Someone mentioned this in the comments recently (thank you ClassicFuzz), so I thought I'd have a look at the photos on Reverb.
The Goldie is a MKI in a MKII enclosure from March 2022, likely to be inspired by this unit found in Germany - which is an absolute train wreck of work.
It looks a lot like a MKII board, it even has a cap to ground on the input - a full set of OC82 transistors is also more likely to be seen on a MKII. That’s about where the differences end - a nice nod to a MKII, but it’s definitely a MKI.
This Goldie should not be confused with the other Goldie, which is a MK1.5 - confusing no?
SOLA SOUND / D*A*M GOLDIE MKI TONE BENDER - 0.15" VERO LAYOUT
Apart from construction, the most obvious difference to a regular MKI is the cap to ground on the base of Q1 (the silver polystyrene cap). I haven't been able to spot the value anywhere - thought I could vaguely see an n3 on one, meaning that it might be a 3n3 or similar low-value cap. D*A*M have used a 3n3 on the input of some MKIs in the past, so probably a safe bet that this is the same.
I also haven't put eyes on the value of the brown box cap, which is most likely 100n (standard value). Same for the input cap, I'm assuming 10n as a standard value, but you never know.
Below is the version with the extra resistor in parallel with the 470k which would change the biasing of Q2. It also appears to have a 47k resistor instead of a 56k resistor on the output. 47k vs 56k makes very little difference. A slight change to the HPF that it forms with the 100n cap, but not much to worry about (34hz vs 28hz respectively). There's probably a similar range of variance just with normal component tolerances.
That's nice! The capacitor to ground is, for sure, to send some screeching out if the trannies have a high HFE! Usually works well until 4n7, more, and for me, it eats a lot of the high end of the circuit.
ReplyDeleteHi Mister Hate - makes sense. I have a MKI sitting on my breadboard at the moment, I’ll try some values and see how it works.
DeleteDoes this always work or do the transistors need to have higher hfe? I am just wondering as I thought OC82 were mostly low gain.
DeleteUsually I have the sizzle and screeching noises when the transistors are higher in gain than what the circuit wants.
DeleteWith low gain usually there's no noises but the sound is kind of bland and unexciting.
If you read in the Zonk comments from here I talk about using a capacitor from input to ground to fight the bacon sizzle, but in this case the capacitor is in the board not offboard as usual.
ClassicFuzz: I guess we don't know the design intent or specifics on the transistors, apart from the fact that they work in a MKI circuit. I'll have to try and find a video - surely Ant Macari has done one?
DeleteMister Hate: I'm yet to have screeching noises. What transistors were you using? I think the highest gain I've probably used has been around 120 with an OC44s and they were quiet.
It's true that this gonna happen a lot more with the Zonk circuit than in a MKI, but, well I tried crazy things with OC43 (HFE +250) and the sizzle were there 😂.
DeleteMaybe this is the reason, to find a place to use the oddball ultra high gain ones he had in the bin... Who knows?
The only thing for sure is the extra cap will take some high frecuencies to ground.
Fair enough - have never gone that high with the hfe. I'll have to give it a try, just to see what happens
DeleteThat was quick. Thank you! :-)
ReplyDeleteNow this one is also on my list. It seems to be very close to Pigdogs 2022 "System" MKI, the only difference being the value of C3.
I am suprised about the transistor selection. Aren't those their favorite unicorn transistors for the MKII?
I think the transistor choice may be a nod to the MKII.
DeleteThe MKI plot thickens. I've never thought about cutting high end from an MKI, even with a Jazzmaster. I agree that values up to 10nF do a good job of taming the hiss and radio stations.
ReplyDeleteAnyway I'm still looking for a transistor with about 150uA of leakage and >100 hFE for Q3 so I can get the collector closer to -8V. I find if the voltage gets too close to -9V there are too many artifacts in the decay of the notes. Artificially lowering the voltage by increasing the 15k on the collector kills gain and high end. What a finicky circuit, I'm surprised you're able to churn out so many.
Confirmed, just build it. I used 3n3 for the unknow capacitor and as a compromise 51k on the output. Soundswise its very close to the Sola Sound Ltd, but it has more oomph which I very much like. The Sola Sounds has always been a touch too high-pitched (is that the right word?) for me.
ReplyDeleteNo its time for a golden MKII enclosure.
Great - more oomph can never be a bad thing
DeleteAnother Blind Test is ready. DM me if you are interested. This time 6 different versions.
DeleteHmmm. Can my ego cope with the humiliation? 😂. I’m up for it.
DeleteI guess my idea to use a 51k wasn't that bad. Maybe this also clarifies why David Main used both 56k and 47k.
Deletehttps://www.flickr.com/photos/195631300@N04/52090755027/in/album-72177720299167393/
Just to be on the safe side, the cap to ground on the base of Q1 does not change the sound, right? If it doesn't, I could use a 68n cap instead of the 10n for the input and end up having a 'Golden Phoenix', right?
ReplyDeleteThe cap to ground on the base has to shave some treble (this is why you here more oomph probably) if you put more than 10nf you will hear a lack of treble.
ReplyDeleteYes, same experience.
DeleteYay, the last comment was me!
ReplyDeleteAnd the reply to was me :)
DeletePity, I would have loved to have both in the same enclosure.
ReplyDeleteBtw, for all of you, here you can see the original in more detail, thanks to Nick Sternberg: https://www.flickr.com/photos/195631300@N04/albums/72177720299167393/
ReplyDeleteThanks - the original has different some different values here and there. Dave Main may have matched the circuits sonically, but did not replicate the component values. examples: 51k resistor to ground on the output, output cap appears to be 50n, not 100n. The original doesn't appear to have the small input cap to ground either.
Delete