SLO build

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dcribbs1412
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SLO build

Post by dcribbs1412 »

Not sure there is any interest here but I started a SLO 100 watt build.
I'm gonna take it slow and see if I can build a decent amp.
Using C3 chassis, Smash boards( from slocloneforums) and MC iron( its monsterous!)
pre amp pcb pic

Darin
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Colossal
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Re: SLO build

Post by Colossal »

Interested. Pulling up a chair...
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Structo
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Re: SLO build

Post by Structo »

Cool!
Always liked the Slo. 8)
Tom

Don't let that smoke out!
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M Fowler
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Re: SLO build

Post by M Fowler »

Yup I'm a big fan of SLO and will enjoy lots of photos. :lol:

Can you build me one too, I can send one of my amps as trade. :lol:
Last edited by M Fowler on Sun Nov 03, 2013 2:29 am, edited 1 time in total.
Lindz
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Re: SLO build

Post by Lindz »

I built one of them last year. Sounds great and was a good challenging build for me at the time - first time using a PCB (the smash boards are nice by the way)

Hardest thing in my build was getting the OD channel quiet (hum) - still a little noisy but I recently bought a scope and hope that as I learn to use it I will be able to better see where the noise is coming from. Clean/crunch channel is nice and quiet.

I'd look hard at using either the DC or elevated heater options on the Power board since my first version was a little noisier with straight AC heaters. I have the elevated options populated on the power board and the heaters are essentially as quiet now as they are powered by a battery, which I tried as I assumed that the filaments may be the cause of the hum (Battery trick was Martin Manning's advice - thanks for the tip)

There is a long thread on chasing hum/grounding over there that you should read as well in terms of grounding issues and a resistor change needed for the 15v tap on the MC Iron for the LDR switching since the original schem assumes 6.3v - you will probably fry your LDR's if you use the value on the schem - saw a few posts of guys that did that. Can't remember what I changed it to off hand - it was in some guys post in the long transformer thread

I originally thought that the Soldano parallel style heater wiring (no twist) was causing the hum so I yanked it and put in twisted and it was not that. Should have used a battery to test it first as that style of wiring looks pretty clean and I would have left it for sure

couple cell phone pics of my build below
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John_P_WI
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Re: SLO build

Post by John_P_WI »

Oh Yeah! Now were talking Darin. Don't forget to read the gazillion page mod thread over at sloclone and serve me up a plate of Warren Haynes gravy....

Mmmmm Mmmm good.
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M Fowler
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Re: SLO build

Post by M Fowler »

Lindz great job on your SLO. :)
dcribbs1412
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Re: SLO build

Post by dcribbs1412 »

Hey guys
appreciate the interest...
Hope to not drag this build out too long
Nice build Lindz.
I will take your advise and use the heater option(not sure which)
The LDR voltage you mention is a concern...thanks for pointing that out.
I have a 15ohm resistor after the DB101 for the LDR's
I'm guessing I'll have to up that...(found a thread that suggested 75ohm 3 watt?)
...I'll have to do research on that.
Not sure how to calculate that.

There are a few mods for this circuit. Thinking of going stock at first,
but the Warren Haynes "gravy" mod and SRV mod are on a list of possibles if
I can get her sounding good stock.

Darin
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Turret
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Re: SLO build

Post by Turret »

Sweet build dcribbs1412, looks nice.

I'm working on something similar, also with Warren Haynes and SRV (with some changes) mods incorporated. I have decided to drop the photocells and use relays instead. I'll build mine on pair of KT66 too. What else... yeah - that will be made on VOX style tagboard, and I'm half way with my own layout.
Facebook Page with my amp plans
Lindz
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Re: SLO build

Post by Lindz »

I was pretty intimidated by this build back then as it was only my 3rd amp and because although it is a fairly well documented build there, I really had to read a lot about it in order to feel comfortable and pull it off without too many problems.

I seem to recall the PCB layout as shown for the panel switches where the 3 switches all inter-connect that bright switch did not switch correctly as shown and I had to change a couple connections there - I think the schem was OK.

Anyway, for the LDR's I took a look at my bookmarks and came across this tidbit about the resistor value in the switching circuit by a guy Baron55 (I think he is Baron Amps if I am not mistaken) - 130r was the value he calculated

"Here is maybe a simpler way to do this.

R61 with C31 forms a RC filter off the bridge rectifier. The load on this power supply to ground is formed by R63 and R64. Ths is a 80R load to ground.

If you run the calculatons thro a PSU simulator, a 6.3VAc into a FWB rectifier with the 15R resistor and 100uF RC filter and a 80R load will give you a supply volatge of approx 5.5VDC depending on transformer regulation. On the scematic is shows a measured voltage of 6.3 VDC This is probably due to the fact that the wall volatge is higher than 120Volts and the actual 6.3 winding is putting out more than 6.3.

So what you can do is increase the size of R61 to 130R this would drop the supply voltage down to approx 5.4 volts which is close to what the original circuit was designed to run at in the first place and variances in wall voltage which usually is higher will still keep you safe. This way you can leave all the LDR resistor values the same.
But use a higher wattage resistor do to the extra dissapation.


When you put the 15VAC tap wihout changing the switching circuit, you put close to 60ma on the led/vactols and the max rating is 40ma. So I bet they are fried."
Sargent
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Re: SLO build

Post by Sargent »

I am currently building a SLO100 PCB (MB-SLO100 Rev 1.3-Purple) made by Ampclones.com and cannot find values for C38-C40 on any of the material I was sent including the BOM. Does anyone know the values for these Radial Electrolytic Caps?
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dcribbs1412
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Re: SLO build

Post by dcribbs1412 »

Lindz wrote: So what you can do is increase the size of R61 to 130R this would drop the supply voltage down to approx 5.4 volts which is close to what the original circuit was designed to run at in the first place and variances in wall voltage which usually is higher will still keep you safe. This way you can leave all the LDR resistor values the same.
But use a higher wattage resistor do to the extra dissapation.
Thanks for the info Lindz
I really appreciate your time. Values added to my next order.
drilled chassis for pcb's and iron
pic of power cap...3/16" clearance, hoping this wont be a problem?
sargent...not sure about your cap values, strange they are not on your schematic or BOM... maybe contact the vendor?

Darin
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Lindz
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Re: SLO build

Post by Lindz »

my power board is just as tight -

re: Ampclones - I am not so impressed with that outfit. I thought I would try one of their builds and sent money for a chassis and PCB almost 6 weeks ago, and still no tracking info, no reply to my emails etc. I heard the quality of the boards is good but so far my experience with them is pretty bad. I hope I at least get the board/chassis in the end and its not money down the drain that I have to try and coax out of my credit card company

For those caps - You could probably figure out the value from the schem at Slocloneforums and by looking at the surrounding components on the board to figure out what it is from the schem. I am pretty certain they more or less knocked off the Sloclone schem for their boards (although it is not exact since there are 7 ldr's on your board looking at your picture)
Sargent
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Re: SLO build

Post by Sargent »

Took almost 3 months to get my boards. Took another two weeks to gather up the components. Still waiting on the LDR's. I am sure you will receive your boards eventually. DK is very difficult to contact at times and hasn't responded to my E-mail's requesting information. In addition, the schematic and layout contain discrepancies. The layout he has for the PSU for example doesn't correspond to the PSU PCB he sent me as his layout contains all axial electrolytic caps while mine has all Radial. Believe there are different versions of these boards and he may not yet have the latest revision. The layout for the mainboard PCB is very difficult to follow and the schematic is 'missing' components and some of the values for the same components are shown twice and are different. It has been difficult, to say the least, trying to figure it all out but I am finally at the point where I only require the values for the caps I mentioned. I am not an audio engineer. If I was I'd design and build my own amp. I will try your suggestion and see where it leads me. Thanks.
Okay. From what I discovered on the BOM, under 'Options' I have determined that these caps are part of the 'DC Heater Mod' and are 4700uf 16v Radial Electrolytic Caps.
Mainboard fully populated. V1 and V2 do not light up. Am thinking of removing all of the components for the DC Heater mod and running a jumper from V3 (pins 4/5 & 9) directly to V1 and V2. Checked voltages per schematic and all are within a few volts. With the exception of a few components that actually show the values most of the components on the PCB's are simply designated by a number which is directly under the components. This requires removing one side of the component to determine it's designation and recheck the values as per the BOM which is incomplete. There is a mini relay on the board which is not noted anywhere. Found one that fit the board but can't be certain it will work correctly with this circuit. Now that I have checked all of the larger voltages I need to check the voltages on the mainboard to determine if wrong resistor values are present. This is the first time I have built a PCB kit that didn't work from the get go and also the first that required actual detective work to determine the values for the missing components. Hope it's worth it.
I finally received a small schematic with the missing component values. The amp is now working but still have a few kinks to work out. BIAS is on the money and the amp has a super clean sweet sound. Unfortunately I don't have any distortion. Neither the OD or Normal gain pots provide any distortion. All the Clean/Dirty switch does is provide more volume on the 'Dirty' channel. Clean channel gets it's volume from Dirty Channel Volume pot. Not sure what to do now. Have sent another E-mail to Ampclones but no reply yet. If anyone has any ideas on where to look on the mainboard for a possible source of the problem please let me know. Thanks.
Last edited by Sargent on Wed Nov 27, 2013 8:18 pm, edited 4 times in total.
dcribbs1412
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Location: Arizona Desert

Re: SLO build

Post by dcribbs1412 »

A little more progress
...I think I have the 47uf cap in the right place for the elevated heater mod,
Along with the 100K and 1M
Used a jumper on the bias in...the MC iron has a 60V bias tap.

Darin
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