A while ago I got a rack unit with this toy, well, to be precise it's actualy the chassis containing the transformer and an empty pcb.

I was curious about the schematic, but that was a dead end. At some point, in the forgotten depht of the internet, I came across the schematic of the Ibanez Starfield SVA1, it's a 2x50W valve amp and preamp, and the preamp has the same controlls as mine. I compared the first part of the preamp schematic with my empty pcb, looks like the preamp is the...

Very interesting for those who want to understand what is going on in the Bassman and its derivative Marshall amps (and how they compare).

Here's part one:

Part two:

I would like to build the footswitch shown in this schematic

I don't have any experience at all with something like this and i would like some guidance please.

I presume that the unmarked diodes are 1N4448 as indicated in the text, but what voltage, current and wattage rating would they be?

Are the footswitches latching or momentary? on/off or on/on?

What voltage LEDs would I need to use and do they have to be red?

The socket symbol is unknown to me, I am confused by the arrow...

anyone have a schematic of HH bass amp with tremolo circuit buil in... (year 69-70)???
thank you in advance

Hi Guys,

I really want to transform my Valve Junior into a push pull amp.
Preferably EL84 again, but suggestions are welcome.
Can I use the power transformer? It is rated 260V at 0.09A (23.4 Watts)?
6.3V Filament power is not an issue. It's got plenty for that.

the issue is I need a power amp with voltage supply LOW enough to meet the current draw restrictions. This is 90mA, yet with the preamp in mind, I think this should be 85mA max.
The lower output as trade off is completely acceptable,...

Hello all I was wondering if anyone knew of any good books on the subject of power supplies in tube amps. I been planning on building a preamp section of a Laney Supergroup LA60 which looks like it is close to a Marshall with a few value changes. I imagine there’s really no one size fits all power supply to power it all up so I imagine I’d have to read up on the subject if I wanted a power supply that wasn’t noisy and powers the whole thing efficiently. Also a question I have is on the LA60 I...

This is a cheap little 5W chinese head I picked up in 2018. It was $99 shipped! The seller was even nice enough to send me the factory schematic on request. :D (attached)

Here's the specs:
• 5 watts via 1x EL84 and 1x 12AX7 (Chinese tubes, of course)
• Treble, Bass, and Volume controls
• 1W and 0.1W attenuation modes (slide switches on rear)
• 8 and 16 ohm outputs

Not a crazy complex amp, but definitely not just another Valve Jr variant. It's definitely worth $99 at the very least.

4 way footswitch for Randall RG100G3

switches are SPDT latching type

Hi there, I'm restoring a guyatone ga-960 black5. So far so good. The problem is that the reverb volume is as loud as the volume coming through each channel. The reverb signal also sounds like it is getting all the frequencies that are going through the channel. I figured the input capacitor may be blown 500pf, but then that would also leak hum from the b voltage......I can post a schematic. Just wondered if anyone had thoughts or had experienced this. It is from the early sixties, maybe this...

Hello guys recently I bought a used Marshall VS15 (8015), but sometimes the sound fails, and I don't no how it happens. I'm searching for a schematic or a service manual from this amplifier.

Please help me.

Thanks

Hi,

I want to mod my fender aa864 to add a master volume ( post phase inverter ). But I have a question... The cable thick does matters? The cable that I have is a XLR mic cable.

thanks.

What are the main issues to be addressed in DC amplifiers? I hope to receive your answer, thanks in advance.

I have a Mesa Boogie Mark IV that doesn't fully power up or produce sound. When powered the tubes glow, but nothing else shows power. The amp doesn't make any sound but a decent hum that does change messing around with a couple dials. Where do I start?

Some years ago I found a web called ampclones, that sell kits for build amps. But now this webpage is down. Anyone have the pcb's for build a Mesa Boogie Mark II? or the layouts?

Thanks.

Hi

I would like to learn the theory of tube amplification and characteristics of tubes in order to design and test a basic tube preamp. Its gonna be a long road and I'm just starting out. I've got some experience. Built some pedals and basic amp kits but I'm ignorant to a lot of the theory.

I am reading about common cathode stages using a triode. Im beginning to read about load lines and how these can determine gain/headroom characteristics but getting caught up on some of the terminology on...

I prepared these images for a GK800RB restoration project I was working on a while back. I ended up repairing the original power amp board instead of etching a new one from scratch.

I thought it would be a good idea to archive these drawings here just in case they could be useful to someone else in the future.

NOTE: these have not been verified. I have triple checked my work, but I cannot guarantee that they are 100% correct.

If you find any errors, please post them here and I will...

hello people of the planet freestompbox..

i have a question how many amperage of the diode bridge if i use a transformer 220volts on primary and 15-0-15v on secondary and its a 6 ampere transformer??

I saw one of these for sale locally, did not find a lot of information but did score a schematic on some odd site. Haven't bought it (yet).

Once you make it through the annoying intro the demo quite nice. Sounds a bit thin, though... but that's probably the speakers. Still has potential I think.

Hey I'm making someone a cabinet merger and was working with some really heavy gauge wire, but its kind of a pain in such a tiny box with small jacks. Would it be OK for me to just use small gauge wire for such a short distance or would that limit the wattage he could use?

Hi everyone, first time poster here. Anyways I wanted to see if anyone has, or would know how to ad an fx loop to an Orange micro terror. I know someone built a clone from the schematic found here . After doing some searching around, it seemed that the lack of a schematic is what kept people from trying it but maybe I'm wrong.

Thanks!
-Justice

I have two handwired chinese 5f1 champ clones, one a Golden Ton Smart-10 and one a Storm Smart-10.
The look identical but they sound very different. I would like to understand why.

One is quite bright and the volume control works as expected. It also takes a while to warm up and pass sound. Let's call it A .
The other one passes sound instantly, is darker tonally and the volume control works almost like a linear pot, even though it is an audio pot. Let's call it B .

Today I took them apart to...

Hi guys,

Any suggest?

I need only power amp section.. To use with another preamp.

Someone Can give me some idea?

Thank you..