stay at home type 69 project

[mdcmdcmdc]

what TwentyTrees says seems right to me. Omit the EQ switches, inductors, caps, and pots. Short R25 and R35, omit C43, and use SW7 and R36 as your pot wiring point. Top of travel at SW7-3, wiper at SW7-2, and bottom of travel at bottom of R36 / com.

I'd also start with R43 omitted. This is the gain set resistor in the second 2128 amplifier. When it is omitted, you get a unity gain follower.

Sounds good - unless I'm misunderstanding I think we're saying the same thing:

(apologies - I was also just taking the omission of all the EQ related stuff as a given, I should've clarified in my first post)

R43 omission also noted - ty!! And once again, a huge thanks for making the project available!

 

[dogears]

looks good to me

 

[oongbac]

Recently I did silly mistake. One day I connected UA Dream 65 to my DIY H9M. After some minutes H9M make some noise like the wild wind and soon stopped working. I assume that symptom is from too hot signal I fed. After I replaced regulator, it's all okay now. It's really nice with E.Guitar!

 

[mdcmdcmdc]

In lieu of trying to mod the full pre/eq PCB to just use the pre section, matt was kind enough to send over a modified pre-only version. Finished up 4 channels last night, all seem to have fired up no problem, just need to get myself sorted out with the panels and away we go.

Just testing them out with a 635A at home, they have a tonne of gain and turn into distortion boxes quite nicely, Should be a really fun set of affordable pres for tracking drums. Taking out the stepped gain switch and the inductors brings the cost per channel down to about $150CAD each, plus whatever you spend on panels.

Thanks again to Matt/dogears for being so generous with his time and expertise on this project!

 

[TwentyTrees]

Hey, nice! It's a really nice sounding preamp, makes sense to work up a trimmed down version of the input module.

 

[mdcmdcmdc]

Thanks! I'm happy to finally have gotten some forward progress after hemming and hawing for a year. I have the parts on hand (minus xformers) to do 4 more channels, so I'll hopefully get around to that before too long. I might try and track down a couple different transformer options to see if there's any practical difference between the hammonds and anything else.

Has anyone had any luck ordering lustraphones from Cyril J?

 

[Chris Lima]

I tried to buy from Cyril in December. I actually paid for 2 transformers, but he no longer responds to my messages...
I suggest you to buying from Sowter.

 

[fritzmyname]

Classic.

Are those transformers worth the hassle? I mean Cinemag and Jensen are good too, right?

 

[Whoops]

Classic.

Are those transformers worth the hassle? I mean Cinemag and Jensen are good too, right?

Well,
Cyril Jones transformers are the only transformers that are exact clones of the original Lustraphone transformers,
it depends how close to the original you want to go in your project.
But the high number of complains of Cyril not replying to messages and emails, which has been happening for years now, is a deterrent for sure.

Cinemag are Great yes, as for Jensen the reports after the takeover from Radial have not been good.

 

[craigmorris74]

Here you go:

View attachment 116451

Make sure the switch wiper is within the range you want, then pop one pin in the "zero" position and one in the appropriate hope for six or eleven stops. Caveat - check everything first, as those pins are very hard to remove if you get it wrong!

Potentially stupid question, but if the pins are inserted like this, how will the indicator line of a knob line up with the values on your faceplate design?
Thanks,
Craig

 

[fritzmyname]

The actual knob is is put on after the fact. So no matter how the entire grayhill (or pot for that matter) is rotated behind the faceplate, you put the knob on, so that it points at the numbers correctly. It‘s just relative to each other.


Maybe it becomes clearer if you think about it as a pot. Say you’re building a guitar amp or a pedal with numerous controls (volume, gain, bass, middle, treble…). You install the pots and the frontplate. Next you have to install the knobs - but how do you know where „0“ is? Easy, you just turn the shaft counterclockwise till it won’t go anymore. Then you screw on the knobs with the pointer all to the left. But as you can see, it doesn’t matter how the actual pot is located behind the faceplate as long as the shaft is all the way ccw! (You could also turn the shaft all the way clockwise and install the knob/pointer to the right).

So now with the grayhill, you just have to make sure that it‘s set to a position you know. If you have 6 stops for gain, you can rotate the shaft either way till it stops. So then you install the knob onto the shaft (pointing at either the highest or lowest number depending on how you set the shaft).

The ONLY IMPORTANT thing is that you don’t move the shaft before you installed the stop pins or you at least remember how the shaft (it has a little dent) was set.

 

[Brian Roth]

Assuming the switch shaft doesn't have a flatted side.....shrug.

Bri

 

[fritzmyname]

Assuming the switch shaft doesn't have a flatted side.....shrug.

Bri

The grayhills I’ve encountered typically have a flatted side

 

[craigmorris74]

Assuming the switch shaft doesn't have a flatted side.....shrug.

Bri

Right, I've attached images showing what I'm talking about. If I install the pins according to Twentytrees's instructions, when I put the knob on the switch, the indicator points in the wrong direction, because of where the flatted side is the switch. Is there a specific type of knob I should be using?

 

[Spacecowboy]

You have to use a knob with a set screw, or with a replaceable indicator. Or, you have to plan in advance on pcb design where you put the positions vs where the flat will be.

 

[craigmorris74]

I just finished up two channels of H9 without the buffer, using the Sowter transformers (Ver 1 board). I powered the first one up, and it's passing signal, but only distorted transients like other people reported earlier. Should I swap a 7908 and D2 like others did to fix the problem?

 

[Spacecowboy]

If you’re using the older design that has a problem, yes, you should switch to the newer design

 

[Cyril Jones]

Well,
Cyril Jones transformers are the only transformers that are exact clones of the original Lustraphone transformers,
it depends how close to the original you want to go in your project.
But the high number of complains of Cyril not replying to messages and emails, which has been happening for years now, is a deterrent for sure.

Cinemag are Great yes, as for Jensen the reports after the takeover from Radial have not been good.

Cyril Here, apologies . Due to a nasty virus hit on Dec. 26th via an incoming P Pal transaction taken twice to so calledib respected company locally who failed to nrectify however a local engineer cleared this situation last week in 10minutes so catching up. Apologies for the situation, just prooves barriers may be broken. A very long period to be closed down.

The Lustraphone transformers are in stock.

A very trying time. Cyril

 

[samic]

interesting project!
I wonder why using the bc550c compared to the 2n5088?
did you make a comparison?

 

[dogears]

in this circuit they will behave much the same. the BC550s have a better noise figure, at least on the datasheet.