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  New member
Posted by: sinusoids - 02-14-2019, 12:55 PM - Forum: New Member Introductions - Replies (2)

After all these years, reading the books, I have joined the forum.  I have built several of the TUT amps, modded more, installed SV1 and 2 and bias kits and built a couple of audio amps (PP and SE) based on and from POP.  Also have read (and built a few projects from) glass audio, audioxpress and VTV.  And I really enjoy this as a hobby.  

Presently building the ToT amp on 2 chassis to enable easy, easy mod and experimentation.  Power supply and PA on the bottom chassis and the pre mounted above, with the hammond chassis cover on top and 12AX7 under.  I also sold my most used combo, bought a 2x12 sealed pine cab on ePay and am loading with 1 driver (taking the idea described in SPKR).  I did not opt for a Force12.  like to hear one in it though.


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  Help with Relay Switching ala the Jim Kelly Project SOLVED
Posted by: makinrose - 02-09-2019, 02:17 PM - Forum: Switching - Replies (3)

Hey guys I started a build that uses the simple relay circuit from the Jim Kelly project in TUT 5 and need some help. I haven't done any relay switching before so my problem is not leaping out at me.  

The pre-amp I'm using different than the Jim Kelly but the concept of how I wanted to switch the channels is the same.  My problem is the when I switch channels the relays I'm using are make no connection at all when the panel channel switch is in the open position.  When it is closed and grounding the relays go the Normally Closed position. 

I'm using the Hammond 272JX and using the 5V taps with the same power supply circuit as the Kelly project.  I'm using this 12V relay:

With the panel switch closed I'm getting ~12 VDC on the positive terminal on the coil and 0 VDC on the negative terminal.  With the panel switch open I'm getting ~13.5 VDC on both the terminals. 

Any ideas?  Thanks!

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  10W amp
Posted by: jmcd - 01-27-2019, 10:58 PM - Forum: Personal Projects - Replies (9)

Hi Gang,

My latest build uses KOC's 10W power transformer (by SumR), KOC's 3H choke (by Hammond), a power-supply PCB (my own design, but borrowed KOC's bias supply), and a turret board for the pre- and power amp. It's got quite a bit of gain on tap. Vintage and modern modes accessible via the front-panel Era switch.

[Image: RD9gikNh.jpg]

[Image: JFKxoVIh.jpg]

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  Silverface Bandmaster Reverb
Posted by: TiCatFan - 01-19-2019, 07:36 PM - Forum: Personal Projects - Replies (11)

The Bandmaster has been out of service for a long time, 25 years maybe? Retired, getting back into electronics. Working on the power supply. Wondering if anyone could suggest good suppliers of electronic parts ( caps, resistors ect), preferably in Canada.


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  Question about the Sigma Project
Posted by: makinrose - 01-05-2019, 12:21 AM - Forum: TUT Q&A - Replies (2)

I'm thinking about building the Sigma as floor based unit with the switching on the unit itself.   Since the unit is going to be remote form the amp with 20ft cable is there any concern about signal loss?  Would it be wise to have cathode follower or transformer to have a lo-z out or is that non-issue?


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  Power Supply Caps Replacement (Blues Deluxe)
Posted by: NGW - 12-17-2018, 10:11 PM - Forum: Power Supplies - Replies (2)

Hi TUT Team,

I have a Blues Deluxe on the bench which needs some attention, including replacing the leaky IC brand HT filter caps.
I have replaced quite a few IC caps in the past, on Fender Hot Rod series amps, using better quality caps.

This amp dates from the mid-'90s and I am wondering whether I should replace the filter caps for the 16V SS supply (C38, 39, 43, 44) and the Bias supply (C37, 40) also.
The reason I ask is; with the flimsy PCB traces and the difficulty removing the solder from these flush mounted radial caps, without damaging the traces, I don't want to add to the cost to the owner and the aggravation to me if they don't usually give trouble. 
I haven't seen any problems with them in the past, but due to the age of this amp, maybe I should persevere and replace them.

Have any of you blokes had problems with these caps, or do you recommend replacing them anyway?

Cheers, Noel.

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  Amp Giveaway - V2 Vibe
Posted by: jmcd - 12-17-2018, 03:15 AM - Forum: Gear for Sale by Forum Members - No Replies

Hi All,

First off - I'd like to thank Kevin for helping me learn to build amps. I've always appreciated his willingness to answer my rather basic questions. 

I've decided to give away an amp that I recently designed and just finished building. It sounds pretty good to my ears. It more-or-less follows TUT design (except with one node of the power supply is shared by two preamp stages - sorry KOC). Distributed filtering, galactic ground scheme, bias adjustment for each power tube. The output section has a pair of octals (6V6; also works well with 6L6) with fixed bias. The preamp has two parallel inputs (bridged internally, of course) and one or two 'twists' that enable the user to go from plexi-ish levels of gain to JCM+ levels of gain.

So how and why am I going to give this amp away? Most of those details will be revealed soon (once I figure them out). I'm pretty sure I'm going to run the 'amp lotto' on my own website or facebook page, and I'm also pretty certain that I won't include a head shell. 

Here is a snapshot of the amp chassis sitting in my lovely black-tweed head shell (that is definitely not up for grabs).

Happy holidays,

[Image: Fb5hoCeh.jpg]

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  Is TUT7 in the works?
Posted by: jmcd - 12-12-2018, 02:38 AM - Forum: TUT Q&A - Replies (2)

And if so, what topic will be covered? 

-- John

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  Traynor Mark 3
Posted by: jmcd - 12-07-2018, 01:00 AM - Forum: Personal Projects - Replies (10)

After re-reading the tube amp FAQ on the LP website, I got a hankering to modify a Traynor Mark 3 with the standard preamp (LPSP). I found a reasonably priced combo in which the stock speakers were replaced by a pair of 16-ohm Jensen Nighthawks. The stock 

The stock speakers are 8R in parallel, so I'd like to know whether the Mark 3 can withstand this impedance mismatch.

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  Master volumes
Posted by: jmcd - 11-24-2018, 03:11 PM - Forum: Preamp Mods & Design - Replies (10)

Here are a few questions about master volumes (not all of which are conventional preamp MVs, so feel free to move this thread elsewhere).

1. According to TUT, the addition of a series 100k resistor between the wiper of a conventional preamp master volume and the PI fixes the low-end roll off. But how does this happen with a series resistor and the series capacitor?

2. In the long list of FAQs on the LP site, it states that the LP-MV automatically keeps the depth of the presence effect proportional to the signal size. Is the LP-MV identical to the bootstrapped MV shown in TUT4 (the one with the dual-ganged pot), or is there an additional circuit to vary the depth of the presence effect?

3. I have yet to try the SL-MV, but I am guessing that it has no effect on the presence control. Is this correct?

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Come in where it's warm!
A warm welcome to those interested in tube and hi-fi audio! Fans of Kevin O'Connor's The Ultimate Tone (TUT) book series form a part of our population. Kevin O'Connor is the creator of the popular Power Scaling methodology for amplifiers.
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