New 70s Hybrid project (colour scheme?)

[ElectronAvalanche]

Thanks Structo!

The logo is a waterside decal.

First I tried to do it myself with some decal paper I had lying around, but the paper and topcoat lacquer was quite old, so I got massive bleed out of the black ink.

I ordered the decal from a source in Germany. They can do white ink decals as well. The decal foil is quite thin, though not the thinnest there is.

As on a Fender guitar you can see the outlines of the Decal depending on the angle you look at the amp. Good enough for me.

There is of course another system called DecalPro that allows you to make rub on decals even in white. This system is a bit costly, you need a laminator as well and the procedure can be a bit tricky (from what I have read on the web).

Hope this helps!

Electron

[Structo]

Thanks!
My chassis has the rough black powder coat so I don't think a waterslide would work very well.

I had thought about using a frisket and cutting out the logo, then spray white paint over it like a stencil but it would be difficult to cut out such tiny letters.

[ElectronAvalanche]

Headshell arrived today!

[Structo]

Nice!

That will look killer!

[ElectronAvalanche]

Stuffed some boards.....

I used ultrafast 1N4007 diodes, thus no caps across the diodes since I think I heard they are not needed with UF diodes?

The caps for the Bias supply are radial unfortunately, but I think they will work. The blue caps for the relay supply are a bit big (had to use these since my supplier did only have these in stock).

Next up: relay boards, FET and main board.

Cheers,

Electron

[hans-jörg]

I have read about the same complaints about Ingo over the years.
One excuse after the other.

Hi guys,
because of the reason it was me who mentioned Ingos transformer
I have to tell that I haad no reason for complaining and I evan didnt heard from third about problems with delivery. As I know Ingo worked hard for his production so there was some time delay.
BUT nobody can complain about the quality of his transformers. I heard in the meantime from a lot of satisfied and proud customer of Ingos production. Make your own decission.
http://www.ig-transformatoren.com/produ ... 4_100.html

Hans-Jörg

[Joost]

i used this small transformer from TubeTown in Germany to power the relays in my 124 ODS build. Works perfectly
http://www.tube-town.net/ttstore/produc ... -7-VA.html

[Joost]

i used this small transformer from TubeTown in Germany to power the relays in my 124 ODS build. Works perfectly
http://www.tube-town.net/ttstore/produc ... -7-VA.html

[ElectronAvalanche]

Finally finished the 70s Clone!

Trannys are from Marble Amps (thanks Arie!). They did a fantastic job for a good price. The PT puts out some healthy 460V under load (4xEL34).

OT is 1k7 Marshall-style.

Only thing is that the transformer potting still smells quite strongly (solvents gassing off). Got quite a headache whilst completing the amp. Hmmm.. should have waited a bit longer...

I followed the BludoTone70s Layout (can be found somewhere on this board. Thanks Jason!

I only two minor mods:

Mid boost has a three way switch (on-off-on). I installed a 2200pF Treble cap either followed by no cap, or 660pF (two 330pF in series) or one 330pF. Thus I can get:

Boosted: 2200pF
or

286pF or 520pF

FET is footswitchable (VERY NICE in these amps).

Deep switch instead of Rock/Jazz (never use Jazz, Deep is great for Clean sounds).

Treble pot is 250k Lin

Amp worked right away and has no hum (installed a hum balance pot 100R).

I need to change one of the octals since I broke of the #2 pin (heaters). Was able to repair that, but in the long run I will replace the socket.

The indicator lamp is a neon lamp (220V) which fits the silver face style nicely.

1st preamp tube is a JJ ECC803S, followed by Sovtek long plate ECC83 and then EH 12AT7WC.

Voltages are a bit on the lower side (from the top of my head, need to measure again tomorrow):

V1a_ 176V, V1b_184V
V2a_190V, V2b_194V

The sound:

WOW, in one word: fantastic. Be aware, that I have had only little time to play this thin, but I think this is the amp for me.

The OD is nice, fat, harmonically rich, with FET and PAB wonderful singing sustain, marshallesque flavour.

Clean to die for, even with Tele bridge you get a fat sound, great mids. The neck is not muddy at all. Same in the OD channel.

FET is a 2N5458 btw. Voltages a bit low as well: 12V and 1.2V. But sounds great.

I might swap the 27k B+-string dropping resistor to 22k. But maybe I will leave it as is.

The Bass Pot (1MA) is a bit on/off. Might play around with the two caps, but maybe I will stick with it for now.

I tested the amp with my new 2x12 TT Dumble-style cabinet sporting vintage G12-65 Celestions. Was able to get another pair of G12-65 ofr my 4x12 (have yet to decide what speakers would supplement the G12-65).

Footswitch is a generic 3-button Marshall-style. I used a 7806 regulator off the 6V AC, gets me some 7.7Vs. Relays are Omron sensitive. I have a dedicated power line to light the LEDS down the Midi cable. 100Ohms dropping resistors on the LEDs.

Hope to get some demo up, but might take awhile since I need to get my Firewire AD.

So now I have:

#124: Fender iron, 6L6GC, really like that amp, the OD is a bit compressed in comparison to the 70s style. Had to use the HF-trim on that amp. FET also footswitchable. Need to replace the XLR (3 conductor) with a MIDI jack to be able to use all three relays.

#HRM: high plate, Hammond OT, Tung-Sol 5881 reiusse, great sound, but a bit unforgiving. 470k//470pF combo before 220k into 100k trimmer. Might have to revisit that amp again. Has internal loop using a stripped down circuit: anode coupled, 100k, 1k, no cathode bypass, into 47k with 2k to ground into dual ganged mix pot into 22k grid (0.1uF decoupling on both).

Very transparent, but I think I will throw that out soon.

My 70s build is not as nice as the builds from a lot of other users, but it delivers the goods (but thanks to Ultrahooked for the inspiration).


Hope to put the chassis in the head cabinet tomorrow. I really hate to drill those holes for the chassis screws into the cabinet. Measure and measure again to make sure not to make a mistake. Any tips and hints for that? Always makes me nervous.

Cheers,

Electron

[sonicmojo]

Nice work! I'd like to hear how those EL34s sound! As far as chassis holes go, I suggest cutting a piece of foam board to the dimesion of your head cab and using it as a template. I usually make my holes a little bigger than the bolts and use larger style furniture washers so there is some slack and forgiveness....depending on how tight a fit the cab is. At least yours looks to have only 4 mounts. I have more trouble with 8.

[Joost]

Very cool! Congrats on a great build! I hope you don't mind answering a few questions.
1) why did you use 715 caps instead of 6p'S caps
2) why did you use a linear treble pot?
3) have you ever tried a set of Scumback M75s? I think they are the best sounding celestion g12-65s ever.
4) most importantly, what is a 100R hum balance pot and how does it work?

Finally finished the 70s Clone!

Trannys are from Marble Amps (thanks Arie!). They did a fantastic job for a good price. The PT puts out some healthy 460V under load (4xEL34).

OT is 1k7 Marshall-style.

Only think is that the amps potting still smells quite strongly (solvents gassing off). Got quite a headache whilst completing the amp. Hmmm.. should have waited a bit longer...

I followed the BludoTone70s Layout (can be found somewhere on this board. Thanks Jason!

I only two minor mods:

Mid boost has a three way switch (on-off-on). I installed a 2200pF Treble cap either followed by no cap, or 660pF (two 330pF in series) or one 330pF. Thus I can get:

Boosted: 2200pF
or

286pF or 520pF

FET is footswitchable (VERY NICE in these amps).

Deep switch instead of Rock/Jazz (never use Jazz, Deep is great for Clean sounds).

Treble pot is 250k Lin

Amp worked right away and has no hum (installed a hum balance pot 100R).

I need to change one of the octals since I broke of the #2 pin (heaters). Was able to repair that, but in the long run I will replace the socket.

The indicator lamp is a neon lamp (220V) which fits the silver face style nicely.

1st preamp tube is a JJ ECC803S, followed by Sovtek long plate ECC83 and then EH 12AT7WC.

Voltages are a bit on the lower side (from the top of my head, need to measure again tomorrow):

V1a_ 176V, V1b_184V
V2a_190V, V2b_194V

The sound:

WOW, in one word: fantastic. Be aware, that I have had only little time to play this thin, but I think this is the amp for me.

The OD is nice, fat, harmonically rich, with FET and PAB wonderful singing sustain, marshallesque flavour.

Clean to die for, even with Tele bridge you get a fat sound, great mids. The neck is not muddy at all. Same in the OD channel.

FET is a 2N5458 btw. Voltages a bit low as well: 12V and 1.2V. But sounds great.

I might swap the 27k B+-string dropping resistor to 22k. But maybe I will leave it as is.

The Bass Pot (1MA) is a bit on/off. Might play around with the two caps, but maybe I will stick with it for now.

I tested the amp with my new 2x12 TT Dumble-style cabinet sporting vintage G12-65 Celestions. Was able to get another pair of G12-65 ofr my 4x12 (have yet to decide what speakers would supplement the G12-65).

Footswitch is a generic 3-button Marshall-style. I used a 7806 regulator off the 6V AC, gets me some 7.7Vs. Relays are Omron sensitive. I have a dedicated power line to light the LEDS down the Midi cable. 100Ohms dropping resistors on the LEDs.

Hope to get some demo up, but might take awhile since I need to get my Firewire AD.

So now I have:

#124: Fender iron, 6L6GC, really like that amp, the OD is a bit compressed in comparison to the 70s style. Had to use the HF-trim on that amp. FET also footswitchable. Need to replace the XLR (3 conductor) with a MIDI jack to be able to use all three relays.

#HRM: high plate, Hammond OT, Tung-Sol 5881 reiusse, great sound, but a bit unforgiving. 470k//470pF combo before 220k into 100k trimmer. Might have to revisit that amp again. Has internal loop using a stripped down circuit: anode coupled, 100k, 1k, no cathode bypass, into 47k with 2k to ground into dual ganged mix pot into 22k grid (0.1uF decoupling on both).

Very transparent, but I think I will throw that out soon.

My 70s build is not as nice as the builds from a lot of other users, but it delivers the goods (but thanks to Ultrahooked for the inspiration).


Hope to put the chassis in the head cabinet tomorrow. I really hate to drill those holes for the chassis screws into the cabinet. Measure and measure again to make sure not to make a mistake. Any tips and hints for that? Always makes me nervous.

Cheers,

Electron

[ElectronAvalanche]

Hi Joost,

Very cool! Congrats on a great build! I hope you don't mind answering a few questions.
1) why did you use 715 caps instead of 6p'S caps
2) why did you use a linear treble pot?
3) have you ever tried a set of Scumback M75s? I think they are the best sounding celestion g12-65s ever.
4) most importantly, what is a 100R hum balance pot and how does it work?

1) because I have a plethora of Sprague 715. The Xicon PP sound nice me thinks and the ITW Blue cap really is a nice addition. In the PI I think you can use 715, since Dumble did this as well?!?

2) the Treble pot in the 70s Hybrid is a 500k Lin. The 250kLin was suggested by Talbany and he was right. I really like the way the TS acts

3) No I have no tried the scumback yet. But might do. Thanks for the tip! Do you know of a european source for scumbacks?

4) that is just a 100OHM pot/trimmer (pot with screwdriver shaft) that replaces the two hum balance 120Ohm resistors. The hum pot lets me dial in the least amount of hum.

Cheers!

Electron

[Joost]

Thanks man! I might be inclined to try that pot thing. Can you show me a picture of where you placed it and how it is connected to replace two resistors?

No, I don't have a European source. I always order them straight from Jim at Scumback. He's great to deal with and help you with customs. I've ordered a LOT from him

Hi Joost,

Very cool! Congrats on a great build! I hope you don't mind answering a few questions.
1) why did you use 715 caps instead of 6p'S caps
2) why did you use a linear treble pot?
3) have you ever tried a set of Scumback M75s? I think they are the best sounding celestion g12-65s ever.
4) most importantly, what is a 100R hum balance pot and how does it work?

1) because I have a plethora of Sprague 715. The Xicon PP sound nice me thinks and the ITW Blue cap really is a nice addition. In the PI I think you can use 715, since Dumble did this as well?!?

2) the Treble pot in the 70s Hybrid is a 500k Lin. The 250kLin was suggested by Talbany and he was right. I really like the way the TS acts

3) No I have no tried the scumback yet. But might do. Thanks for the tip! Do you know of a european source for scumbacks?

4) that is just a 100OHM pot/trimmer (pot with screwdriver shaft) that replaces the two hum balance 120Ohm resistors. The hum pot lets me dial in the least amount of hum.

Cheers!

Electron

[ElectronAvalanche]

Hi Joost,

look at the attached pic. The hum pot is the brass one on the back of the Brown amp next to the AC inlet socket.

It is a simple 100 Ohm balance pot from CTS. Middle lug to ground, CW and CCW go to one half of the heater wiring each.

Cheers,

Electron

http://www.tubeampdoctor.com/de/shop_Po ... r_Fen_2129

[ElectronAvalanche]

@Sonicmojo:

thanks for your tip! I managed to get it done. Took repeated measurements and thankfully it worked out.

That is always the most exciting part since you do NOT want to drill another set of holes into your nice looking headshell!!!

Cheers,

Electron