Search found 229 matches

by Wolfgang
Sat Jun 20, 2020 4:13 pm
Forum: Everyones Projects
Topic: The Other 13E1 SE-OTL
Replies: 227
Views: 90577

Re: The Other 13E1 SE-OTL

Great results Ray. It always feels good if listening results are comparable. I had the same impression with the 6C33 OTL and it says something about multi tube and single output tube OTLs IMO. J. Broskie has mentioned somewhere that 6 and more output tubes connected in parallel would actually sound ...
by Wolfgang
Tue Jun 09, 2020 4:16 pm
Forum: Speakers
Topic: Speaker Protection
Replies: 17
Views: 10609

Re: Speaker Protection

If B+ was connected to the speaker, the current would depend entirely on the output impedance of the power supply. This happened not with a HV psu but with the SLB (active bridge rectifier, cap multiplier)at 38V which can deliver 5A max /2x15kuF for the dual rail version. The SLB has a very low out...
by Wolfgang
Tue Jun 09, 2020 1:42 am
Forum: Speakers
Topic: Speaker Protection
Replies: 17
Views: 10609

Re: Speaker Protection

Ok, then let's rephrase: how much current would flow through a 8ohm speaker if there is a short circuit in a tube or some other unforeseen problem connecting B+ with the output? I lost a $1200 Lowther DX4 (but they have very good replacement deals) because of a simple short in a tube socket (tiny ha...
by Wolfgang
Mon Jun 08, 2020 9:03 pm
Forum: Speakers
Topic: Speaker Protection
Replies: 17
Views: 10609

Re: Speaker Protection

Question: will an OTL pass enough DC current to worry a speaker? I'm wondering if there's any need for protection here. B+ in case of a faulty tube or a simple discharge if the tube is gassy. This only applies to PP or OTLs without an otuput cap like the InvOTL. The Pinnacles use a TVS diode agains...
by Wolfgang
Mon Jun 08, 2020 6:05 pm
Forum: Speakers
Topic: Speaker Protection
Replies: 17
Views: 10609

Re: Speaker Protection

Yes, I've looked at them before but they're not up to the potential DC voltages in a valve amp, not even the modest 150V in the Mellow OTL. There is a simple way of how to use them for any psu voltage and without the built-in SSRs. I like them because they put the detection circuit between two opto...
by Wolfgang
Tue May 26, 2020 11:34 pm
Forum: Everyones Projects
Topic: Any Interest - Soft Start PCBs
Replies: 4
Views: 2862

Re: Any Interest - Soft Start PCBs

He has made that very complex just to avoid using a £2 AVR (IMHO). Not sure why bother using a thermistor instead of some resistors as they will be out of circuit after half a second. But at least that’s the way I do it. It's really too complex! Not necessary IMO. Using a thermistor instead of resi...
by Wolfgang
Mon May 18, 2020 5:29 pm
Forum: Everyones Projects
Topic: The Other 13E1 SE-OTL
Replies: 227
Views: 90577

Re: The Other 13E1 SE-OTL

Patience is a virtue Wolfgang...
Very mysterious answer... :wink:

...and I am working on something in order to overcome the dynamic limitations of 1-2W SE OTLs with the help of Maid reg.
by Wolfgang
Mon May 18, 2020 4:59 pm
Forum: Everyones Projects
Topic: The Other 13E1 SE-OTL
Replies: 227
Views: 90577

Re: The Other 13E1 SE-OTL

Very nice, Ray. Your patience pays off.

But it looks like you won't use Maida reg. for the 13E1 tubes. Why?
by Wolfgang
Wed May 13, 2020 12:53 am
Forum: Everyones Projects
Topic: Inverted OTL with 6SN7/6AS7
Replies: 125
Views: 60455

Re: Inverted OTL with 6SN7/6AS7

Metalwork is one of my pet hates, what did you get and how are you finding it? I got the E4. Now it has been replaced by the “Evolution 4”. Basically the same but with the one piece spoilboard and a stronger router mount, important for precision which was actually the only weak point IMO with the E...
by Wolfgang
Tue May 12, 2020 4:13 pm
Forum: Everyones Projects
Topic: Inverted OTL with 6SN7/6AS7
Replies: 125
Views: 60455

Re: Inverted OTL with 6SN7/6AS7

I finished my InvOTL some time ago and thought the result is worth a picture. InvOTL.jpg DC offset can be easily readjusted with the two pots in the back. The mV meters can be turned ON/OFF for checking and getting it down to 0mV. I mounted all the tubes on a separate aluminum board (would have been...
by Wolfgang
Sat Mar 28, 2020 1:31 pm
Forum: Speakers
Topic: Sound damping material
Replies: 32
Views: 20489

Re: Sound damping material

If that's the frequency response of the driver in a baffle then it will work even at lower frequecnies. Must be a hell of driver!
by Wolfgang
Thu Mar 26, 2020 6:08 pm
Forum: Speakers
Topic: Sound damping material
Replies: 32
Views: 20489

Re: Sound damping material

I wonder how they would perform with a full range unit, like the Lii Audio ones, run open on a small baffle? They subs are limited to 120Hz max with the internal x-over because of servo control precision. The higher the frequency the harder for the servo to react precisely enough. Using the LFE inp...
by Wolfgang
Wed Mar 18, 2020 1:55 am
Forum: Speakers
Topic: Sound damping material
Replies: 32
Views: 20489

Re: Sound damping material

Obviously a misunderstanding.
The drivers are the SW-12-08
http://www.rythmikaudio.com/GR_drivers.html
can be ordered here: http://gr-research.com/drivers.aspx

Couldn't find the link for the H-frame plans so I attached the pdf.
H-frame 2.pdf
(81.11 KiB) Downloaded 324 times
by Wolfgang
Tue Mar 17, 2020 3:50 pm
Forum: Speakers
Topic: Sound damping material
Replies: 32
Views: 20489

Re: Sound damping material

And the OB subs? The subs come with a 370W RMS into 4 ohm amp (linear psu) per channel with the servo control board built in. A370XLR3 (2).jpg All controls are analog which is not my favorite way of doing this kind of stuff so I bypass them (LFE input ) and use my digital x-over for controlling Kli...
by Wolfgang
Mon Mar 16, 2020 11:16 pm
Forum: Speakers
Topic: Sound damping material
Replies: 32
Views: 20489

Re: Sound damping material

Simon, I listen with active (TS 300B PP/Burmester clone) modified Klipsch La Scala horns. The photo shows what I did. KH_sub.jpg The original sound has changed a lot, more open and relaxed than the typical KH sound. The midrange horn/300B PP needed some EQ for sounding lush and full rather than anem...