Supreaux 24 complete

[ALBATROS1234]

Kinda proud of this one. My best build yet. I basically used sluckeys schematic and layout design albeit the ps board is separate and there is no tremolo. Otherwise it has 1 input and channels are permanently bridged. It sounded a bit too trebly but with sluckeys advice i increased the size of the input resistor and puy in larger coupling caps in the preamp. After trial and error i ended up with a 270k input resistor and .02 coupling caps in after v1 plates.thanks sluckey as well as all of the el34 forum for helping the handicapped to build better amps.

[ALBATROS1234]

Oh btw the pt is from a sony tc500 the ot is from a 1960s european stereo amp that had 2 telefunken 7189s and a 7199 per channel. The rectifier is a sylvania nos 6ca4 because the sony pt didnt have a 5v winding but had 3 6.3v ones. The power tubes are used but strong rca grey plate 6973s .v1 is an amperex bugle boy and v2 is a long black plate nos rca.  The ot is pretty beefy prob why it sounds so smooth.

[66Strat]

You didn't by chance name your dog Phideaux?

https://www.youtube.com/watch?v=CcKWbRI2Qz4

[ALBATROS1234]

ah justin wilson, the eaux is a new orleans thing. we have a huge french population a lot of boudreaux , thibadeaux etc. LSU fans even have shirts that say geaux tigers. i figured it was a supro 24 clone may as well call it a supreaux.

[66Strat]

NOLA and Southern Louisiana is a lot of fun. I went to Mardi Gras several times while I was in my twenties and in my forties attended NCAA Final Four and SEC Tournaments held there. The music and the food can't be beat. I used to go fishing out of Venice with my Dad and my Uncle. We made two trips a year, April and October. Good times.

[ALBATROS1234]

i also wired the pt sockets to take not only 6973 tubes but also 6cz5,6em5 and 6cm6. the 6973 has 2 pins for g1 and g2 these 3 tubes will all work with those pins jumped. they all look and sound virtually identical , i have nos rca versions of all the replacements and they are drastically cheaper.

6cz5 -designed as a vertical deflection for tv sets. it only lists vert deflection stats and maxs so plate diss is 10w instead of 12w and max voltage is 350 instead of 440 but 6973 is listed as p.p. class ab1 vs vert defl. plate/tube structure identical.

6em5- also a vert deflect tube but has higher filament current .8 vs .45 and has higher transconductance 5100 vs 4800umhos . plate resistance is 50k instead of 73k of 6973. also only rated as a vert deflection tube so plate diss says 10w max instead of 12 watt max

6cm6- says its a vert deflection type but states for class a and typical operation to refer to the 6v6gt and also says use the curves for avg plate charcteristics see 6aq5. plate resistance only 1960 ohm trans 5000umhos. under max ratings it says 12 max plate diss but 9max as vert deflection. so it looks like the 10 max of the above 2 would also be 12 if used for audio.

all in all it seems after alot of research the 6cz5 seems the closest to being identical to a 6973 although others have said they are re badged and are the same tube. i read on a forum a while back that rca released the 6973 and marketed it as high end audio and was getting top dollar for them. the 6cz5 is the same tube but rebadged (only pin8 is no connection instead of a second g2 pin)and sold cheap to tv manufacturers for vert deflection duty. some tv sets actually used 6v6gt in vert and/or horizontal deflection amps in tv sets.i just wanted to pass on this info so guys interested in 6973 type amps but not wanting to spend 6973 money there are very very close nos subs.in my side by side tube rolling. the 6973 sounds slightly glassier 6cz5 sound almost identical. 6em5 sounds slightly different in the midrange. and 6cm6 sounds a touch smoother. but i would guess many could not tell the difference i really scrutinized and went back and forth playing for a few minutes changing sets and repeat. cheers

[ALBATROS1234]

yea venice is good fishing, and yea great jazz great food and such.many parts of the city are beautiful and unique. there used to be a killer rock scene too , even a thriving underground indy/alternative scene which gradually got stomped into the ground by the forcing of ghetto music and culture into the mainstream. i dont know how it is where you are but down here the vast majority of sub 30y.o. kids are brainwashed into thinking rap is music and rappers are poets. i guess cursing over a programed beat is poetry now lol. to hell with spending years to refine you skills on an actual instrument lol. cheers.

[66Strat]

FWIW, Sylvania 6CZ5 specifications include maximum ratings for class A power amp as well as vertical deflection amp ratings. Class A maximum plate voltage and plate dissipation ratings are 350 Volts and 12 Watts, Design Center. Screen grid maximum ratings are 285 volts and 2 watts. The Vertical deflection ratings are the same as RCA.

[PRR]

> 6em5- ...filament current .8 vs .45 and has higher transconductance 5100 vs 4800umhos . plate resistance is 50k instead of 73k of 6973.
6cm6- ...plate resistance only 1960 ohm trans 5000umhos.

The very different heater power means it is a different tube/guts.

Gm is related to the current in the test. You may find that "5100" on one was taken at 10%-15% higher current than the "4800" data.

Plate resistance of a pentode is nearly irrelevant in audio. (Also very sensitive to test current, and voltage.)

1,960 rp on a 6AQ5/6V6 type tube is the *triode* plate resistance.

[DummyLoad]

5/6CZ5 have published data for P-P AB1 as well as A1 single tube. see attached. 

6EM5 has a steeper slope than 6V6/CZ5/CM6/AQ5, etc... for 6V6 family with Vg1 @ 0V, Vg2 @ 250V, Eb @ 250V then Ia ≈140mA - for 6EM5 with same parameters. Ia is well over 200mA.

you can use 6EM5 for audio.

--pete

[DummyLoad]

so, instead of the common names "John Doe & Jane Doe" you have "Bubba Daux & Jeanne Daux"?

one set of grandparents were from jefferson parish, LA...      


--pete

[ALBATROS1234]

thanks i was just going by my rc-21 book. i understand the 6em5 is least like the bunch with the higher filament draw etc. but poking around in the nether regions there were other guys that were using them successfully in 6973 circuits. so i bought a pair of each. i have made adapters for many different tube types so i can test the way different tubes react in different situations. look i am not new to electronics but i am new to tubes so i dont fully grasp all of the details. i generally use the books and the experience of others along with experimentation to build on my knowledge. all i know is all these tubes have been tryed and used by many others so i tried and found good results as far as what they sound like and by doing some testing with the meter throughout my circuits i make sure there are no problems with over excess voltage , plate dissipation , i weed out problems to the best of my present ability. one day i will get to the point where i know all the rules and which ones i can safely break. thank you for your help.

[ALBATROS1234]

i am actually living in jefferson parish at the moment, moved from new orleans proper in january. i spent most of my childhood here. its really no distance, jefferson touches new orleans. i am living almost to kenner now but still can be inside new orleans in less than 15 min if traffic is moving.

[66Strat]

I was referencing the Maximum Ratings for the tube and contrasting rating differences rather than operating points. RCA only provides maximum ratings for use as a vertical deflection amplifier. Sylvania provides maximum ratings for use as a Class A power amplifier as well as a vertical deflection amplifier. Also, the Sylvania and RCA ratings for the 6CZ5 are specified under two different rating systems. The RCA ratings are Design Maximum ratings. The Sylvania ratings are quoted under the more conservative Design Center Rating System. In comparing the maximum ratings, I would venture that the Sylvania AB1 operating points would be safe for the RCA 6CZ5 as well as the Sylvania version.
https://frank.pocnet.net/sheets/049/6/6CZ5.pdf
https://frank.pocnet.net/sheets/137/6/6CZ5.pdf

Edit:
The 6CZ5 maximum ratings also provide insight as to the operating points for the 6973 that would be safe for the 6CZ5.
https://frank.pocnet.net/sheets/049/6/6973.pdf

[bmccowan]

all in all it seems after alot of research the 6cz5 seems the closest to being identical to a 6973 although others have said they are re badged and are the same tube. i read on a forum a while back that rca released the 6973 and marketed it as high end audio and was getting top dollar for them. the 6cz5 is the same tube but rebadged (only pin8 is no connection instead of a second g2 pin)and sold cheap to tv manufacturers for vert deflection duty. some tv sets actually used 6v6gt in vert and/or horizontal deflection amps in tv sets.i just wanted to pass on this info so guys interested in 6973 type amps but not wanting to spend 6973 money there are very very close nos subs.in my side by side tube rolling. the 6973 sounds slightly glassier 6cz5 sound almost identical. 6em5 sounds slightly different in the midrange. and 6cm6 sounds a touch smoother. but i would guess many could not tell the difference i really scrutinized and went back and forth playing for a few minutes changing sets and repeat. cheers

My experience is the same for the 6cz5 and 6cm6. Across the same mfg (RCA) the 6cz5 and the 6973 sound and look identical, except for the pin connection. I agree that the 6cm6 sounds a bit different, but tweak the tone stack a bit, and to my ears (although they kind of suck from decades of loud music) they sound the same. I have looked at the RCA 6973 and 6cz5 with a good magnifying glass and the structure is identical. I played around with different Gibson and Valco type circuits and a favorite is a GA-40 preamp (5879) and the 6cz5/6973 built from a Hammond A0-39 chassis & iron.

[ALBATROS1234]

thats all i was trying to say. the 6cz6 and 6cm6 are so close to the 6973 is uncanny. the plate strucutre seems to be identical as you say. the 6cmg sounds a little smoother. the 6em5 is also very close but the midrange is a tiny bit different. i was just trying to report the findings of my tests. theres a lot of really great nos tubes that are ignored and dirt cheap because of unfamiliarity . as time goes on an the " good audio tubes" get scarce we need to search for other options that sound great but dont break the bank. thanks for the interest .

[ALBATROS1234]

also just to say in my experimentation. tubes with a higher filament current tend to sound really ballsy. i found this with the 6em5 but also as a general rule, some transformers may not be rated to handle the difference but in general when i find a tube that is similar to popular audio tubes but has a higher filament draw in my experience these tubes have a really raw powerful sound.

[bmccowan]

I have never thought about filament current affecting the sonic performance - only wondered if my PT had enough juice as I use a lot of salvaged PTs. I'm wondering if you have ever experimented with the 6CY7? It's another vertical deflection (not that I know what that means ) produced for televisions. There is an interesting audio amp design for it on the diy audio projects site and I have thought about trying it for a guitar amp. I picked up a few tubes but have not drawn up a circuit yet. I'm very much a trial and error guy so it could be a process. If it does not work out, I will build that audio amp.
Enjoy that Supreaux. I built a similar one, also using Sluckey's great documentation, but I have since converted it to the 5879 preamp I mentioned. I think Dirty Girl amps used to make a 5879>6973 amp. But the owner took a break and is now making beautiful black powder muzzleloaders. 

[ALBATROS1234]

never tryed a 6cy7. the filament current is just something i discovered by experimentation. i bought a few tube lots to get some tubes i wanted as well as just digging through tube manuals. before i used my variac like eddie van halen did as a volume control i used to try to make a pentode amp that had low wattage so i could crank it without pissing off neighbors so i tryed things like the 6G6g which sounds great but you need lower voltage and i tryed the 6bk5 which i bought because it was plate dissiation  9 watts i didnt notice until later but it has i high filament current of 1.2a but those tubes sound really good . playing around with other tubes there seemed to be alot of tubes i liked that have high filament draw, i noticed they tend to sound ballsy. the 6BQ6 i like which has a similar pinout to 6v6 except it has a post on top for the plate sounds killer. it also draws 1.2a filament. 6cu5 sounds killer too. again 1.2a filament. of course this is in my experiment amp which is a single ended amp sort of like a champ except it has a 6SL7 preamp tube and 2 gain knobs one after the 1st triode and one after the 2nd triode before the power tube. if you crank the 1st knob and use the 2nd as volume you are basically cranking the preamp distortion and you mostly hear the 6SL7. if you crank the 2nd knob and use the 1st as a volume you hear mostly power tube and it doesnt break up until you get the 1st knob at least half way up. i guess its sorta like a master volume but much simpler with a s.e. amp.
  have not tryed a 5879 but want to at some point. i really like pentode preamp tubes. i have used a 6SJ7 and those sound super sweet also 6267 which is basically an ef86. 6au6 is fun. i have also played with several pentode/triode combo tubes like 6u8a and 6an8. one amp i did a 6u8a with pentode in 1st position and the triode giving it extra boost before the power tube. one amp that turned out quite nice i used a 6267with a 12ax7 in a s.e. amp where i copied the idea from a 5e3 where one input goes into the 6267 the other input is half of a 12ax7, each have a volume, theres a master tone like the 5e3 then it hits the other half of the 12ax7 followed by a 6v6. you can use the volumes to blend channels like the 5e3 . my fav settings are plug into the 12ax7 channel use its volume as a volume and the 6267 volume works to blend in as much of the 6267 as i want. it adds a sweet thickness and extra o.d. oddly after 2 oclock on the knob it maxes out the clarity and drive. if you continue to crank vol 2 it gets no more gain but gets more bass. i love amps that blend channels and i like the sound of parallel tube stages as the 1st tube. this supro clone is no exception. i think my next amp build is going to be something similar to what i just described but i am gonna go octal with a 6SJ7 as one channel a 6SQ7 as channel 2 with the same 5e3 dual vol and shared tone but next it will use a 6SL7 probably with half as a gain stage and half as a cathodyne into a pair of 6v6s although perhaps i will use the 6SL7 as a paraphase pi. who knows. each amp is its own thing. i already have a 6SJ7 in a one channel version using a 6SL7 as 2nd gain stage/p.i. into a pair of 6aq5s which sound very nice and super lofi vintage reminding me of a 1940a gibson or national type great for blues. i want to step it up with a blended channel and use 6v6s for the new one.

[bmccowan]

I'm sure you'd like the 5879 if you like 6SJ7s. I like them both and they sound pretty similar. I am soon going to try one or the other as V2 in a Matchless Clubman type build. I may go all octal 6SL7>6SJ7>6SL7>2/EL34 as its easier for my tired old eyes and arthritic fingers. Clubman's had either 6SH7s or EF86s in V2 position. I find I like 5879s better than EF86s. You can find them for good prices on the bay. I've had good luck with RCA and Tungsol. Bought a 5-sleeve of NOS Philips and 4 of them had lost vacuum and had white getters. Seems like sellers ought to at least look at their tubes.
You're doing some interesting stuff.
 

[Latole]

ah justin wilson, the eaux is a new orleans thing. we have a huge french population a lot of boudreaux , thibadeaux etc. LSU fans even have shirts that say geaux tigers. i figured it was a supro 24 clone may as well call it a supreaux.

Braveaux ou je veux plutôt dire bravo bel ampli !
I went to New Orleans fews years ago, I love it.

[bmccowan]

My wife and I have visited 5 times - each time we take a week in New Orleans and then a week somewhere in a rural area. Last time we went to the "Cajun Prairie" Arnaudville - a bit North of Breaux Bridge. Was great. Zydeco Breakfast in Breaux Bridge is a treat. Here in New England nobody dances until the third drink. In Louisiana, everybody young and old is up dancing on the first note.

[DummyLoad]

6GK6 is another vert-deflection tube that appears to be nothing more than a re-wired 7189/6BQ5. all the 6BQ5/7189-A GE tubes i have are the same as the 6GK6 i have, e.g., i cannot tell one tube from the other looking at the plate structure. i bought a box full of them when they were still cheap. still gathering dust 15 yrs later.

another tube to add to the experimenters pile.

attached is something i had on a breadboard about 10 years ago. fun amp, just too many odd-ball tubes and construction. 


--pete
 

[ALBATROS1234]

that schematic is interesting dummyload. i really like 6bk5s. i got a pair of nos tung sols begging to be built into something. i really think theres 2 kinds of guys that fool with tubes. guys that build clones and guys that are on a tone quest and we cant leave well enough alone lol. i really enjoy the experimentation. and my friends like what i am doing. i have built amps for like half dozen guys all of which are damn good players and i have built complete one offs for each guy and built it to what i thought their taste would be, they are all thrilled. the last guy i built a 6L6 single ended with a 6SL7 preamp. i tweaked it until i thought it sounded so sweet and told my friend set the knobs here its the sweet spot and tell me what you think. his reply was "it sounds perfect." so i know i am on the right track and or i have decent ears . usually when i try to build a vintage clone it always disappoints me on some aspect and i have to tweak it. this supro is quite sweet but i had to play with a few value on this one too. albeit this is for all intents and purposes an my 1st actual clone. thanks fellas for the input.