Search found 115 matches

by Optical
15 Aug 2021, 22:52
Forum: DIY Projects
Topic: Baja Presence and Resonance 091118 [documentation]
Replies: 44
Views: 47032

Re: Baja Presence and Resonance 091118 [documentation]

andersrain wrote: 13 Jul 2021, 17:51 it is possible to make this modification?
Image
These tubes should have a flat frequency response from any given circuit.
That switch might be a as simple as altering the clean headroom - a selection of clipping diodes perhaps.
by Optical
21 Jul 2021, 22:18
Forum: Amplifiers
Topic: Suhr Reactive Load [schematic]
Replies: 152
Views: 76437

Re: Suhr Reactive Load [schematic]

Interesting, I'll try that.
I should mention it only gets warm when the amp is absolutely cranking. But I'll see if there is any audible effect from the position!
by Optical
18 Jul 2021, 21:14
Forum: Amplifiers
Topic: Suhr Reactive Load [schematic]
Replies: 152
Views: 76437

Re: Suhr Reactive Load [schematic]

On mine the part that gets the hottest is the air-core inductor. - with a 100W tube amp
I'm using the nichicon caps that someone mentioned here earlier. They get a little warm but nothing to worry about.

Image
by Optical
22 Jun 2021, 00:32
Forum: Amplifiers
Topic: Mesa Boogie Mk I input resistors
Replies: 4
Views: 1584

Re: Mesa Boogie Mk I input resistors

Agree both are likely right, Mesa changed the circuits all the time in those days.
It's so trivial anyway, why not try both and see what you prefer?
by Optical
17 Feb 2021, 03:43
Forum: Amplifiers
Topic: Suhr Reactive Load [schematic]
Replies: 152
Views: 76437

Re: Suhr Reactive Load [schematic]

The mark III output isnt isolated (just a divider on the output), so you might have ground loop issues.
But you can add the line transformer isolator easily to resolve

I also have a Mark II (green stripe), great amps
by Optical
15 Feb 2021, 01:47
Forum: Boutique Stompboxes dissected...
Topic: Laney Black Country Customs Tony Iommi Signature Boost Pedal
Replies: 35
Views: 10672

Re: Laney Black Country Customs Tony Iommi Signature Boost Pedal

That input stage is interesting, dont think ive seen that before. Anyone know what that's about?
by Optical
10 Feb 2021, 08:22
Forum: Pimp-My-Cheap-Pedal
Topic: Line 6 M5 mod suggestions
Replies: 2
Views: 2019

Re: Line 6 M5 mod suggestions

Yeah maybe a footswitch operated snapshot change wired to the expression input
There are a couple of signal path mods Ive read about but havent looked into it much
by Optical
28 Jan 2021, 23:20
Forum: Amplifiers
Topic: Valveste 8080 copy EXPERIMENTAL tube gain stage mod
Replies: 19
Views: 5267

Re: Valveste 8080 copy EXPERIMENTAL tube gain stage mod

Those bypass caps will add a lot of gain for sure.
If the tube is clipping, the signal level wont be any greater coming out of the tube stages. However, you could replace R13 and R14 with a pot to control the level, or just R13 as a variable resistor actually...
by Optical
24 Nov 2020, 23:29
Forum: Amplifiers
Topic: ADA MP1 into a pedal
Replies: 39
Views: 8563

Re: ADA MP1 into a pedal

That's cool.
Def need a buffer before the gain control - Probably any FET buffer will sound the same, there's no tone shaping going on that I can see.
by Optical
18 Nov 2020, 02:51
Forum: Amplifiers
Topic: ADA MP1 into a pedal
Replies: 39
Views: 8563

Re: ADA MP1 into a pedal

btw what are you doing for an EQ?
by Optical
18 Nov 2020, 02:48
Forum: Amplifiers
Topic: ADA MP1 into a pedal
Replies: 39
Views: 8563

Re: ADA MP1 into a pedal

I'd be inclined toward ditching that whole input stage and replacing it with a clean boost into that 33n cap on the U4 output. There isnt any frequency shaping that i'm aware of within the input stage, so a simple noninverting opamp with variable gain might do the job.. Have you tried shorting that ...
by Optical
18 Nov 2020, 01:38
Forum: Amplifiers
Topic: ADA MP1 into a pedal
Replies: 39
Views: 8563

Re: ADA MP1 into a pedal

what's your power supply for U4? The diodes in the feedback path are designed to clip before the signal hits the rail and clips the opamp. The MP1 has +/-15V on the opamps
Might be clipping the opamp on your setup?
by Optical
18 Nov 2020, 00:51
Forum: Amplifiers
Topic: ADA MP1 into a pedal
Replies: 39
Views: 8563

Re: ADA MP1 into a pedal

I hooked everything up, and does not sound good. I now it has something to do with the U4 op amp circuit. When I turn the gain pot up it is clean until up to 8 of 10 then starts to distort. Then at 9 of 10 it distorts way to much and feed back is uncontrollable. I removed the U4 op amp from the pat...
by Optical
18 Nov 2020, 00:45
Forum: Amplifiers
Topic: ADA MP1 into a pedal
Replies: 39
Views: 8563

Re: ADA MP1 into a pedal

caspercody wrote: 16 Nov 2020, 21:19 Is C34 47nf?

Do the (4) diodes in the op amp U4 look to be 1N4148?
Yes and yes
by Optical
16 Nov 2020, 20:15
Forum: Amplifiers
Topic: ADA MP1 into a pedal
Replies: 39
Views: 8563

Re: ADA MP1 into a pedal

I have an MP1 in pieces on my desk. R92 is 510, but as said it doesnt matter much.
The input buffer could probably just be an opamp. I cant remember the explanation of that input circuit and why it was used, I believe it was just intended to be a high impedance buffer
by Optical
13 Nov 2020, 04:22
Forum: Amplifiers
Topic: ADA MP1 into a pedal
Replies: 39
Views: 8563

Re: ADA MP1 into a pedal

U5 is an opto-resistor controlled by the microprocessor. Essentially a pot and is the main gain control. You can use a pot there instead for a pedal. T2 in the feedback path of U4 is a gain trimmer for pickup variations, and also probably because U5 had a wide tolerance range between units, so the t...
by Optical
13 Nov 2020, 00:37
Forum: Amplifiers
Topic: ADA MP1 into a pedal
Replies: 39
Views: 8563

Re: ADA MP1 into a pedal

Cool project Q6 and Q7 are a high impedance input buffer U4 is the processor controlled gain control U5 is a pcb mounted gain trimmer with clipping diodes to avoid opamp clipping (supposedly to allow gain trimming to match the input response across various high/low output pickups) Q3 is active on ga...
by Optical
15 Sep 2020, 21:50
Forum: Amplifiers
Topic: power amp for Eleven Rack?
Replies: 9
Views: 2787

Re: power amp for Eleven Rack?

I had an elevenrack a while back. It sounds reasonable with either a solid state or tube power amp. There are power amp types you can switch in the settings to fiddle with the response. Overall I thought it sounded a bit average however. The ADC and DACs were good though so it's a quality interface....
by Optical
12 Aug 2020, 02:20
Forum: Amplifiers
Topic: Suhr Reactive Load [schematic]
Replies: 152
Views: 76437

Re: Suhr Reactive Load [schematic]

I figured - thanks.
I'm wondering if the enclosure might affect the inductance of those coils, the bass resonance models to quite a high frequency. Are you able to test whether the inductor values change when the enclosure is assembled?
by Optical
11 Aug 2020, 22:41
Forum: Amplifiers
Topic: Suhr Reactive Load [schematic]
Replies: 152
Views: 76437

Re: Suhr Reactive Load [schematic]

Here's the schematic. Values for the inductors were measured with my Atlas LCR. They match close to off-the-shelf values for speaker crossover inductors. Should be an easy DIY if you're interested. The isolated grounding is smart and works well. Can't speak to whether it would sound better with a p...