DC (300htac) should i measure the quiescent idling current through the 6V6GT at it's cathode's 470 ohm 5 watt resistor? this gives total mA draw thru the puny OT which just appears in appearance as the future weak link of disaster. help me get a stronger one, used one is ok. 4 ohm spkr's are hard to come by. if an upgrade OT is recommended, I'd like 16 ohms because most of my existing slave spkr's are 16 ohms for the vc2110r's by SLM.
5. or, do i abort shuguang tubes and reinstall usa rca sylvania ge 5Y3GT and 6V6GT and 12ax7B ?
6. or is that peavey 8" 4 ohm very poor performance ?
7. there's just too many things to eliminate as the cause of the plain sounding tele. for all we know, it could very well be the 6 foot spkr extn cable that is soldered into the peavey's 8" paper speaker tabs (transistor side leads lifted isolated)
8. pl assist, need more sparkle, shimmering, glistening signature (just like vc508!)

[hewo]

Found_Line_Out_Spkr_Isolation_Transformer

Jensen_Line_Out_Transformer_Schematic.pdfJensen_Line_Out_Transformer_Schematic.pdf

1. 5F1 Fired it up on the 300 htac and received 339.4DC first condesner node. That's perfect per legacy 5F1 schematic!
2. But I don't like the purity and I think it's that MV 1M log pot. It's gotta be lowered 4 fold maybe? you'd think it would get louder with the 1M log pot. Any disagreements? can this 1M log pot MV be impeding signal flow out from the preamp into the 6V6GT?
3. The tele plays clean just like yesteryears but appears to missing sparkle glisten shimmer. Could this be caused by the too tightly twisted ac wiring (Line_Utility's including snubber/fuse, PT's, OT's are spiraled coils both sides) ? the amp has absolutely zero motorboating, spectacular! But why no distortion dialed way up? even with 22K NFB disengaged still no distortion. could it be the cannibalized 4 ohm peavey 8" paper spkr still cabbed inside the transistorized peavey rage 108 ? or do i need a bypass silver mica, 220pico, on the preamp's 1M log pot? or do the legacy interstage coupling .022 caps 600wvdc need to be necked down to .01?
4. If proportional (PT primary to secondary ratios), can I engage the htac selectable to 330htac ? I did the math for 300htac into 330htac which yields by proportionality 372.96DC for the 1st condenser node, i.e., x=(333.4)*[339.4/303.4]
5. with 339.4DC (300htac) should i measure the quiescent idling current through the 6V6GT at it's cathode's 470 ohm 5 watt resistor? this gives total mA draw thru the puny OT which just appears in appearance as the future weak link of disaster. help me get a stronger one, used one is ok. 4 ohm spkr's are hard to come by. if an upgrade OT is recommended, I'd like 16 ohms because most of my existing slave spkr's are 16 ohms for the vc2110r's by SLM.
5. or, do i abort shuguang tubes and reinstall usa rca sylvania ge 5Y3GT and 6V6GT and 12ax7B ?
6. or is that peavey 8" 4 ohm very poor performance ?
7. there's just too many things to eliminate as the cause of the plain sounding tele. for all we know, it could very well be the 6 foot spkr extn cable that is soldered into the peavey's 8" paper speaker tabs (transistor side leads lifted isolated)
8. pl assist, need more sparkle, shimmering, glistening signature (just like vc508!)

[Steve A.]

1. So how does the Peavey speaker sound plugged into other amps? If it sounds okay plugged into other amps then that is probably not the problem.
2. When I think of a 5F1 I think of grind not sparkle.
3. Another thought- are you sure that you got the two input jacks wired up correctly? It can be tricky getting them right. For the higher gain input jack you want a 34k grid resistance and a 1M grid load. With a guitar cable plugged into that jack you should get a reading of 1M to ground.

Steve Ahola

[Chuck H]

+1
hewo, does the guitar still sound "right" through other amps? Do you want or expect all amps to sound the same? Do you need a balanced line out for some particular reason? can you post a schematic of the amp for evaluation of the master volume circuit?

Incidentally, you don't seem to like this amp. Why don't you get a different amp?

[hewo]

Potential_Ground_Fault_Clash_at_Church_Courtesy_Line_Out _Guitar_Amp

Just wondering if you have talked about your plan to the soundman at your church- some or most of them would not want to connect a homemade device to their PA system. At least that was my own experience.

There are all sorts of DI boxes but for a 5F1 I think it that you would get the best signal just miking the cabinet. Is that an option?

Steve Ahola

P.S. Chuck- I got a stiff neck trying to read your chart so I took the liberty of rotating it 90 degrees clockwise...

[ATTACH]20258[/ATTACH]

I hadn't heard that quote from R.G.- it makes a great signature!

"I have George Washington's own axe, the one he chopped the cherry tree down with. 'Course, it's been repaired over the last couple of centuries; it's had three new handles and two new heads." R.G.

Thanks Steve
1. Those long long hard wiring stage to sound engineer involves significantly larger energies. Larger energies can cause great grief!
2. My recommendation to "float" tube amp's line out verbatim means the isolation transformer method, impedance matching too, to deter unnecessary spkr energy robbing in these extremely low powered single ended tube amps is fruitful.
3. trouble is writing to the transformer companies to get the right one.
4. my peavey tele (excessively super long strapping horn, has a chrome bridge ground lift causing aerial collection of irritating buzz except when fleshed over by hands, flesh feet grounded. Lord be with me as I disassemble and seek and restore this interrupt essential ground. Church rehearsal today is at 5pm and my immediate neighbor is drugging me (unintentionally) severely with some potent combustion emissions, powerful stoggie maybe? I can't get up off of the floor tiling it is so incapacitating.
5. Out of forum discuss sequence: I errored severely by not placing the Peavey Rage 108 8" 4 ohm paper spkr at ear level (5F1 tested with spkr on floor tiling). That 5F1 sings beautifully! But you must place the 8" spkr at elevation proximate to ears (spkr spray path). Success!
6. Must ho backwards now and examine mods Steve cautioned, 250K log pot MV (currently 1M log pot replaces 220K grid tie down resistor legacy schematic) and Steve cautioned 6V6GT input grid stopper, 1K to 1.2K. With the current 1M log MV, 6V6GT input signal grid could drift in voltage higher than cathode, bad thing, causing excessive draw of energies thru the 6V6GT and supporting powering circuitry.

[Chuck H]

2. My recommendation to "float" tube amp's line out verbatim means the isolation transformer method, impedance matching too, to deter unnecessary spkr energy robbing in these extremely low powered single ended tube amps is fruitful.

Well, since the standard speaker driven line out has a circuit impedance of about 1k there shouldn't be any significant current through it. If you can hear the difference between 4 watts and 3.98 watts you get a cookie.

[hewo]

Thankyou Chuck H

Well, since the standard speaker driven line out has a circuit impedance of about 1k there shouldn't be any significant current through it. If you can hear the difference between 4 watts and 3.98 watts you get a cookie.

1. The intentional purpose of isolation by transformer aligns to Steve A's cautionary "church equipment safeguards" but rather vice versa, guitarist's tube amp circuitry safeguarding. Realize the church won't have a crew assigned like the pro's for aerosmith or the stones.
2. The isolation impedance matching transformer wins two ways: it can be fused should super unexpectant unwanted energies come about on either side of the isolation impedance matching transformer.
3. I saw on a solid state ROAD amp schematic from the early 70's 600 ohm line out so that's target output impedance.
4. On the spkr side the impedance would need to be very high ($ windings) so that minimal energies kick back reactance effects (flyback phenomena?) which would affect spkr locomotion (reactive currents)
5. Correct me if I am astray. Maybe the piezo microphone impedance coupling transformer might get me close enough? piezo's are super high output impedances.

[kleuck]

A simple speaker simulator Led me to that : Simple, passive, Speaker sim, ground-lifted, secure.

[Steve A.]

A simple speaker simulator Led me to that : Simple, passive, Speaker sim, ground-lifted, secure.

That looks amazing! I did have a few questions. Do you have a source for the transformer? Also can you confirm that I am reading the numbers correctly? I assume that the pot is 10k, the tapering resistor on the pot is 1k8 and the specs of the transformer are 1k5 input and 600 ohm output.

Steve Ahola

[hewo]

Thankyou kleuck, Steve A and Steve C for your responses/affirms

That looks amazing! I did have a few questions. Do you have a source for the transformer? Also can you confirm that I am reading the numbers correctly? I assume that the pot is 10k, the tapering resistor on the pot is 1k8 and the specs of the transformer are 1k5 input and 600 ohm output.

Steve Ahola

1. Steve A is requesting (kleuck) confirm of the illegibile numeral "7" or be it a "1" that consistently recurs?
2. Hewo requests (kleuck) confirm of "TM022" as the manufacturer's model number of the impedance matching transformer.
3. Hewo requests (kleuck) source "TM022"
4. Use specialty type self-centering isolation fibre washers to mount 600 ohm line out receptacle sleeved thru steel tube amp chassis.
5. Why is inductor dual option? Or is pictorial interpretation series inductors using commonly available inductor values? If so, series inductor value can be hand made (inductor measuring DVM), and, improved, by quality ferrite core (audio quality)?
6. Non-Polarized 10Mfd (bulky at 35rms but eliminates hysterisis?) is equivalent to pictorial's oppositional series paired 22Mfd electrolytics?
Thankyou in advance

[kleuck]

Hello The Xformer i use is a Xicon TM022, cause it has a good inductance (requested) and the impedance ration is already interesting i think (indeed 1K5/600 ohms), i buy them at Banzai (Europe) but you can find them through all the usual suspects.Others can be used, but they are readily available, cheap, small. I used two caps cause i did not have any NP on hand at the time, and i draw usually what i've really built, a 10µf NP would be fine. The 1K8 resistor is not mandatory obviously, and the caps were meant at the time to emulate a Jensen P10R, bright and no big lows, so you can increase these values (by small leaps, remember, inductance : square ratio)

[hewo]

Thankyou kleuck for your responses

Hello The Xformer i use is a Xicon TM022, cause it has a good inductance (requested) and the impedance ration is already interesting i think (indeed 1K5/600 ohms), i buy them at Banzai (Europe) but you can find them through all the usual suspects.Others can be used, but they are readily available, cheap, small. I used two caps cause i did not have any NP on hand at the time, and i draw usually what i've really built, a 10µf NP would be fine. The 1K8 resistor is not mandatory obviously, and the caps were meant at the time to emulate a Jensen P10R, bright and no big lows, so you can increase these values (by small leaps, remember, inductance : square ratio)

1. There are two low power audio single ended tube amps involved:
2. The 1st is the VC508 featuring TL072 -->ECC83(1a) --> ECC83(1b) --> EL84 --> 8 ohm
3. The 2nd is the legacy Champ 5F1 ECC83(1a) --> ECC83(1b) --> 6V6GT --> 4 ohm
4. Will utilize kleuck pictorial verbatim on both amps

[kleuck]

Of course, to keep the ground-lift benefits, you have to use an output jack made of plastic, and keep it's ground unconnected to the chassis or the primary of the Xformer.

[kleuck]

If you have an inductance-meter, you can calculate the low-cut cap after measuring the primary inductance (i did with all my Xicon -have a lot- unfortunately, my meter died a few days ago, and i can't figure where i noted the values but it should be line the 2-3 H range if i remember)
The Hi-cut cap is more a guess and try work.
Anyway, these little Xformers alone have already a limited bandpass, and are enough to provide ground-lifting and a more natural response trough a PA if there's a way to tame the highs on the PA ; but with the right caps, the speaker sim if not perfect (cannot give notches with a that simple design) is really great already, and 100% passive.
I suppose that it's possible to get a more accurate response with two Xformers, but it's out of my knowledge (don't know how to simulate anything) and perhaps useless, as there will always be a parasitic variable parameter : the input impedance of the amplifier, can be a PA (line inputs do not always have the same impedance) or a guitar amp (same) etc.
As it is, it behaves like a charm in a PA or in an amp, i put this sim in my attenuators (25 K pot), so far customers love it.

Remember it's not my idea, i just made a proto with readily available Xformers.

[Steve Conner]

Glad to see someone got some benefit from my old circuit!

Just in case it isn't obvious: If you're connecting the circuit across your existing speaker, you don't need the big 8.2 ohm resistor and inductor.