Recent Posts

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91
Brewery / Re: Seeking a second opinion
« Last post by gyraf on August 19, 2019, 02:33:57 AM »
I don't see how he can expect you to pay a repair that you did not ask for?

You asked for it shipped back, he wouldn´t do that, your responsibility pretty much ends right there.

And as you cannot know what potential damage has been done during unauthorized local repair, the warranty is off.

Jakob E.
92
Black Market / Re: Binder 7-pin 691 Series cable mounted connector, NEW
« Last post by duantro on August 19, 2019, 02:14:19 AM »
No reply, I guess I’ll just buy a new one. 
93
Regarding the externally mounted capacitors, you have plenty of room in relation to adjacent components that it wouldn't matter if you go with the fatter ones. For the one that mounts to the PCB, you will probably want to get the skinnier version to ensure it fits through the opening in the back of the chassis.

If you're really uncertain then go here:

https://hayseedhamfest.com/products/ua-176

This is what I used and it works great. I believe this is where Martin got his caps for his prototype.

Thanks!

Paul
Thank-you Paul. It's strange they have two nearly identical - and also fail to put the dimensional differences on their site...

Edit: my real concern is I don’t know the quality of the hamfest caps. I trust in the CE Mallory name more than off-label generics...although the CE’s are only rated to 65C and the hamfest to 105C...
94
Thank you paul
I think I will use the 370bx
I will do my math and see :)

edit.

the 370bx deliver 2x275v instead of 2X325v
on the schematic going from ac to dc with GZ34+Choke 10HY add 40v
maybe with the 370bx it will add also 40v or maybe less like 35v
so 275+35v=310v

310V is the voltage needed after the first dropping 1,5k resistor (R44).
too much resistance is going to reduce  the voltage on the 12BH7 plate.

so do I need to remove completely the first resistor?
put only 300ohm or something and lower the second resistor (R43)?

On the spec sheet for Electro Harmonix branded 12BH7 it shows maximum plate voltage for class A circuits listed at 300V and for typical applications 250V. With all things being equal and you do end up with with 310V after AC to DC conversion with the 370bx transformer and you also get the 50V drop across R44 as shown on the schematic, that will still put you at 260V, which is above the typical plate voltage from the 12BH7 spec sheet. If the voltage does indeed prove to be too low, you can try using something like 1k for R44 and see if that satisfies the power requirements.

I would not recommend or condone leaving off any resistors from this PSU for safety purposes.

Thanks!

Paul
95
Another Question about the CE cap (C11). There's 2 listed at tubesandmore.com

https://www.tubesandmore.com/products/capacitor-ce-mfg-475v-20202020-f-electrolytic-25-height

https://www.tubesandmore.com/products/capacitor-ce-mfg-475v-20202020-f-electrolytic

They both have same electrical specs, but one is shorter and fatter and the other longer and skinnier. Or so the pictures seem. But they both claim to have bottom diameter of 1.375".

Anyone has bought this cap (C11) and knows which is the right one?

Thanks,

Mike

Regarding the externally mounted capacitors, you have plenty of room in relation to adjacent components that it wouldn't matter if you go with the fatter ones. For the one that mounts to the PCB, you will probably want to get the skinnier version to ensure it fits through the opening in the back of the chassis.

If you're really uncertain then go here:

https://hayseedhamfest.com/products/ua-176

This is what I used and it works great. I believe this is where Martin got his caps for his prototype.

Thanks!

Paul
96
Brewery / Re: Simple wood finishes
« Last post by alexc on August 19, 2019, 12:54:08 AM »
 ..  lover of fine traditional finishes  ..  on  fine woods  :)

I'm no expert ... 

I like love  tung oil, lots of time to age,   and with  buffing (wiv a cheap electric  car-finish buffer,   in my case)

Apart from that, old style thin  'lacquer'  is good, again with aging and buffs.

I stripped the white paint from my rick bass decades ago (a 1976 rick james model   8))  and redid it natural in a simple thin lacquer ... and after 20 years it has a nice sheen from natural usage  and a vintage patina all over.  It plays superbly too.

Of course, shellac and spirit finishes are great if you can do them or know someone. Beeswax, beetle casings, volatile spirits and pom-poms.  What's not to love?

But for cost effective 'artisan',  I've really come aboot to thin skin or no  finishing  for tone ..   woods

Not that I have anything against thick, armoured coatings .. they can be really good for sure.
97
Another Question about the CE cap (C11). There's 2 listed at tubesandmore.com

https://www.tubesandmore.com/products/capacitor-ce-mfg-475v-20202020-f-electrolytic-25-height

https://www.tubesandmore.com/products/capacitor-ce-mfg-475v-20202020-f-electrolytic

They both have same electrical specs, but one is shorter and fatter and the other longer and skinnier. Or so the pictures seem. But they both claim to have bottom diameter of 1.375".

Anyone has bought this cap (C11) and knows which is the right one?

Thanks,

Mike
98
Preamplifiers / Re: Feeler: Classic Solo
« Last post by kambo on August 19, 2019, 12:06:48 AM »
hey Ian, ur Mu Followers are freaking ROCKING  ;D i forgot how good they were.
especially in ur mu follower distortion notes, 6SN7 8mA version, is the best of all to me...
edit: i think i like sound of 6SN7 compared to 6092.
600ohm load is a breeze at 20dbu, which i have anyway!

will make 12-15mAmp versions just to experiment/play!

thanks
and
cheers !

99
Brewery / Re: Seeking a second opinion
« Last post by simonsez on August 18, 2019, 11:42:34 PM »
Sounds to me like he is trying to scam you.

Cheers

Ian

I believe it's not about money,  but something else.
100
Drawing Board / Re: Ampex 600/601 Tube mic & Line amp
« Last post by PRR on August 18, 2019, 10:09:59 PM »
> I realised my main PSU output is WAY above the expected values.... 370VDC.

So? Tubes love voltage. (Until something smokes.) That's not your distortion.

Measure voltages at all points. An unhappy tube usually shows unhappy voltages.

The plan posted earlier has V102B working into a large/infinite voltage divider with the Line Level pot. It may not be able to hump enough level into V105A for good output.
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