Heyboer Transformers
Heyboer Transformers - Company Overview
Drop them an email, with specs, for a quote & leadtime estimate.
ObEdit:
I see I was beaten to the punch by mctavish
Heyboer Transformers - Company Overview
Drop them an email, with specs, for a quote & leadtime estimate.
ObEdit:
I see I was beaten to the punch by mctavish
Perhaps your expectations were unmet. Heyboer’s website is definitely not set up to operate an online catalog and online ordering, but it is a good company. Call them!
Another great post from you (George?), which is why I rate you as one of the (few) people (in the world) I can count on one hand who actually know what they are on about!
True that
Why 5K? Plate load is quoted as 3K when I looked.
An option is Toroidy, via TME in The States?
KT88 SE
Less than half the price. I am a satisfied customer for power, SE and PP products, and tey have also provided custom parts at just a small price increase.
I haven’t yet checked out Heyboer myself but I know they’ve torn down some highly regarded Peerless output transformers for the purpose of making replacements for restoring/recreating Heathkit mono blocks and the consensus on the results is highly positive.
The 1628SE can still be used as a Plate Choke (LOL!). I did this with the 811A as well, using the Legendary Radio Shack Nickel Cored 70V Matching Transformer as a Parafeed OPT. Sounded real real nice, but only good for 2.5W.
I still have them lurking around in the junk bucket. I've thought about sending them off to the metal recycler. But the voices in my head tell me to hold onto them and use them to build the modulator stage of a simple tube based Transmitter for 80m. LOL!
I still have them lurking around in the junk bucket. I've thought about sending them off to the metal recycler. But the voices in my head tell me to hold onto them and use them to build the modulator stage of a simple tube based Transmitter for 80m. LOL!
They did OK for a SE bass guitar amp with a pair of KT88's wired in parallel and the 4 ohm speakers connected on the 8 ohm tap. The guy I sold them to made a stereo bass rig with two complete SE amps each making about 15 watts. His 5 string bass went into a DSP pedal board that had stereo outputs. His cabinets had two different sized speakers wired in parallel. It was far louder that I expected for the power level and could do clean Jazz bass very well, and get quite nasty with some pedal FX. Max high frequency content on an uber distorted and compressed bass guitar is about 5KHz. Even a 1628SE can handle that.
Since Transcendars are no longer generally available it's now about the possible alternatives.
I have a pair of the Toroidy TTG-KT88PSE 1500 ohm OPT's. After some considerable tinkering with the circuit I have them sounding quite nice on two different sets of test speakers. At 20 watts of power I actually prefer them to the 3000 ohm Transcendars, but that is not a true comparison due to the different impedances. Neither speakers have much response below 70Hz, so I can't vouch for what will happen at say 30 Hz.
I got them from TME and shipping to the US took about two weeks in January of 2020.
More details about budget SE OPT's can be found here:
SE Output xfmrs....who are the current suppliers for not many $$$
I have not measured the response yet, but as I tried to explain in a previous post the actual frequency response will vary greatly depending on the circuit it is used in. My Toroidy's are currently wired into an UNSET board that uses TV sweep (line output) tubes with local feedback. I will get measurements on this board when I get time.
What output tubes do you plan to use, and under what conditions?
What output tubes do you plan to use, and under what conditions?
Since my amp was already on the bench and connected up, I ran a quick frequency test to find the -1 dB and -3 dB points at 1,5,10, and 15 watts. They are all the same.
The low frequency points are determined by the coupling caps, not the transformer The current values put one pole at 7 Hz and another at 16 Hz. These were arbitrarily chosen to limit warm up and bias adjustment issues in an output stage that can easily pass a few AMPS of current since the output tube is rated for 1.4 Amp peaks.
There are two high frequency poles in the amp design due mosfet gate capacitance. The dominant pole is at 45 KHz possibly limiting the high frequency response. I'm still using big mosfets until I get some more testing done to avoid blown parts. The response is fine for my 68 year old ears and small speakers, so I'm not in a hurry to change it.
-1db is at 27 Hz and 18.5 KHz
-3db is at 14.6 Hz and 38.9 KHz.
Some transformer distortion is seen on the scope at 14.6 Hz and 15 watts. It's clean (2.2%THD) at 10 watts.
Your response in a different application will vary.
The low frequency points are determined by the coupling caps, not the transformer The current values put one pole at 7 Hz and another at 16 Hz. These were arbitrarily chosen to limit warm up and bias adjustment issues in an output stage that can easily pass a few AMPS of current since the output tube is rated for 1.4 Amp peaks.
There are two high frequency poles in the amp design due mosfet gate capacitance. The dominant pole is at 45 KHz possibly limiting the high frequency response. I'm still using big mosfets until I get some more testing done to avoid blown parts. The response is fine for my 68 year old ears and small speakers, so I'm not in a hurry to change it.
-1db is at 27 Hz and 18.5 KHz
-3db is at 14.6 Hz and 38.9 KHz.
Some transformer distortion is seen on the scope at 14.6 Hz and 15 watts. It's clean (2.2%THD) at 10 watts.
Your response in a different application will vary.
Since I didn't make it clear and someone asked, the Toroidy OPT's that I mentioned above are SE OPT's.
They do work great when used in something similar to the application listed on their web site. The TTG-KT88PSE's that I have are specified for use with a parallel pair of KT88's or 300B's per channel. You will get 20 watts or less on about 150 mA from two of either of these tubes. I am getting just over 20 watts from a single TV sweep tube on about 125 mA.
The Toroidy's work great under these conditions. I have connected them to my test speakers and they sound good too. I have NOT tried them with 300B's or KT88's.
Right on the transformers it says " Ia = 500 mA" and Nominal Power = 60 W" They will not pass any bass at anywhere near these levels. Severe saturation was seen below 100 Hz with two tubes in parallel running 250 mA and power levels up to 45 watts. MAX undistorted power at 20 Hz with 250 mA flowing was under 2 watts.
