Glenn Studio Amplifiers

In my experience, rectifiers often do have a "sound". And I wonder if it might be due to some of the same reasons you list above? It seems to me that instead of putting an analog signal on the grid, in the case of a rectifier, an analog 60 Hz (in the US) signal is applied to the cathode. And again, perhaps due to some of the reasons listed above, perhaps the pulsating DC output carries along with it an additional low-level complex wave form resulting from the interaction of the structure of the tube and the 60 Hz signal? And given that this DC current flows through every other tube, perhaps the additional low-level complex wave form affects the sound of all the other tubes? But for sure, this is a feeble attempt on my part, based largely on intuition, to try to understand what I am hearing.

An example. I have three rectifiers with the same measured voltage drop. An FW4-500 manufactured in Mullard's Blackburn factory, an FW4-500 manufactured in British Tungsram's Tottingham factory and an AZ50 (the European Philips equivalent to the FW4-500) manufactured in the Eindhoven factory. According to the spec sheets, these rectifiers can provide a maximum DC output current of 250ma at 500 volts. And measured in my amp, they all have the same voltage drop, 35 volts.

And they all sound different. And quite interestingly, their sound is very similar to that of double triodes manufactured in the same factories. Which makes some sense as the approach to designing and constructing a vacuum tube assembly line was likely uniformly applied within each factory, but somewhat different from that used in other factories. And it also leads me to believe that some of reasons you listed above are at play in both double triodes and rectifiers.

But again, this is based on my attempts to intuitively understand what I am hearing and I welcome and appreciate the comments and explanations of those who have a much better understanding of the science and technology involved.

Cheers

 

Glenn has been working on my OTL.



The smaller tube at the front is an E80CC that will be used as a cathode follower for the pre-amp outputs. The tall blue cylinders are 440 uF ClarityCap TC600 metalised film capacitors. Two of them are the final filters in the quasi dual mono power supply, while the other two are output capacitors.

Really looking forward to hearing this. I'll let you know when I have an ETA.

 

Very nice, those are some gigantic caps. I'm enjoying my Glenn 300B very much, I'm sure you will with yours.

 

Great looking amp MoatsArt. Looking forward to your impressions

 

A few people have been asking me if I'll be receiving my Glenn OTL later this week. Short answer: No.

Based on the pictures Glenn sent me this weekend, the E80CC socket hole has been drilled/punched, but the socket itself isn't yet installed. There is no indication of screws in place where I would expect terminal strips to be positioned. It looks like the large, externally mounted parts are in place, but that no electrical work is underway yet.

Glenn doesn't give out expected completion dates as there are number of things that often get in the way of his amp building. I don't know when I'll have it, but it will be a matter of weeks or months, not days. I'd be very surprised if I see it before Christmas. Good things come to those who wait.

 

On Friday @2359Glenn told me that he hoped to get a lot of work done on my amp this weekend. Looking forward to hearing back from him so that I can share it here.

 

Deleted posts now restored. Thanks @The Alchemist

Fingers crossed, Glenn might have it finished this weekend.

 

Congrats,
Your patience has prevailed

 

Running out of patience and realising I can't justify owning such an extravagant piece of equipment. Contemplating (yet again) selling the OTL before I even hear it. The whole affair is making me nauseous, and I'm not using a figure of speech.

This isn't a reflection on Glenn, who has good reason for delays.

f**k it. I'm done. Make me an offer. Guide price of $3K USD, which includes shipping up to $500. Will be posting in the for sale thread shortly.

 

@jelt2359 has kindly sold me his pre-Lundahl GOTL. I'm desperately trying to select and find some tubes for it as it will arrive before Christmas.

I'm keeping the Tung Sol 6SN7 BGRP tube and am looking for a pair of 6AS7G/6080 tubes. I need your advice on a five volt rectifier. I'd like something cheap with a low voltage drop. What do you recommend? Particularly interested to hear from @gibosi .

Edit: Glenn has just given me a recommendation. Thanks.

 

Glenn sent me this today. Didn’t expect it to be ready this soon but very excited. Best part is tubes are all very reasonably priced. The el3ns can be had for 25.00ea. & the 3dg4 rectifiers can be had for just 4.00

 

How much was it @Ray? looks beautiful and high quality!

 

Few hundred more than ZDS but I had a few upgrades done.

 

I wait with baited breath for your impressions compared to your Zana Deux...

 

Currently running my Glenn 300B amp in the following setup:

PC -> Sungxer SU-1 -> AES -> Pavane (w/DAC TWO modules) -> Glenn 300B (modded) -> HEKv2 (modded).

I cannot fault the SQ in anyway. None. It is fantastic.

For those thinking about a custom tube amp build I can only recommend Glenn. Talk to him and agree on the setup that best suits your needs. If I had to do it over again now I would stick with SS rectification and C3g drivers, but perhaps step down from 300Bs to 45s as the output tube. That's still plenty to drive most headphones, but without the crazed costs of the best 300B glass.

I had my Glenn amp modded locally with soft start and SS rectification - for technical reasons as well as SQ. Currently running TA300B glass - which is about as good as 300Bs get (vintage WE300B included).