Feeler: Classic Solo

[funkymonksf]

Thanks! I figured the spst was actually a spdt, so that helps.

Now I am onto wiring the DI jack. It’s a S4 isolated, switch version (Amphenol) the 6 lugs are the same as Cliff. I’ve read the wiring DI portion of the instructions, but I’m still unsure how to wire the lugs to J4 & J5. In the picture of the Hammond case with the DI it looks like the screen is wired to the jack on both J4 & J5, but the instructions say not to connect screen to jack on J5. Can one of you enlighten me?

I want to be able to fully use the TRS for stereo equipment. What difference is there from the DI and Line in? I know one goes through the input transformer, so I more so asking what are the pros/cons and reasoning behind this? Why not go through the input transformer for DI? If you wired the S4 style jack for the line input would that change how it’s wired to the lugs? If so, how?

I know that’s a mouthful. Again, I’m grateful for all your help and input.

Cheers

 

[ruffrecords]

A DI is intended for high impedance unbalanced sources like guitars. Line inputs are usually intended for low impedance balanced sources. Except for headphones, TRS connectors are not used for stereo in pro gear; they are used for balanced mono connections.

For the Classic Solo DI you need a 4 lug jack not a 6 lug one.

Cheers

Ian

 

[funkymonksf]

Ok so with a 4 lug input, how do I wire it?

 

[ruffrecords]

Ok so with a 4 lug input, how do I wire it?

Ok so with a 4 lug input, how do I wire it?

Have you looked at the description of how to do it in the instructions? Go to the DIY page of my website.

Custom Tube Consoles - DIY

Scroll down and click on the Classic Solo folder then open the documentClassicSoloLoHumBuildInstructionsV0.2.pdf. Configuration #4 in this document describes how to wire a DI.

Cheers

Ian

 

[funkymonksf]

Yea, I’ve been over the guide on how to wire the DI. Maybe I’m not asking the question effectively. I simply am unsure on how one wires a switch jack. I understand how to wire a basic TRS jack, but throw in the switch lugs and I’m lost.

I also see the screen connected to the jack for both J4 and J5 in the guide’s photo (Hammond enclosure w/ DI), so that added to my confusion. You’re using a TRS vs TS jack, so maybe that’s why? I too, will be using TRS jacks as they are what I have.

I fear posting redundant newb questions… but here I am.

 

[ruffrecords]

Yea, I’ve been over the guide on how to wire the DI. Maybe I’m not asking the question effectively. I simply am unsure on how one wires a switch jack. I understand how to wire a basic TRS jack, but throw in the switch lugs and I’m lost.

I also see the screen connected to the jack for both J4 and J5 in the guide’s photo (Hammond enclosure w/ DI), so that added to my confusion. You’re using a TRS vs TS jack, so maybe that’s why? I too, will be using TRS jacks as they are what I have.

I fear posting redundant newb questions… but here I am.

No problem. It is always difficult to gauge the level of skill and knowledge when someone asks a question so I always refer them first to the documentation.

So, to answer you question directly. You can use either a 4 lug (TS) or 6 lug (TRS) socket. The only difference is you parallel the R and S on the TRS. (I am sure you know that TRS stands for Tip, Ring and Sleeve). So the type of jack socket you need is like the one attached - it is important it has the insulated fixing. You need to wire it as shown in the attached schematic.

So, looking at the jack socket you need to wire ring and sleeve together on the lright hand side of the socket. You can leave these two lugs on the left side unconnected,

The output of the mic transformer is connected to J5 on the PCB. So when the DI is unplugged we want this to be routed via the jacks socket to J4 which is the input of the first tube amplifier stage. The 0V of the transformer is already connected to the 0V of J4 on the PCB so we do not need to duplicate this because it could cause a ground loop but we do want to screen the signal from the transformer. So you connect a screened cable from J5 but you do not connect the screen at the jack socket. Instead you just connect the centre wire to the Tip pin on the left hand side of the jack socket (which is the one on the left).

The you need to connect the switched signal back to J4. So you need a screened lead connected to J4. The other end of this connects to the jack socket. The screen goes to Ring and Sleeve on the right hand side and the centre wire goes to the Tip on right side of the jack socket. And that is it.

Hope that helps.

Cheers

ian

 

[3nity]

Hi Ian.
I am about to start building or completing a Classic Solo pre.
Have you compared the carnhills vs the Edcors or outputs? Wich one are you liking better?

 

[ruffrecords]

Hi Ian.
I am about to start building or completing a Classic Solo pre.
Have you compared the carnhills vs the Edcors or outputs? Wich one are you liking better?

Both are very good. In some situations I and others have found the Edcors to be less susceptible to hum pick up. measurement wise there is nothing to choose between them. I use Carnhills simply because they are cheaper fro me here in the UK. The price of Edcors is encouragingly low but shipping costs are crazy.

Cheers

Ian

 

[funkymonksf]

I’m in the wiring stage and pretty excited to get this all completed and put to work!

I have yet to find any opinion(s) on how this pre sounds and functions. Although that may be due to a my own shortcomings in performing the right query.

For those who’ve completed and actually used this pre, what are your thoughts?

Btw, here’s a shot of the enclosure at this time (pre-wired):

 

[ruffrecords]

I’m in the wiring stage and pretty excited to get this all completed and put to work!

I have yet to find any opinion(s) on how this pre sounds and functions. Although that may be due to a my own shortcomings in performing the right query.

For those who’ve completed and actually used this pre, what are your thoughts?

Btw, here’s a shot of the enclosure at this time (pre-wired):

Cool. By the way, when it is finished can I ask you to send me some pictures of it, outsides and insides? I send these to my friend Pierre in Canada who hosts an independent gallery of DIY builds of my designs.

Also, most people say they love the way it sounds, but I am biased so take no notice.

Cheers

Ian

 

[funkymonksf]

Sure thing!

 

[funkymonksf]

Powers up. Looks good for the most part. This thing has gain for sure.

I noticed that the tubes don’t get that warm and V1 on both channels don’t light up. Or at least not enough to clearly notice. I’ve let them run for approximately 20 minutes and I can still touch both tubes comfortably. They’re warm, so I’m assuming they’re getting “heated”.

Is this to be expected?

Are there any junction or points in the circuit I can measure to ensure it’s being powered up and the currents flowing as designed?

I’m using the Antek AS-05T240 (50VA) w/ 240v and 6.3v going to there respective ports as shown in the documentation.

I measured 364 volts at the positive C14 on the PCB #2.

It’s really difficult and reasonably scary to move around the circuit as it’s in a tight fit (see pictures).

Any input is appreciated!

 

[funkymonksf]

Also I see in the docs that pads A & C, B & D need to be connected if using 6.3V. This poses a problem as I’m using the original “V1” Classic boards and they don’t have those pads.

Any wisdom on this is greatly appreciated.

 

[ruffrecords]

Also I see in the docs that pads A & C, B & D need to be connected if using 6.3V. This poses a problem as I’m using the original “V1” Classic boards and they don’t have those pads.

Any wisdom on this is greatly appreciated.

The Classic Solo went through several revisions. I just checked the PCB layout. The board you have is the first version designed for use with 12V heaters. You are powering them from 6.3V which explains why you can barely see the heaters and why the tubes only get warm. The V3 had the links for 12VAC or 6.3VAC but your board is different.. Here is a pic showing how to fix this:


First you need to cut the heater track between V1 and V2 shown as the red rectangle under C. Then you need to add two wire links as shown in red from the tube pins to the pins of the heater AC input connector. If you do this the tubes should light up properly. In normal operation they do get rather hot.

Cheers

ian

 

[funkymonksf]

For 2 channel builds, using the Lo-Hum pcbs, do you need the variable resistor (VR-1) on both pcbs?

 

[ruffrecords]

For 2 channel builds, using the Lo-Hum pcbs, do you need the variable resistor (VR-1) on both pcbs?

If you are running both boards off a single heater supply then you only need to fit one. Adjust it for the lowest overall hum.

Cheers

ian

 

[FarisElek]

Anyone have any advice on how to get the hum down on those smaller hammond cases? I've tried everything and I just can't seem to get it down. I think it might be partially a ground issue, as hum isn't bad at all when I use condensors and as a DI. Dynamic mics are BAD though I can only turn up to about 50% of the way before it's quite noticable. I made some quirky deicisons when I built the preamp and I think they may account for most of the problem. For instance, I put a bulb at the front of the preamp to display when It's on, and it's powered by the heaters. Which is probably too close to all the audio components.

Ryan

 

[ruffrecords]

@Ryan: if you post a pic of the innards of your classic solo it might give us a clue as to what things you could try to improve the hum.

Cheers

Ian

 

[My3gger]

Both are very good. In some situations I and others have found the Edcors to be less susceptible to hum pick up. measurement wise there is nothing to choose between them. I use Carnhills simply because they are cheaper fro me here in the UK. The price of Edcors is encouragingly low but shipping costs are crazy.

Cheers

Ian

I have Edcor WSM 600:150 output transformer with the same ratio as 2400:600 used for Classic Solo, it was meant for SS project. Would inductance of 600:150 be way off compared to WSM 2400:600?

 

[ruffrecords]

I have Edcor WSM 600:150 output transformer with the same ratio as 2400:600 used for Classic Solo, it was meant for SS project. Would inductance of 600:150 be way off compared to WSM 2400:600?

Quite probably yes. It will probably have half the turns of thicker wire. Inductance will be a quarter of what it should be. So it might work but there would probably bee some bass loss. If you do try it let me know how you get on.

Cheers

Ian